4>-'^ o s 3& ^ of WORKS OF JOHN S. REID PUBLISHED BY JOHN WILEY & SONS. A Course in Mechanical Drawing. 8vo. viil + 186 pages, 168 figures. Cloth, $2.00. Mechanical Drawing and Elementary Machine Design. By John 8. Reid, Professor of Mechanical Draw- ing, Armour Institute of Technology, and David Reid, formerly Instructor in Mechanical Drawing, Sibley College, Cornell University. 8vo.xii-f 439 pages, 301 figures. Cloth, $3.00 A TEXT-BOOK OF MECHANICAL JQefcAWING ELEME MACHINE DESIGN. BY JOHN S. Professor of Mechanical Drawing and Designing, Armour Institute; Member of the American Society of Mechanical Engineers; AND DAVID REID, Formerly Instructor in Mechanical Drawing and Designing, Sibley College, Cornell University, Ithaca, N. Y. SECOND EDITION, REVISED AND ENLARGED. TOTAL ISSUE, SEVEN THOUSAND..., NEW YORK: JOHN WILEY & SONS. LONDON: CHAPMAN & HALL, LIMITED. 1908. Engineering Library K ' ' Copyright, 1900, 1908 BY jfOhN S. AND DAVID REID. Rnbrrt Driunnuutft anil (Sompattg PREFACE TO THE SECOND EDITION. THE increasing use of this book for students of all kinds of engineering, in teaching machine drawing and elementary machine design, and the changes which have naturally occurred since the first edition was published, have made a revision and the following additions both necessary and desirable. Course II has been prepared for students in machine drawing and elementary machine design who have completed the full course given in "A Course in Mechanical Drawing," by John S. Reid, published by John Wiley & Sons, New York, or its equivalent. The number of problems, their scale and size, have been selected to properly fill a certain size of sheet, together with notes, bill of material, and title. New cuts have been introduced illustrating bills of mateiial and titles, with dimensions for con- struction. A decidedly new feature has been introduced here in giving the minimum time allowed for finishing each plate according to directions in the text, and should be much appreciated by Instructors when determining the amount of work to require from their students in any given term. The time allowed to finish the different plates has been carefully determined, and any 262658 IV PREFACE. student of fair intelligence who will honestly try can finish any of the plates in the time given. The Course in Lettering has been added for the benefit of students who have not had its equivalent in their preparatory .course in mechanical drawing. Course III is a short course which has been added here as a supplement to Course II, and consists of practical machine sketching, the making of working drawings from sketches, isometrical drawing of a lay-out of piping, and machine design. The report on the "Present Practice in Drafting Room Methods," which will be found at the end cf the book, is also new, and will interest Instructors and enable them to adopt a system in their drawing courses that may closely approximate the best practice in the leading and most progressive drafting rooms in the United States. The thanks of the authors are due and are most cordially extended to those who have used this book in the past and have encouraged and assisted them by gracious words and timely suggestions. JOHN S. REID. D. REID. ARMOUR INSTITUTE OF TECHNOLOGY, Chicago, 111., September, 1908. PREFACE. To properly prepare students for advanced machine design it has been found necessary to introduce a course designed to apply the principles of mechanical drawing to the solution of practical problems in machine construction and to familiarize the student with the arrangement and proportions of the most important machines and their details recognized by competent engineers to be the best practice of the present time. It is essential to intelligent study and an economical expenditure of time and labor that, before attempting to design a new machine or improve an old one, the student should post himself with all possible information concerning what has already been done in the same direction. To this end the present work has been prepared. In it we have attempted to show what is the best United States practice in the design and construction of various machines and details of machines, using rules and formulae whenever feasible in working out practical problems. In addition to this will be found the latest and most approved drafting-room methods in use in this country, with- out which most drawings would be practically useless. Up to the present time no text-book that we know of has been VI - PREFACE published in the United States that could in the best way fill the need as explained above. Books of a somewhat similar nature have been published in Great Britain, showing that the same need has been felt there as here. These books, modified to suit American prac- tice, have been used to some extent in this country because they were the best to be had, but are not by any means all that can be desired for our purpose in their present form. While preparing this course for the sophomore students in Sibley College the authors endeavored to secure samples of the actual machines or parts of machines as collateral in illus- trating the exercises given in the book, with a result that in our drafting-rooms we have many examples of modern machine construction placed convenient to the students' hands, so that they may examine and handle the actual thing itself while solving the problems in drawing and designing. This we believe of great importance in the study of machine design and construction, because few are able to describe a machine even with the assistance of a drawing so well as to enable the student to conceive it in his mind as it actually is. The preparation necessary for the proper understanding and execution of the problems contained in this book is as follows: use of instruments, instrumental drawings applied to drawing geometrical problems in pencil and ink, thorough knowledge of the conventional lines, hatch-lining and colors for sections, mechanical and free-hand lettering, orthographic projection in the third angle, isometrical drawing in brief all that is contained in " A Course in Mechanical Drawing," by John S. Reid, published by John Wiley & Sons, New York. In the preparation of the drawings for this work we are PREFA CE. v ii indebted to many of the leading engineering firms of this and other States, who have kindly supplied us with drawings and samples of the latest and best practice of the day. Our thanks are especially due to the Dodge Manufacturing Com- pany, the Detroit Screw Works, the Buckeye Engine Co., the United States Metallic Packing Co., the National Tube Works, the Ridgeway Dynamo & Engine Co., the Murray Gun Works, Henry R. Worthington, Robt. Pool & Sons, the Baldwin Locomotive Works, the Schenectady Locomotive Works, the American Pulley Co., the Hyatt Roller Bearing Co., the Macintosh and Seymour Engine Co., and many others. Our acknowledgments are also due to many of the best authorities on the different subjects treated, among which may be mentioned Thurston's " Materials of Construction," A. W. Smith's "Machine Design," Klein's "Machine Design," Unwin's " Machine Design," Barr's " Boilers and Furnaces," Peabody and Miller's "Steam Boilers," Low and Bevis's " Drawing and Designing," John H. Barr's " Kinematics," Thurston's " Steam Boilers," Reuleaux's " Constructor," the " Proceedings of the American Railway Master Mechanics' Association," etc., etc. J. S. R, D. R. CONTENTS. INTRODUCTORY INSTRUCTIONS. J. S. R. PAGE MECHANICAL DRAWING i COMPLETE OUTFIT 2 USE OF INSTRUMENTS y SHADE-LINES AND SHADING 15 WORKING DRAWINGS 17 LETTERING ig FIGURING 19 STANDARD CONVENTIONS 20 CROSS-SECTIONS 26 CONSTRUCTIONS 26 ELEMENTARY MACHINE DESIGN 29 MATERIALS OF CONSTRUCTION 30 STRENGTH OF MATERIALS 36 USEFUL TABLES, ETC. 41 CHAPTER I. D. R. SCREWS, NUTS, AND BOLTS 48 CHAPTER II. D. R. KEYS, COTTERS, AND GIBS 109 CHAPTER III. J. S. R. RIVETS AND RIVETED JOINTS 125 CHAPTER IV. J. S. R. SHAFTING AND SHAFT-COUPLINGS 157 ix X CONTENTS. CHAPTER V. J. S. R. PIPES AND PIPE-COUPLINGS 189 CHAPTER VI. D. R. BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES . 206 CHAPTER VII. J. S. R. BELT GEARING 238 CHAPTER VIII. J. S. R. TOOTHED GEARING 262 CHAPTER IX. J. S. R. VALVES, COCKS, AND OIL-CUPS 278 CHAPTER X. J. S. R. & D. R. ENGINE DETAILS 305 ELEMENTARY MACHINE DRAWING (Course II) 38i (Course III) 39} PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS AND METHODS IN MAKING PRACTICAL WORKING DRAWINGS 419 SUGGESTED COURSES. FALL TERM. 1. Ex. i, 3, 4, 5.6, 7, 10, 12, 13, 15, 19, 22, 24, 26, 29, 30, 32, 34, 38, 40, -46, Si- 2. Ex. 2, 3, 4, 5, 6, 8, 10, n, 14, 16, 18, 20, 24, 27, 29, 31, 33, 35, 39, 41, 47, 51- 3. Ex. i, 3, 4, 5, 6, 8, 9, 12, 13, 17, 19, 22, 23, 25, 29, 30, 32, 34, 38, 42, 48, 5i. 4. Ex. 2, 3, 4, 5, 6, 7, 9, n, 14, 15, 18, 21, 24, 28, 29, 31, 33, 36, 38, 43, 49, 5i. 5. Ex. i, 3, 4, 5, 6, 8, 10, 12, 13, 16, 19, 22, 23, 26, 29, 30, 32, 34, 38, 44, 50, 52. 6. Ex. 2, 3, 4, 5, 6, 7, 9, ", *4, 17, 18, 21, 24, 27, 29, 31, 33, 37, 39, 45, 50, 52. FALL TERM CONTINUED. 1. Ex. 52, 54, 59, 64, 68, 73, 77, 86, 89, 90, 93. 2. Ex. 52, 55, 60, 65, 70, 74, 84, 87, 90, 92, 94. 3. Ex. 52, 54, 61, 66, 71, 75, 85, 88, 90, 91, 93. 4. Ex. 52, 56, 62, 67, 70, 76, 84, 86, 90, 92, 94. 5. Ex. 53, 57, 63, 68, 71, 77, 85, 87, 90, 91, 93. 6. Ex. 53, 58, 64, 69, 72, 76, 84, 88, 90, 92, 94. WINTER TERM. 1. Ex. 95, 97, 99, lor, 103, 106, 108, in, 113, 117, 119, 121, 124, 130, 136, 139, !42, 145, 147, 149- 2. Ex. 96, 98, 100, 102, 104, 105, 107, 112, 114, Il8, 120, 122, 12$, 131, .137, 140, 143, 146, 148, 149. 3. Ex. 95, 97, 99, 101, 104, 107, no, 112, 115, 117, 121, 123, 126, 132, 138, 139, 142, 145, 147, 140. 4. Ex. 96, 98, 100, 102, 103, 106, 108, in, 113, 116, 119, 122, 127, 133, 136, 138, 144, i%6, 148, 149. 5. Ex. 95, 97, 99, 101, 104, 105, 108, in, 113, 116, 120, 121, 128, 134, 137, 140, 142, 145, 147, 149. 6. Ex. 96, 98, 100, 102, 106, 107, no, 112, 115, 117, 119, 122, 129, 135, 136, 138, 143, 146, 148, 149. DRAWING AND DESIGNING. INTRODUCTORY INSTRUCTIONS. MECHANICAL drawing as applied to machine drawing and design consists of the application of descriptive geometry or orthographic projection to the delineation of machines and parts of machines (modified sometimes by certain conven- tions) generally recognized by experienced draftsmen. It is comparatively a simple matter for any person of average intelligence to acquire the ability of making a fairly accurate mechanical drawing of a machine, given the dimen- sions, but it is altogether a different and more difficult prob- lem to determine those dimensions that will give the best form and proportion to the different parts of the machine as will enable them to properly perform the functions for which they are intended in accordance with the strength of the material of which they may be made. A mere copy of a drawing unaccompanied by some means for compelling the student to study (i) the form and propor- tions given and reasons for same or (2) the illustrations of some principle connected with projection is not of much moment in the study of machine drawing and design. But a problem in drawing and design illustrated by a drawing of the object, representing the best modern practice and requir- ing the calculation of the proportions o{ the different parts 2 DRAWING AND DESIGNING. from rules and formulae, will induce the student to think, and tend to develop any natural ability he may have in this direc- tion. It has been the aim of the authors in the arrangement of problems to accomplish this purpose in the highest degree possible. The following notes on the complete outfit of instruments and materials should be consulted before buying, because it is very essential to the best results that a good outfit be secured. The outfit for students in mechanical and machine drawing is as follows: (i) THE DRAWING-BOARD for academy and freshman work is i6"X2i"Xj", the same as that used for free-hand drawing. The material should be soft pine 2nd constructed as shown by Fig. i. FIG. i. (2) i SCRIBBLING PENCIL with rubber tip. (3) PENCILS, one 6H and one 4!! Koh-i-noor or Faber. (4) The T-SQUARE; a plain pearwood T-square with a fixed head is all that is necessary. Length 21". (5) INSTRUMENTS. "Pocket Book" Set, shown by Fig. 2, recommended as a first-class medium-priced set of instruments. It contains A COMPASS, 5^" long, with fixed needle-point, pencil, pen INTRODUCTORY INSTRUCTIONS. 3 and lengthening bar; a SPRING Bow PENCIL, 3" long; a SPRING Bow PEN, 3" long; a SPRING Bow SPACER, 3" long; FIG. 2. 2 DRAWING-PENS, medium and small, i HAIR-SPRING DIVIDER, 5" long; a nickel-plated box with leads. FIG. 3. (6) A TRIANGULAR BOXWOOD SCALE graduated as follows: 4" and 2", 3" and ij", i" and.*", f" and f", T y and ^". (7) i TRIANGLE 3oX6o, celluluid, 10" long. Fig. 4. i " 45 , " 7" " (8) i IRREGULAR CURVE. No. 13. Fig. 5. (9) EMERY PENCIL POINTER. (10) INK, black waterproof. Fig. 7. (i i) INK ERASER, Faber's Typewriter. No. 104. DRAWING AND DESIGNING. (12) PENCIL ERASER, "Emerald" No. 211. Fig. 9. (13) SPONGE RUBBER or CUBE OF "ARTGUM." Figs. 10, u. FIG. 4. FIG. 5. FIG. 6. (14) TACKS, a small carton of i oz. copper tacks, and i doz. small thumb tacks. (15) ARKANSAS OIL STONE. 2 // XJ // XiV / . (16) PROTRACTOR, German silver, about 5" diam. Fig. 12. (17) SCALE GUARD, " " Fig. 13. INTRODUCTORY INSTRUCTIONS, FIG. 7 FIG. 8. FIG. 9. FIG. 10. FIG. ii. DRAWING AND DESIGNING. (18) 2 sheets of "CREAM" DRAWING PAPER. i5"X2o' (19)2 l< " IMPERIAL TRACING CLOTH. i5"X2o" ; (20) i CROSS-SECTION PAD. 8"Xio". (21) i SCRIBBLING PAD. FIG. 12. FIG. 13. (22) i ERASING SHIELD, nickel plated. (23) 2 LETTERING PENS, "Gillott" No. 303. (24) 2 " " "Ball Point/' No. 506. (25) 2 " " " " No. 516. (26) i TWO-FOOT RULE. IN TROD UCTOR Y INS TR UCTIONS. INSTRUMENTS. IT is a common belief among students that any kind of cheap instrument will do with which to learn mechanical drawing, and not until they have acquired the proper use of the instruments should they spend money in buying a first- class set. This is one of the greatest mistakes that can be made. Many a student has been discouraged and disgusted because, try as he would, he could not make a good drawing, using a set of instruments with which it would be difficult for even an experienced draftsman to make a creditable showing. If it is necessary to economize in this direction it is better and easier to get along with a fewer number, and have them of the best, than it is to have an elaborate outfit of question- able quality. The instruments shown in Fig. 2 are well made of a moderate price, and with care and attention will give good satisfaction for a long time. USE OF INSTRUMENTS. The Pencil. Designs of all kinds are usually worked out in pencil first, and if to be finished and kept they are inked in and sometimes colored and shaded; but if the drawing is only to be finished in pencil, then all the lines except construction, center, and dimension lines should be made broad and dark, 8 DRA WING AND DESIGNING. so that the drawing will stand out clear and distinct. It will be noticed that this calls for two kinds of pencil-lines, the first a thin, even line made with a hard, fine-grained lead- pencil, not less than 6H (either Koh-i-noor or Faber's), and sharpened to a knife-edge in the following manner: The lead should be carefully bared of the wood with a knife for about ^", and the wood neatly tapered back from that point ; then lay the lead upon the emery-paper sharpener illustrated in the outfit, and carefully rub to and fro until the pencil assumes a long taper from the wood to the point ; now turn it over and do the same with the other side, using toward the last a slightly oscillating motion on both sides until the point has assumed a sharp, thin, knife-edge endwise and an elliptical contour the other way. This point should then be polished on a piece of scrap drawing-paper until the rough burr left by the emery-paper is removed, leaving a smooth, keen, ideal pencil-point for draw- ing straight lines. With such a point but little pressure is required in the hands of the draftsman to draw the most desirable line, one that can be easily erased when necessary and inked in to much better advantage than if the line had been made with a blunt point, because, when the pencil-point is blunt the incli- nation is to press hard upon it when drawing a line. This forms a groove in the paper which makes it very difficult to draw an even inked line. The second kind of a pencil-line is the broad line, as explained above ; it should be drawn with a somewhat softer pencil, say 4H, and a thicker point. All lines not necessary to explain the drawing should be INTRODUCTORY INSTRUCTIONS. make a minimum of erasing and cleaning after the drawing is; finished. When drawing pencil-lines, the pencil should be held in a. plane passing through the edge of the T-square perpen- dicular to the plane of the paper and making an angle with: the plane of the paper equal to about 60. Lines should always be drawn from left to right. A soft conical-pointed pencil should be used for lettering, figuring, and all free-hand work. The Drawing-pen. The best form, in the writer's opinion, is that shown in Fig. 14. The spring on the upper blade FIG. 15. spreads the blades sufficiently apart to allow for thorough cleaning and sharpening. The hinged blade is therefore unnecessary. The pen should be held in a plane passing- through the edge of the T-square at right angles to the plane of the paper, and making an angle with the plane of the paper ranging from 60 to 90. The best of drawing-pens will in time wear dull on the point, and until the student has learned from a competent 13 DRA WING AND DESIGNING. teacher how to sharpen his pens it would be better to have Ihem sharpened by the manufacturer. It is difficult to explain the method of sharpening a draw- ing-pen. If one blade has worn shorter than the other, the blades rshould be brought together by means of the thumb-screw, and :placing the pen in an upright position draw the point to and -fro on the oil-stone in a plane perpendicular to it, raising and .lowering the handle of the pen at the same time, to give the proper curve to the point. The Arkansas oil-stones (No. 21 of " The Complete Outfit ") are best for this purpose. The blades should next be opened slightly, and holding "the pen in the right hand in a nearly horizontal position, place the lower blade on the stone and move it quickly to and fro, .slightly turning the pen with the fingers and elevating the .handle a little at the end of each stroke. Having ground the Jower blade a little, turn the pen completely over and grind tthe upper blade in a similar manner for about the same length .of time ; then clean the blades and examine the extreme points, and if there are still bright spots to be seen continue -the grinding until they entirely disappear, and finish the .sharpening by polishing on a piece of smooth leather. The blades should not be too sharp, or they will cut the paper. The grinding should be continued only as long as the bright spots show on the points of the blades. When inking, the pen should be held in about the same position as described for holding the pencil. Many drafts- men hold the pen vertically. The position may be varied with good results as the pen wears. Lines made with the pen should only be drawn from left to right. INTRODUCTORY INSTRUCTIONS. II THE TRIANGLES. The triangles shown at Fig. 4 (in " The Complete Outfit ") are 10" and 7" long respectively, and are made of transparent celluloid. The black rubber triangles sometimes used are but very little cheaper (about 10 cents) and soon become dirty when in use ; the rubber is brittle and more easily broken than the celluloid. Angles of 15, 75, 30, 45, 60, and 90 can readily be drawn with the triangles and T-square. Lines parallel to oblique lines on the drawing can be drawn with the triangles by placing the edge representing the height of one of them, so as to coincide with the given line, then place the edge rep- resenting the hypotenuse of the other against the corre- sponding edge of the first, and by sliding the upper on the lower when holding the lower firmly with the left hand any number of lines may be drawn parallel to the given line. The methods of drawing perpendicular lines and making angles with other lines within the scope of the triangles and T- square are so evident that further explanation is unnecessary. THE T-SQUARE. The use of the T-square is very simple, and is accom- plished by holding the head firmly with the left hand against the left-hand end of the drawing-board, leaving the right hand free to use the pen or pencil in drawing the required lines. THE DRAWING-BOARD. If the left-hand edge of the drawing-board is straight and the T-square, then Horizontal lines parallel to the upper edge of the paper and perpendicular to the left-hand edge may be drawn with the T-square, and lines perpendicular to these can be made by means of the triangles, or set squares^ as they are sometimes called. 12 DRAWING AND DESIGNING. THE TRIANGULAR SCALE. This scale, illustrated in Fig. 3 (in "The Complete Out- fit "), was arranged to suit the needs of the students in machine drawing. It is triangular and made of boxwood. The six edges are graduated as follows; -fa" or full size, -fa", |" and f" = I ft., i" and i" = I ft., 3" and ij" = I ft., and 4" and 2" = i ft. Drawings of very small objects are generally shown en- larged e.g., if it is determined to make a drawing twice the full size of an object, then where the object measures one inch the drawing would be made 2" ', etc. Larger objects or small machine parts are often drawn full size i.e., the same size as the object really is and the draw- ing is said to be made to the scale of full size. Large machines and large details are usually made to a reduced scale e.g., if a drawing is to be made to the scale of 2" = i ft., then 2" measured by the standard rule would be divided into 12 equal parts and each part would represent i". THE SCALE GUARD. This instrument is shown in No. 17 (in "The Complete Outfit "). It is employed to prevent the scale from turning, so that the draftsman can use it without having to look for tee particular edge he needs every time he wants to lay off a measurement. THE COMPASSES. When about to draw a circle or an arc of a circle, take hold of the compass at the joint with the thumb and two first fingers, guide the needle-point into the center and set the pencil or pen leg to the required radius, then move the thumb and forefinger up to the small handle provided at the top of INTRODUCTORY INSTRUMENTS. 13. the instrument, and beginning at the lowest point draw the line clockwise. The weight of the compass will be the only down pressure required. The sharpening of the lead for the compasses is a very im- portant matter, and cannot be emphasized too much. Before commencing a drawing it pays well to take time to properly sharpen the pencil and the lead for compasses and to keep them always in good condition. FIG. 16. The directions for sharpening the compass leads are the s?tne as has already been given for the sharpening of the straight-line pencil. THE DIVIDERS OR SPACERS. This instrument should be held in the same manner as de- scribed for the compass. It is very useful in laying off equal distances on straight lines or circles. To divide a given line into any number of equal parts with the dividers, say 12, it is best to divide the line into three or four parts first, say 4, and then when one of these parts has been subdivided accu- rately into three equal parts, it will be a simple matter to step off these latter divisions on the remaining three-fourths of the given line. Care should be taken not to make holes in the paper with the spacers, as it is difficult to ink over them without blotting. THE SPRING BOWS. These instruments are valuable for drawing the small cir- cles and arcs of circles. It is very important that all the small arcs, such as fillets, round corners, etc. , should be care- fully pencilled in before beginning to ink a drawing. Many 14 DRAWING AND DESIGNING. good drawings are spoiled because of the bad joints between small arcs and straight lines. When commencing to ink a drawing, all small arcs and small circles should be inked first, then the larger arcs and circles, and the straight lines last. This is best, because it is FIG. 17. much easier to know where to stop the arc line, and to draw the straight line tangent to it, than vice versa. IRREGULAR CURVES. The irregular curve shown in Fig. 5 is useful for drawing irregular curves through points that have already been found by construction, such as ellipses, cycloids, epicyloids, etc., as in ths cases of gear-teeth, cam outlines, rotary pump wheels, etc. When using these curves, that curve should be selected that will coincide with the greatest number of points on the line required. INTRODUCTORY INSTRUCTIONS. 15 THE PROTRACTOR. This instrument is for measuring and constructing angles. It is shown in Fig. 12. It is used as follows when measuring an angle : Place the lower straight edge on the straight line which torms one of the sides of the angle, with the nick exactly on the point of the angle to be measured. Then the number of degrees contained in the angle may be read from the left; clockwise. In constructing an angle, place the nick at the point from which it is desired to draw the angle, and on the outer circum- ference of the protractor, find the figure corresponding to the number of degrees in the required angle, and mark a point on the paper as close as possible to the figure on the protractor; after removing the protractor, draw a line through this point to the nick, which will give the required angle. SHADE LINES AND SHADING. Shade Lines are quite generally used on engineering work- ing drawings ; they give a relieving appearance to the projec- ting parts, improve the looks of the drawing and make it easier to read, and are quickly and easily applied. The Shading of* the curved surfaces of machine parts is sometimes practiced on specially finished drawings, but on working drawings most employers will not allow shading be- cause it takes too much time, and is not essential to a quick and correct reading of a drawing, especially if a system of shade lines is used. The Source of Light is considered to be at an infinite dis- tance from the object, therefore the Rays of Light will be rep- resented by parallel lines. The Source of Light is considered to be fixed, and the Point of Sight situated in front of the object and at an infinite dis- i6 DRAWING AND DESIGNING. tance from it, so that the Visual Rays are parallel to one another and per. to the plane of projection. Shade Lines divide illuminated surfaces from dark surfaces. Dark surfaces are not necessarily to be defined by those surfaces which are darkened by the shadow cast by another part of the object, but by reason of their location in relation to the rays of light. It is the general practice to shade-line the different pro- jections of an object as if each projection was in the same plane e.g., suppose a cube, Fig. 18, situated in space in the third angle, the point of sight in front of it, and the direction FIG. 18. FIG. 19. of the rays of light coinciding with the diagonal of the cube, as shown by Fig. 19. Then the edges affi*, b v c" will be shade lines, because they are the edges which separate the illumi- nated faces (the faces upon which fall the rays of light) from the shaded faces, as shown by Fig. 19. Now the source of light being fixed, let the point of sight INTRODUCTORY INSTRUCTIONS. I/ remain in the same position, and conceive the object to be re- volved through the angle of 90 about a hor. axis so that a plan at the top of the object is shown above the elevation, and as the projected rays of light falling in the direction of the diagonal of a cube make angles of 45 with the hor., then with the use of the 45 triangle we can easily determine that the lower and right-hand edges of the plan as well as of the ele- vation should be shade lines. This practice then will be followed in this work, viz. : Shade lines shall be applied to all projections of an object, considering the rays of light to fall upon each of them, from the same direction. Shade lines should have a width equal to 3 times that of the other outlines. Broken lines should never be shade lines. The outlines of surfaces of revolution should not be shade lines. The shade-lined figures which follow will assist in il- lustrating the above principles ; they should be studied until understood. WORKING DRAWINGS. Working drawings are sometimes made on brown detail- paper in pencil, traced on tracing-paper or cloth, and then blue printed. The latter process is accomplished as follows : The tracing is placed face down on the glass in the print- ing-frame, and the prepared paper is placed behind it, with the sensitized surface in contact with the back of the tracing. In printing from a negative the sensitized surface of the prepared paper is placed in contact with the film side of the negative, and the face is exposed to the light. * DRAWING AND DESIGNING. The blue-print system for working drawings has many- drawbacks, e.g., the sectional parts of the drawing requires to be hatch-lined, using the standard conventions already re- ferred to for the different materials. This takes a great deal of time. The print has usually to be mounted on cardboard, although this is not always done, and unless it is varnished the frequent handling with dirty, oily ringers soon makes it unfit for use. Changes can be made on the prints with soda-water, it is true, but they seldom look well, and when many changes or additions require to be made it is best to make them on the tracing and take a new print. And the sunlight is not always- favorable to quick printing. So taking everything into con- sideration the system of making working drawings directly on cards and varnishing them is probably the best. It is the system used by the Schenectady Locomotive Works and many other large engineering establishments. In size the cards are made 9" X 12", 12" X 18" ', 18" X 24"; they are made of thick pasteboard mounted with Irish linen record- paper. The drawings are pencilled and inked on these cards- in the usual way, and the sections are tinted with the conven- tional colors, which are much quicker applied than hatch- lines. The face of the drawing is protected with two coats of white shellac varnish, while the back of the card is usually- given a coat of orange shellac. The white varnish can easily be removed with a little alcohol, and changes made on the drawing, and when revar- nished it is again ready for the shop. In the hands of an experienced workman a working drawing is intended to convey to him all the necessary INTRODUCTORY INSTRUCTIONS. 19 information as to shape, size, material, and finish to en- able him to properly construct it without any additional in- structions. This means that it must have a sufficient num- ber of elevations, sections, and plans to thoroughly explain and describe the object in every particular. And these views should be completely and conveniently dimensioned. The dimensions on the drawing must of course give the sizes to which the object is to be made, without reference to the scale to which it may be drawn. The title of a working drawing should be as brief as possible, and not very large a neat, plain, free-hand printed letter is best for this purpose. Finished parts are usually indicated by the letter '* f," and if it is all to be finished, then below the title it is customary to write or print " finished all over." T4ie number of the drawing may be placed at the upper left-hand corner, and the initials of the draftsman immedi- ately below it. Lettering. All lettering on mechanical drawings should be plain and legible, but the letters in a title or the figures on a drawing should never be so large as to make them ap- pear more prominent than the drawing itself. The best form of letter for practical use is that which gives the neatest appearance with a maximum of legibility and re- quires the least amount of time and labor in its construction. Figuring. Great care should be taken in figuring or di- mensioning a mechanical drawing, and especially a working drawing. To have a drawing accurately, legibly, and neatly figured is considered by practical men to be the most important part of a working drawing. 20 DRA WING AND DESIGNING. There should be absolutely no doubt whatever about the character of a number representing a dimension on a drawing. Many mistakes have been made, incurring loss in time, labor, and money through a wrong reading of a dimension. Drawings should be so fully dimensioned that there will be no need for the pattern-maker or machinist to measure any part of them. Indeed, means are taken to prevent him from doing so, because of the liability of the workman to make mistakes, so drawings are often made to scales which are dif- ficult to measure with a common rule, such as 2 "and 4" = I ft. STANDARD CONVENTIONAL SECTION LINES. Conventional section lines are placed on drawings to distin- guish the different kinds of materials used when such drawings are to be finished in pencil, or traced for blue printing, or to ; : used for a reproduction of any kind. Water-colors are nearly always used for finished drawings and sometimes for tracings and pencil drawings. The color tints can be applied in much less time than it takes to hatch-line a drawing. So that the color method should be used whenever possible. To apply the color tint. Great care should be taken in de- termining the depth of the tint to be used; when only the section parts are to be colored the tints should be quite light because it is much easier to obtain an even wash and a softer and more artistic effect. Before applying the color the draw- ing board should be cleared of drawing instruments, etc., so that it may be easily turned to enable the student to keep INTRODUCTORY INSTRUCTIONS. 21 the bounding color line always to his left, and keeping the brush in such position that the color just touches the bound- ing line transfer the color to the drawing with long sweeps of the brush until the surface is covered. Press out all color remaining in the brush with the fingers and apply the brush again to the little puddles remaining on the paper. The brush will draw it back into itself and leave an even tint all over the section. FlG. 20. This figure shows a collection of hatch-lined sections that is now die almost universal practice among draftsmen in this and other countries, and may be considered standard. No. i. To the right is shown a section of a wall made of rocks. When used without color, as in tracing for printing, the rocks are simply shaded with India ink and a 175 Gillott steel pen. For a colored drawing the ground work is made of gamboge or burnt umber. To the left is the conventional representation of water for tracings. For colored drawings a blended wash of Prussian blue is added. No. 2. Convention for Marble. When colored, the whole section is made thoroughly wet and each stone is then streaked with Payne's gray. No. 3. Convention for Chestnut. When colored, a ground wash of gamboge with a little crimson lake and burnt umber is used. The colors for graining should be mixed in a separate dish, burnt umber with a little Payne's gray and crimson lake added in equal quantities and made dark enough to form a sufficient contrast to the ground color. No. 4. General Convention for Wood. When colored the ground work should be made with a light wash of burnt sienna. 22 DRAWING AND DESIGNING. INTRODUCTORY INSTRUCTIONS. 2$ The graining should be done with a writing-pen and a dark mixture of burnt sienna and a modicum of India ink. No. 5. Convention for Black Walnut. A mixture of Payne's gray, burnt umber and crimson lake in equal quanti- ties is used for the ground color. The same mixture is used for graining when made dark by adding more burnt umber. No. 6. Convention for Hard Pine. For the ground color make a light wash of crimson lake, burnt umbei, and , gamboge, equal parts. For graining use a darker mixture of of crimson lake and burnt umber. No. 7. Convention for Building-stone. The ground color is a light wash of Payne's gray and the shade lines are added mechanically with the drawing-pen or free-hand with the writing-pen. No.- 8. Convention for Earth. Ground color, India ink and neutral tint. The irregular lines to be added with a writ- ing-pen and India ink. No. 9. Section Lining for Wrought or Malleable Iron. When the drawing is to be tinted, the color used is Prussian blue. No. 10. Cast Iron. These section lines should be drawn equidistant, not very far apart and narrower than the body lines of the drawing. The tint is Payne's gray. No. : i. Steel. This section is used for all kinds of steel. The lines should be of the same width as those used for ca'st- f - - ,--.,., - r < iron and the spaces between the double and single lines should be uniform. The color tint is Prussian blue with enough crim- son lake added to make a warm purple. No. 12.. Brass. This section is generally used for all kinds of composition brass, such as gun-metal, yellow metal. 24 DRA WING. AND DESIGNING. bronze metal, Muntz metal, etc. The width of the full lines, dash lines and spaces should all be uniform. The color tint is a light wash of gamboge. Nos. 1320. The section lines and color tints for these numbers are so plainly given in the figure that further in- struction would seem to be superfluous. Sometimes draftsmen will Crosshatch all the sectional parts with a uniform space and ilne like that used for cast iron and mark the names of the different materials or their initials in some convenient place on the parts themselves. This does not look as well nor is it any more convenient to experienced men than the other method. CONVENTIONAL LINES. FlG. 21. There are four kinds: (i) The Hidden Line. This line should be made of short dashes of uniform length and width, both depending some- what on the size of the drawing. The width should always be slightly less than the body lines of the drawing, and the V 1 ' * p "~~~ "" ~~ "" - - - _ _____ (2 FIG. 21. length of the dash should never exceed ". The spaces between the dashes should all be uniform, quite small, never exceeding T V'. This line is always inked in with black ink. (2) The Line of Motion. This line is used to indicate point paths. The dashes should be made shorter than those of the hidden line, just a trifle longer than dots. The spaces should of course be short and uniform. INTRO D UCTOR Y INS TR UCTIONS. (3) Center Lines. Most drawings of machines and parts of machines are symmetrical about their center lines. When penciling a drawing these lines may be drawn continuous and as fine as possible, but on drawings for reproductions the black- inked line should be a long narrow dash and two short ones alternately. When colored inks are used the center line should be made a continuous red line and as fine as it is possible to make it. (4) Dimension Lines and Line of Section. These lines are made in black with a fine long dash and one short dash alternately. In color they should be continuous blue lines. Colored lines should be used wherever feasible, because they are so quickly drawn and when made fine they give the drawing a much neater appearance than when the conventional black lines are used. Colored lines should never be broken. . CONVENTIONAL BREAKS. FlG. 22. Breaks are used in drawings sometimes to indi- cate that the thing is actually longer than it is drawn, some- FIG. 22. 26 DRAWING AND DESIGNING. times to show the shape of the cross-section and the kind of material. Those given in Fig. 22 show the usual practice. CROSS-SECTIONS. FlG. 23. When a cross-section of a pulley, gear-wheel or other similar object is required and the cutting-plane passes through one of the spokes or arms, then only the rim and hub should be sectioned, as shown at xx No. I and zz No. 2, and the arm or spoke simply outlined. Cross-sections of the arms may be made as shown at AA No. 2. In working drawings of gear-wheels only the number of teeth included in one quadrant need be drawn ; the balance is usually shown by conventional lines, e.g., the pitch line the same as a center line, viz., a long FIG. 23. dash and two very short ones alternately or a fine continuous red line. The addendum line (d) and the root or bottom line (b) the same as a dimension line, viz., one long dash and one short dash alternately or a fine continuous blue line. The end ele- vation of the gear-teeth should be made by projecting only the points of the teeth, as shown at No. 2. Other conventions will be referred to in the text con- nected with the figures in which they are illustrated. Constructions. To draw the curve of intersection that is formed by a plane cutting an irregular surface of revolution. INTRODUCTORY INSTRUCTIONS. 2J Figs. 24 and 25 show examples of engine connecting- rod ends where the curve 7 is formed by the intersection of FIG. 24. the flat stub end with the surface of revolution of the turned part of the rod. FIG. 25. Divide the line AB, Figs. 24 and 25, into any number of equal parts and through them describe arcs cutting the center line CD. Through the intersections of these arcs with CD draw horizontals to intersect the curve or fillet G. 28 DRA WING AND DESIGNING. Through the intersections on G draw perpendiculars and from the divisions on AB draw horizontals to intersect the perpendiculars; these latter intersections are points in the curve /. The curve E can be found in a similar way as shown by the figure. B D FIG. 26. FIG. 27. To draw the projections of a V-threaded screw and its nut of 3" diam. and |" pitch. Begin by drawing the center line C, Fig. 26, and lay off on each side of it the radius of the screw ij". Draw A B and 6D. Draw A6 the bottom of the screw, and on AB step off the pitch = f", beginning at the point A. INTRODUCTORY INSTRUCTIONS. 29 On line 6D from the point 6 lay off a distance = half the pitch = ", because when the point of the thread has com- pleted half a revolution it will have risen perpendicularly a distance = half the pitch, viz,, f". .Then from the point 6" on 6D step off as many pitches as may be desired. From the points of the threads just found, draw with the 30 triangle and T-square the V of the threads intersecting at the points b . . b . . the bottom of the threads. At the point O on line A6 draw two semicircles with radii = the top and bottom of the thread respectively. Divide these into any number of equal parts and also the pitch Pinto the same number of equal parts. Through these divisions draw hors. and pers. intersecting each other in the points as shown by Fig. 26, which shows an elevation partly in section and a section of a nut to fit the screw. Through the points of intersection draw the curves of the helices shown, using No. 3 of the "Sibley College Set" of Irregular Curves. ELEMENTARY MACHINE DESIGN. A machine, according to Prof. John H. Barr, is " a combination of resistant bodies for modifying energy and doing work, the members of which are so arranged that, in operation, the motion of any member involves definite, rela- tive, constrained motion of the others." In order to obtain the most desirable results in designing such a structure it is necessary to give the several bodies composing it such form and proportion as will enable them to perform their functions in the best possible way and at the same time present a pleasing appearance to the experienced 30 DRAWING AND DESIGNING. eye. And, moreover, it must not be forgotten that these desired results should be sought with a due regard to economy of material and construction. The form of a machine will probably depend largely upon the designer's experience and his natural ability or intuition. The proportion of the several parts may be calculated if the opposing forces are known, but in many cases these forces cannot be accurately determined and the designer must rely upon the most approved practice of the past had under similar conditions. MATERIALS USED IN MACHINE CONSTRUCTION. The principal materials used in machine construction may be divided into three heads, viz.: Cast Metals, Wrought Metals, and Wood. CAST METALS. Among the cast metals the more important in machine construction are cast iron, malleable cast iron, cast steel, brass, copper-bronze or gun-metal, phosphor-bronze, and aluminum. Cast Iron. Three kinds of white cast iron and three of gray are used in different ways in machine construction. The whitest iron is very hard and is used like the others of its class for making wrought iron. The gray irons do not melt as readily as the white, but are more fluid when melted. The grayest irons are the weakest and are used only for mixing with others in the cupola. IN TROD UCTOR Y INS TR UCTIONS. . 3 I Ordinary cast iron contains from 3$ to 5$ of carbon, which in the white iron is fully combined with the iron, while only .6$ to 1.5$ is combined in the gray iron and 2.9$ to 3.7$ shows as graphite crystals. Iron castings of machine-parts are made from patterns. These patterns are made of wood, usually soft pine, in form exactly like the castings desired. The patterns are used to make moulds in sand in the foundry and into these moulds is poured the molten iron. Cast iron after solidifying in the moulds contracts while cooling about J" per foot of length. To allow for this con- traction pattern-makers use a special rule called a shrink-rule for measuring patterns; it is -J" per foot longer than the standard rule. Sharp corners in patterns do not cast sharp and square in the metal, but come out ragged and blunt, so that whenever possible sJiarp edges should be rounded and sharp concave corners filleted or partially filled in; the result is a stronger and better-looking casting. To avoid irregular internal strains in iron castings when cooling it is necessary that the section of the casting be made as uniform as possible, so that the metal may contract uni- formly throughout. Chilled Castings. Melted gray cast iron if cooled quickly retains in chemical combination a large amount of carbon which otherwise would be separated from the casting. The result is a white hard iron called chilled cast iron. To secure this quick cooling the mould into which the metal is cast is made of thick cast iron, which draws the heat from the molten metal in much less time than does the sand mould. 32 DRAWING AND DESIGNING, Malleable Castings are made by putting a gray-iron cast- ing in a suitable box and covering it with powdered red hematite, which is an oxide of iron, and keeping it in a furnace at a bright-red heat for from two to thirty hours or even longer, depending upon the size of the casting; such castings are valuable for small light parts of machines, because they are tough and strong. Malleable castings can be worked like wrought iron, but will not weld. Cast Steel is made by melting broken pieces of blister- steel in a closed crucible and casting into ingots. Brass is very much used, because it is easy to work, is cheap, strong, and tough, and of a good cdor. The usual composition of brass is 2 of .copper to I of zinc, with some- times a little lead added. Muntz Metal is a brass composition of 3 parts copper to 2 of zinc. It can be rolled or forged when hot and is used in the shape of bolts and nuts, sheets for sheathing wooden vessels, and often takes the place of iron or steel because of its ability to withstand the corrosive action of water. Copper. Pure copper with a small addition of phos- phorus makes fairly good castings, but it is difficult to obtain sound castings from copper alone. Copper has a reddish- brown color and is very malleable and ductile when pure. It can be hammered, rolled, and forged when hot or cold; joints can be united by brazing, but welding is difficult. The annealing of iron and steel is effected by heating and slow cooling, while copper can only be annealed by heating and quick cooling. Bronze or Gun-metal. The best composition is made of 9 parts of copper to I of tin. For bearings designed to sus- INTRODUCTORY INSTRUCTIONS. 33 tain great pressure very hard bronze is often used, in which the proportion of tin is increased to 14 parts with 86 parts of copper. Phosphor-bronze. This alloy is made by adding from 2% to 4$ of phosphorus to the common bronze. It is used for many things in place of iron and steel, such as pump-rods, ship-propellers, etc. ; it is also used quite largely for locomo- tive axle.-bearings and shows excellent wearing qualities. Babbitt Metal. This is a soft white metal that is used quite largely for lining shaft-bearings. Its composition is usually as follows: copper 4 parts, antimony 8, tin 24, melted together, and before using this alloy is melted with an addi- tion of twice its weight of tin and applied to the bearings while molten. So the real composition of the lining is copper 4, antimony 8, and tin 96. Aluminum. This is a very light metal, soft, malleable, and ductile, and of a silvery-white color with a bluish tint. A process for producing it with comparative cheapness was discovered in 1890, and since then its production has been rapidly increasing. It is thoroughly non-corrosive e WROUGHT METALS. These consist of wrought iron and steel of various qualities. Wrought Iron or Malleable Iron is a white metal not easily melted and is very strong and tough. It is made from the white cast irons by abstracting the most of the latter's car- bon in a puddling-furnace. It is taken from this furnace in large spongy masses called blooms, and shingled by repeated squeezing and hammering and rolled into what is known as puddled bars. The puddled bars are then cut into short 34 DRAWING AND DESIGNING. pieces and piled into faggots; these are heated again and rolled into what is known as merchant bars. The best quali- ties of wrought iron are piled together, reheated, and rolled in the same way many times, giving the iron its fibrous nature which makes it so tough and strong. A valuable property of wrought iron is that it can be welded at a temperature of from 1500 to 1600 Fahr. Case-hardening. This is a hardening of the surface of finished parts of machines, such as the links, guides, etc , of steam-engines, so that their wearing qualities are very much increased. It is effected as follows: the piece to be case- hardened is placed in a suitable receptacle and surrounded by bone-dust, horn-shavings, yellow prussiate of potash, or any such substance that is rich in carbon, and heated to about a red heat, when the wrought iron will absorb some of the carbon surrounding it and be converted into steel, which can be hardened by immersing in water. Steel is made from wrought iron by adding a little carbon or from cast iron by extracting some of its carbon. There are three ways of doing this: the Bessemer, Siemens-Martin, and cementation processes. Bessemer Steel is made by pouring melted cast iron into a converter through which a blast of air is forced. In this way the carbon in the cast iron is burnt out, leaving almost pure iron. To this is added a certain quantity of spiegeleisen, which is a compound of iron, carbon, and manganese, and then the molten metal is cast into steel ingots'. Siemens- Martin Steel is made by melting wrought iron and cast iron, or cast iron and certain kinds of iron ore s together on the hearth of a reverberatory gas-furnace. INTRODUCTORY INSTRUCTIONS. 35 The Cementation Process consists of embedding bars of wrought iron in powdered charcoal in a fire-clay trough and placed in a furnace for several days at a high temperature. The iron combines with portions of the carbon and forms blister-steel, so called from the blisters found on its surface. Bars of blister-steel about 18" long are then bound together by strong steel wire and heated to a welding heat, then hammered and rolled into bars called shear-steel. WOODS. The woods used in machine construction are principally pine, fir, beech, boxwood, ash, elm, hornbeam, lignum-vitae, mahogany, oak, and teak. Pine and Fir are strong, cheap, and easy to work, and are largely used for a variety of purposes. White and Yellow Pine are much used in pattern-making. Beech is used for the cogs of mortise-wheels; it takes a smooth surface and is very close-grained. Boxwood is much used for sheaves of pulley-blocks and bearings. It takes a smooth surface, is hard, heavy, and of a bright-yellow color. Elm is very durable in water, and is therefore used for paddle-wheel floats, piles, etc. Hornbeam is often used for cogs of mortise-wheels. Lignum-vitae. This is a very hard wood of great strength and durability under water. For these reasons it is used for bearings under water and other purposes requiring hardness and strength. Its specific gravity is 1.33; i.e., i-J times the weight of the same volume of water. Mahogany is a favorite for making small patterns. It is 36 DRA W 'ING AND DESIGNING. . straight-grained, strong, and durable, and does not as readily change its form when seasoning as most other woods. Oak is. tough and straight-grained, very durable, whether used dry or in water. It is used for machine-framing and supports. Teak is a strong, tough, durable wood. It shrinks very little when seasoning, and is very valuable on that account. Bolts passing through it are prevented from rusting by the oil it contains. STRENGTH OF MATERIALS. DEFINITIONS. Load. The load on any member of a machine is a total of the external forces acting on it. The useful load is the load which the member is designed to carry outside of itself; e.g., the useful load on the springs of a railway-car is the load which may be placed upon the car in addition to the load arising from the weight of the car itself. A live load is a variable load applied and removed continuously. A dead load or constant load is that which has an unvarying and continuous straining action. Strain and Stress. Strain is the change of form pro- duced by the action of a load. If the load does not exceed the elastic limit of the material the strain will disappear when the load is removed. Machine-members should be designed strong enough to resist permanent set under maximum load. Stress is the force which causes strain. The different kinds of stress are : tensile stress or pull, compressive stress or IN TROD UCTOR Y INS TR UCTIONS. 37 thrust, shearing stress or cross-cutting, bending or combined thrust and pull, and torsional or twisting stress. Resistance of metal to change of form is due to the inherent cohesive force of its molecules. Elasticity or spring is the inherent property in a material of regaining original form after an external load has been removed. Elastic Limit. The elastic limit is the limit of extension or compression to which a material can be subjected without permanent set. Within the elastic limit strain and stress are proportional. Modulus of Elasticity. Dr. Thomas Young of the British Royal Society propounded the following formula for the modulus of elasticity (E) in 1826, known as " Young's Modulus " : stress per sq. in. in Ibs. E = : : . f . r (within the elastic limit). inch of length v strain per TABLE 1. ELASTIC MODULI. Material. Modulus of Elasticity. Material. Modulus of Elasticity. \Vrought iron bars. . . 2Q OOO OOO Pine average i 500 ooo Wrought iron plates 26 ooo ooo Beech i 350 ooo 30 ooo ooo i 800 ooo Cast steel tempered. . 36 ooo ooo Ash i 600 ooo 30 ooo ooo Elm 31 ooo ooo Cast iron average 17 ooo ooo i 300 ooo Brass and bronze 1 2 OOO OOO Oak English i 700 ooc Muntz metal 14 ooo ooo Teak 2 300 OOO Copper average .... 12 OOO OOO Leather 2A. ^OO 720 ooo Ultimate Strength is the smallest load that will fracture a member under stress. DRAWING AND DESIGNING. The Proof Strength is nearly equal to the load that will cause permanent set; i.e., to the maximum elastic resistance. The Factor of Safety is the ratio of the ultimate strength of a member to the working load, or the breaking load to the actual load. The factor of safety changes for different materials and for different uses of the same material. It is of course much greater under live loads than under constant dead loads. The following table gives the ordinary factors of safety in general use: TABLE 2. FACTORS OF SAFETY. Material. Ratio of Ultimate Load to Working Load. Dead Load. Live Load. Shocks. Cast iron 4 3 3 3 5 8 10 7 5 to 8 5 to 8 5 to 8 8 10 20 15 9 to 13 9 to 13 10 to 15 10 to 15 14 to 18 30 Mild steel Copper and similar metals and alloys Wood Strength of Cast Iron. The average American ca-t iron has a tenacity of about 20,000 Ibs. per sq. in., but cast iron has been made which showed an ultimate tensile strength of 35,000 Ibs. per sq. in. The ultimate compressive strength of cast iron is from 4 to 6 times its tenacity, the average is about 90,000 Ibs. per sq. in., and the average shearing strength is about 20,000 Ibs. per sq. in. The elastic limit of cast iron is from -| to nearly equal to the breaking strength. INTRODUCTORY INSTRUCTIONS. 39 Strength of Wrought Iron. The elastic strength of wrought iron is usually over half its ultimate strength; good bars and plates will show an elastic limit of about 26,000 Ibs. In ascertaining the strength of a particular piece of wrought iron it will be necessary to know the elongation per cent of specimen. The elongation is greater for short than for long specimens. The usual length of specimens for tensile test is 8". Wrought iron loses its strength in forging; this loss of strength is equal to about 20$. The difference between the strength of wrought iron when pulled against the grain and in the direction of the grain is from 3000 to 9000 Ibs. per sq. in., the strength in the direction of the grain being the greater. The tensile strength of wrought iron varies from 40,000 to 60,000 Ibs. per sq. in. Strength of Steel. The steel cast from blister-steel is the strongest, having a tensile strength of from 100,000 to 130,000 Ibs. per sq. in., but it is hard and brittle, with an elongation of only about 5$. It is therefore unsuitable for constructive purposes. A good plate steel for steam-boilers has a tensile strength of from 55,000 to 60,000 Ibs., with an elongation of about 20$ in a length of 8". The following tables were compiled after consulting various authorities; e.g., Thurston, Unwin, Kent, Moles- worth, etc. 40 DRAWING AND DESIGNING. TABLE 3. AVERAGE ULTIMATE AND ELASTIC STRENGTH OF VARIOUS MATERIALS AND MODULI OF ELASTICITY IN POUNDS PER SQUARE INCH. Material. Ultimate Strength. Elastic Strength. E. With the Grain. E'. Trans- verse. Tension. Compression. ti c rt 4) JS C/5 Tension. c 1 Q. u 1 1 C/5 Cast iron, common. Wrought iron, bars,. Wrought iron, plates. Wrought shape iron.. Wrought stay bolt 20,000 50,000 48,000 48,000 90,000 48,000 46,000 46,000 49,000 48,000 125,000 66,000 50,000 45,000 58.000 10,500 6,000 10,000 2O.OOO 40,000 38,000 38,000 40,000 38,000 38,000 64.000 50,000 45,000 12,000 26,000 26,000 26,000 28.000 26,000 23 500 70,000 32 ,000 .29,000 23,000 26,000 26,000 26,000 28,000 26,000 27,000 9,000 22.000 22,000 22,000 24,000 22,OOO 20.000 64.000 25.000 15,000,000 29,000,000 29,000,000 29,000,000 29,000,000 29,000,000 24,530,000 30,000,000 30,000.000 29.000,000 7,000,000 0.500,000 0,000,000 0,000,000 0,000,000 0,000,000 3,500,000 1,000,000 1 ,000,000 0,500,000 Wrought rivets Malleable cast iron... Cast steel Soft-steel plates Steel rivets.., . . 50,000 32,000 88,000 55,000 52,665 23,000 34.000 36,000 15,000 Forged copper 4,500 6,200 4,000 3,000 5,200 4.200 15,000,000 9,200,000 10,000,000 1,600,000 1,700,000 25,000 6,00^,000 3,500,000 4,000,000 90,000 82,000 "'650' 2,300 Gun metal . Wood, pine Wood, oak, fcnglish . 6,000 , ,?, Wrought Iron has a specific gravity of 7.5 to 7.8 accord- ing to its chemical composition and physical structure. Cast Iron has a specific gravity of 7.25. The tensile strength of metals varies with their tempera ture, generally decreasing as their temperature is increased. 7 to 12 Lead . . . . Tin . . . . Zinc . . . . Worked copper TABLE 4. RELATIVE TENACITIES OF METAL. (THURSTON.) Cast iron . . J.o 1.3 . 2.0 12 to 20 Wrought iron . . 20 to 40 Steel 40 to loo USEFUL TABLES AND MISCELLANEOUS INFORMATION. WEIGHTS AND MEASURES. AVOIRDUPOIS OR COMMERCIAL WEIGHT. SQUARE MEASURE. 16 drach'ms .... ounce. 144 square inches . I square foot. 16 ounces pound. 9 feet . . i yard. 14 pounds stone. 30^ ' yards . . i rod. 28 " quarter. 40 ' rods . . i rood. 4 quarters . . I cwt. 4 ' roods . . i acre. 2240 pounds ton. 640 ' acres . . i mile. MEASURE OF VOLUME, A cubic foot has 1728 cubic inches. An ale gallon has 282 A standard or wine gallon has 231 A dry gallon has 268.8 A bushel has 2150.4 A cord of wood has 128 feet. A perch of stone has 24.75 A ton of round timber has 40 A " hewn " " 50 A box igf X 19! inches, 19! inches deep, contains . . i barrel. A " i2\l X i2^| " I2^f " " " .... i bushel. A " 8i X 8 " , 8| " . . i peck. A " 6 T 7 , X 6 T ^ 6/g " . . i " A ' 4iff X 4yff 4iV . . i quart. An acre contains . 4840 square yards. 209 feet long by 209 feet broad is I acre. TABLE OF DISTANCE. A mile is ... A knot is ... A league is A fathom is . A metre is nearly A hand is ... A palm is ... A span is ... 5280 feet or 1760 yards. 6086 feet. 3 miles. 6 feet. 3 feet 3! inches. 4 inches. 3 " 9 MEASURE OF LENGTH. 12 incnes 3 feet , 2 yards feet i foot, i yard. I fathom, i rod. 4 rods . 10 chains . 8 furlongs 3 miles I chain, i furlong i mile. i league. 41 DRAWING AND DESIGNING. Each nominal horse-power of boilers requires i cubic foot of water per hour. In calculating horse-power of steam-boilers consider for Tubular boilers 15 sq. ft. of heating-surface equivalent to I horse-power. Flue boilers 12 sq. ft. of heating-surface equivalent to i horse-power. Cylinder boilers 10 sq. ft. of heating-surface equivalent to i horse-power. To find the area of a piston , square the diameter and multiply by .7854. To find the pressure in pounds per square inch of a column of water, multiply the height of the column in feet by .434. A horse-power in machinery is estimated at 33,000 pounds raised one foot high in a minute, or one pound raised 33,000 feet high in a minute. Iron under the influence of the hammer and of constant use gradually assumes, by repeated vibration, a different texture from that it had when the piece was new. The metal becomes crystalline, loses its tenacity, and becomes brittle. WEIGHT OF WATER. One cubic foot at 39.1 F. = 62.425 Ibs., at 212 F. = 59.833. At 62 F. the weight varies from 62.291 to 62.360. The figure generally believed to be the most accurate is 62.355. Weight of i gallon at 39.2 = 8.3389 Ibs. WEIGHTS OF CAST-IRON WATER-PIPES. IN POUNDS PER FOOT RUN, INCLUDING BELLS AND SPIGOTS. Diameter. Philadelphia Chicago Cincii inati. Regular Light. Weight. Thickness. Standard. 2-inch. . . . 7 6 1 5 ooo 17 1' JC r* 6 .... 8 10 .... 12 .... 16 21. Ill 30. 106 40.683 52.075 69.162 IO2 522 24.167 36.666 5O.OOO 65.000 83.333 125 ooo 23 50 65 so 100 T7O r 22 33 42 60 75 20 30 40 55 70 20 147 68 i 2OO 1* 2/1 250 ooo 22d on 2QO i" *6 450 ooo 4. 3O i>" Water-pipe is usually tested to 300 pounds pressure per square inch before delivery, and a hammer test should be made while the pipe is under pressure. The Cincinnati lengths are uniform for all diameters, 12 feet exclusive of bell. Standard lengths aie for 2-inch pipe 8 feet, and all other sizes 12 feet. USEFUL TABLES AND MISCELLANEOUS INFORMATION. 43 THICKNESS OF CAST-IRON WATER-PIPE. The following formula, adapted from Neville, is believed to be a safe equation for the thickness of cast-iron pipe for public water-supply: - -32, where t thickness of pipe in inches, h = head or pressure in feet, d = diameter of pipe in inches, S =, the tensile strength of metal in tons of 2000 pounas. What should be the thickness of a 2O-inch water-main subject to a maximum pressure of 150 pounds per square inch, or 150 X 2.308 = 346.2 feet head, with cast-iron of 18,000 pounds tensile strength ? 9 f /346.2 \ "1 / = - X .ooi6( -^j- + loj X 20 + .32 = .9757'- What should be the thickness of 4O-inch pipe for same service and of same metal ? / = ~- X .ooW^- + loj X 40 + .32 = 1.6313" The speed at which millstones should be run is For 3-feet stones 230 to 250 revolutions per minute. " 3i " " 200 " 4 " " . 180 41 4^ " " . . 160 " " Speed of bolting-reels 30 to 35 " " " " " conveyers for flour . . . . 35 to 40 ' "- " " " *' " " wheat . . .451050 " " " 41 elevators 30 to 35 " " smut-machines from 550 to 700 revolutions per minute, accord- ing to size of machine. For merchant mills allow 20 horse-power to a pair of burrs (4 feet), and the necessary machinery for cleaning and bolting; and for country mills about 10 horse-power to a pair of burrs. For a single upright saw allow 10 horse-power, speed about 150 revolu- tions per minute. For circular saws the best average working speed is 650 to 700 rev. per min. for 36-in. saw. 60010650 " " " " 40 " " 55010600 " " " " 42 " " 500 to 525 lev. per min. for 48-in.saw. 47510500 " " " " 54 " " 40010450 60 " " 52510550 " " " " 44 A 6o-saw gin requires 6 horse-power to gin 500 pounds of lint in 2 hours. A sumac-mill requires 15 horse-power. 44 DRAWING AND DESIGNING. To reduce for round cores and core-prints, multiply the square of the diameter by the length of the core in inches, and the product by 0.017 i* the weight of the pine core, to be deducted for the weight of the pattern. SHRINKAGE OF CASTINGS. Pattern-maker's rule should be for of an inch longer per linear foot. PROPERTIES OF THE CIRCLE. Diameter X 3.14159 = circumference. Diameter X .8862 = side of an equal square. Diameter X .7071 = side of an inscribed square. Diameter 2 X -7854 = area of circle. Radius X 6.28318 = circumference. Circumference -5- 3.14159 = diameter. WROUGHT-IRON WELDED TUBES FOR STEAM, GAS, OR WATER. Nominal Diameter. Actual Inside Diameter. Actual Outside Diameter. Thickness, Weight per Footof Length. No. of Threads per Inch of Screw. Inches. Inches. Inches, Inches. Pounds. .270 .405 .068 .243 27 .364 54 .088 .422 18 494 .675 .091 .561 18 .623 .84 .109 845 14 .824 1.05 ."3 I.I26 14 I 1.048 I.3I5 .134 1.670 Ij 1.380 1.66 . 140 2.258 II* i 1.611 1.9 .145 2.694 II* 2 2.067 2-375 .154 3-667 H* 2^ 2.468 2.875 .204 5-773 8 3 3.067 3-5 .217 7-547 8 3i 3.548 4.0 .226 9-055 8 4 4.026 4-5 -237 10 728 8 4* 4-508 5-0 .247 12-492 8 5 5-045 5-563 259 14.564 8 6 6.065 6.625 .280 18,767 8 7 7-023 7.625 .301 23.410 8 8 7.982 8.625 .322 28.348 8 9 9.001 9.688 344 34.077 8 10 10.019 10.75 .366 40.641 8 USEFUL TABLES AND MISCELLANEOUS INFORMATION. 45 DIFFERENT COLORS OF IRON CAUSED BY HEAT. (POUILLET.) Cent. 2IO 221 256 26l 370 500 525 700 800 QOO 1000 IIOO 1200 1300 I4OO 1500 1600 Fahr. 410 430 493 502 ) 680 \ .932 977 1292 1472 1657 1832 2012 2192 2372 2552 2732 2912 Color. Pale yellow. Dull yellow. Crimson. Violet, purple, and dull blue; between 261 C. and 370 C. it passes to bright blue, to sea- green, and then disappears. Commences to be covered with a light coat- ing of oxide; loses a good deal of its hardness, becomes much more impressible to the hammer, and can be twisted with ease. Becomes nascent red. Sombre red. Nascent cherry. Cherry. Bright cherry. Dull orange. Bright orange. White. Brilliant white welding heat* Dazzling white. TABLE OF DECIMAL EQUIVALENTS OF ONE INCH. 1/64 .015625 17/64 .265625 33/64 515625 ! 49/64 .765625 1/32 .03125 9/32 .28125 17/32 53125 25/32 .78125 3/64 .046875 19/64 .296875 35/64 .546875 51/64 796875 1/16 .0625 5/i6 3125 9/16 5625 13/16 .8125 5/64 .078125 21/64 .328125 37/64 .578125 53/64 .828125 3/32 09375 11/32 -34375 19/32 59375 27/32 .84375 7/64 .109375 23/64 359375 39/64 -609375 55/64 .859375 1/8 .125 3/8 375 5/8 .625 7/8 875 9/64 . 140625 25/64 .390625 41/64 .640625 57/64 .890625 5/32 .15625 13/32 .40625 21/32 .65625 29/32 .90625 11/64 171875 27/64 .421875 43/64 .671875 59/64 921875 3/i6 .1875 7/16 4375 11/16 .6875 15/16 9375 l3/4 .203125 29/64 .453125 45/64 .703125 61/64 953125 7/32 .21875 15/32 .46875 23/32 .71875 31/32 .96875 15/64 234375 31/64 .484375 47/64 734375 63/64 984375 i/4 25 1/2 50 3/4 75 i 4 6 DRAWING AND DESIGNING. MELTING-POINT OF METALS, ETC- Names. Fahr. Platina 459 Antimony 842 Bismuth 487 Tin. 475 Lead 620 Zinc 700 Cast iron . 2100 Names. Fahr. Wrought iron 2900 Steel 2500 Copper 2000 Glass 2377 Beeswax 151 Sulphur 239 Tallow 92 TABLE 5. WEIGHT OF VARIOUS SUBSTANCES. RULE. Divide the specific gravity of the substance by 16 and the quotient will give the weight of a cubic foot of it in pounds. , .cj rt y ^C feh > o>-. lit o 1 - 1 Substances Metals. a'i *j U II Substances Metals. i! w " ii oP SO CJ c/i ^ t/3 ? 2 560 0926 1 1 352 4106 Brass plate 8 380 II 388 41 IQ 8 214. 2Q72 13 ^Q8 4Ql8 8 700 OT/17 13 580 8 788 3I7Q Mercury 212 T 1 Q *7( ) 4836 8 608 3146 7 806 .2823 8 880 3212 Steel soft 7 833 2833 72O7 2607 Steel wire 7 847 Iron, cast, gun-metal . 7,308 .264 Tin, Cornish, hammered 7,390 .2673 7 788 2817 Zinc cast 6 861 .2482 77O4 .2787 7IQI 26 TABLE 6. WEIGHT OF TIMBER PER CUBIC FOOT. Ash 46 Ibs. Beech 44 " Birch 45 " Boxwood ....... 62 " Elm 34 " Larch 34 " Lignum-vitae 80 " Mahogany, Honduras . . 35 Ibs. Spanish ... 53 " Oak, English 54 " Pine, red 30 to 44 '* " yellow . . . . 29 to 41 " 11 white 30 " Teak 41. to 55 " USEFUL TABLES AND MISCELLANEOUS INFORMATION. 47 CIRCUMFERENCES AND AREAS OF CIRCLES ADVANCING BY EIGHTHS. Diam. Circum. Area, i Diam. Circum. Area. Diam. Circum. Area. 1/64 .04909 .00019 3 11/16 8.4430 5.6727 65/8 20 813 34-472 i/S 2 3/64 .09818 .14726 .00077 00173 3/4 13/16 8.6394 8.8357 5-9396 6.2126 3/4 : 7/8 21.206 21.598 35-785 37.122 1/16 .i9 6 35 .00307 7/8 9.0321 6.4918 3/32 29452 .00690 '5/'6 9.2284 6.7771 7 21.991 38-485 1/8 39270 .01227 1/8 22.384 39-871 5/32 .49087 .01917 3 9.4248 7.0686 1/4 22.776 41.282 3/i6 .58905 .02761 j 1/16 9.6211 7.3662 3/8 23.169 4 2. 7I 8 7/32 .68722 03758 ; 1/8 9.81-75 7.6699 i/a. 23.562 - 44.179 i/4 .78540 .04909 3/i6 10.014 7.9798 5/8 23-955 45.664 9/3 2 .88357 . 062 i 3 i/4 10.210 8.2958 3/4 24-347 47.173 5/i6 98175 .07670 5/i6 10.407 8.6179 7/8 24.740 48.707 11/32 .0799 .09281 3/8 10.603 8.9462 3/8 .1781 11045 7/16 10 799 9.2806 8 25-133 50.265 IS/3 2 .2763 .12962 1/2 10.996 9.6211 1/8 25-525 51.849 7/16 3744 15033 9/16 ii . 192 9.9678 i/4 25.918 53-456 IS/3 2 .4726 17257 5/8 11.388 10.321 3/8 26 .311 55-088 1/2 .5708 .19635 11/16 11-585 10.680 1/2 26.704 56-745 J 7/3 2 .6690 .22166 3/4 11.781 11.045 5/8 27.096 58.426 9/16 .7671 .24850 13/16 11.977 11.416 3/4 27.489 60.132 9/3 2 8653 .27688 7/8 12.174 "793 7/8 27.882 61.862 5/8 9635 .30680 \ 15/16 12.370 12.177 21/32 .0617 33824 9 28.274 63.617 11/16 .1598 .37122 4 12.566 12.566 1/8 28.667 65.397 23/32 .2580 40574 i/i 6 12.763 12.962 i/4 29.060 67.201 3/4 35 62 44179 1/8 ia-959 13-364 3/8 29.452 69.029 25/32 4544 47937 3/i6 13.155 1.3-772 i/a 29.845 70.882 13/16 55 2 5 5'849 : i/4 13-352 14.186 5/8 30.238 72.760 27/32 .6507 -55Q14 5/i6 13-548 14.607 ~ 3/4 30.631 74.662 7/8 .7489 .60132 3/8 13-744 15-033 7/8 31.023 76.589 29/32 .8471 .64504 7/16 I.3-94I 15.466 t5/'6 9452 .69029 1/2 i4-!37 15-904 10 31.416 78.540 31/32 3. 434 .73708 9/1 6 14-334 16.349 1/8 31.809 80.516 5/8 14-53 16.800 i/4 32.201 82.516 I 3.1416 7854 11/16 14 726 17-257 3/8 32-594 84-54I 1/16 3.3379 .8866 3/4 14-923 17.728 1/2 32-987 86.590 1/8 3-5343 .9940 13/16 15.119 18.190 5/8 33-379 88.664 3/'6 3.7306 1075 . 7/8 15-3I5 18.665 3/4 33-772 90.763 i/4 3.9270 .2272 15/16 15-512 19.147 7/8 34-165 92.886 5/'6 I2 33 353 3/8 3197 .4849 5 15-708 19. 6 35 II 34.558 95-033 7/16 .5160 .6230 1/16 15-904 20. 129 1/8 34.950 97.205 I/a .7124 .7671 1/8 16.101 20.629 i/4 35-343 99.402 9/1 6 .9087 9'75 3/i6 16.297 2i.i35 3/8 35-736 101.62 5/8 11/16 5-io5i 5-3 01 4 0739 .2365 i/4 5/i6 1^-493 16.690 21.648 22.166 1/2 5/8 36.128 36.521 103.87 106.14 3/4 5.4978 4053 3/8 16.886 22.691 3/4 36.914 108.43 13/16 5- 6 94i .5802 ! 7/16 17.082 23.221 7/8 37-306 110.75 7/8 5.8905 .7612 ! 1/2 17.279 23-758 i5/'6 6.0868 9483 9/16 17-475 24.301 12 37-699 113.10 5/8 17.671 24.850 1/8 38.092 "5-47 2 6.2832 3.1416 11/16 17.868 25.406 i/4 38.485 117.86 3/8 7-4613 4.4301 3/8 38-877 120.28 7/16 7.6576 4.6664 6 1/8 19.242 29.465 1/2 39.270 122.72 i/a 7.8540 4.9087 i/4 19-635 30.680 5/8 39.663 125.19 0/i6 8 .0503 5.1578 3/8 20.028 3i.9i9 3/4 40.055 127.68 5/8 8.2467 5-4"9 1/2 20.420 33-183 7/8 40.448 130-19 To find the -weight of castings by the weight of pine patterns, multiply the weight of the pattern by 12 for cast iron, 13 for brass, 19 for lead, 12.2 for tin, 14.4 for zinc, and the product is the weight of the casting. 47' DRAWING AND DESIGNING. Number. Square. Cube. Square Root. Cube Root. '5 .2 25 3 35 .01 .0225 A .0625 .09 .1225 .OO T .0034 .008 .0156 .027 .0429 .3162 .3873 4472 500 5477 .5916 .4642 .6300 .6694 .7047 4 45 5 55 .6 .65 .16 .2025 25 .3025 .36 .4225 .064 .Ogil a664 .216 .2746 6 3 2 5 .6708 .7071 .7416 .7746 .8062 7368 .7663 7937 .8193 7 75 .8 .85 9 95 .49 5625 .64 .7225 .81 .9025 343 .4219 .512 .6141 .729 .8574 .8367 .8660 .8944 .9219 .9487 9747 .8879 .9086 .9283 9473 9655 .9830 i 2 3 4 5 i . 4 ,t 25 i 8 % ':. 125 I.OOOO 1.4142 1.7321 2.OOOO 2.2361 I.OOOJ 1.2599 1.4422 1.5874 1.7100 6 7 8 9 10 36 49 64 81 I OO 216 343 512 729 I OOO 2.4495 26458 2.8284 3.0000 3.1623 1.8171 1.9129 2.OOOO 2.0801 2.1544 ii 12 13 14 15 I 21 i 44 i 69 i 96 2 25 I 331 I 728 2 197 2 744 3 375 3.3166 3-4641 3.6056 3-7417 3.8730 2.2240 2.2894 2.3513 2.4101 2.4662 16 17 18 *9 20 2 5 6 289 3 24 3 61 4 oo 4 096 4 9 T 3 5 832 6 859 8 ooo 4.0000 4.1231 4.2426 4.3589 4.4721 2.5198 2.57!3 2.6207 2.6684 2.7144 21 22 23 24 25 4 4i 4 84 I? 6 25 9 261 10 648 12 167 I 3 82 4 15 625 4.5826 4.6904 . 4.7958 4.8990 5.0000 2.7589 2.8020 2.8439 2.8845 2.9240 26 2 7 28 29 30 6 76 7 29 784 841 9 oo 16 576 19 683 21 95 2 24 389 27 ooo 5.0990 5.1962 5.2915 5.3852 -5.4772 2.9625 3.0000 3.0366 3-0723 3.1072 31 3-2 33 34 35 9 61 10 24 10 89 ii 56 12 25 29 791 32 768 35 937 39 304 42 875 5.5678 5-6569 5.7446 5.8310 5.9161 3- I 4i4 3-1748 3-2075 3-2396 3.2711 36 i 39 40 12 96 13 69 14 44 15 21 16 oo 46 656 50 653 54 872 59 39 64 ooo 6.0000 6.0828 6.1644 6.2450 6.3246 3-3019 3-3322 3-3620 3-3912 3.4200 4 1 42 43 44 45 16 81 17 64 18 49 19 36 20 25 68 921 74 088 79 507 85 184 91 125 6.4031 6.4807 6.5574 6.6332 6.7082 3.4482 3.4760 3-5034 3-53^3 3.5569 46 47 48 49 50 21 l6 22 09 23 04 24 01 25 oo 97 336 103 823 no 592 117 649 125 ooo 6.7823 6.8557 6.9282 7.0000 7.0711 3-5830 3.6088 3-6342 3.6593 3.6840 USEFUL TABLES AND MISCELLANEOUS INFORMATION. 47* Number! Square. Cube. Square Root. Cube Root. 5 1 5 2 53 54 5S 26 01 27 04 28 09 29 l> 30 2; I 3 2 651 140 Oc8 148 877 157 464 166 375 7.1414 7..'! I I 7.2801 7.3485 7.4162 3.7084 3-73^5 3-7563 37798 38030 56 I 59 60 3' 3 ( ' 3 2 49 33 6 4 34 81 36 oo 175 616 l8 5 193 105 112 205 379 216 ooo 7.4833 7.5498 7.6158 7.68II 7.7460 3-8259 3.8485 38709 3-893 3-9 r 49 6[ 62 * 3 64 65 37 2i 3 8 44 39 6 9 40 96 42 25 226 981 238 328 250 047 262 144 274 625 7.8102 7.8740 7-9373 8.0000 8.0623 3-93 6 5 3-9579 3-979 l 4.0000 4.0207 00 6 7 68 69 70 43 S^ 44 89 46 24 47 61 49 oo 287 496 300 763 3*4 43 2 328 509 343 oco 8.1240 8.1854 8.2462 8.3066 8 3666 4.0412 4.0615 4.0817 4.1016 4.1213 7i 72 73 74 75 50 4i 5^ 84 53 29 54 76 56 25 357 9" 373 2 n 8 389 017 405 224 421 875 8.4261 84853 8.5440 8.602 5 86603 4.1408 4.1602 4-1793 4-1983 4.2172 76 77' 7 79 80 57 76 59 29 60 84 62 41 64 oo 438 976 456 533 474 55 2 493 39 512 oco 8.7178 8.7750 8.8318 8.8882 8.9443 4-2358 4.2543 4-2727 4.2908 4.3089 81 82 83 84 85- 86 87 88 89 90. 6s 61 67 24 68 89 70 56 72 25 53' 44i 55i 368 57i 787 592 7^4 614 125 9.0000 9-5S4 9.1104 9.1652 9 2195 4-3267 4-3445 4.3621 4-3795 4.3968 73 9 6 75 6 9 77 44 79 21 8 1 oo 636 056 658 503 68 i 472 704 969 729 ooo 9.2736 9-3274 9.3808 9 4340 9.4868 4.4140 4.4310 4.4480 4.4647 44814 91 9 2 93 94 95 82 81 84 64 86 49 88 36 90 25 753 57i 778 688 804 357 830 584 857 375 95394 9-59'7 9- 6 437 9.6954 97-l333 21.6564 21.6795 7.752<) 7.7584 7.7639 7.7695 7-775 47i 472 473 474 475 22 l8 41 22 27 84 22 37 29 22 46 76 22 56 25 104 487 III 105 154 048 105 823 817 106 496 424 107 171 875 21.7025 21.7256 21.7486 21.7715 21.7945 7-7805 7.7860 7.7915 7.7970 7.8025 476 477 47 479 480 22 65 76 22 75 29 22 84 84 22 94 41 23 04 oo 107 850 176 108 53 1 333 109 215 352 109 902 239 no 592 ooo 21.8174 21.8403 21.8632 21.8861 21.9089 7.8079 7-8134 7.8188 7.8243 7.8297 481 482 483 484 485 23 13 61 23 23 24 23 32 89 23 42 56 23 52 25 III 284 641 in 980 168 112 678 587 "3 379 94 114 084 i2; 21.9317 21.9545 21.9773 22.0000 22.0227 7-8352 7.8406 7.8460 7.85M 7-8568 486 487 488 489 49 23 61 96 23 71 69 23 81 44 23 91 21 24 01 oo 114 791 256 115 50! 303 116 214 272 116 930 169 117 649 ooo 22.0454 22.0681 22.0907 22.1133 22.1359 7.8622 7.8676 7.8730 7.8784 7-8837 491 492 493 494 495 24 10 81 24 20 64 24 30 49 24 40 36 24 50 25 118 370 771 119 095 488 119 823 157 120 553 784 121 287 375 22.1585 22.1811 22.2036 22.2261 22.2486 7.8891 7.8944 7.8998 7.9051 7-9 I0 5 496 497 498 499 500 24 60 16 24 70 09 24 80 04 24 90 01 25 oo oo 122 023 936 122 763 473 I2 3 505 99 2 124 251 499 125 ooo ooo 22.271 1 22.2935 22.3159 22.3383 22.3607 7-9 5 8 7.9211 7.9264 7-93 ! 7 7-9370 47' DRAWING AJfD DESIGNING. JNumberj Square. Cube. Square Root. Cube Root 501 502 503 54 55 25 10 01 25 20 04 25 30 09 25 40 16 25 So 25 125 751 501 126 506 OO8 127 263 527 128 024 064 128 787 625 22.3830 22.4054 22.4277 22.4499 22.4722 7-94? 3 7.9476 7.9528 7.9581 7.9634 506 57 508 59 5io 25 60 36 25 70 49 25 80 63 25 90 81 26 01 oo 129 554 216 130 323 843 131 096 512 131 872 229 132 651 ooo 22.4944 22.5167 22.5389 22.5610 22.5832 7.9686 7-9739 7.9791 7.9843 7.9896 5' 5 12 5'3 54 5iS 26 II 21 26 21 44 26 31 69 26 41 96 26 52 25 *33 432 831 134 217 728 135 005 697 J35 796 744 136 590 875 22.6053 22.6274 22.6495 22.6716 22.6936 7-9948 8.0000 8.0052 8.0104 8.0156 516 5'7 sis 519 520 26 62 56 26 72 89 26 83 24 26 93 61 27 04 oo 137 388 096 138 i 88 413 !3 8 99 i 832 r 39 798 359 140 608 ooo 22.7156 22.7376 22.7596 22.7816 22.8035 8.0208 8.0260 8.0311 8.0363 8 0415 521 522 523 524 525 27 H 4i 27 24 84 27 35 29 27 45 76 27 56 25 141 420 761 142 236 648 143 55 66 7 143 877 824 144 703 125 22.8254 22.8473 22.8692 22.8910 22.9129 8.0466 8.0517 8.0569 8.0620 8.0671 526 527 528 5 2 9 53 27 66 76 27 77 29 27 87 84 27 98 4-1 28 09 oo J 45 53i 576 146 363 183 H7 197 95 2 148 035 889 148 877 ooo 22-9347 22.9565 22.9783 23.0000 23.0217 8.0723 8.0774 8.0825 8.0876 8.0927 531 532 533 534 535 28 19 61 28 30 24 28 40 89 28 51 56 28 62 25 149 721 291 150 568 768 IS 1 4i9 437 152 273 304 T 53 13 375 23-0434 23.0651 23.0868 23.1084 23.1301 8.0978 8.1028 8.1079 8.1130 8.1180 536 III 539 540 28 72 96 28 83 69 28 94 44 29 05 21 29 i 6 oo i53 99 656 154 854 153 155 720 872 156 590 819 157 464 ooo 23.I517 23.1733 23.1948 23.2164 23.2379 8.i23[ 8.1281 8.1332 8.1382 8-1433 54 1 542 543 544 545 29 26 81 29 37 64 29 48 49 2 9 59 3 6 29 70 25 158 340 421 159 220 088 I 60 103 OO7 160 989 184 161 878 625 23.2594 23.2809 23.3024 23.3 2 38 23.345 2 8.1483 8.1533 8-1583 8.1633 8.1683 546 547 548 549 550 29 81 16 29 92 09 3 3 4 30 14 01 30 25 oo 162 771 336 163 667 323 164 566 592 165 469 149 i 66 375 ooo 23-3666 23.3880 23.4094 23.4307 23.4521 8-1733 8.1783 8.1833 8.1882 8.1932 USEFUL TABLES AND MISCELLANEOUS INFORMATION. 47 Number Square. Cube. Square Root. Cube Root. 55' 552 553 554 555 30 36 01 3 47 04 30 58 09 30 09 16 30 80 25 167 284 151 i 68 196 608 169 112 377 170 031 464 170 9-^3 875 23.4734 234947 23.5160 23-5372 23-5584 8.1982 8.2031 8. 208 1 8.2130 8.2t8o 556 557 558 559 560 30 91 36 31 02 49 3' '3 64 31 24 81 31 36 oo 171 879 616 172 808 693 173 741 112 174 676 879 175 616 ooo 23-5797 23.6008 23.6220 2 3-6432 23.6643 8.2229 8.2278 8.2327 8.2377 8.2426 561. 562 5 * 3 5 * 4 565 31 47 21 3 1 58 44 31 69 69 31 80 96 31 92 25 176 558 481 177 504 328 178 453 547 179 406 144 180 362 125 23.6854 23.7065 23.7276 23.7487 23.7697 8.2,75 8.2524 8-2573 8.2621 8.2670 566 567 568 569 570 3 2 3 S 6 3 2 H 89 32 26 24 32 37 61 3 2 49 oo 181 321 496 182 284 263 183 250 432 184 220 009 185 193 ooo 23.7908 23.8118 23.8328 23.8537 23-8747 8.2719 8.2768 8.2816 8.2865 8.2913 57i 572 573 574 575 32 60 41 32 71 84 32 83 29 3 2 94 76 33 06 25 186 169 411 187 149 248 i 88 132 517 189 119 224 190 109 375 23.8956 23.9165 23.9374 23-9583 23-9792 8.2962 8.3010 8.3059 8.3107 8.3155 576 577 578 579 580 33 17 76 33 2 9 2 9 33 40 84 33 52 41 33 64 oo 191 IO2 976 192 100 033 *93 I0 55 2 194 104 539 195 112 OOO 24.0000 24.0208 24.0416 24.0624 24.0832 8.3203 8.3251 8.3300 8.3348 8.3396 5 ^ 582 583 584 585 33 75 61 33 87 24 33 98 89 34 10 56 34 22 25 196 122 941 197 137 368 198 155 287 199 176 704 2OO 2O I 625 24.1039 24.1247 24.1454 24. 1 66 1 24.1868 8-3443 8.3491 83539 8.3587 8.3634 56 587 588 589 590 34 33 96 34 45 % 34 57 44 34 69 21 34 8 i oo 201 230 056 202 262 003 203 297 472 20 4 336 469 205 379 ooo 24.2074 24.2281 24.2487 24.2693 24.2899 8.3682 8.3730 8-3777 8.3825 8.3872 59 1 592 593 594 595 34 9 2 8l 35 4 64 35 l6 49 35 28 36 35 40 25 206 425 071 207 474 688 208 527 857 209 584 584 210 644 875 24.3105 24.33 11 24.3516 24.3721 24.3926 8.3919 8.3967 8.4014 8.4061 8.4108 596 597 598 599 600 35 S 2 16 35 64 09 35 76 04 35 88 01 36 oo oo 211 708 736 212 776 173 213 847 192 214 921 799 21 6 OOO OOO 2.4.4131 24.4336 24.4540 24-4745 24.4949 8.4155. 8.4202 8.4249 8.4296 8-4343 47 1 DRAWING AND DESIGNING. Number Square. Cube. Square Root. Cube Root. J 601 602 603 604 605 36 12 01 36 24 04 36 36 09 36 48 16 36 60 25 217 081 801 218 167 208 219 256 227 220 348 864 221 445 125 24-5 I 53 24-5357 24.5561 24.5764 24.5967 8.4390 8.4437 8.4484 8.4530 8.4577 606 607 608 609 610 36 72 36 36 84 49 36 96 64 37 08 81 37 21 oo 222 545 016 223 648 543 224 755 712 225 866 529 226 981 ooo 24.6171 24.6374 24-6577 24.6779 24.6982 8.4623 8.4670 8.4716 8.4763 8.4809 611 612 *'3 614 615 37 33 21 37 45 44 37 57 69 37 69 96 37 82 25 228 099 131 229 220 928 230 346 397 231 475 544 232 608 375 24.7184 24.7386 24.7588 24.7790 24.7992 8.4856 8.4902 8.4948 8.4994 8.5040 616 617 618 619 620 37 94 S 6 38 06 89 38 19 24 38 31 61 38 44 oo 233 744 896 234 885 113 236 029 032 237 176 659 238 328 ooo 24.8193 24.8395 24.8596 248797 24.8998 8.5086 8.5132 8.5178 8.5224 8.5270 621 622 623 624 625 3* & 4i 38 68 84 38 81 29 3 8 93 76 39 C 6 25 239 483 061 240 641 848 241 804 367 242 970 624 244 140 625 24.9199 24.9399 24.9600 24.9800 25.0000 8-53'0 8.5362 8.5408 8.5453 8.5499 626 627 628 629 630 ~63~ 632 633 * 34 635 39 '8 76 39 3 29 39 43 84 39 S 6 4i 39 60 oo '245 3H 376 246 491 883 247 673 152 248 858 189 250 047 ooo 25.0200 25.0400 25.0599 25.0799 25.0998 8.5544 8.5590 8-5635 8.5681 8.5726 39 81 61 39 94 24 40 06 89 40 19 56 40 32 25 251 239 591 252 435 968 2 53 636 137 254 840 104 256 047 875 25.1197 25.1396 25.1595 25.1794 25.1992 8.5772 8.5817 8.5862 8.5907 8.5952 636 637 638 639 640 40 44 96 40 57 69 40 70 44 40 83 21 40 96 oo 2 57 259 456 258 474 853 259 694 072 260 917 119 262 144 ooo 25.2190 25.2389 25.2587 25.2784 25.2982 8-5997 8.6043 8.6088 8.6132 8.6177 641 642 643 644 645 41 08 81 41 21 64 4i 34 49 4i 47 36 41 60 25 263 374 721 264 609 288 265 847 707 267 089 984 268 336 125 25.3180 25-3377 25.3574 25.3772 25.3969 8.6222 8.6267 8.6312 8.6357 8.6401 646 647 648 649 650 4i 73 l6 41 86 09 41 99 04 42 12 OI 42 2; oo 269 586 136 270 840 023 . 272 097 792 273 359 549 274 625 ooo 25.4165 25.4362 25.4558 25.4755 254QV1 8.6446 8.6490 8.6535 8.6579 8.6624 USEFUL TABLES AND MISCELLANEOUS INFORMATION. 4/ 1 Number,! Square. Lube. Square Root. Cube Root. <\ 65^ 653 6 54 655 42 38 01 42 51 04 42 64 09 42 77 16 42 90 25 275 894 451 277 167 808 278 445 077 279 726 264 281 on 375 255M7 2 5-5343 25-5539 2 5-5734 25-5930 8.6668 8.67.3 8.6757 8.6801 8.6845 650 657 6 5 8 659 660 43 3 36 43 l6 49 43 2 9 6 4 43 42 81 43 56 oo 282 300 416 283 593 393 284 890 312 286 191 179 287 496 ooo 25.6125 25.6320 25-65I5 25.6710 25 6905 8.6890 8.6934 8.6978 8.7022 8.7066 66 1 662 663 664 665 43 6 9 2 * 43 82 44 43 95 69 44 08 96 44 22 25 288 804 781 290 117 528 291 434 247 292 754 944 294 079 625 25.7099 25.7294 25.7488 25.7682 25.7876 8.71 10 8.7154 8.7198 8.7241 8.7285 666 667 668 669 670 44 35 S 6 44 48 89 44 62 24 44 75 61 44 89 oo 295 408 296 296 740 963 298 077 632 299 418 309 300 763 ooo 25.8070 25.8263 25.8457 25.8650 25-8844 8.7329 8.7373 8.7416 8.7460 8.7503 671 672 673 674 ^75 45 02 41 45 *5 84 45 29 29 45 42 76 45 56 25 302 III 711 303 464 448 304 82c 217 306 182 024 307 546 875 25-9 37 25.9230 25.9422 25.9615 25.9808 8.7547 8.7590 8.7634 8.7677 8.7721 676 677 678 679 680 45 6 9 76 45 83 29 45 9 6 84 46 10 41 46 24 oo 308 915 776 310 288 733 311 665 752 313 046 839 314 432 ooo 26.0000 26.0192 26.0384 26.0576 26.0768 8.7764 8.7807 8.7850 8-7893 8-7937 68 1 682 683 684 685 46 37 61 46 51 24 46 64 89 46 78 56 46 92 25 315 821 241 317 214 568 318 611 987 320 013 504 321 419 125 26.0960 26. 1 1 5 1 26.1343 26.1534 26.1725 8.7980 8.8023 8.8066 8.8109 8.8152 686 687 688 689 690 47 05 96 47 19 69 47 33 44 47 47 21 47 61 oo 322 828 856 324 242 703 325 660 672 327 082 769 328 509 ooo 26.1916 26.2107 26.2298 26.2488 26.2679 8.8194 8.8237 8.8280 8.8323 8.8366 69 1 692 693 694 695 47 74 81 47 88 64 48 02 49 48 16 36 48 30 25 329 939 37i 33i 373 888 332 812 557 334 255 384 335 702 375 26.2869 26.3059 26.3249 26.3439 26.3629 8.8408 8.8451 8.8493 8.8536 8.8578 696 697 698 699 700 48 44 16 48 58 09 48 72 04 48 86 01 49 oo oo 337 i53 S3 6 338 608 873 340 068 392 341 532 099 343 ooo ooo 26.3818 26.4008 26.4197 26.4386 26.4575 8.8621 8.8663 8.8706 8.8748 8.8790 47 15 DRA WING AND DESIGNING. Numbe Square. Cube. Square Root. Cube Roor. 701 702 703 704 705 49 14 or 49 28 04 49 42 09 49 56 16 49 70 25 344 472 101 . 345 948 408 347 428 927 348 913 664 350 402 625 26.4764 26.4953 265141 2 6.5330 26.5518 8.8833 8.8875 8.8917 8.8959 8.9001 7 06 707 708 709 710 49 8 4 3 6 49 98 49 5O 12 64 50 26 8 i 50 41 oo 351 895 816 353 393 2 43 354 894 912 356 400 829 357 911 ooo 26.5707 26 5895 26.6083 26.6271 26.6458 8.9043 8.9085 8.9127 8.9169 8.9211 711 712 713 7H 715 50 55 21 50 69 44 50 83 69 50 97 96 5 1 J 2 25 359 425 43i 360 944 128 362 467 097 3 6 3 994 344 3 6 5 5 2 5 875 26.6646 26 6833 26.7021 26.7208 26.7395 8-9253 8.9295 89337 8.9378 8.9420 716 717 7 l8 719 720 51 26 56 51 40 89 51 I 5 I 4 51 69 61 51 84 oo 367 06 i 696 368 601 813 370 146 232 37i 694 959 373 248 ooo 26.7582 26.7769 26.7955 26.8142 26.8 v8 8.9462 8.9503 8-9545 8.9587 8.9628 721 722 723 724 725 51 98 41 52 12 84 52 27 29 52 41 76 52 56 25 374 80 5 361 376 367 048 377 933 067 379 53 424 381 078 125 26.8514 26.8701 26.8887 26.9072 26.9258 8.9670 8.9711 8.9752 8.9794 89835 726 727 728 72 9 730 52 70 76 52 85 29 52 99 84 53 H 4i 53 2 9 382 657 176 384 240 583 385 828 352 387 420 489 389 017 ooo 26.9444 26.9629 26.98 1 5 27.0000 27.018; 8.9876 8.9918 8.9959 9.0000 9.0041 731 732 733 734 735 53 43 61 53 58 24 53 72 89 53 87 56 54 02 25 390 617 891 392 223 i 68 393 832 837 395 446 904 397 065 375 27.0370 27-0555 27.0740 27.0924 27.1109 9.0082 9.0123 9.0164 9.0205 9.0246 736 737 738 739 740 54 i 6 96 54 31 69 54 46 44 54 6l 21 54 76 oo 398 688 256 400 315 553 401 947 272 403 583 4'9 405 224 ooo 27.1293 27.1477 27.1662 27.1846 27.2029 9.0287 9.0328 . 9-3 6 9 9.0410 9.0450 74i 742 743 744 745 54 9 8l 55 05 64 55 2 49 55 35 36 55 5 2 5 406 869 021 408 518 488 410 172 407 411 830 784 413 493 62 5 27.2213 27.2397 27.2580 27.2764 27.2947 9.0491 9-0532 9.0572 90613 9.0654 746 747 748 749 75 55 65 16 55 80 09 55 95 04 56 10 01 56 25 oo 415 160 936 416 832 723 418 508 992 420 189 749 421 875 ooo 27.3130 27- 33 i 3 27.3496 27.3679 27.3861 9.0694 9-0735 9-0775 9.0816 9.0856 USEFUL TABLES AND MISCELLANEOUS INFORMATION. Number Square. Cube. Square Root. Cube Root. 75 [ 75 2 753 754 755 56 40 01 56 55 04 56-70 09 56 85 16 57 oo 25 423 5 6 4 75 1 425 259 008 426 957 777 428 66 i 064 430 368 875 27.4044 27.4226 27.4408 27.4591 27-4773 9.0896 9.0937 9.0977 9.1017 9- I0 57 756 757 758 759 760 57 15 3^ 57 30 49 57 45 6 4 57 60 81 57 76 oo 432 081 216 433 798 093 435 5'9 5 12 437 245 479 438 976 ooo 27-4955 27-5!36 27-5318 27.5500 27.5681 9.1098 9.1138 9.1178 9. 1 2 1 8 9.1258 761 762 763 764 765 57 91 21 58 06 44 58 21 69 58 36 96 58 52 25 440 711 08 1 442 450 728 444 194 947 445 943 744 447 697 125 27.5862 27.6043 27.6225 27.6405 27.6586 9. 1 298 9-I338 9.1378 9.1418 9.1458 766 76 7 768 769 770 58 67 56 58 82 89 58 98 24 59 *3 6l 59 29 oo 449 455 96 451 217 663 452 984 832 454 756 609 456 533 o 27.6767 27.6948 27.7128 27.7308 27.7489 9.1498 9-1537 9- '577 9.1617 9- l6 57 771 772 773 774 775 59 44 41 59 59 84 59 75 29 59 9 76 60 06 2$ 458 314 on 460 099 648 461 889 917 463 684 824 465 484 375 27.7669 27.7849 27.8029 27.8209 27.8388 9. 1 696 9.1736 9-!775 9.1815 9-1855 776 777 778 779 780 60 21 76 60 37 29 60 52 84 60 68 41 60 84 oo 467 288 576 469 097 433 470 910 952 472 729 139 474 552 ooo 27.8568 27.8747 27.8927 27.9106 27.9285 9.1894 9-933 9- T 973 9.2012 9.2052 781 782 783 784 785 60 99 6 i 61 15 24 61 30 89 6 1 46 56 61 62 25 476 379 54i 478 2ii 768 480 048 687 481 890 304 483 736 625 27.9464 27.9643 27.9821 28.0000 28.0179 9.2091 9.2130 9.2170 0.2209 9.2248 786 787 788 789 790 61 77 96 61 93 69 62 09 44 62 25 21 62 41 oo 485 587 656 487 443 403 489 33 872 491 169 069 493 039 ooo 28.0357 28.0535 28.0713 28.0891 28.1069 9.2287 9.2326 9-2365 9. 2404 9.2443 791 792 793 794 795 62 56 81 62 72 64 62 88 49 63 04 36 63 20 25 494 913 671 496 793 088 498 677 257 500 566 184 502 459 875 28.1247 28.1425 28.1603 28.1780 28.1957 9.2482 9.2521 9.2560 9.2599 9.2638 796 797 798 799 800 63 36 16 63 52 09 63 68 04 63 84 01 64 oo oo 504 358 336 506 261 573 508 169 592 510 082 399 512 ooo ooo 28.2135 28.2312 28.2489 28.2666 28.2843 9.2677 9.2716 9.2754 9-2793 9.2832 47' DKA WING AND DESIGNING. Numbe Square. Cube. Square Koot. Cube Root 80 I 802 803 804 8o S 64 i 6 01 64 32 04 64 48 09 64 64 1 6 64 80 25 513 922 401 515 849 608 517 781 627 519 718 464 521 660 125 28.3019 28.3196 28.3373 28.3549 28.3725 9.2870 9.2909 9.2948 9 .2 9 86 9-3 2 5 806 807 808 809 810 64 96 36 65 12 49 65 28 64 65 44 81 65 61 co 523 606 616 525 557 943 527 514 112 529 475 129 531 441 ooo 28.3901 28.4077 28.4253 28.4429 28.4605 9.3063 9.3102 9.3140 9-3'79 9.3217 811 812 813 Ti 4 815 65 77 21 fj 93 44 66 09 69 66 25 96 66 42 .25 533 4ii 73i 535 387 3 2 8 537 3 6 7 797 539 353 M4 54i 343 375 28.4781 28.4956 28.5132 28.5307 28.5482 9-3255 9-3294 9-333 2 9-3370 9.3408 816 817 818 819 820 66 58 56 66 74 89 66 91 24 67 07 61 67 24 oo 543 338 49 6 545 338 5 T 3 547 343 43 2 549 353 2 59 551 368 ooo 28.5657 28.5832 28.6007 28.6182 28.6356 9-3447 9-3485 9-3523 9-356i 9-3599 821 822 823 824 825 67 40 41 67 56 84 67 73 29 67 89 76 68 06 25 553 387 66 i 555 412 248 557 44i 767 559 476 224 561 515 625 28 6531 28.6705 28.6880 28 7054 28.7228 9-3637 9-3675 9-37I3 9-375 1 9'3789 826 827 828 829 830 68 22 76 68 39 29 68 55 84 68 72 41 68 89 oo 563 559 976 565 609 283 567 663 552 569 722 789 571 787 ooo 28.7402 28.7576 28.7750 28.7924 28.8097 9.3827 9-3865 9.3902 9.3940 9.3978 831 832 833 834 835 69 05 61 69 22 24 69 38 89 69 55 56 69 72 25 573 856 191 575 93 3 68 578 009 537 580 093 704 582 182 875 28.8271 28.8444 28.8617 28.8791 28.8964 9.4016 9.4053 9.4091 9.4129 9.4166 836 837 838 839 840 69 88 96 70 05 69 70 22 44 70 39 21 70 56 oo 584 277 056 586 376 253 588 480 472 59 589 7i9 592 704 ooo 28.9137 28.9310 28.9482 28.9655 28.9828 9.4204 9.4241 9.4279 9.4316 9-4354 841 842 843 844 845 70 72 81 70 89 64 71 06 49 71 23 36 71 40 2S 594 823 321 596 947 688 599 077 107 60 1 211 584 603 351 125 29.OOOO 29.0172 29.0345 29.0517 29.0689 9-439 i 9-4429 9.4466 9-4503 9.4541 846 847 848 849 850 71 57 16 71 74 09 71 91 04 72 08 01 72 25 oo 605 495 736 607 645 423 609 8co 192 611 960 049 614 125 ooo 29.0861 29.1033 29.1204 29.1376 29.1548 9-4578 9.4615 9.4652 9.4690 9.4727 USEFUL TABLES AND MISCELLANEOUS INFORMATION. 4/ Number N[iiar DRAWING AND DESIGNING. if n be the number of threads per inch. For the length of tube-end throughout which the screw-thread continues perfect the empirical formula used is T= (o.SD -j- 4.8) X where D is the actual external diameter of the tube through- out its parallel length, and is expressed in inches. Further back, beyond the perfect threads, come two having the same taper at the bottom, but imperfect at the top. The remain- ing imperfect portion of the screw-thread, furthest back from the extremity of the tube, is not essential in any way to this system of joint ; and its imperfection is simply incidental to the process of cutting the thread at a single operation. Exercise 4. Draw a section of a pipe-screw (Fig. 34) for a wrought-iron pipe 8" in diameter. Scale five times full size. FIG. 34. Construction. Draw two lines parallel to each other at a distance apart equal to the thickness of metal as given in the table ; then draw the vertical line 2 to represent the end of the pipe, and from 2 along the line I mark off 3, 4, equal to T. Taper I in 32 means an inclination of I unit in height to every 32 units in length. From the point 4 draw the line 5 at the required inclination. On the line 5 from where it intersects 2 mark off points at a distance apart equal to the pitch, and through these points with the 30 triangle draw the SCREWS, NUTS, AND BOLTS. 59 threads. The bottoms of the last 4 threads are cut off by drawing a line from the bottom of the last thread that is full at the bottom to a point on the surface of the pipe which is a distance beyond the screwed part equal to the pitch. Screw-thread Conventions. The method of drawing screws to represent their true form is shown in Fig. 28, but it is quite obvious that it is unnecessary for the drafts- man to perform this lengthy geometrical construction to indicate each screwed piece upon the drawing. Instead he adopts some convention suitable to the class of draw- ing he is making that can be quickly drawn and is generally understood to represent a screw-thread. Fig. 35, No. I, rti FIG. 35. shows a convention for a double V thread; No. 2, a single V thread; No. 3, a single square thread; No. 4, a single left-hand V thread; No. 5, a double right-hand square thread; No. 6, any V thread of small diameter; No. 7, any thread of very small diameter. The method adopted on rough drawings and sketches is shown at No. 7. The dotted lines indicate the bottom of the thread, and the distance they extend along the piece the length of the 60 DRAWING AND DESIGNING. screwed part. At Nos. I, 2, 4 are shown conventions adopted upon finished drawings to represent threaded screws of a large diameter and wide pitch. There are various ways of improving the appearance of this convention : one is by shading the lower lines of each thread, as shown in Fig. 37, and another method is to fill in completely the under side of the thread, as shown in Fig. 39. At No. 6 is shown a method adopted on working drawings to represent screw-threads upon pieces of a small diameter or large screws drawn to a small scale. Here the narrow lines indicate the top and the wide lines the bottom of the screw-thread. When a very long screw has to be represented upon a draw- ing, as is often the case with the square-threaded screw, a few threads are drawn at the beginning of the screwed part, and the length of the screw is indicated by dotted lines drawn from the bottoms of the threads. The Nut. The most common application of the screw for producing contact pressure is the bolt, used in conjunction with a nut, of which there are different forms. The form most in use is the hexagonal (Fig. 37). The standard proportions for hexagonal nuts are : H= height = diameter of bolt (d). F = distance across the flats = it^/+ i of an inch. D = distance across the corners = (ij^ + -g-") 1.155. Fig. 35 shows the true form of the curves when the end of the nut is machined to form a part of a sphere or cone. This rounding or bevelling off of the corners is called cham- fering. The radius r of the chamfering is made from i^d to 2 and radius r equal to d draw the arcs 3 to intersect the lines I and 2. These points of intersection will be the centres of the arcs of the side face. The method of finding the centres, of the curves on the end view is clearly shown on the draw- ing. Through the points where the outside diameter of the bolt intersects the top of the nut with a radius r* = d draw the arc representing the bolt-point. / FIG. 38. SCREWS, NUTS, AND BOLTS. 65 When representing small nuts or nuts drawn to a small scale, it is usual to make the distance across the angles = 2d. This method does not give the correct proportions and should only be used on nuts and bolt-heads when d is less than i" in diameter when drawn to scale. When nuts are chamfered on the upper side only, it is usual to cut the cprners parallel to the axis, thus leaving a cylindrical projection on the under side, which bears on the piece the nut is holding, as shown in Fig. 39. FIG. 39. The diameter of the cylindrical projection is equal to the distance across the flats (\\d-\- "). Exercise 7 Draw a hexagonal nut for a bolt J" in diam- eter chamfered on the upper side and finished on the under side as shown in Fig. 39. Make the distance across the angles = 2d, and draw the curves by the method shown in Fig. 38. Scale full size. Construction. Draw the semicircle i, 2 and divide it into 66 DRAWING AND DESIGNING. three equal divisions at the points i, 2, 3, 4; through these points draw perpendicular lines to intersect the top of the nut. The method of finding the centres of the arcs of the side faces will be clearly understood from Fig. 38, where r is in each case = d. Machine fastenings are most commonly effected by means of bolts, keys, or rivets. When two or more pieces have to be held together with the intention of disconnecting them again, a bolt or key is used; the rivet being used only when the connection is to be permanent. The most common form FIG. 40. 01 oolt used in general machine construction is the hexagonal, headed bolt shown in Fig. 40. Exercise 8. Draw a hexagonal headed bolt and nut in position on a cast-iron pipe-flange (Fig. 41). Make the bolt y in diameter. Scale full size. Construction. First draw the lines representing the thickness of the pipe and flanges. The angles of the nut should be clear of the fillet about J-" and the radius (r) should be at least -J". Therefore, the distance (b) will be equal to lialf the distance across the angles of the nut -\- ^" -\- r. To give the flange a proper finish, the distance (a) is made frorr, SCREWS, NUTS, AND BOLTS. O/ J" to J" greater than half the distance across the angles of the nut. The number of threads per inch will be found in Table 8. FIG. 41. The Square-headed Bolt. Fig. 42 is a cheaper make than the hexagonal and is generally used in structures of rough iron. It is sometimes, however, adopted in machine- and engine-construction generally when the head is let into a recess, as shown in Fig. 42. It is used in this instance in preference to the hexagonal head, because it is easier to make the square recess in the pattern. In Fig. 42, it is shown in combination with a square nut, the sides of which give a better gripping surface for the wrench than the hexagonal, but the latter can be screwed up in a more con- fined position, as it is only necessary to turn it through art angle of 60 to get the wrench or spanner on to the next two parallel faces; while the square nut has to be turned through an angle of 90 under the same conditions. 68 DRAWING AND DESIGNING. TABLE UNITED STATES STANDARD OF Screw-threads. Diameter of Screw. Number of Threads per Inch. Diameter at Bottom of Threads. Area at Bottom of Threads in Square Inches. Area of Bolt Body in Square Inches. 5/i6 H 2O 18 16 .185 .240 291 .027 045 .068 .049 .077 .no 7/16 14 -344 093 .150 # 13 .400 .126 .196 9/16 12 454 .162 .249 # II 507 .202 307 10 .620 302 .442 ft 9 731 .420 .601 i 8 .837 550 .785 3 7 7 .940 .065 .694 .893 994 1.227 1/8 6 .160 1-057 1.485 I# 6 .284 1.295 1.767 r* 5K 389 I.5I5 2.074 ' i# 5 .491 1.746 2.405 i# 3 .616 2.051 2.761 2 4X .712 2.302 3.142 ^ 4K .962 3.023 3-976 2* 4 2. 176 3.7I9 4.909 2# 4 2.426 4.620 5.940 3 , 3X 2.629 5-428 7.069 3% 3^ 2.879 6.510 8.296 3% 3X 3.100 7.548 9.621 3# 3 3-3I7 8.641 11.045 4 3 3.567 9.963 12.566 4X 2^ 3.798 11.329 14.186 4^ 2^ 4.028 12-753 15.904 4# 2# 4.256 14.226 17.721 5 2K 4.480 I5.763 19-635 5X 2^ 4-730 17.572 21.648 5K 2/8 4-953 19.267 23.758 5^ 2^ 5.203 21.262 25-967 6 2X 5.423 23.098 28.274 NOTE. The above table gives the sizes of the rough nuts and bolt-heads. The finished SCREWS, NUTS, AND BOLTS. 6 9 8. SCREW-THREADS, BOLTS, AND NUTS. X 5/i6 7/16 9/16 Nuts. X 19/32 11/16 25/32 % 31/32 I 2tf 37/64 9/10 3 M. --- -1 7/10 10/12 63/64 * 64 i 311 311 Heads. Tap Dn!l. 5/16 7/16 FM X 19/64 11/32 25/64 7/16 31/64 17/32 23/32 13/16 29/32 23/64 13/32 15/32 17/32 27/32 31/32 2 2X 2X 3X 3X 4X 4X Ix % 6 J/ $ 4ff 4H 5}i 7M 8 !ft Tiff 2X 2X 2X \y. 3X 4 4X 4X sX 6 Mi 2|| 3 T V 3X 3H 4 4T 3 T 4H sS sizes are: /f=^- DRA WING AND DESIGNING. Exercise 9. Draw a bolt with a square head, and nut, as shown in Fig. 42. Make the bolt i'' in diameter. Scale full size. Construction. The proportions of heads and nuts will be found in Table 8. The radius (r) is made equal to F and tangent to the top of the nut or head. A Stud-bolt consists of a bar screwed at both ends (Fig. 43), one end being screwed into the piece upon which the connection is made. The other piece is then passed over the studs and secured by a nut. To allow the nut to make a tight joint, the length of the body or plain part must always be less than the thickness of the piece into which it passes. Studs are used only when it is impossible, or at least very inconve- nient, to use an ordinary bolt. When FlG - 42. studs are screwed into cast material, the screwed part should extend into the metal at least ij times their diameter, and FIG. 43. should never be allowed to bear on the bottoms of the holes. Fig. 44 shows a stud used to secure the cylinder-cover (c) to SCREWS, NUTS. AND BOLTS. D R FIG. 44. 72 DRAWING AND DESIGNING. the cylinder. Studs are preferred to bolts for this purpose because the flanges can be made very much smaller, and the cover can be removed and replaced without disturbing the cylinder-lagging. A stud should not be placed nearer to the edge of the metal than a distance equal to (d) measured from the centre of the stud, and in steam-tight joints it is usual to make the distance (a) equal to \\d, as shown in Fig. 44- Fig. 43 shows the form of stud in general use. The body of this stud is made cylindrical and equal in diameter to the diameter of the screw. As the weakest part of the stud is at the change of section, the form of stud shown in Fig. 44, if subjected to a greater stress than it could with- stand, would break off, leaving the screwed part in the metal, but by cutting a semicircular groove of a depth = the depth of the thread on the end of the body that comes in contact with the piece into which the stud is screwed, as in Fig. 43, this part is strengthened and the stud would then break where the upper screwed part joins the body. The broken stud can then be easily removed by means of a pipe-wrench. FIG. 45. In Fig. 45, the stud has a square body which serves as a shoulder, against which the stud may be screwed up tight by menrs of a wrench applied to the square part. Studs with round bodies are screwed into position by means of a tool SCREWS. NUTS, AND BOLTS. 73 called a stud-nut; this consists of a long nut fitted with an internal screw, as shown in Fig. 46. To avoid damaging the FIG. 46. point of the stud, the bottom of the screw in the stud-nut is lined with copper. By applying a wrench to the stud-nut, the stud can be screwed into the tapped hole in the metal until stopped by the plain portion on the stud. The stud- nut can then be removed by a quick turn back. Exercise 10. Draw a section of a steam-cylinder end- flange, showing the method of securing the cylinder-cover or head (c) to the cylinder (Fig. 44). Scale full size. When a bolt-head is of such form, or in a position in which it cannot be held with a wrench to keep it from revolv- ing when screwing up the nut, the bolt is provided with some DR FIG. 47. FIG. 48. device in the body to overcome the difficulty. The spherical or button-headed bolt, shown in Fig. 47, is provided with a square part under the head, which fits into a corresponding hole in the material through which it passes. Another de- 74 DRA WING AND DESIGNING. sign used for the same purpose is shown in Fig. 48 ; this is called a snug, and consists of one or two projections forged on the neck of the bolt and made to fit a correspondingly shaped hole in the metal. Fig. 49 shows a bolt with a countersunk head and nut. The bolt is kept from revolving by a pin (/), which is driven into a hole drilled in the body of the bolt close to the head. The projecting part of the pin fits into a recess cut to receive it. The nut is provided with holes to receive the spanner used in screwing it up, and may be made equal in diameter to half the amount of metal between the bottoms of the threads FIG. 49. and the outside of the nut. The depth of the holes may be made .2$ of H, the height of the nut. The projecting part of the pin (/) is usually made square and equal to .25^. The pin (/) is sometimes screwed into the bolt to avoid its being lost when the bolt is withdrawn. The T-headed Bolt shown in Fig. 50 has the sides of the head level with the square neck or body of the bolt, and is used where there is not sufficient room to use bolts of the hexagonal or square-headed form. A common application of this form of bolt is shown in Fig. 50. SCREWS, NUTS, AND BOLTS. 75 The Tap-bolt shown in Fig. 51 makes a fastening with- out the use of a nut. The bolt is screwed into a tapped hole in one of the pieces to be connected, while the head FIG. 50. FIG. 51. presses on the other piece. This form of bolt is used in place of a stud where the piece to be connected could not, if studs were used, be passed over the projecting studs, as in a pipe-fastening where two of the faces are at an angle to each other. There is no standard for the foregoing bolt-heads and nuts, but the following proportions are in general use: h = .7d, H=d, n = .6d, I = \\d. Exercise n. Draw a spherical or button-headed bolt with. a square neck; and a head with a snug on the neck, as shown in Figs. 47 and 48. A counter sunk- headed bolt with a counter- sunk nut as shown in Fig. 49, a T-headed bolt with a square 7 6 DRA WING AND DESIGNING. neck, as shown in Fig. 50, and a tap-bolt, as shown in Fig. 51. Make d in each case = i". Scale full size. Hook-bolt. This form of bolt is used where it is im- possible or undesirable to have bolt-holes through one of the connected pieces. A common application of this bolt is fastening pieces (such as hangers) to flanged beams, as shown in Fig. 52. To keep the bolt from turning, the body is DR FIG. 52. made square in cross-section and passes into a correspond* ingly shaped hole in the connected piece. The diameter of the screw is equal to the square body. Exercise 12. Draw an ELEVATION of a hook-bolt, fasten- ing a piece to a flanged beam, as shown in Fig. 52, and PLAN of the bolt only, looking down on the bolt head. Scale full size. , NUl'S, AND BOLTS. 77 Tapered Bolts are used to facilitate fitting where it is necessary that the bolt should be a perfect fit in the hole. Fig. 53 shows a tapered bolt that is in common use in the couplings of propeller-shafts of steamships. As coupling- bolts have only to resist the shearing force, caused by the twisting strain on the shaft, the diameter of the bolt is the diameter on the line where the two flanges come to- Ttd* gether, and its strength is equal to f s . As the screwed part of the bolt has only to resist the tension due to screwing up, this part is made smaller in diameter than the small end of the tapered part. In practice, the diameter of the screwed part is generally made equal to , and the height of the nut from y to J" less than the diameter of the screw. The advan- tages gained by using tapered instead of parallel bolts for couplings are: they can be made a perfect fit in the hole, which insures that the different lengths of shaft are in better alignment, are easier withdrawn, and, owing to the diameter of the screw being much smaller than the diam- eter at the junction of the shafts (i.e., the effective diam- eter), the flanges can be made smaller. Exercise 13. Draw a tapered bolt for a marine shaft- 78 DRAWING AND DESIGNING. coupling, showing a part of the shaft-flanges, to the dimen- sions given in Fig. 53. Scale half size. Construction. Draw the centre line of the bolt, then the line showing the junction of the flanges, and on this line mark off the diameter of the bolt. From the point (a) draw the line ab 12 inches long and parallel to the axis of the bolt, and from b draw be perpendicular to ab and T 3 ^- // long, join ac which makes the required taper. The radius (r) is equal to the diameter of the bolt at the large end. Exercise 14. Draw a tapered bolt as in the preceding exercise, leaving off the parts of the shafts, and making the diameter of the bolt 3 inches, and the length of the body equal to 8 inches. Scale half size. Foundation-bolts. This class of bolts is employed for fastening engine- and machine-frames to stone, brick, or con- crete foundations. The Rag-bolt (Fig. 54). This form of bolt is fastened to stone by cutting a Lewis hole, which increases in size as it descends. The small end of the hole is made from J" to \" larger than the large end of the bolt-head. After the bolt-head is placed in the hole, the space between it and the sides of the hole is filled with molten lead or sulphur, thus securing the bolt firmly in position. The frame is cast with a projecting foot through which a hole is cored. This foot passes over the foundation-bolt and the engine- or machine- frame is held in position by the pressure of the nut. The diameter of the hole through the foot is d -\- \" . The diameter of the washer w is equal to 2d -f- \" , and the thick- ness 3 of d. The distance a is = half the diameter of the washer -\- -f". The section of the bolt-head is oblong and SCREWS, NUTS, 4ND BOLTS. 79 FIG. 54- 8O DRAWING AND DESIGNING. purposely made rough and jagged, which obviously increases the resistance the bolt offers against being withdrawn from the hole. The length L of the head (h) is usually made equal to 6d and has a taper = \^" per foot. Exercise 15. Draw a rag-bolt in elevation and plan with a part of a cast-iron engine-frame as shown in Fig. 54, making (d) i-J-" in diameter. Scale full size. Construction. Draw the centre line and the line repre- senting the top of the stone foundation, then mark off to (b) the distance which the beginning of the head is below the level of the top of the foundation, and from the point (b) find the taper on one side of the axis in the same manner as in Exercise 13. Make the top of the hole de J" greater than the large end of the bolt-head, and through (e) draw a line parallel to the side of the bolt-head be, which will represent the edge of the hole. To complete the other side of the bolt-head mark off with the dividers equal distances on the other side of the centre line. The Lewis Bolt, shown in Fig. 55, is used, in some cases, in preference to the rag-bolt, because it can be much more easily removed, which is accomplished by withdrawing the key K. The side be of the bolt-head (Ji) has a taper of Ij" per foot, while the opposite side is parallel to the axis of the bolt. The length L of the head may be made as in the design of the rag-bolt, equal to 6d. In Fig. 55, the bolt is shown holding down the pedestal shown in Fig. 54, page 79. The hole that the bolt passes through is rectangular, to allow the pedestal to move laterally. The proportions of the washer are the same as in the last exercise. The thickness (t) of the key is made SCREWS, NUTS, AND BOLTS. 3i FIG. 55. D.R. 82 DRAWING AND DESIGNING. sufficient to allow the large end of the bolt-head to pass through the small end of the hole + i" f r clearance, and the point should stop from " to \" up from the bottom of the hole. The length of the key-head is made equal to 2/, and its thickness equal to t. Exercise 1 6. Draw an ELEVATION of a Lewis bolt show- ing the method of securing it to the foundation, a section of pedestal-base and a PLAN showing the shape of the hole through which the bolt passes, as in Fig. 55- Draw also an END VIEW of the bolt leaving out the foundation-stone and pedestal-base. Make d = 2" in diameter. Scale half size. Construction. Proceed in the same manner as in the previous exercise. The distance (a) in this case should be equal to the diameter of the washer (w) + the longitudinal movement + ". Make e= a -+2 f ' t /=^+ half the "W longitudinal movement, r = \- J" '. Anchor-bolts passing through the foundation are recom- mended in preference to the rag or Lewis bolts wherever it is possible to use them. The heads are made removable, so that the bolts can be inserted from the top, and are either under the foundation or in a recess on the side, as in Fig. 56. The simplest form of removable head is made by screwing a nut upon the lower end after the bolt is in position and driving a split pin through it to keep it from working loose. The objection to this form of head, however, is that the nut cannot be removed without difficulty after it has been in place long enough to rust. The usual and most suitable form of removable head for this class of foundation-bolt is SCREWS, NUTS, AND BOLTS. FIG. 56. 84 DRA WING AND DESIGNING. shown in Fig, 56. In this design the head end is made square in section, and has a rectangular hole into which the cotter C is fitted. The bolt is kept from turning when the nut is being screwed up by the square end fitting into a corresponding hole in the washer W. To keep the cotter C from working out of place it is provided with gib-heads at the ends. As the strength of a bolt in tension is due to the area at the bottom of the thread, the body of the bolt may be reduced to this extent without reducing its strength. The proportions of the cotter and the bolt-end through which the cotter passes are b l for shear would = , but owing to the uncertainty of the longitudinal shearing resistance of the material, it is usual in practice to make it equal S, which insures ample strength. The length / of the cotter should not be less than 25+ J" and is usually made = 3^, which gives a better support to the washer W. The washer W is usually made round or square. When round, D, the diameter, will be found by the formula from which D =%d to d. The angle of the cone and hanger set-points is usually 45 or 60. Strength of Bolts. In an ordinary bolt with a V thread employed for holding two or more pieces together by the pressure due to the screwing up of the nut, the bolt would yield (i) by tension combined with a torsional stress due to the friction between the threads of the nut and those of the bolt. This combination of tension and torsion causes the bolt to part where the thread ends, because of the rapid change of section ; (2) by shearing off the threads; (3) by shearing off the bolt-head. Comparing (i) with (2) it will be found that the shearing strength of the thread on the nut is SCREWS, NUTS, AND BOLTS. II 8 9 FIG. 59. SET-SCREWS. "No. I. Regular round point, set. 44 2. Cup point, set. 1 5. Flat " * 4 4. Cup " headless. 44 5. Round point, headless. 44 6. Cone No. 7. Flat, pivot point. 41 8. Round, " " 9. Hanger, set " 44 10. Cone point. 44 ii. Necked style. Diameter 1 of screw f Threads j to inch | X 20 5/16 18 X 16 7/16 14 12 9/i6 12 II 10 9 I 8 7 7 90 DRA WING AND DESIGNING. equal to about twice the strength of the section at the bottom of the thread, but in practice it is found that when the depth of the nut is made less than .7 of the bolt diameter, the threads are injured. Bolts or studs used for face-joints on vessels subjected to internal pressure, depend upon the care exercised by the workman to leave sufficient strength to withstand the pressure after the bolt is screwed up. As the amount of strength left is an unknown and uncertain quantity, the stress upon the bolts calculated from the internal pressure should be kept very low, and no face- joints, unless very small ones, should have bolts less than -f" in diameter. In permanent joints the stress thus calculated per square inch of section of bolt at the bottom of thread should not exceed 6000 Ibs. ; and for bolts in joints frequently broken the stress should be as low as 2000 Ibs. Thus DRA WING AND DESIGNING. part of the nut may be made equal to twice the pitch of the Z7* ^/ threads. The diameter of the screw 5 , where F= distance across the flat sides of the nut, and */ nominal diameter of bolt. As there is not sufficient room on nuts under i" in diameter to use a set-screw, they are locked by partly closing the saw-cut with a hammer blow before the nut is put upon its screw. FIG. 65. Nuts Locked by Means of Set-screws. The arrange- ments shown in Fig. 65 are used on quick-moving parts of SCREWS, NUTS, AND BOLTS. 97 machines. They are neat in appearance, simple, and effect- ive when subjected to the worst conditions. In Fig. 65 the lower part of the nut is turned to form a cylindrical projec- tion which fits into a corresponding counterbore in one of the pieces connected by the bolt. Through the latter passes a set-screw S, the point of which presses on the bottom of the groove cut upon the cylindrical projection, to keep the burs raised by the set-screw from interfering with the nut being removed. The follov/ing proportions agree with general practice: //" = d -\- J"; G= diameter of set screw at 5 = \d -f '' ; the bottom of the threads ; F= 5; = if -f'; / = d\ r = half the distance across the angles of the nut-J--J". In addition to the locking device it is usual, on quick- moving parts, to extend the bolt beyond the nut. This extension E, called a pin-point, has the threads cut off and a hole drilled through it into which is fitted a split pin SP. This renders the nut secure against coming off, but does not necessarily prevent its slacking. The diameter of the split pin SPis .05^+ .13, /= 2j times the diameter of the split pin, d l = diameter at the bottom of the threads. A method of drawing split pins is shown in Fig. 69. Exercise 19. Draw a plan, front elevation and end eleva- tion of the locking arrangement, shown in Fig. 65, showing the application of the arrangement on a connecting-rod end of the form shown in Fig. 66. Make d = 4^". Scale half size. 98 DRA WING AND DESIGNING. Construction. Locate the centre lines, draw the hexagon and the part of the connecting-rod end in plan. This is as far as we can proceed without the elevation. Draw the part of the connecting-rod in front elevation and complete the locking arrangement, projecting the parts already drawn in the plan view. Taking our measurements from the plan, and projecting from the front elevation, we can complete the end elevation. We can now complete the plan from the front elevation by projecting the parts not already drawn in that view. The method of drawing the curve formed by cutting the fillet to allow the nut to bear upon a flat surface, will be understood by fol.lowing the construction lines I, 2, 3, 4, 5, 6. In drawing office practice this curve is usually drawn by an arc of a circle passing through the limiting points. All parts are dimensioned in inches. When it is undesirable to counterbore the piece upon which the nut bears, as in Fig. 65, the cylindrical portion of the nut is made to fit into the collar C, Fig. 66, which is carried upon the outer surface of the connected piece, and kept from rotating by means of the pin P. The nut is secured by the set-screw 5 passing through the collar and pressing on the bottom of the groove which is cut upon the cylindrical part of the nut. In some cases the pin P is fitted into the hole in the connected piece, but in the example shown in Fig. 66 it is screwed into the piece to avoid the risk of losing it when the nut and collar are removed. The proportions of the nut are the same as in the last exercise. The collar proportions are D = 2d, c = 28 = \d + |". The diameter of P = \d + T y. The length of P = 2 times its diameter, half of which fits into the collar. SCREWS, NUTS, AND BOLTS. 99 Exercise 20. Draw an elevation of the locking arrange- ment shown in Fig. 66. Make d= 2". Scale full size. x FIG. 66. Circular Nut-locking Device. The nut and its locking arrangement shown in Fig. 67 are used for securing the piston-rod to a cross-head of the form shown in Fig. 67. On the outer surface of the nut N, longitudinal grooves are cut, into which the projections on the spanner, employed for screwing it up, fit. The locking-plate LP consists of a plate shaped to suit the curvature of the nut, and has a projection which fits into one of the spanner grooves. The stud 5 is screwed into the surface upon which the n'ut is carried, pass- ing through the groove in the locking-plate (LP) and is pre- vented from unscrewing by making the part within the IOO \DRAWING AND DESIGNING. luare. The method of locking the nut is as >tud S is screwed into the metal at the proper FIG. 67. distance from the centre of the nut A 7 ", forming an angle with the radial line which passes through the centre of the projec- SCREWS, NUTS, AND HOLTS. IOI tion on the locking-plate equal to half the angular distance between two of the spanner slots. This allows the nut to be locked in any position. After the nut N is screwed into position, the locking-plate LP, with its projection fitting into one of the grooves, is passed over the stud until it rests upon the piece fastened by the nut N. The nut can then be locked securely by clamping the locking-plate LP, by screw- ing down N. The nut N has a cylindrical projection on the under side which fits into a corresponding recess in the piece upon which it bears. This insures that the outside of the nut is concentric with the arc which passes through the centre of the locking-plate. It also gives a greater length of nut without increasing the distance which the nut projects from the piece it is fastening. The proportions of the nut and its locking device are as follows: "-. f D = diameter across the angles of the hexagon; F = diameter across the flats of the hexagon; H=d+ i"; t = W= .04^ + .13. Make the diameter d' of the stud 5 = J" when nut N is 2" or under, and f" for all nuts over 2" in diameter. The width of the groove in the locking-plate equal to the diam- eter of the stud + T V'. The width of the square body on the stud =.d' and its length = / ". Exercise 21. Draw a fluted circular nut and locking 102 DRAWING AND DESIGNING. arrangement, as shown in Fig. 67. Make d = 6". Scale 8" to the foot. Construction. Locate the centre lines, draw the circle making the diameter F= ij^+i"- Tangent to the circle draw the line 2 to make an angle of 30 with the horizontal. Determine the radius r of the arc passing through the centre of the nut-lock and complete the plan of the nut-lock. Determine the centres of the spanner grooves by circumscrib- ing on the half of the circle I, three sides of a hexagon, as in Fig, 67. The sides of the groove are parallel to the radial lines which bisect the angles formed by the sides of the hexagon. Projecting from the plan complete the elevation. Construction lines are not to be inked in. In Fig. 68 is shown a nut-locking device used for secur- ing the piston-rod to the piston shown in Fig. 66. The nut N in this case is of cast steel and has a projection on the under side which fits into a corresponding recess in the lock- ing-plate LP, which in turn fits into a circular recess on the piston. The locking-plate has a tapped hole through it, and through this tapped hole, at right angles to its axis, the ring is cut. After the nut with its locking-plate has been screwed into place a tapered plug P is inserted into the tapped hole. This opens the saw-cut and forces the locking-plate against the sides of the circular recess on the piston. The nut is thus securely locked by the friction caused by the pressure of the locking-plate against the sides of the recess. The following proportions may be used for the nut and locking- plate : d = nominal diameter of screw; F= distance across the flats J"; SCKEWS, NUTS, AND BOLTS. 103 DRAWING AND DESIGNING. t = thickness of standard nut having the same number of threads per inch ; H = d + thickness of locking-plate ; T .09^/4- .7. The size of the pipe-tap is = \d, but need not exceed f" pipe-tap. The projection on the under side of the nut =7"+ ^V to allow the nut to bear upon the piston. W ' = twice the diameter of the tapped hole at the small end. Exercise 22. Draw the nut-locking arrangement shown in Fig. 68, showing part of the piston and piston-rod. Make d = 3" and having 5 threads per inch. Scale full size. Construction. To find the distance across the flats of the hexagon turn to Table 8, page 72, and find the thickness of a nut having 5 threads per inch by subtracting the radius of the screw from half the distance across the flats. To find the diameter of the tapped hole at the small end, turn to the table of Wrought-iron Pipes on page 57. The size of the actual outside diameter is the diameter of the tapped hole at the large end, and the hole is -fa" less in diameter for every i" of its length. Complete the drawing, substituting the dimensions in inches for the reference letters, and give the number of threads per inch on the piston-rod screw and the nominal diameter of the pipe-tap. Pin and Pin-joints. Pins connect pieces by their resist- ance to shearing at one or two cross-sections. Split Pins, when made of a uniform diameter from wire of a semicircular cross-section and provided with a head, as in Fig. 69, are used for preventing pieces from sepa- rating, while allowing a slight motion in the direction of the axis of the piece that they pass through, as in Fig. 67. SCREWS, NUTS, AND BOLTS. 105 The method of drawing split pins is clearly shown in Fig. 69. The diameter of the pin, in proportion to the diameter d of D.R. FIG. 69. the piece it passes through, may be = .05^+ .13, taking the nearest size in -fa". Taper Pins, shown in Fig. 70, are used for securing one piece to another in a- fixed position, as shown in Fig. 71. FIG. 70. They are sometimes split at the small end, and opened out in the same manner as the ordinary split pin, to prevent slacking back. The diameter of the tapered pin at the large end, in proportion to the diameter (d} of the piece through which it passes, may be made = .o6^/+ .13 and taking the nearest size from Table 10. io6 DRAWING AND DESIGNING. TABLE 10. STANDARD STEEL TAPER-PINS. Taper one-quarter inch to the foot. Number I 2 3 4 5 6 7 8 9 10 .706 Diameter at ( large end I .156 .172 193 .219 .250 .289 341 .409 492 591 Approximate ) fractional V sizes ) 5/32 11/64 3/i6 7/32 X 19/64 11/32 13/32 X 19/32 23/32 Longest limit (_ of length ) I iX i# iK 2 2X 3 1 X 3X 4/2 5X 6 A Knuckle-joint is a pin-joint used for connecting two rods in such a manner that one of them will have a rotary .*tx j * ^ -4- 3 J FIG. 71. FIG. 72. motion in one plane. The connection is made, as shown in Fig. 71, by the pin P passing through the fork, or double eye, formed on the rod R, and the single eye, on the rod R\ SCREWS, NUTS, AND BOLTS. 107 which fits into the fork. The parts of the rods near the tye and fork are either left square or have the corners taken off for a distance, which makes a part of the rod octagonal in cross-section. In the arrangement shown in Fig. 71, the pin P is allowed to turn and is kept in place by the collar C, which is secured to the turning-pin P by driving a taper-pin through it and the collar. The width W of the collar should not be less than 2j times the diameter of the taper-pin. Another method in common use for holding the turning- pin in place is to use a loose washer (W) and split pin, as shown in Fig. 72. In Fig. 73, the pin P is held against FIG. 73. turning by a taper-pin/ driven transversely through one of the eyes on the rod R and partly into the pin P. By this arrangement all the wear, due to the turning motion, is on the eye of the rod R' t which is fitted with a steel or bronze bush. IO8 DRAWING AND DESIGNING. The Proportions given in Figs. 72 and 73 make the joint stronger than the solid rod. This is necessary to allow for bending stresses produced when the pin becomes worn. Unit of proportions d. Exercise 23 Draw a PLAN, ELEVATION, and END VIEW of the joint shown in Fig. 71, showing the method of holding the pin in place by means of a split pin and washer. Make d \" Scale full size. Exercise 24 Draw a PLAN partly in section, an ELEVA- TION and SECTIONAL END VIEW (the plane of section passing through the rod at the line ab) of the knuckle joint shown in Fig. 73. Make d= ij". Scale full size. CHAPTER II. KEYS, COTTERS, AND GIBS. Keys are employed to connect wheels, cranks, cams, etc,, to shafting transmitting motion by rotation. They are generally made of wrought iron or steel, and are commonly rectangular, square, or round in cross-section. The form of key in general use is made slightly tapered and fits accurately into the key-way, offering a fractional holding power against the keyed piece moving along the shaft. The groove or part where the key fits on the shaft, and the groove into which it fits on the piece it is holding is called the key-bed, key- way or key-seat. For square or rectangular keys, when the keyed piece is stationary on the shaft, the bottom of the groove on the shaft is parallel to the axis, while that of the groove in the piece it is securing is deeper at the one end than the other to accommodate the taper of the key. Keys may be divided into three classes: I. Concave or saddle key; 2. flat key; 3. sunk key. Saddle Key. This form of key has parallel sides, but is slightly tapered in thickness and is concaved on the under side to suit the shaft, as shown in Fig. 74. As the holding power depends entirely upon the frictional resistance, due to the pressure of the key on the shaft, the saddle key is only 109 no DRAWING AND DESIGNING. adapted for securing pieces subjected to a light strain. When this key is used for securing a piece permanently, the taper is usually made I in 96, but when employed on a piece requir- ing to be adjusted, such as an eccentric, the taper is increased to i in 64 to allow the key to be more easily loosened. FIG. 74- FIG. 75- Flat Key. This form of key, Fig. 75, differs from the saddle key in that it rests on a flat surface filed upon the shaft. It makes a fairly efficient fastening, but as it drives by resisting the turning of the shaft under it, there is a tend- ency to burst the keyed-on piece. TABLE 11. DIMENSIONS OF SADDLE AND FLAT KEYS. 3/i6 7/16 5/i6 3 5/i6 5 7/16 9/16 Sunk Keys are so called because they are sunk into the shaft and the keyed-on piece, Fig. 76, which entirely pre- vents slipping. For engine construction they are usually rectangular in cross-section and made to fit the key-seat on all sides When subjected to strains suddenly applied, and KEYS, COTTERS, AND GIBS. Ill DJt. FIG. 76. in one direction, they are placed to drive as a strut, diagonally, as in Fig. 77. FIG. 77- FIG. 78. The following table, taken from Richards's " Machine Construction," agrees approximately with average practice: TABLE 12. DIMENSIONS OP' RECTANGULAR SUNK KEYS. D B T 5/32 5/i6 3/i6 7/16 9/32 2 5/i6 5/8 3 7/i 6 4 5 6 7 8 i 13/8 i% # 11/16 13/16 7/8 i In mill-work, for fastening pulleys, gear-wheels, coup- lings, etc., to shafting they are made slightly greater in depth 112 DRAWING AND DESIGNING. than breadth. For machine tools they are generally square in cross-section. The following table gives the sizes of keys used by Wm. Sellers & Co. both for shafting and machine tools: TABLE 13. n a n M a II it t/ D & i% 2 2^ 2^ 23^ 3 3 1 A 3^ B 5/16 5/i6 7/16 7/16 9/16 II/I6 11/16 11/16 11/16 T H 3 /* y 2 # ^8 X * K # D 4 4/2 5 *k 6 V/2 7 7J^ 8 B 13/16 13/16 13/16 15/16 15/16 I5A6 IT' iyV iiV T H ft # i i I 1/8 1/8 i>l Round Keys. Taper-pins (Fig. 78) are sometimes used as keys to prevent rotation where a crank or wheel is shrunk on to the end of a shaft or axle. Round keys are used in such a case because of the ease in forming the key-way, which is simply a tapered round hole drilled half into the shaft and half into the shrunk-on piece. The standard pro- portions of the pins are given on page 106. The size at the large end nearest to of the shaft diameter may be used for this purpose. Fixed Keys are used when it is undesirable to cut a long key-way on the shaft to allow the key to be driven into place after the keyed-on piece is in position. The fixed key is sunk into the shaft, as in Fig. 79, and the keyed-on piece is driven into position after the key is in place, When a keyed-on piece has to be adjusted to different positions on the shaft, to avoid the trouble of drawing a tight key in and out. it is made to slide in the key-way, and the keyed on piece is held against moving along the shaft by means of set-screws, as shown in Fig. 80. KEYS, COTTERS, AND GIBS. 1*3 -L__j 1 J. _SHAFT ~ FIG. 79. FIG. So. Sliding Feather Key. This system of keying secures the piece to the shaft, to transmit motion of rotation, and at the same time allows the keyed-on piece to move along the FEATIM KEY \ ~ - wr m L J lit. i FIG. 81. FIG. 82. shaft. They may be secured to the keyed piece and slide in a groove on the shaft, as in Fig. 81, or secured to the shaft and slide in the groove in the keyed piece, as in Fig. 79. The dimensions for this form of key may be taken from Table 13. Woodruff Keys This system of keying (Fig. 820) is used for machine tools, or wherever accurate work is of first importance. With this form of key, as the key rights itself to the groove in the keyed-on piece, there is no danger of 114 DRAWING AND DESIGNING. the work being thrown out of true by badly fitted keys, and, being deep in the shaft, it cannot turn in the key seat. FIG. 820. Key-heads. When the point of a key cannot be con- veniently reached for the purpose of driving it out, a head is formed on one end, as shown in Fig. 76, Which shows the proportions and method of construction given in RlCHARDS'S '* MACHINE CONSTRUCTION." Strength of Keys. The driving power of saddle keys or keys on flits cannot be calculated with any degree of accuracy. They are used only where "the power transmitted by the keyed on piece is small. Sunk Keys are subjected to shearing and crushing strain?, and are required (i) to transmit the whole of the power transmitted by the shaft, as in crank-shaft couplings, etc., or (2) only a part of the power transmitted by the shaft, as when fastening pulleys, eccentrics, etc. As a general rule, however, all keys are proportioned to suit the first conditions, unless where the amount of power trans- mitted by the shaft is exceedingly great in comparison with that taken off at the keyed-on piece. Let B = breadth of key; L = length of key; = radius at which key offers a resistance; 2 KEYS, COTTERS, AND GIBS. 11$ the shearing of the material which is = 9000 for wrought iron and 1 1,000 for steel. .igod a / s = modulus of the section of shaft for torsion \j2od* for wrought-iron and 2i82*/ 3 for steel shafts; R = the radius of arm through which P, the power, is transmitted. Under the first conditions the strength of a tight key would be found by the formula ...... (16) and under the second conditions by the formula f.BL^=PR ........ (17) In the system of sliding keys the crushing action on the key is greater than when the key is a tight fit in the key- way, and keys of this type should be proportioned to have the moment of shaft torsion = the moment of key shearing = moment of key crushing. Then -, . . . (18) and if we take f e = 2/ s , then T = B. In practice, however, B is generally greater than T. Length of Key. From the foregoing formulae it will be seen that the strength of the key is directly proportional to (L) the length. To find the length L when the full power of Il6 DRAWING AND DESIGNING. the shaft is to be transmitted through the key. From formula No. 1 noooBL- = 2i82<2", , 5500 substituting the value of B from Table 12 in terms of d 2182^ L = - > = I . oa. 5500 X . Hence when the shaft and the key are of the same material, the length (L) of the common key (Table 12) should not be less than i.6d. When the hub of the keyed-on piece is so short that one key has not sufficient strength, two or more keys are used. Where two keys are used they should be placed at right angles to each other. By this arrangement the keyed-on piece is held upon three points, which prevents it from rocking upon the shaft when the shaft is not a tight fit in the hole. are keys employed to connect pieces which are subjected to tensile and compressive forces. They are driven trans- versely through one or both of the connected pieces and transmit power by a resistance to shearing at two cross- sections. The cotters are usually made rectangular in cross- section, and the ends rounded, as shown in Fig. 83. The cotter-way with the rounding ends is generally adopted, as it is easier to make, which is done by drilling two KEYS, COTTEXS, AND GIBS. 1 1/ holes of a diameter equal to the thickness of the cotter and cutting out the metal between them. Again, this form of cotter-way does not weaken the cottered pieces to quite the same extent as when the corners are left sharp. The cotters, however, are not so easily fitted into cotter-ways with round ends, and for that reason some engineers make the cotters of rectangular cross-section, fitted into corresponding cotter* ways. FIG. 83. Taper of Cotters. When cotters are employed as a means of adjusting the length of the connected pieces, or for drawing them together, they are made tapered in width, as in Fig. 83, but when used as a holding-piece only, the sides are parallel, as in Fig. 56. When tapered cotters depend upon the friction between their bearing-surfaces for retaining Il8 DRAWING AND DESIGNING. them in position the taper should not be more than I in 24 (i" P er f ot )' but where special means are employed for holding the cotter against slacking, the taper may be made as great as I in 6 (2" per foot). Forms and Proportions of Cotter-joints. When the fastening is subjected to tension only, the arrangement shown in Fig. 84 is used for securing two pieces together by means of a cotter. Fig. 83 shows a method of fastening two rods, R and R ', together to resist thrust and tension. The joint is made by fitting the end of the rod R into a socket ^ formed on the end of the rod R', and through the socket and rod end driving a cotter until the collar C bears against the socket end. As a cotter-joint is proportioned to withstand the greatest longitudinal force transmitted by the rod, all parts will there- fore be proportional to the diameter d^ of the rod, unless where the dimensions of the rod are increased to insure stiff- ness. The following proportions are in accordance with good practice: b t breadth of cotter = 1.3^,; t, thickness of cotter = .3^; ^d, diameter of pierced rod = 1.2^; D, diameter of socket in front of cotter = 2.4^ or 2^. /}, , diameter of socket behind cotter = 2^,; Z> 3 , diameter of collar on rod R = i.5<^, ; t, thickness of collar on rod R J^; /, the length of the rod and socket beyond the cotter = from KEYS, COTTERS, AND GIBS. When d is known the diameter of the solid rod (d^ = The clearance c may be made ". The cotter need not extend beyond the greatest diameter of the socket more than " when driven home. Fig. 84 shows an arrangement often used for securing an engine piston-rod to the piston. Here, instead of having a collar 'on the rod R to resist the thrust, the rod-end is tapered. FIG. 84. FIG. 85. In Fig. 85, the pierced part of the rod has a smaller diameter than the solid rod. Such a condition is possible when the diameter of the rod is increased in consequence of its having to resist buckling stresses. The joint being sub- jected only to tension and compression, the rod would under these conditions be excessively strong if proportioned to the diameter of the solid rod. We must therefore find the diameter (d,) and proportion the joint independently of the actual rod diameter, d, is found by the formula from which d. ~ =: - (19) V / - j ~tj i . Where P is the pull on the rod. For steel rods/, may be taken at 7000 and -5000 for wrought iron. The taper of the I2O DRAWING AND DESIGNING. rod-end may be made from J" to i" per foot of length, i.e., from I in 12 to I in 24. The diameter d on the tapered rod- end is taken, when the cotter-way is curved at the end, where the curve begins, as in Fig. 84, and at the end of the cotter-way when the cotter-way is rectangular. Exercise 25 Draw a SECTIONAL ELEVATION, a HALF PLAN, and HALF SECTIONAL PLAN of the cotter-joint shown in Fig. 83. Make ^=2". Scale full size. Exercise 26. Design cotter-joints suitable for fastening a steel piston-rod to the piston and cross-head, as shown in Figs. 84 and 85. Make the diameter of the rod d 9 = 2f" and assume that the rod is subjected to a load of 9000 Ibs. The rod-ends having a taper of I in 12. Scale full size. Construction. Having determined the diameter (d) of a rod suitable for resisting tensile stresses, then from ^find the other proportions of the joints, as in Exercise 25. Measure off the distances / and b along the centre line and mark off the diameter (d) at the proper point according to the shape of the cotter in cross-section, then in the manner given in the construction in connection with Exercise 13 draw the rod- end to the given taper. The construction for finding the taper need not be inked in. Complete the drawing, filling in the actual dimensions and leaving off all reference letters. COTTER AND GIB. When one of the pieces connected by the cotter is a thin strap, as in Fig. 86, a second cotter, called a gib, is used. The gib is provided with a head at the ends which project over the strap S, thus preventing it KEYS, COTTERS, AND GIBS. 121 (tne strap) from being forced open by the friction between it and the cotter as the latter is driven into place. Figs. 86 and 89 show the application of gib and cotter to strap-end connecting-rods, where R is the rod and 5 the strap. When two gibs are used, as in Fig. 88, the sliding surface on each side of the cotter is the same. Instead of having both gibs tapered, as shown in Fig. 88, one of them may be parallel and the taper all on one side of the cotter. The strength of the gib and cotter in combination is made the same as the FIG. 86. FIG. 87. FIG. 88. single cotter and should be proportional to the strap S. The working strength of the strap at the thinnest part is found by the equation from which (20) where P is the maximum pull on the re-*, T the thickness, 122 DRAWING AND DESIGNING. and B the breadth of the strap. Then as the gib and cottrr are to have the same strength as the single cotter, and as B is equal to, or a little greater than d (the diameter of the rod). t may be made equal to ,2$B and T', the thickness of the strap where it is pierced by the cotter, should not be less than 1.32". /', the distance from the gib to the end of the strap, = 2 T. /, the distance from the cotter to the end of the rod, = 1.5 T. c, the clearance, should not be less than c' (the difference between the widest part of the cotter and the width of the cotter at the top of the gib- head). The method of constructing gib-heads is shown in Fig. 87, where h y the height of the gib-head, = i \t. Cotter-locking Arrangements. A simple method, and one that is used in nearly all cases, where possible, is to screw one or two set-screws through the rod until the point or points press against the cotter. To keep the burs, raised by the point of the screw, from interfering with the motion of the cotter, the set-screw bears on the bottom of a shallow groove cut on the side of the cotter, as shown in Fig= 89. The diameter of the set-screw need not exceed f". The length of the groove is equal to the travel of the cotter + the diameter of the set-screw. The travel of the cotter is the distance from the top of the gib (or where no gib is used r from the top of the piece into which the cotter passes) to the top of the cotter when the cotter is just in place. The width of the groove j s equal to the diameter of the set-screw point, and the depth = T 1 ^-". KEYS, COTTERS, AND GIBS. 123 In Fig. 90 the cotter is locked by an upper and lower nut upon a screwed extension of the gib, which passes through a head formed on the cotter. This arrangement is used for fastening in, and may be used for forcing the cotter into, oosition. d, the diameter of the screw = /; /z, the height of the head = \\d. As the axis of the locking-screw is not parallel with the side of the cotter that is in contact with the gib, the hole in the cotter head through which the screw passes is elongated D.B. FIG. u / FIG. go. to an amount equal to the taper of the cotter in its length of travel -f- T 1 ^" for clearance. Exercise 27 Draw a SECTIONAL ELEVATION and a HALF SECTIONAL PLAN, a PLAN, and SECTIONAL END VIEW of n gib- and cotter- joint to resist a tension of 12,000 Ibs. Make the diameter (d) of the rod = 2". The cotter to have an adjust- 124 DRAWING AND DESIGNING. ment of \" with a taper = i in 8. Show the method of locking the cotter by means of a set-screw. Scale full size. Exercise 28. Draw a SECTIONAL ELEVATION AND PLAN of a double gib- and cotter-joint as shown in Fig. 88, with the locking arrangement shown in Fig. 90. The joint to be proportioned to resist a tension of 33,000 Ibs., the cotter to have an adjustment of f" and a taper of I in 10. Take the diameter of the rod = 3'' '. Scale full size. CHAPTER III. RIVETS AND RIVETED JOINTS. RIVETS are made from round bars of steel, wrought iron, copper, or brass, and are used to fasten two or more plates permanently together. The plates to be riveted are either drilled or punched with holes T V' larger in diameter than that of the rivet-shank. When the rivet is placed in position through the plates a sufficient length of shank projects beyond the plates to pro- vide for forming the rivet-point head either by hammering or by machine-pressure (see Fig. 92). Unwin calls a riveted joint the " simplest permanent fastening." Rivets are made by being pressed into shape while red-hot with rivet-making machines using dies of suitable size and form. The names and proportions of rivet-heads shown by Figs. 92 to 96 will be given later. The end of the rivet opposite to the head before riveting up is called the point and after riveting the point-head. Just before using the rivet is heated red-hot and when placed in position for hand-riveting is held there by means of a large hammer with a long handle fulcrumed at a convenient distance from the rivet and a man's weight applied at the end, while the point-head is made by two riveters either in the form of the steeple head by hammers only or the snap head (Fig. 92) by using a cup-shaped die called a snap. 125 126 DRAWING AND DESIGNING. In machine-riveting the point-head is pressed into shape by suitable dies, the motive power being either a lever, steam, hydraulic, or pneumatic pressure. Machine-riveting upsets the rivet and fills the hole much better than hand-riveting, be- cause the steady even pressure of the former is exerted uni- formly through the whole of the rivet. Hydraulic riveting is preferred to steam-riveting, because the pressure from the former can be gradually applied, while the force from the latter generally comes upon the rivet with such rapid blows that sufficient time is not allowed for the rivet to properly fill the hole. Rivet-holes punched through rigid steel plates should always be annealed after punching, because the punching in- jures the material surrounding the hole to such a dangerous extent that the elasticity of the plate is destroyed, and when the joint is subjected to strain the stress is not uniformly dis- tributed between the rivet-holes. Another difficulty with punched holes is the imperfect spacing of the rivet-holes. Drilled holes are usually more expensive than punched holes and the sharp square edge is not as favorable to the re- sistance of the rivet to shearing, but they are more accurate in size and spacing, and the resistance of the rivet to shearing can be increased by slightly rounding the edges of the holes. Calking. No riveted joint is ever perfectly steam-tight without calking. This is a process by which a narrow strip of the bevelled edge of one plate is brought into forcible contact with he plate beneath it. At #, Fig. 91, is shown the calking-tool commonly used in hand-calking, and at b an improved form of calking-tool patented bv Mr. J. W. Connery of Philadelphia and known as RIVETS AND RIVETED JOINTS. 127 the concave calking-tool from the concave finish -aven to the calked edge oT the plate. This is a favorite style of calking with locomotive-builders for high-pressure boilers. FIG. 91. Calking with pneumatic calking-hammers has become quite general in most first-class boiler-shops. Peabody and Miller in their " Steam-boilers" describe a pneumatic caik- ing-machine as follows: " In general principle it resembles a rock-drill and consists of a cylinder in which works a piston and rod on the end. of 128 DRAWING AND which is the calking-tool. Air is supplied for working the piston at a pressure of 50 or 60 Ibs. through a flexible tube. It makes about 1500 working strokes a minute T 3 /' long. The calker which is about 2^" in diameter outside and 15" long over all, is held by a workman who presses it slowly along the seam to be calked. The edge of the tool is well rounded, so as not to injure the lower plate. Work can be done four times as rapidly with the pneumatic calker as by hand." The edges of rivet-heads are not calked except when they show a leak during the process of testing. In some of the largest boiler-shops an inspector is employed part of whose duty it is when examining a boiler to discover if any of the rivets are loose. This is done by placing a finger on the under side of the suspected rivet and tapping the top of it with a small hammer made for the purpose ; if the rivet is not per- fectly tight it will be easily detected by the finger; in such a case the loose rivet is cut out and replaced by a new one. The Forms of Rivets. The standard forms of rivets in general use are: (i) the button head (Fig. 92); (2) the T" FIG. 92. RIVETS AND RIVETED JOINTS. I2 o conical head (Fig. 93); (3) the steeple head (b) (Fig. 94); (4) the steeple head (d) (Fig. 95) ; (5) the countersunk head (Fig. 96). The button head, or, as it is sometimes named, the snap head, is usually made with a machine-riveter. The conical'^ also a machine-formed head and is commonly used' with a button point-head or tail and sometimes with a steeple point. FIG. 94. 130 DRAWING AND DESIGNING. The steeple point-head is the form mostly used in hand- riveting. The countersunk point-head is only used when there is not sufficient room for one of the other forms and should never be used unless it is impossible to avoid it. It is more costly than, and not as strong as, the other forms. FIG. 95. FIG. 96. Proportions of Rivet-heads. The proportions given in the figures in terms of the diameter d are those used by the Champion Rivet Co. and agree closely with general practice. Length of Rivet-shank. The length L (Fig. 92) for countersunk point-head and 2 plates. id For countersunk point-head and 3 plates id +i" For steeple point-head For steeple point-head, large, machine-driven For button point-head The above proportions are good for ordinary boiler-plates, but, since the holes are ^" larger than the rivet, the shank RIVETS AND RIVETED JOINTS. l^l should be increased in length for thick plates to properly fill the additional annular space. The rivet-shank is usually about ^" smaller in diameter than the hole and has a slight taper toward the point. Exercise 29. Make a drawing of each style of riveting shown in Figs, 92 to 96, making / equal to f " and selecting from Table 14, page 135, the diameter of rivet. For con- ventions see page 22. Scale full size. Riveted Joints. There are in common use at least five different styles of riveted joints, viz. : the single-riveted lap- joint (Fig. 97); the double-riveted lap-joint with staggered spacing (Fig. 98) ; the double-riveted lap-joint with chain spacing (Fig. 99) ; the single-riveted butt-joint with chain spacing (Fig. 100); the double-riveted butt-joint; the mul- tiple-riveted lap-joint which has more than two rows of rivets in the lap ; the multiple-riveted butt-joint which has more than two rows of rivets on each side of the line where the plates butt together (Fig. 103). NOTATION. d = the diameter of the rivet-hole or of rivet when riveted up. / = the pitch of the rivets, i.e., the distance from the cen- tre of one rivet to the centre of the next in the same row (Fig. 97). / the distance from the centre of rivet-hole to edge of plate (Fig. 97). r = the distance between the rows on double-riveted joints. fi = the distance between outside rows of rivets on lap- joints with welt-strip and butt-joints. 132 DRAWING AND DESIGNING. m = the least distance between the edge of rivet-hole and edge of plate = margin (Figs. 97 to 103). i = the thickness of plate. /i = thickness of outside welt-strips for butt-joint. /, = thickness of inside welt-strips for butt-joint. /' = thickness of inside welt-strips for lap-joint. ft = the tensile strength per square inch of the plate in Ibs. f f = the shearing strength per square inch of the rivet in Ibs. ft = the shearing strength per square inch of the plate in Ibs. f c = the compressive or crushing strength per square inch of the plate in Ibs. '/? = the radius of boiler in inches on the outside of course of smallest diameter. ft = the width of widest welt-strip. K = the width of narrowest welt-strip. P = working pressure in Ibs. per square inch. ./> outside diameter of boiler-shell at course of smallest diameter. F = factor of safety. E = efficiency of riveted joint. T = total tensile stress. a = area of rivet-hole = .7854^*. Strength of Single-riveted Joint There are five differ- ent ways in which a single-riveted lap-joint may give way : (1) Shearing the rivet, as shown at I in Fig. 91. (2) Tearing plate along the centre line of rivets, shown at 2, 2. (3) Tearing the plate through the margin, shown at 3. RIVETS AND RIVETED JOINTS. (4) Crushing the rivet or the plate in front of the rivet (4, 4). (5) Shearing the plate in front of the rivet (5, 5). The shearing strength of the rivet nd* = X/,= X 38,000. ... (i) 4 The resistance of plate to tearing on centre line of rivet .f t ....... (2) The resistance of the plate to tearing at 3 has been found by experiment to be great enough when the distance /is made equal to i^d, and, as this rule agrees with general practice, it will be maintained throughout this work. The compressive resistance of the plate at 4 is t X d X f e . ...... (3) The resistance to shearing the plate in front of the rivet as shown at 5, 5. = 2t X / X // ..... . (4) But if the joint is made strong enough to resist shearing the rivet or tearing the margin it will be strong enough to resist shearing or crushing the plate in front of the rivet, so that the latter may generally be disregarded. The thickness of the boiler-plate is PX XX F PR The value for / should be taken as the nearest even six- teenths of an inch. Take E = .70. 134 DRAWING AND DESIGNING. The thickness of dome-sheet may be calculated by the same formula. In locomotive-boilers the thickness of tube-sheets for f" shells and over should be \" to -jV'. When shells are less than f " thick it is usual to make the thickness of tube-sheets equal to / -f- \ n '. The throat-sheet is usually made -J-" thicker than the shell to allow for extra flanging. In thick shells, f" or over, T V thicker will be sufficient. When the back tube-sheet is separated from the fire-box throat-sheet the latter should be made the same thickness as the fire-box side sheets, viz., y 5 /'- The fire-box crown-sheet is usually made " and the side and door sheets $" thick. Diameter d of Rivet-hole. It is very desirable in design- ing riveted joints to obtain the highest efficiency and still maintain a proper tightness by using a pitch not too long for calking. In determining the diameter d of the rivet it is necessary that it should be strong enough to resist both shearing and crushing. Now the resistance to shearing is while that of crushing is dtf c , which shows that the latter increases as the diameter and the former as the square of the diameter. So that if we can ob- tain such a relation between the length of the pitch and the RIVETS AND RIVETED JOINTS. 135 diameter of the rivet-hole as will give the highest efficiency consistent with tightness the crushing strength of the rivet or the plate in front of the rivet need not be considered. To our knowledge the maximum limit for the length of pitch that will insure perfect tightness of the joint has never been ascertained by experiment or test, so that we have to depend largely on existing practice in determining the ratio between d and /. Mr. Wm. M. Barr in his " Boilers and Furnaces" gives the following ratios between the thickness of the plate and the diameter of the rivet for single-riveted lap-joints, using the nearest even sixteenths of an inch, for steel plates and steel rivets (tensile strength of plates 55,000 Ibs. and shearing strength of rivets 44,625 Ibs. per square inch): TABLE 14. Pitch of Rivets. P . , A f /y t d\.ot. d Equivalent. Sq. In. Decimal. Working Fraction. I 2-75 2.40 11" 8" .6875 .75 371 442 I.8Q2 1.897 if" 1 2.17 2.OO 1 .8125 875 .518 .601 1-934 1.990 ^ f TV 1.87 1.78 9375 1. 000 .690 .7854 2.058 2.133 1; r 1.70 IT 1 ," 1.0625 .887 2.205 2rV 1.64 1.125 .994 2.298 * 1.58 ift" 1.1875 I.I08 2.386 2t" A committee of the Railway Master Mechanics' Associa- tion on riveted joints in 1895 gave the following ratios between d and /in their report for single-riveted lap-joints (steel plates of 55,000 Ibs. tensile strength and iron rivets of 38,000 Ibs. shearing strength per square inch) 1 36 DRAWING AND DESIGNING. TABLE 15. t Ratios. Mean Ratios. d > - 1 2.25 to 3.00 2.OO to 2.8O 2.OO to 2.6O 2.62 2.40 2.30 !: if f 55- 3# 1.71 to 2.42 1.75 to 2.35 2.06 2,05 jr **" 52.8^ Si.SJf TV' 1.77 to 2.33 2.05 IA" 2 yV r 1. 60 tO 2.10 1.8 5 2A " 50.2^ Pitch / of Rivets. The total strength of a boiler-plate is reduced by the rivet-holes, and the shorter the pitch the weaker the plate, but on the other hand if the pitch is too long the rivet will shear unless it is increased in diameter to correspond in shearing strength to the tensile strength of the net section of plate, but a long pitch and large rivet diameter are also limited by the fact that under high pressures such a joint is hard to make tight. The mean ratios between the thickness / of plate and the diameter d of the hole given in TaJDle 15 are recommended as good modern practice. To find the pitch / in terms of the thickness of the plate / and the diameter d\ (6) Exercise 30. Design a single-riveted lap-joint for a boiler 48" diameter and carrying a steam-pressure of 148 Ibs. per square inch, plates to be soft steel of 55,000 Ibs. tensile strength per square inch and iron rivets of a shearing strength = 38,000 Ibs. per square inch. Scale 6" = / foot. (i) Find thickness / of plate by formula 5, page 132. RIVETS AND RIVETED JOINTS. 137 (2) Determine diameter d of rivet from the mean ratio in Table 15. (3) Calculate the pitch/ by formula 6, page 136. ===i Sect ion at SS. FIG. 97. Make complete drawings as shown in Fig. 97, giving ac- tual dimensions in place of letters. Single-riveted lap-joints are commonly used for circumfer- ential seams of steam-boilers. To determine whether a circumferential seam should be single- or double-riveted let us take the following example : Diameter of boiler 48". Steam-pressure per square inch 148 Ibs. Diameter of rivet = .875". Pitch ^ 2". Thickness of plate = .375". The total force will be .7854> a P= 1809.6 X 148 = 267,820.8 Ibs. . (7) The resistance due to the rivets ^. (8) 138 DRAWING AND DESIGNING. n = the number of rivets in the circumferential seam. F= the factor of safety = 6. Therefore, substituting, we have = 285,475 and, subtracting the force from the resistance, we have a dif- ference of 17,654.2 Ibs. in favor of the rivets. The total resistance of the plate is (/> d) X * Xft X n _ 1.125 X .375 X 55>QQQ X 75 x F 6 ' (9> = 288,750 Ibs., and, subtracting the total force, 267,820 Ibs., from 288,750, there remains a difference of 20,929 Ibs. in favor of the plate, which shows that a single-riveted lap-joint is strong enough for the circumferential seams of a boiler of the above dimen- sions. Prof. Lanza referring to the efficiency of riveted joints in his "" Applied Mechanics" says: " A riveted joint of maximum efficiency should fracture the plate along the line of rivets, for it is clear that if failure occurs in any other manner, as by shearing the rivets or tear- ing out the rivet-holes, there remains an excess of strength along the line of riveting, or, in other words, along the net section of plate if in a single-riveted joint which has not been made use of; but when fracture occurs along the net section an excess of strength in other directions is imma- terial. RIVETS AND RIVETED JOINTS. 139 " If the. strength per unit of metal of the net section is constant it would be a very simple matter to compute the efficiency of any joint, as it would be merely the ratio of the net to the gross areas of the plate. " The tenacity of the net section, however, varies and this variation extends over wide limits." This being so, the pitch in the last example is slightly longer than is necessary. Double-riveted Lap-joints The arrangement of the rivets in Fig. 98 is called chain riveting and in Fig. 99 zigzag riveting. The double-riveted joint is stronger than the single-riveted joint because of the greater net section of plate and smaller diameter of rivet-holes. All longitudinal seams in steam-boilers should be at least double-riveted. Steel plates and iron rivets are considered the safer practice because of the danger of overheating the steel rivets. Wm. M. Barr in his " Boilers and Furnaces" referring to the heating of steel rivets says: "It is important that steel rivets be uniformly heated throughout, and not the points merely, as is the ordinary method of heating iron rivets; neither should they be heated as highly as iron rivets, and should never exceed a bright cherry-red. Particular attention should be given to the thickness of the fire. " If excluded from free oxygen steel cannot be burned; if the temperature is high enough it can be melted ; but burn- ing is impossible in a thick fire with moderate draft." Chain riveting with rivets of the same pitch has been found by experiment to be stronger than the zigzag riveting. See Barr's " Boilers and Furnaces," page 85, where it states that the lap is wider for chain riveting, "and no doubt the fric- 140 DRAWING AND DESIGNING. tion of this wider joint contributes towards the observed in- crease in strength," but the late D. L. Barnes and others who have tested riveted joints state that the friction between the plates cannot be considered, because long before the ulti- mate strength of the lap is reached the plates are so far apart that " you can stick a knife-blade between them." The zig- zag riveting is preferred in locomotive-boiler seams, because the joints are tighter under the high pressures carried than they would be with the wider lap of the chain riveting. 25' Section atSS. FIG. 98. Exercise 31. Make the drawings for a double-riveted lap- joint, chain riveting, like Fig. 98, except that the actual di- mensions should be given instead of the letters shown. Steel plates and iron rivets. Thickness of plate = -|", / = 3 T 5 ^ ' ', d= if, t= \%d, r' = 2d+ I", R = 30". Scale 6" = i ft, Calking need not be shown now. Calculate the efficiency of this joint in comparison with the strength of the plate. RIVETS AND RIVETED JOINTS. 141 Taking/, at 55,000 and/ at 38,000 as before, the total strength of solid plate is / X t Xft = 3-3 I2 5 X .625 X 55,000= 110,000 Ibs. The strength of the net section of plate is (/-<*)(// =(3-3125- 1. 125). 625 X 55.000 = 75,735. The shearing strength of the rivets . 7854^' X 38,000 X 2 (for 2 rivets) = 75,544, nearly equal to the strength of the net section" of the plate. Therefore the efficiency of the joint is equal to 75,544 E = = 69 per cent nearly. 110,000 The following ratios of d to / for double-riveted joints were calculated from the report of a committee on riveted joints to the Am. Ry. M. M. Association in 1895 : TABLE 16. / Ratios, Max. and Min. Ratios, Mean. d p a Area of Rivet. F. I" (-375) 2.OO to 2.66 2-33 r 3 T y .6 71.4 &" (-4375) 1.71 to 2.42 2.O6 H" 3l" .69 69.7 4" (-5) T V'(.562 5 ) 1.75 to 2.375 1.77 tO 2.22 2.063 i-99 iff & .8866 994 69.6 68.4 I" (-625) W (-6875) 1. 6O tO 2.OO 1.54 to I-909 i. 80 1.72 I*" iV 1 994 1.107 660 64.7 f" (-75) 1.416 to 1.75 1.58 IT' 3*" 1.107 62.7 To find the pitch p for double-riveted lap-joints with steel plates and iron rivets. 2 X a Xf s . 2 X a X 38,000 To find the distance between the centres of rows of rivets Fi g- 99)- 142 DRAWING AND DESIGNING. Prof. Kennedy gives for the diagonal pitch, r may be found graphically or calculated by formula T r "~- Table 17 gives the distances (r) calculated by this formula for the different sizes of rivets. Exercise 32 Make drawings as per Fig. 99 of a double- riveted lap-joint, zigzag riveting. t = ", ratio of d to t = Sectioa at SS. FIG. 99. 1. 80, R = 30". / = \\d in even T V". ^cale 6" i foot. Find r by formula II. Find/ by formula 10. Exercise 33. Make drawings similar to those in Fig. 100 showing the junction of a double zigzag-riveted longitudina' seam with a single-riveted circumferential seam for a steam- boiler, t = T V'> d calculated from the mean ratio in Table 16, / to be determined from formula 10, /' from Table 14, R = 29", r may be calculated from formula 1 1. Scale 6" ~ i foot. Actual dimensions to be placed on drawing where letters RIVETS AND RIVETED JOINTS. 143 show in figure. Steel plates and iron rivets. Finish sheet according to directions given on pages 19 and 20. Lap-joints with Inside Welt-strip. This style of rivet- ing, shown in Fig. 101, is used for both single- and double- Section a/SS i'IG. IOO. riveting and possesses some of the features of the butt- ana lap-joint. In the single-riveted joint of this kind the middle row of rivets which rivet the three thicknesses of plate should be spaced according to the rule given for p in the single- riveted lap-joints on page 136 and the spacing of the outer rows = 2/>. These joints are better than the simple lap-joint, but are Uiore expensive, and are not any better than the butt-joint {Fig. 102), which is simpler and less expensive. 144 DRA WING AND DESIGNING. The double-riveted lap-joint with inside welt (Fig. 101) may fail in any one of the following ways : (1) By shearing the rivets holding plate (a). Resistance against shearing = ^a X f, S a X 38,000. (12) (2) By tearing plate (a) along the outside row of rivets. Resistance against tearing plate as above = (2/ - d)t Xf t = (2p - a)t X 55,000. . . (13) (3) By tearing plate (a) along the intermediate row -f- the shearing of one rivet. Resistance = (2p 2a)t X 55,ooo. . . (14) Strength of solid plate = 2p X t X f t - (16) least resistance ~ strength of solid plate * -* Exercise 34. Make complete drawings of a double-riveted lap-joint with inside welt, zigzag spacing, Fig. 101. The sectional view of this figure is wrongly projected with inten- tion. Student must make correct projection. Take the remaining dimensions from the following table : TABLE 17. DOUBLE-RIVETED LAP-JOINTS WITH INSIDE WELTS. < d > m - " * Efficiency. t If f i 3 T v; 12" 87.0 85-5 8;.8 F 4" 4" *Tff 2 B " 4f'' l $ 85.0 84.3 The Double-riveted Butt-joint with Inside and Outside Welts. This style of joint is a very common one for longi- RIVETS AND RI VEILED JOINTS. 145 tudinal seams of steam-boilers with plates f" thick and over. As shown by Fig. 102, the boiler-shell is rolled to a perfect cylinder and the two edges of the plate which butt together FIG. 101. are held by two welt-strips riveted 'to each other and to the ends of the plate. In a repeating section of the plate = 2p there are two rivets in double shear and two half rivets in single shear. From experiments made by the English Admiralty and others it has been demonstrated that I rivet in double shear is equal to 2 rivets in single shear. For convenience we will assume this to be so at present, although it is quite usual for designers of steam-boilers to use a value of from 1. 75 to 1.90 146 DRAWING AND DESIGNING, for rivets in double shear; and, as the latter values agree more nearly with general practice for butt-joints, it will be neces- sary for us to modify our proportions in this regard, as will appear later. Therefore to prevent the plate a pulling out from between the welt-strips the resistance to shearing will be 5 X a X /, , there being two rivets in double shear and two half rivets in single shear = 5 areas in single shear. Resistance to tearing the net section of plate at the outer row is (2p-d)tf t . Resistance to tearing the plate between the inner row of rivets and shearing rivets in outer row is (2/ - 2. but this makes the pitch too long, because of the excess of strength in the rivets against shearing. A better proportion RIVETS AND RIVETED JOINTS. '47 and one that conforms to good practice is .85(909 2/=- tf d. /, and / a are usually equal to /, but occasionally t l will be FIG. 102. found T V' thicker than t. The Hartford Steam-boiler In- spection & Insurance Company give all welt-strips ^" less in thickness than /. For the remaining dimensions see the following table : TABLE 18. For double-riveted butt-joints with outer and inner welt-strips. t Ratio of d\.ot. Diameter of Hole. Pitch. rj = 2 / JiT Average. d P f" 9 " 2.19 1-93 1.92 1.92 F m $ 1- 3 " r f r . 12" * 1.72 iiV" 2f si" 6r iaf 148 DRA WING AND DESIGNING. Triple-riveted Butt-joint with Outer and inner Welt- Strips (Fig. 103). This joint has three rows of rivets on each side of the butt. One row passes through the boiler-plate and one welt-strip and two rows pass through the sheet and two welts. The resistance to tearing along line xx is - d)tf t 09) FIG. 103. The resistance to pulling the plate out from between the welt-strips is 9X a X/, X .85. K1VETS AND A/FETED JOINTS. 149 The resistance to tearing on line yy and shearing rivets on xx is A glance at the figure will show that this joint cannot fail along the line zz, because there are two rivets in double shear and one rivet in single shear in addition to the net section of plate, which is equal to the net section on yy. Exercise 36. Make the drawings for a triple-riveted butt- joint like Fig. 103. Steel plates and iron rivets. / = -|", d = ij". Scale 4!' = I foot. The other dimensions may be taken from the following table : TABLE 19. t d p m r * jRT Efficiency. In. In. In. In. In. In. In. Per Cent. f H 2 if .13 x li 8| I3 f 86.1 3ft i i|J 81 86.2 " if 31 }l X 5i 86.1 iS 3J ft 2"?7 ioj 86.2 " ft 4ft I 2 "Jff Ilf J8g- 86.1 ' ift 2-jV 12 J 9i 86.2 " ji 4i\ ii 2f I2| 20^- 86.3 i ift 4ft aft 12 igl. 86.2 4 4ft J i at I2f 2O 86.3 M IT B * 4* ift at I3f 2l5- 86.1 H Ift 4f at I3f 2iir 86.1 if 5 if 2! 14 22^ 86.2 f it 5 if 4 14 22^ 86.2 Calculate efficiency and if possible show where improve- ment might be made. 150 DRA WING AND DESIGNING. Exercise 37. Draw the junction of a longitudinal double- riveted butt-joint with a single-riveted circumferential lap- joint (Fig. 104). / = f", d = \y . The remaining dimen- sions may be taken from Tables 18 and 14. Scale 6" = I foot. FIG. 104. Exercise 38. Make drawings of the staying for the back- head and fire-box crown-sheet of a locomotive-boiler as shown by Fig. 105. Scale ' 3" = i foot. v" This is an example of what is known as the croivn-bar staying for locomotive-boilers. The design is suitable for an engine with cylinders 19" X 24", steam-pressure 180 Ibs. per square inch, and is similar to that used in the Empire State Ex- press locomotive designed by Wm. Buchannan, Supt. of Motive Power of the N. Y. C. R. R. A A shows a cross-section and a partial elevation of one crown-bar which consists of two- RIVETS AND RIVETED JOINTS. \^\ wrought-iron plates 5" deep X f" thick and welded together at the ends. The fire-box crown-sheet is supported by " rivets, which, passing through a washer b and between the plates A of the bar and through thimble G, is riveted on the under side of the crown-sheet as shown. These rivets are placed from 4" to 4^" apart, and as many as the crown-bars will ac- commodate at these centres, the end bolts being placed about 4" from the inside of the fire-box side sheets. As seen from the figure, the crown-bars are placed in a transverse position 152 DRAWING AND DESIGNING. ' on the crown-sheet, and as many as the longitudinal length of the sheet will allow, with equal spacing, about 4%' apart. Should these bars be insufficient to support the crown-sheet against the downv/ard pressure of the steam, which is equal to the area of the crown-sheet X the steam-pressure per square inch, then what remains is held up by .$-/z'#--stays hung from the outer shell and fastened to the crown-bars by links and pins, one link of which is shown at d in the transverse cross-section. The flat upper part of the back-head, which has no stay- bolts passing through it like those which bind the fire-box and outer shell together, as shown at D, is stiffened with a liner f" thick, the shape of which is shown by dotted lines on the transverse section, and to this liner are riveted as many lengths of 3" X 3" angle-iron as can be placed on the liner, with a clearance-space of only about " between. To these angle- irons are bolted longitudinal stay-rods I j-" in diameter similar to that shown in Fig. 106. To support that curved part of the outside shell just above the fire-box transverse stay-rods C are carried between each crown-bar, screwed through the shell on each side, and riveted over on the outside. The body of the rod is \\" in diameter and the screwed ends ij" diameter. The fire-box stay-bolts D are screwed through both fire- box and outer shell and riveted over outside and inside. It will be seen that while the screwed part of the bolt is-J" diam- eter the body is turned down to J", which reduces its stiffness and allows it to give somewhat to the unequal expansion of the fire-box and outer shell of the boiler. In certain places the stay-bolts are more liable to break than in others ; in such RIVETS AND RIVETED JOINTS. 153 places hollow stay-bolts are used, so that when broken they may be easily and quickly detected. Hollow stay-bolts have an -J" hole drilled completely through from fire-box to the outside of the outer shell, so that" 154 DRAWING AND DESIGNING. if one should break the escaping steam and water will soon inform the engineer. A detail view of one of the crown-bar thimbles is shown at G. Construction. Draw the perpendicular centre line 6' 6" from the left-hand margin, and the longitudinal centre line 4' 6" from the upper margin ; then draw the transverse and FIG. 107. longitudinal cross-sections of the boiler and construct the crown-bars and other staying as shown. It will be seen in the figure that where the plates should come together they have been left slightly apart ; this is a convention followed by draftsmen to facilitate inking without blots and to improve the appearance of the drawing. Exercise 39. Fig. 106 gives an example of a longitudinal stay-rod with details and a crow-foot for a locomotive-boiler. Make the drawings to a scale of 6" = / foot. RIVETS AND RIVETED JOINTS. 155 Exercise 40. Figs. 107 and 108 show examples of riveting the corner of a locomotive fire box ring (sometimes called a FIG. 108. 145 :rm FIG. 109. mud-ring) to the bottom of the fire-box and outer shell of the boiler. Fig. 108 is that of a large boiler 58" diameter 156 DRAWING AND DESIGNING. and carrying 180 Ibs. steam-pressure per square inch, and Fig. 107 is for a smaller boiler of 48" diameter at waist. Make drawings of both figures as shown to a scale 0/4!' = / foot. Exercise 41. Fig. 109 shows the setting of a tube in the front and back tube-sheets of a fire-tube boiler for a locomo- tive. Both ends show the tubes swedged, rolled, and beaded, and with copper ferrules between the tubes and the sheets. Make a drawing like that shown by the figure to the scale of full size. Fig. no is a section of a locomotive-boiler dome, dome- ring C and dome-base B. The base and ring are made of soft steel and formed in dies by hydraulic pressure. Fxercise 42 Make half sectional elevation, half outside elevation with transverse view and plan. Also show the curves of intersection between the dome-base and boiler, Scale 2" = I foot. CHAPTER IV. SHAFTING AND SHAFT-COUPLINGS. UNDER the term shafting may be included line shafting and axles. Line Shafting. This name is given to the long line of rotating, cylindrical or square shafting used' in workshops and factories for transmitting turning power or twisting moments from the prime movers. They are in some ways an extension of the prime mover. Such shafting is subjected to torsional and bending stresses, the latter being due to the pull of belts and the weight of pulleys, gears, levers, etc. "It is usual to make line shafting of uniform diameter throughout, as shown in Fig. ill, enlarged ends being^ only used occasionally for FIG. in. exceptional purposes. Steel of a grade containing .3 to .\% of carbon is now used almost entirely for shafting in prefer- ence to iron in this country. The commercial lengths of shafting for ordinary diameters, as from 2". to 3". run from 1 6 ft. to 30 ft., the shorter lengths being more convenient for transportation, for replacing pulleys, gears, etc. But the 158 DRAWING AND DESIGNING. longer lengths are frequently used when objections do not arise from these considerations." * Torsional or Twisting Moment. Figs. 112 and 113 show a lever, a gear wheel and pinion keyed to their respec- tive shafts; R is the radius of the lever and the pitch circle of the gear through which the power P is transmitted. This force P produces a twisting action on the shaft, and the prod- uct RP is called the torsional moment (T) on the shaft. . FIG. 112. FIG. 113. FIG. 114. So in Fig. 1 14 P is equal to the tension T, 7", , and the radius R multiplied by the force P is again equal to the torsional moment on the shaft. The torsional moment is usually expressed in inch-pounds, i.e., the force P in pounds into the radius R in inches is equal to the torsional moment in inch-pounds. The moment of resistance to torsion of a cylindrical shaft is equal to the greatest stress multiplied by the modulus of the section. Let F t be the greatest shearing stress and Z t the modulus ; then T=F s Z t (I) * A. & P. Roberts Company. SHAFTING AND SHAFT-CQUPL-1NGS. and Z t = rf'=. 19635^ ! so for cylindrical shafts T=. 19635^ and for square shafts (2) (3) ^ = diameter of the cylindrical shaft and length of side of square shaft in inches; f, = shearing strength in pounds per square inch; T = torsional moment in inch-pounds. To Find the Diameter of a Wrought -iron or Steel Shaft. If we take the resistance to shearing for iron equal to 40,000 Ibs. per square inch and for soft steel at 50,000 Ibs., and using a factor of safety of 4^, we have: For cylindrical iron shafts T = I72Ooo X 140 __ - - _ - -- 396,000 396,000 In terms of the H.P., ...;-: r = 63.057 H.P. ...... n and Besides the twisting stresses on shafts which we have alone taken account of in the above formulae, there is usually a bending moment to be considered. Let a shaft be subjected SHAFTING AND SHAFT-COUPLINGS. l6l to a torsional moment T and supporting a bending moment B\ these two stresses will be equal to a twisting moment T t =+i/(3*+T'). . . .^. (ii) 7", is called the equivalent twisting moment, and should be used in place of T in figuring the diameter of a shaft sub- jected to combined torsion and bending. The bending stresses in revolving shafts are continually changing from tension to compression and from compression to tension, so that for combined bending and twisting the factor of safety 4i given for twisting alone should be increased in the follow- ing ratio: When B is more than .3 T and not more than .67", the factor of safety should be 5 ' when over .6 T and not more than T, 5J; and when greater than T, 6. Example 2. Determine the diameter of a wrought-iron shaft which has to resist a torsional moment of 400,000 inch- pounds and a bending moment of 200,000 inch-pounds. By formula (11) the equivalent twisting moment =200,000+ 4/20p,ooo 3 +400,ooo ) = 200,000+447,213. 5=647, 2 13. 5 in.-lbs. ; and by equation (4) r - *'/ 3~V 647,213.5 - 7t Example j. When the bending moment exceeds the tor- sional moment. A non-continuous steel shaft has its bearings 8 ft. apart and carries a pulley of 50" diameter at its centre; the pulley is driven by a 10" belt, the effective weight and 1 62 DRAWING AND DESIGNING. belt-pull being 500 and 800 Ibs. respectively. What should be the diameter of the shaft ? In this case the factor of safety will be 6 and equation (4) becomes ./ r. " V '634 (12) 800 + 500 X 96 B = = 31,200 mch-lbs. ; = 800 X 25 = 20,000 inch-lbs. ; 7; = 31,200+ t'3 1, 200' + 20,000' = 68,230; and 68,230 , =3 * nearly> Deflection of Shafting. A maximum deflection of of an inch per foot of length /for continuous shafting is given as good practice by the Pencoyd Iron Works. The weight of bare shafting = 2.-6*/ a X / = W, and for loaded shafts, allowing 40 Ibs. per inch of width for the vertical pull of the belts, W = i$d*l. Then for bending stress alone, taking the modulus of transverse elasticity at 26,000,000, we can derive from authoritative formulae the maximum length between bearings /= ^873^* for bare shafts; .... (13) /= Vi/5^ 3 for loaded shafts. . . . (14) SHAFTING AND SHAFT-COUPLINGS. 163 For line-shafting hangers 8 ft. apart Thurston gives ^ d*n 8 /oo H.P. H.P. = --3d \ / f r wrought iron; H.P. - d = **/ for cold-rolled iron. V * Hollow Shafts. -Weight for weight the hollow shafts are stronger than solid shafts, because the portion of material removed is the least effective in resisting torsion. The resistance to torsion in a solid shaft and a hollow shaft will be equal when the moduli of the sections are equal. Let d be the diameter of a solid shaft, and + 4"; n = number of bolts = 3 -| (18) Taking the nearest even number, d = diameter of bolt = j . . . . (19) n 4 FIG. 118. The remaining dimensions can be found from the propor- tions given in the figure in terms of d, the diameter of the bolt. The taper of the hub may be made equal to j-" in 12". The shaft in this figure is shown sectioned for wrought iron, but in the drawing required it may be sectioned with steel color. Figs. 1 1 8 and 1 19 show plate couplings made by the Hill Clutch Company. SHAFTING AND SHAFT-COUPLINGS. 171 Exercise 46. Make drawings as required for Exercise 45 of a " Hill " plate coupling for a 4J" shaft. The dimensions for A and B to be taken from Table 20. The number of TABLE 20. DIMENSIONS FOR THE "HILL" PLATE COUPLINGS. Diameter Shaft. A B Diameter Shaft. A B Diameter Shaft. A B *& 7 6 ! 2H "i 9* 5i 17* 16 IT 7 * IU m 2T g iff tfl r^co 06 oo O M M M 6 6 6* 6* 8 8i 3A 3rV 3H 3it 4T 7 * 5 II* 12* fa* 13 14* 16* 10 10* loi IJ 12^ Ml 6 6^ 7 8 9 10 20 21 22 24 26 28 17 is* 20 22 24 26 bolts to be determined from equation (18), and the diameter of the bolts from equation (19) The remaining proportions to be worked out according to the student's judgment. The Sellers Clamp Coupling (Fig. 120). This is a special form of a muff coupling which is turned to a cylin- DRAWING AND DESIGNING. drical form on the outside, but has a double conical section inside. Two conical sleeves or bushes turned to fit the FIG. 120. inside of the muff and bored out to fit the shafts are pulled together by three bolts. The sleeves are split on one side through one of the bolt-holes, so that the more the bolts are screwed up, the tighter the sleeves clamp the shafts and bind them firmly together. Keys are also used to further prevent slipping. Exercise 47, Make the drawings shown in Fig. 121 of a Sellers clamp coupling. Scale full size. The taper of the conical sleeve is 2%' per foot of length on the diameter ; e.g., if the sleeve was 6" long and the large diameter measured 4", the small diameter would measure 2-f-". For the dimensions of the Sellers clamp coupling for various diameters of shaft, use the following table. SHAFTING AND SHAFT-COUPLINGS. 173 -r-J 174 DRA WING AND DESIGNING. TABLE 21. SELLERS CLAMP COUPLINGS. D . .4 B c ^ I d Z> ^4 - C E i I*" 4*" 5ft" 2i" si TV 3" 8V iif" 4V 6f" I* J f 51 2| 4 ^ 3^ 91 I 3s~ 5* 7| 2 6* 84 If 4| 5 I 4 5 ii i4 i8i 6 8| 10 J 1 2i 7* 9^ 31 5! | 6 14* 21* 9 ni 21 7* 10* 4s 1 6 T Frictional Coupling. Fig. 122 shows three views of Butler's frictional coupling. It is somewhat like the Sellers coupling, except that it has neither bolts nor keys, the conical bushes being held in position by round nuts threaded into the muff. The conical bushes are split at the side, and when they are in position on the shaft the split sides are at right angles to each other; this arrangement allows a key-driver to be introduced through one of these openings (after the nuts have been removed) to drive out the other bush when it is desired to remove the coupling from the shaft. The bushes are guided into position by small dowel-pins which enter short grooves provided for them inside the muff. The \" round holes shown in top and bottom at the centre of the muff are used to see when the ends of the shafts come together, for then only will the coupling be in its proper position. Exercise 48. Make complete working drawings of the Butler coupling like Fig. 122, except that the shaft shall be of steel and the sectioning shall be appropriately colored instead of hatch-lined. Scale = full size. The threads on the lock-nuts should be that number per inch used on a pipe whose outside diameter is nearest to the SHAFTING AND SHAFT-COUPLINGS. 176 DRAWING AND DESIGNING. outside diameter of the nut. The lock-nuts are screwed into position by means of a spanner wrench having projecting pieces which fit into the recesses shown in end elevation, The taper of the conical bushes may be made J" in 12" on the diameter. The faces marked with small f are to be finished. The principal proportions of this coupling are as follows: d = diameter of shaft; D = diameter of muff 2.2$d\ L = length of muff = \d. Stuart's Clamp Coupling. This coupling, shown in Fig. 123, differs from the Sellers coupling in having tapered FIG. 123. wedges instead of conical sleeves; these tapered wedges and opposite halves of each end of the muff are bored to the size of the shaft. Studs and nuts hold the wedges in place, making, on the whole, a cheap and effective coupling without the us? of keys. Exercise 49. Make drawings of a Stuart's coupling cu shown in Fig. 124 for a if shaft. Scale = full size. SHAFTING AND SHAFT-COUPLINGS. 177 178 DRAWING AND DESIGNING. The principal dimensions of this coupling for various diameters of shaft are given in the following proportions: Let d = diameter of shaft; D diameter of muff; L = length of muff. Then for shafts from I J" to 2f" diameter for shafts from 2f " up D = 3 '/,; : . .0(20) and taking f, at 50,000 for the steel shaft and 40,000 for the wrought-iron bolts, and using a factor of safety of 5, we have =0 - 55 \/5 (21) It is evident that we must find R before we can deter- mine d. The following table, by D. A. Low, gives values of d and n for solid shafts: TABLE 22. FLANGED SHAFT-COUPLINGS. D n d n d D n d n d 3 3 \\ 4 7 14 6 3& 8 2ft 4 3 4 J F 15 6 3T5 8 3s 5 4 I lV 6 i A 16 6 3lt 8 31 6 4 1 T \ 6 i 17 6 8 3v$ 7 4 2 6 18 6 4ik 8 3| 3 8 4 2i 6 ll 19 8 4 9 9 6 2 F 8 ll 20 8 4A 9 4 10 6 2$ 8 2* 21 8 9 ii 6 2| 8 22 8 4^ 9 4i 12 6 2 ?T 8 2f 23 8 4rf 9 4T 9 *r 13 6 3i 8 2f 24 8 5iV 9 4il /, = diameter of screwed part of bolt H height of nut |^, to \d^. 9 When the bolts are I J" diameter or over they are usually tapered, and tapered bolts are often made without heads. For taper of bolt use f" in 12" '. (See Exercise 13.) C = diameter of bolt centre = D + 2.25^. SHAFTING AND SHAfT-COUPUMGS. l8l While the shearing resistance of the bolts increases as the diameter C increases with the same diameter of bolt, yet to avoid the unnecessary use of material in the flanges, and secure a maximum of tightness in the coupling, the diameter C should be made as small as it is convenient to make it. / = thickness of flange = .3/^1 F*= diameter of flange =-/? -f- 3;.9 I5 / 16 . 2| 2* 3S 3/4 51 1/2 If 1/4 1/4 1/2 if 2| 4 7/8 6ir 5/8 If 1/4 3/8 1/2 I tV 3* 3 4i 15/16 6| 3/4 M ^/i6 3/8 1/2 i T V 3* 3l 4l J iV 7/8 2 5/i6 3/8 1/2 itt 4, 31 5i ll 7-i i 2 3/8 1/2 iif 4f 4 s| tl 8| i^ 2 | 3/8 7/i6 1/2 aft si 4^ tl 9 li 2* 7/i6 7/i6 5/8 5J 4f 7" J T 9 ?f lol i| a| 1/2 7/i6 5/8 2 lt 6 5i 71 I Iff I0 1 J i 2 i 1/2 9/1 6 5/8 6| 5! Sir T TS io| if 2 iV 9/16 9/1 6 5/8 3i 7 iv 7.1 6| 9-7 X T 12 if 2 i i 5/8 5/8 5/8 $ft 8* 7^ TO? 2 lV 13 r| 3s 11/16 11/16 3/4 4T 7 * 9i 8| ii| 2^ 13! 2 3i 5 13/16 3/4 3/4 I O.V 13! 2g 24 2| 13/16 13/16 3/4 5r 7 ff nl IOy 14! 2| 16^ 2 ir 4i 7/8 13/16 3/4 5 i{ Ilf 16 3 i8| 8| 4^ 15/16 15/16 7/8 6 " 13* 13 I7i 3i I9l 2 " 5 I* i of its kind. It is readily thrown in and out of gear by means of a lever and fork working in a groove shown at the right of FIG. 128. the figure. This style of clutch is adapted to the transmis- sion of motion in one direction only. 1 84 AND DESIGNING. SHAFTING AND SHAFT-COUPLINGS. 185. Exercise 52. Make drawings of a spiral-jaw coupling for a 2\" shaft, as shown in Fig. 129. Scale 6" = i foot. The Universal-joint Coupling. This most common of flexible couplings is best known as Hooke's coupling. Reuleaux says : "If not the original inventor of the Universal Joint, the Italian Cardan was the first to describe it (1501- 1576), and the Englishman Hooke (1635-1702) first applied it for the transmission of rotary motion." The practical value of this form of coupling is that it can be used to con- nect two shafts whose axes intersect, and the angle between the shafts may be varied during rotation ; this latter feature makes it suitable for ship propeller-shafts, to allow for the flexure due to the elasticity of the hull of the vessel. The coupling shown in Fig. 130 is called a double-joint coupling because of the intermediate piece shown at S, and is such that two shafts in the same plane and making equal angles with the intermediate piece (S) will rotate with uniform angular velocity. This coupling is made by the Dodge Mfg. Co., Mishawaka, Indiana. Exercise 53 Make complete drawings as shown in Fig. 130. Scale 6" = I foot. Propeller-shaft Coupling. Fig. 131 shows a. propeller- shaft coupling, designed by the Campbell & Zell Co., Baltimore, Md. The material of the coupling and coupling- nut is wrought steel. The design is neat, compact, compara- tively inexpensive, and has given good satisfaction. Exercise 54. Make drawings of Fig. 131 as shown, except that the diameter of the bolts is to be calculated by equa- tions (20) and (2 i) (so that the resistance to shearing of bolts will be equal to resistance to torsion of shaft divided by R). 1 86 DRAWING AND DESIGNING. SHAFTING AND SHAfT-COUf 'LINGS. I8 7 1 88 DRAWING AND DESIGNING. and make the diameter of the bolt-centre circle and the outer diameter of the coupling to suit. Scale 6" = i foot. In equation (20) use D equal to the mean diameter of the tapered part of the shaft, and from the result of equation (21) take the nearest commercial bolt diameter found in Table 8. CHAPTER V. PIPES AND PIPE-COUPLINGS. Pipes. Pipes are made of cast iron, wrought iron, steel, copper, and brass, and used to convey steam, water, or gas. Copper pipes are used most largely in marine work, and brass pipes or tubes are used to some extent in Europe for the fire- tube boilers of locomotives and for other purposes. Thickness of Pipes to Resist Internal Pressure. Let D = internal diameter of pipe or mean diameter for very thick pipes; / = length of pipe in inches, inside of flanges; P= internal pressure in pounds per square inch; / thickness of pipe in inches; f t = safe tensile stress in material in pounds per square inch. Then the total force tending to separate two sections of the shell = P X D X /, which is resisted by the two thick- nesses of the shell X the length of the pipe X the pressure per square inch, or 2 (/(/<); from this we get PD * = Tf . . . . ... . -co This formula gives a thickness somewhat less than is used in practice. 189 190 DRAWING AND DESIGNING. D. A. Low gives _PD , k +C ' ' and the values of k and c as follows: TABLE 24. (2) k e 4 ooo O 7 3 coo 17 OOO 40 ooo 7 OGO O I A C.Q OO For foundry reasons cast-iron pipes should never be less than -f-%" thick, and long lengths not less than T 7 ". For tables giving the thickness of pipes for various pres- sures and equivalent heads see Kent's " Mechanical Engineers* Pocket-book," p. 189. PIPE-COUPLINGS. Cast-iron Pipe-couplings The most common method of connecting cast-iron pipes is by flanges cast on the pipes as shown in Fig. 131. Exercise 55. Make drawings of a cast-iron pipe-coupling like Fig. 131. D 8". Calculate remaining dimensions by the following formulae. Scale 6" = i foot. t 0.023/2 F= 0.327; 0.56; PIPES AND PIPE-COUPLINGS. igl = 1.125/7 + 4.25; C = 1.092/7 + 2.566; d o.on/7 + 0.73; n = number of bolts = 0.78/7+ 2.56; w = weight of pipe per foot = 0.24/7* + 3/7; W= " ll flange = .ooi/7 8 + o.i/7 2 + /7 + 2. This joint has the flanges faced all over, and is used for pressures up to 75 Ibs. per square inch (170 ft. of head); for FIG. 131. higher pressures the joint may be made with a string smeared with red lead between the flanges or a lead, india-rubber, or gutta-percha ring. Exercise 56. Make drawings of a cast-iron-pipe flange coupling, Fig. 132. Inside diameter of pipe to be 9", other dimensions to be taken from Table 25. Scale 6" = I foot. DRAWING AND DESIGNING. FIG 132. TABLE 25. STANDARD CAST-IRON FLANGES. (.Dimensions are in inches.) Stress on D t n C F E d Each Holt per Sq. Inch at Bottom of / Stress on Pipe per Sq. Inch at ~ T , Thread at 200 Lbs. 200 Lbs. Pressure. 2 .409 4 4! 5/8 6 5/8 825 i/4 460 2* .429 4 5 11/16 7 5/8 1050 i/4 550 3 .448 4 6 3/4 7* 5/8 1330 i/4 690 3i .466 4 6J 13/16 8^ 5/8 2530 5/i6 7OO 4 .486 4 7i 15/16 9 3/4 2100 5/i6 800 4i .498 8 7! 15/16 9* 3/4 1430 5/i6 goo 5 .525 8 si 15/16 10 3/4 1630 3/8 1000 6 .563 8 9* i ii 3/4 2360 3/8 ic6o 7 .60 8 lOf A 121 3/4 32OO 3/8 I12O 8 639 8 * I '3i 3/4 4190 3/8 1180 9 .678 12 13 15 3/4 3610 3/8 1310 10 .713 12 Ml i ft 16 7/8 2970 3/8 1330 12 79 12- 1*1 I* 19 7/8 4280 3/8 1470 This table was adopted by a conference of committees of the A.S.M.E. and the Master Steam and Hot Water Fitters Association in July, 1894. S : zes up to 24" diameter are designed for 200 Ibs. pressure per square inch or less. PIPES AND PIPE-LOUPLINGS. I3> Spigot-and-socket Joint. This is the usual joint for pipes that have to be embedded in the earth for conveying water or gas. Fig. 143 shows a joint of this kind. About half of the space between the spigot and socket is first filled' with rope gasket and into the remaining half is poured molten* lead, which when it cools is calked tightly into the socket with a hammer and round-nosed tool. FIG 133. Exercise 56^.. Make drawings of a spigot-and-socket coup- ling for an 8" cast-iron pipe carrying a pressure of 100 Ibs. per square inch (Fig. 133). Scale 6" I foot. Same elevations and sections as in Ex. 55. Calculate the dimensions from the following proportions: D = internal diameter of pipe; PD ' . t = thickness of pipe = f- c from equation (2) ; ft 194 DRAWING AND DESIGNING. C= . i"; /== . Exercise 57. Make working drawings for the spigot-and- socket cast-iron pipe-coupling shown in Fig. 134. Internal diameter of pipe 10". Elevations, and 'sections similar to Ex. 55. Scale 6" = i foot. FIG. 134. The dimensions for this problem are to be calculated from the proportions given for Ex. 56. The turned and fitted part E is made with a taper of f" in 12" '. Exercise 58. Make working drawings of an 8" cast-iron- pipe flange coupling like Fig. 135. Elevations and sections as in Ex. 55. Scale 6" i foot. Dimensions to be taken from Table 25. PIPES AND PIPE-COUPLINGS. '95 These pipe-ends and flanges are strengthened with ribs drawn at an angle of 45 with the axis of the pipe, and the FIG. 135- joint is made by means of fitting- strips cast on the flanges equal in width to the thickness of the pipe. The faces of these strips are finished perfectly square with the axes of the pipes, and before bolting up are smeared with red lead. Exercise 59. Make drawings of the loose flange coupling for a copper pipe shown in Fig. 136. Inside diameter of pipe 8". Scale 6" = / foot. This joint is the invention of Mr. R. B. Pope of Dumbar- FIG. 136. 196 DRA WING AND DESIGNING. ton, Scotland, and is given by Low and Bevis. The flange rings may be made of cast iron, wrought iron, wrought steel, or cast steel; the latter is preferred. It is evident from Fig. 136 that the rings must be placed on the pipes before the ends are flanged. These joints have been used for steam-, feed-, and exhaust-pipes from ij-" to 36" diameter. The dimensions may be taken from the following table: TABLE 26. POPE'S PIPE COUPLINGS. (Dimensions are in inches.) D /i B C d No. of Bolts. D A B c * No. of Bolts. U 7/8 7/8 4 3/4 5 4 15/16 *i$ 7$ 7/8 8 2 7/8 I5A6 4* 3/4 5 5 I ii 8 i 8 2\ 7/8 15/16 5i 3/4 6 6 I I T? 9s i 9 3 15/16 15/16 i i | 7/8 7/8 6 6 8 l i TO* Hi 'I 9 10 4 I5/I6 ** 7/8 7 9 J IT S * r| 10 Wrought-iron and Steel Pipe-couplings. Fig. 137 shows a very efficient form of joint for wrought-iron pipes. The flanged ends of the pipes are countersunk into the cast flange rings, and the bolt-heads are also countersunk about f of an inch. Between the flanged ends of the pipes is placed a ring of lead $" thick and from f " to f " wide. Exercise 60. Make drawings of the joint shown in Fig. 137 for a 6" wrought-iron pipe. Scale full size. A should be made equal to 1.25^. / may be taken from Table 7. Remaining dimensions may be taken from Table 26. PIPES AND PIPE-COUPLINGS. 197 FIG. 137. The " Converse" joint for wrought-iron and steel pipes is shown at Fig. 138. It is manufactured by the National Tube Works, McKeesport, Pa. This joint consists of a cast-iron sleeve with a space for lead at each end ; there are also internal recesses plainly shown in Fig. 138, into which are FIG. 138. inserted rivet-heads on the ends of the pipes, and by a turn of the pipes the flanges become locked in position. Molten lead is poured into these recesses around the rivet-heads and tightly calked at the ends of the sleeves, as shown in Fig. 139. 198 DRAWING AND DESIGNING. Exercise 61. Make drawings of the Converse joint for a 7" wrought-iron pipe, according to the dimensions given in Fig. 139. Elevations and cross-sections same as in Ex. 55. Scale 6" = i foot. FIG. 139. Screwed flange Pipe -coupling. Fig. 140 shows a wrought-iron pipe-joint made by screwing cast-iron flanges on the ends of the pipes and held together by bolts. It is used by the Philadelphia & Reading Coal and Iron Co. for their steam-pipes. The threads of the screws on the pipes are made according to the Briggs standard. The lugs shown in the figure on the right-hand flange are cast on, and have their inner surfaces finished to fit the cylindrical fitting-piece on the other flange. The ring shown between the flanges is of gum rubber and makes the joint steam-tight. The pipes are made in lengths of from 16 to 20 ft. Exercise 62. Draw a screwed-flange pipe-coupling like Fig. 140 for an 8" wrought-iron pipe. Scale 6" = i foot. Dimensions may be taken from the following table : PIPES AND PIPE-COUPLINGS. 199 200 DRAWING AND DESIGNING. TABLE 27. NNECTIONS OF PHILA. & READING COAL AND IRON CO. (Dimensions are in inches.) *o i^ / - ^^ A * c E No. of Bolts. d F G H No. of Lugs. 7 3 .111 5 1/2 6 7f 4 3/4 3/4 1/2 7/8 4 3/4 3* .226 54 1/2 6| 8* 4 3/4 3/4 1/2 7/8 4 3/4 4 237 6 1/2 7* 9i 4 7/8 7/8 1/2, 7/8 4 3/4 5 259 7 1/2 8* 10* 4 7/8 7/8 I/2J 7/8 4 3/4 6 .280 8 1/2 10 12 6 7/8 i 1/2 7/8 4 3/4 7 .301 9 1/2 ii 13 6 7/8 i 1/2 7/8 4 3/4 8 .322 10 5/8 12 14 6 7/8 ii 1/2 7/8 6 I 9 .322 II 5/8 13 15 8 i T i 1/2 7/8 6 I 10 .366 12 5/8 14 i6i 8 i * 1/2 7/8 6 I Screwed-socket Coupling. Fig. 141 shows a screwed- socket coupling for a wrought-iron pipe. The socket is screwed half-way on to the end of one pipe, and the other pipe is then screwed into the remaining half of the socket. When it is not feasible to screw the long lengths of pipe into the projecting end of the socket, a screw is cut on one length of pipe and the socket is screwed fully on to this length, and when the pipes are butted together the socket is screwed back until it is half on each pipe. For other wrought-iron or steel pipe-connections, see samples in drafting-rooms. Exercise 63. Make drawings of a wrought-iron socket pipe-coupling 7" nominal diameter, to dimensions given in Fig. 141. Elevations and sections same as Ex. 55. Scale full size. Locomotive Steam-pipe Ball Joint. This joint (Fig. 142) is made between the steam branch pipe (a) and the tee- PIPES AND PIPE-COUPLINGS. 201 pipe (b) which conducts the steam from the dome and dry- pipe to the steam-chests of the cylinders on each side of the engine. The pipes are of cast iron, and the spherical joint-ring is of brass. The ball joint allows for expansion and contrac- tion and for the pipe to be set at various angles with the perpendicular and horizontal. 2O2 DRAWING AND DESIGNING. Exercise 64. Make drawings, as shown by Fig. 142, of a locomotive steam-pipe ball joint to dimensions given. Scale 6" = i foot. PIPES AND PIPE-COUPLINGS. 203 Wrought-iron Flange Pipe-coupling. Fig. 143 shows a pipe-coupling made with angle-iron for a steel pipe. The angle-iron is rolled and welded into rings and riveted to the pipes. 7/hese flanges are used for either wrought iron or T FIG. 143- steel pipes. The joint is made steam-tight by means of a lead ring inserted between the flanges as shown. Exercise 65. Make drawings of a steel pipe with wrought iron flange coupling like Fig. 143. Nominal size of pipe 8" diameter. Elevations and sections like Ex. 55. Scale 6" = I foot. Couplings for Brass and Copper Pipes. The coupling shown in Fig. 144 is used on locomotive-boiler feed-pipes, injector-pipes, etc. The sleeves (a) and (b] are brazed to the pipes, and a thin copper gasket placed between the ends of the sleeves makes the joint thoroughly tight when screwed up with the fluted nut (c). Exercise 66. Make drawings, as shown in Fig. 144, of a brass pipe-coupling, outside diameter to be 2\" . Scale full size. The dimensions may be taken from Table 28. 204 DRAWING AND DESIGNING. a TABLE 28. COUPLINGS FOR BRASS, COPPER, AND WROUGHT IRON PIPES. (Dimensions are in inches.) d - B c D E - G - j K ^ M t Ii ift I 5/i6 Itt It 2 3/4 i 2 i 3/8 5/8 2* , J H I 3/8 2 rV l| 2i 3/4 i 2 J 3/8 5/8 2 il if ifl I 3/8 2 T 5 7r 2 2 | 3/4 i 2f 3/8 5/8 3i% 2 ii 3/8 2 rl 2i 3 7/8 i^. 3| 7/16 3/4 3l 2i ii 7/16 1/2 3 Y 2^ 3i 7/8 7/8 J i 31 7/16 7/i6 3/4 3/4 4i ft PIPES AND PIPE-COUPLINGS. 205 TABLE 29. __JL 7854AB .0982BA CHAPTER VI. BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. ALL pieces employed in the transmission of power, rotating about a geometrical axis, must be supported in such a manner as to allow free rotation. The supports receive the general name of bearings, the various types being designated accord- ing to the direction of the pressure acting upon them. When the pressure is perpendicular to the axis of the shaft they are journal-bearings, and when bearings of this type and the frame- work connected with them are independent parts of a machine, they are indiscriminately called Plummer Blocks, Pillow Blocks, or Pedestals. When the pressure is parallel to the axis of the shaft and the shaft terminates at the bearing surface, Fig. 164, the bear- ing is a pivot-bearing. When this type of bearing is employed for supporting the weight of a vertical shaft, it is termed a step- or footstep-bearing. When the pressure is parallel to the axis of the shaft and the shaft is continued through the bearing, the latter is termed a collar-bearing. Wnen pivot- or collar-bearings are used on horizontal shafts they are called thrust-bearings. Journals are the parts of the shafts or axles that revolve on the bearings. They are made cylindrical, conical, or spherical, of which the cylindrical is the most common form. 206 BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. 2O/ To limit the longitudinal motion of journals the shafts are turned down or have collars forged upon them to form shoulders which come in contact with the faces of the bear- ings upon which the journals revolve. When practicable the length of journals should be about one per cent greater than that of their bearings. The' Area of a Bearing is the width of the chord of the arc in contact with the journal, multiplied by the length of the bearing. This is sometimes called the projected area, because it is the area of the contact surface projected on to a plane perpendicular to the direction of the pres- sure. Thus the area of a cylindrical journal-bearing, Fig. 164, is D X L. The area of a pivot- bearing, Fig. 278, is . The area of a collar-bearing is - (D* /V) N. Where 4 4 D is the diameter of the shaft D l is the outside diameter of collars and N the number of collars. Solid Journal-bearings. The simplest form of journal- bearing is made by drilling a hole through the frame of the machine, and to provide sufficient bearing surface the length of the bearing is increased by casting projections, which are termed bosses, upon the frame, as in Fig. 145. In this form of bearing there is no provision for wear, and the shaft can be returned to its initial position only by renewing that part of the frame that carries the shaft, or, when the hole wears oval, reboring the bearing sufficiently to fit it with a cylindri- cal sleeve or bush, as in Fig. 146. Such a bearing may be provided with a bush or lined with soft metal, and can be restored to its original condition by renewing the bush or lining. The end movement of the shaft may be limited 208 DRAWING AND DESIGNING. by making the diameter of one of the journals less than the diameter of the shaft, thereby forming a shoulder which limits the end movement in one direc- tion, and securing a separate collar to the shaft, by means of a set-screw or taper-pin, in such a position as to limit the end movement in the other direction, as shown in Fig. 145. Another method is to make the shaft of uniform section throughout its length, limiting its end motion by means of two separate collars which may be arranged in three different positions. Exercise 67. Draw two solid journal-bearings support- ing a shaft 2" in diameter, mak- ing the area of the bearing sur- face 6 square inches, and show an arrangement for limiting the end movement in either direc- tion by means of one loose collar, as shown in Fig. 145. Draw also one bearing if" in diameter with a brass bush or sleeve, as shown in Fig. 146. Make / equal .to o.-id + iV'- Parts dimensioned in decimal BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. 209 fractions are proportional to d. Complete and fill in the actual dimensions to the nearest sixteenth. Scale full size. As the shafts supported by solid journal-bearings cast with the machine-frame have to pass through one bearing to the other, this form of bearing cannot be used when there are projections on the shaft. A solid bearing can be used, how- ever, for supporting a shaft upon which there are projections, by making the bearings independent parts and securing them to the machine-frame by means of bolts. By this arrange- ment the shaft is turned down on the ends to form the journals, and one of the bearings is placed on its journal before it is secured to the frame. This form of bearing, Fig. 147, consists of a hollow cylinder cast upon a base through which bolts are passed into the machine-frame or supporting bracket. Fig. 147 shows a design of a solid journal-bearing used for supporting the valve-gear reversing-shaft of a locomotive. Such a bearing can be used for this purpose because it is subjected to a comparatively light load, while the journal has a slow and intermittent movement. The length and shape of the bearing in this design are determined by local condi- tions, the bearing being carried forward further on one side of the base than on the other to suit the shaft. The width of the base is determined by the thickness of the frame, and is provided with strips on the under side to facilitate fitting. Exercise 68. Draw an elevation and plan of a solid journal-bearing of the form shown in Fig. 147, making d = 2^" and L = 2d. The parts dimensioned in decimal fractions are proportional to d. Scale full size. 210 DRA WING AND DESIGNING. Construction. First draw the centre lines and complete the cylindrical part of the bearing. Make the distance a equal to the outside radius of the cylindrical part -\- r, the FIG. 147. radius of the fillet, which we will make equal to, say, J" -j- half the distance across the angles of the nut -f- -J" for clear- ance. The distance b can be made equal to half the distance across the angles of the nut +'. Divided Bearings Where the conditions are such that the shaft cannot be placed upon its bearings endwise, the bearings are parted and the parts fastened together by means of bolts or screws. The division is generally made on the line normal to the resultant pressures on the bearing. BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. 211 III Fig, 148 is shown what is generally termed a two-part bearing. It consists of the block P, upon which the^jodrnal is supported, and the cap C, which is secured to the block by the bolts CB. In this design the journal is intended to be lubricated with semi-liquid grease which is passed through the opening O. The bearing is lined with Babbitt metal, .c3Z> + T y thick. The holes through which the holding- down bolts pass are made oblong to horizontally adjust the pedestal. Wall Box-frames are built into the wall for the purpose of supporting a bearing for shafting which passes from one room or building to another. Fig. 149 shows a wall box- frame with an arched top to support the wall above it. On FIG. 149. the sides are cast projecting webs W which fit into the wall to keep the frame from moving endwise. The upper side of the base is provided with raised machined strips FS upon which the pedestal rests, as shown in Fig. 150, and at each end of this surface are projections S, on the sides of the frame, which are also machined. To adjust the pedestal horizontally, wooden keys of the necessary thickness are fitted between the surface 5 and the pedestal base. The height H is equal 212 DRAWING AND DESIGNING. to the highest point of the pedestal cap when raised clear of the cap-bolts CB -f- about 6" to allow the engineer to remove the cap. The length /, is equal to /, the length of the base, + the amount of horizontal adjustment allowed on the pedestal ? FIG. 150. -f- y f . The width w is made to suit the thickness of the wall, which is usually built to average from 8" to I2 r> '. The proportioning of such a piece is largely a matter of experi- ence, none of the parts being calculated for strength. Exercise 69. Draw a pedestal and wall box-frame of the designs shown in Figs. 148 and 150, placing the pedestal in position on the wall box-frame, to which it is secured by two square-headed bolts the heads of which project below the base. Make the pedestal to suit a shaft 2\" in diameter, the length L equal to $D, and the width w of the frame equal to 8". Show a half-elevation and half-sectional elevation of the pedestal, and an elevation of the wall box-frame, also a plan view of the pedestal with half of the cap removed, and in combination with this view show a section of the wall box- frame at the line AB. Make also an end view of the pedestal BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. 213 and a sectional end view of the wall box-frame. All parts of the pedestal are proportional to the diameter D of the journal* Fill in all dimensions omitted. Scale full size. Construction. Draw the vertical and horizontal centre lines of the journal, then determine the distances from centre to centre of the bolts by drawing the line I which represents the top of the cap-flange, and the arc 2, which represents the top of the cap at the centre of the bearing. The centres of the cap-bolts can now be determined by making the corners of the nuts from ^" to \" clear of the fillet which joins the lines i and 2. It is obvious that the bolts may be brought nearer together by either increasing the thickness of the cap- flange or cutting out the curve 2 around the nut, but on small pedestals for line shafting this is unnecessary. The radius r is made equal to half the distance across the angles of the nut -j- i" for finish. The distance from centre to centre of the holding-down bolts is equal to the distance b -f- the horizon- tal adjustment (equal to the length of the hole diameter of bolt) -)- the diameter of the washer-)- the radii of the fillets,, which may be made equal to about J". Determine the radius r of the arched top of the wall box-frame by making e V, the versed sine of the arc, equal to . > 4 Half the elevation is sectioned, to show more clearly the method employed to keep the Babbitt lining from turning with the shaft, the form of head on the cap-bolts, and also that the diameter of the holes through which the cap-bolts pass is greater than the bolt diameter. The plan view is^ shown with the cover removed from one side of the bearing, to show the form of that part of the bearing through which. 214 DRAWING AND DESIGNING. the shaft passes. The fitting-strips on the under side of the base are of the same proportions as in the previous exercise. When practicable it is usual to provide the piece to which the bearing is fastened with fitting-strips also, as in Fig. 150. Post Bearings. When the bearing has to be secured to a vertical surface, the base is cast on the side, as shown in Fig. 151. In the design shown in Fig. 152 it is necessary to provide the cap with four bolts because of the webs W, which are in the way cf the bolts being placed on the centre as in Fig. 148. The bearing is arranged in this case for two grease-cups, which are screwed on to the cap at the tapped holes O. The cap-bolts are kept from turning when the nuts are being screwed down by projections h cast on the under side of the box. Exercise 70. Draw the elevation and an end view half in section, as shown in Fig. 152. Draw also a plan view of the top projected from the elevation. Make D 2f ", and L = three times D. Parts not dimensioned are in the same proportion to D as in the preceding exercise. Scale half size. Construction. Draw the centre lines of the bearing, taking care t6 leave sufficient space to draw the plan. Mark off the distance that the bearing projects from the post, then determine the length and width of the base. The centres of the bolts PB should be in a distance at least equal to the radius of the washer + i" from the ends of the base. FIG. 151. BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. 21$ FIG. 148. FIG. 152. 216 DRAWING AND DESIGNING. The vertical adjustment a is made equal to ij". As the oblong holes are cored, the width e is " greater than the diameter of the bolts. Wall Brackets are employed to carry pedestals which support a horizontal shaft running parallel and near to a wall. The bracket, Fig. 153, is fastened to the wall by means of three bolts which pass through it and the wall. The pedestal f BOLTS. FIG. 153- is secured to the upper surface by square- or T-headed bolts which slide in the .Z -shaped slot 5 which runs the whole length of the bracket. By this arrangement the distance that the pedestal is from the wall can be adjusted. Exercise 71 Draw a wall bracket to the proportions given in Fig, 153. Make the slot 5 suitable for a J-" square-headed bolt. JJraw also a section, the plane of section passing through the bracket at the line AB. Scale half size. BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. SELF-ADJUSTING BEARINGS. Bearings for supporting line shafting may be divided into two classes, Rigid and Self-adjusting. When shafting is supported upon a number of rigid bearings it is essential that they all be in line, one with another, in order that the pres- sure be distributed over the entire surface of each. This is possible with bearings of the " rigid form " having compara- tively long boxes when they are rigidly supported, but when supported upon insecure foundations, which are liable to sink, the bearing will assume such a position in relation to its journal as is shown in Fig. 154, where the entire load is carried DR. FIG. ISA- upon a small portion of the bearing. Such a condition exists also where the distance between the bearings is great in com- parison with the shaft diameter, owing to the lateral deflection of the shaft by the gearing. Under such conditions the oil is forced out from between the rubbing surfaces, causing the metals to heat and seize by metallic contact. To avoid this localization of pressure, bearings with a ball-and-socket joint are used, which to a limited extent adjust themselves to the various positions of the shaft, so that 2l8 DRAWING AND DESIGNING. the axis of the bearing will always coincide with that of the journal. This form of bearing makes it practical to use a long box, thus keeping the pressure between the journal and bearing light enough to retain an unbroken film of lubricant between the rubbing surfaces. With these conditions the boxes may be made of cast-iron, which is the cheapest and, if well lubri- cated, the most desirable metal for the purpose. Many engineers, however, prefer to line these boxes with a white metal which rapidly wears and adjusts itself to any irregulari- ties on the journal, making a perfect bearing more rapidly than would be the case with a harder material. Again, with the cast-iron box, should the lubricant fail and the metals come in contact^ they will adhere and destroy the journal, while, under the same conditions, the babbitt metal would melt without materially injuring the shaft. Drop Hanger-frame. When a shaft is supported over- head and is not near a wall the bearings are carried upon a frame, called a hanger frame, which is secured to the ceiling girders. Two forms are used, the U form, which braces the bearing on both sides, as shown in Fig. 155, and the J, which braces one side only. The objection to the U form as commonly made is the difficulty in getting the shafts in and out of the hanger. This has been overcome to some extent by making the hangers open at the bottom of the U, as it were, and connect- ing the sides with bolts. The J form has the advantage of facilitating the mounting and dismounting of the shaft, but is liable to vibrate unless made comparatively heavy. BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. 2 19 Fig. 156 shows a hanger made by the Dodge Manufac- turing Co. which combines the advantages of both forms. This is attained by making the hanger open on one side and providing it with detachable links L, tl which are split, and by bolts LB, drawn together upon taper cones C, cast on the FIG. 155- hanger frames F, which match corresponding recesses in the parts of the links. These links are thus drawn up to a positive bearing and form a connection which is virtually solid, and yet they are easily removed and replaced." Fig. 1 56 shows a shaft hanger with an adjustable bearing B, which is carried between the adjusting screws P and P', called the plungers. These plungers are screwed into the frame F and serve a double pur- pose; first, they are a means of obtaining a vertical adjust- 220 DRA WING AND DESIGNING. ment ; second, they provide the sockets, with which the spherical surfaces on the box engage, to form the ball-and- socket joint. The plungers are locked in position by the set- screws S. The bearings are lubricated by filling the cups 8f - T FIG. 156. O and O' with grease, or cotton saturated with oil. The drippings of waste oil from the box are caught in the oil dish OD attached to the frame by hooking the head over the pin P, which is cast on the frame. Exercise 72. Draw the front and end elevations partly in BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. 221 section, as shown in Fig. 156, a half plan and a half-sectional plan of the side to the right, the plane of section passing through the hanger at the centre line. Scale half size. Draw also full-size sections of the frame, the plane of sec- tion passing through the hanger at the lines AB, CD, and EF. Fig. 157 shows Sellers method of forming the ball-and- socket joint on adjustable hanger bearings. The plungers P and P' have shallow threads which extend along a portion of the plungers, while the threads in the boss are cut the entire length of the boss. The plungers are locked in position by the set-screws S, the points of which are made to press against the plain part of the plungers below the threads. The plungers are cast hollow, and are used as lubricators by filling them with cotton saturated with oil, which, under ordinary conditions, is sufficient to lubricate the journal. The open- ings O and O' are filled with tallow which is solid at ordinary temperatures but melts should the bearing become heated. The outer end of the plungers has a hexagonal hole to receive a key by means of which the screw is turned when adjusting the bearing. Exercise 73. Design a hanger- frame and bearing, altering the frame shown in Fig. 156 to suit the arrangement of plungers and bearing shown in Fig. 157, and design a method of fastening a drip-catcher to the frame, other than that shown in Figs. 155 and 156, which must be so arranged that it can be easily removed and replaced. Show a complete FRONT ELEVATION, SECTIONAL END VIEW, and PLAN projected from the front elevation. Make D = 2\" , and length of bearing = 4 D. Unit oj proportions is 1.4 D -f- .2. Scale half size. 222 DRAWING AND DESIGNING. FiG. 157 BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. 223 Wall- or Post-hanger is employed to serve the same purpose as the - Wall bracket with its separate pedestal. The frames of these hangers are designed on the same FIG. 158. general lines and principles as the drop hanger-frames shown in Fig. 156, This hanger is shown in Fig. 158, with and without the double brace links, fitted with chain lubricating- bearings of the design shown in Fig. 160. Exercise 74 Draw FRONT ELEVATION and two END VIEWS as shown in Fig. 159, and a PLAN VIEW projected from the front elevation. Scale 8" to the foot. Show also full- sized sections, the plane of section passing through the frame at the lines AB, CD, and EF. DKA WING AND DESIGNING. FIG. 160. BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. 22$ Chain Lubricating-bearing. This type of bearing is de- signed to be lubricated by means of endless chains C which hang over the shaft, and as it revolves the chains revolve with it, passing through the oil in the reservoirs OR formed at each end of the box. The chain C consists of a series of parallel links which form surfaces to which the oil adheres by capillary attraction, and is carried to the shaft, spreading through the channels O C to all parts of the bearing. All surplus oil falls back into the oil reservoirs, to be used again until it becomes thick or dirty, and is then drawn off by removing the plugs 5. Exercise 75. Draw the chain lubricating-bearing shown in ,Fig. 161, showing a HALF ELEVATION and HALF SECTIONAL ELEVATION; an END VIEW projected from the right HALF SECTIONAL END VIEWS projected from the left-hand end, the plane of section passing through the bearing at the lines AB and CD, and a PLAN with half of the upper box re- moved. Scale full size. Draw also an ELEVATION AND PLAN of a part of the lubricating chain as shown in Fig. 163. Scale four times full size. Construction. Fig. 162 shows a method of finding the centres of the chain represented in the end-view in position on the shaft. In this construction the centres may be taken on the curve unless from the points I to 2, where the radius is small. At this part step off chords equal in length to the pitch of the chain, and, parallel to the chords, draw lines tangent to the arcs. The intersection of the tangent lines may be taken as the centres of the chain at that part. 226 DRAWING AND DESIGNING. BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. 22J Bushes, Steps, or Brasses are names given indiscrimi- nately to the bearings proper, i.e., the brass or bronze parts, that are in contact with and support the journal. They afford a means of taking up the lost motion due to wear, thus insur- ing that the journal with which they engage will have the re- quired motion about the given axis. They must be made of a material that will allow the journal to run in contact with it with a minimum amount of friction, and will withstand wear without wearing the journal. They must also have sufficient strength to resist the stresses that come upon them, without undue yielding. When supporting a wrought-iron or steel shaft, gun-metal, to a limited extent, fulfils all these require- ments. Other metals possess some of these qualities in a higher degree without having them all. White metals, such as ' * babbitt's " or * ' magnolia " metals, offer less frictional resistance, and their surfaces may be de- stroyed without injuring the surface of the journal (as would be the case with the bronzes), but they are too soft to be used alone unless subjected to an exceptionally light load. The position of the bush in the supporting frame depends upon the direction of the pressure. In the majority of bear- ings the resultant pressures are in one or two directions, and all lost motion can be taken up by making the bearings in two parts. The ordinary forms of two-part bearings are shown n Figs. 164 to 167. The forms shown in Figs. 164 and 165 are turned, and the supporting frame is bored with a cylin- drical hole into which the bearings are fitted. To prevent these forms from rotating with the shaft they are provided with rectangular lugs L, as in Fig. 165, or with steady pins P, as in "Fig. 164. DRAW1-NG AND DESIGNING. s BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. 229 The pins may be either cast with the bush or driven in. The forms shown in Figs. 166 and 167 are cast square or octagonal and planed to fit correspondingly shaped surfaces in the supporting frames. The square form is the cheaper, but should it become hot it is liable to be distorted, owing to the unequal distribution of metal. To facilitate fitting, and reduce machining on bearings, it is usual to support them at their ends only, by forming projecting faces F S at each end. This may be done successfully on small bearings subjected to a steady load, but on crank-shaft bearings it is advisable to support them over their length. The bearings should be divided on a line normal to the resultant pressures and, as they will wear very little at that part, they may be made thinner than at the part where the pressure is greatest. To keep the bearings from moving laterally along the shaft they are provided with flanges F, between which the supporting frame fits, as shown in Fig. 169. Sole-plates. When a pedestal is secured to masonry or brickwork it is necessary to spread the pressure upon the journal over a large surface. For this purpose a Sole- or Base-plate is employed. These usually consist of a flat cast- iron plate with a bevelled surface upon which the pedestal can be adjusted horizontally by means of the wood keys K, which are driven in between the joggles J and the ends of the pedestal base, as shown in Fig. 169. The pedestal is fast- ened to the sole-plate by the bolts P B, which pass through it and the base of the pedestal. The sole-plate is secured to the foundation by the bolts F B. The width (b) of the sole- plate should be equal to (a) width of pedestal base -f- the amount of movement of pedestal along shaft -f- say ". 23O DRAWING AND DESIGNING. Adjustable Base-plates are used for adjusting bearings vertically and horizontally. The vertical adjustment is made by sliding wedges which may be arranged either laterally (as in Fig. 168) or longitudinally. The horizontal adjustment is FIG. 168. effected by means of set-screws which take the place of the wooden keys shown in Fig 169. Pedestal or Pillow-block Bearings are used where it is necessary to have a bearing that is rigid and yet adjustable. Fig. 169 shows the ordinary form of pedestal bearing em- ployed for supporting shafting from 3" to 8" in diameter. The inner surfaces of the block P and cap C are formed to suit the outer surface of the bushes. When the block is pre- pared by hand-work to receive the bushes it is provided with fitting strips F S to facilitate fitting, but when prepared by planing, the strips are unnecessary. Some engineers make the bushes that they do not touch each other when the shaft is in position, and as the bushes wear, a space being left be- tween the cap and the pedestal, they are brought nearer to- gether by screwing down the cap C by means of the bolts C B. To keep the cap from being screwed down too far, causing the bushes to bind the journal, the space between the cap and the pedestal is sometimes filled with hard wood and the wear is taken up by filing down the hard-wood distance- BRAKINGS, SOLE-PLATES, AND WALL BOX-FRAMES. 231 pieces, thus allowing the cap to be screwed down a limited distance. Others make the bushes in contact with each other, as in Fig. 169, when the bushes fit the shaft, and when they become worn they are filed down sufficiently to compensate for the wear. When the bushes do not come in contact with, each other and no distance-piece is used, the cap-bolts should be provided with double nuts. After the pedestal has been FIG. 169. adjusted to suit the shaft, it is held in position by the bolts P B. The holes in the base- and sole-plate through which the bolts P B pass are made oblong to aljow the pedestal to- be moved along the shaft or transversely to it. To facilitate the fitting of the pedestal to the piece upon which it is carried, the base is provided with fitting-strips around the edges and across the centre. The oil-cup is usually 232 DRAWING AND DESIGNING. cast with the cap C, or screwed into the tapped hole O, Fig. 169. On pedestals having journals less than 3" in diameter O may be made to receive an oil-cup with a J" pipe tap- shank, and when over 3", with a f" pipe tap-shank. Exercise 76. Draw a general arrangement of a pedestal and sole-plate, Fig. 169, substituting the form of bearing shown in Fig. 164. Show a HALF ELEVATION and HALF SECTIONAL ELEVATION, the plane of section passing through the centre of the block ; also a HALF PLAN and HALF SEC- TIONAL PLAN, the plane of section passing transversely through the centre of the journal. From the elevation project a HALF END-ELEVATION and HALF SECTIONAL END-ELEVATION, the plane of section passing through the centre of the pedestal. Make the length of the holes through the sole-plate and pedes- tal-base sufficient to allow the pedestal to move J" in either direction. Make D = 4" and L = 2D. Scale half size. Construction. All parts dimensioned in decimals are in terms of D (the diameter of the journal). Parts marked in inches are constant. Any parts not dimensioned can be de- termined by the student from knowledge derived from previ- ous exercises. A method of drawing the joggles^ is shown at Fig. 169, which will be readily understood from the drawing. SELF-LUBRICATING PEDESTAL. In this design, Fig. 170, an oil reservoir OR is formed on the under side of the bearing, in which loose rings R arc revolved by their friction on the journal, thereby raising a c ^ntinuous supply of oil to the upper side of the ber.nng, keeping the journal thoroughly lubricated and not BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. 233 234 DRAWING AND DESIGNING. wasteful, as the surplus oil that flows out of the bearing is caught in the chambers CC and carried back to the reservoir OR, As the same oil, in this form of lubricator, is being used repeatedly, after a time it becomes dirty and thick and is then useless. By removing the screws 5 the old oil is drained off, and the reservoir can then be replenished by pouring new oil into the openings in the cover. These openings are made large, so that the engineer can see if the rings are revolving. This pedestal is designed for down pressure, and as there will be very little wear on the upper bush it is cast with the cap C. The lower bush B is a separate piece, as shown by the sketch, Fig. 171. To reduce the machining it is pro- vided with projecting faces MS, called machining strips, which fit upon corresponding projections on the pedestal,, and are made concentric with the shaft, so that to remove the bush it is not necessary to withdraw the shaft, as the bush when relieved from the load can be turned to the upper side of the journal. By this arrangement the pedestal is practically independ- ent of wear, as the bushes can be removed and re-babbitted with little trouble or expense. To keep the bush from moving laterally, flanges F are cast at each end which fit inside of the end machining strips on the pedestal. The lower bush is kept from turning by the distance piece DP, which also keeps the cap from being screwed down too far and -clamping the shaft. To take up the wear of the bushes, the distance pieces DP are planed to let the cap go further into the pedestal. To allow this, a space BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. 235 A is left between the pedestal and the cover. This space need not be greater than the thickness of the babbitt lining, which should be from f" to " thick. The cap is made to fit into the pedestal so as to sit squarely upon the journal, and does not depend upon the cap bolts to prevent lateral movement. The cap is usually held down by two bolts, but to avoid large bolts in the larger sizes of pedestals it is quite common practice to use four. The bolts in this case are made square in section, and have T heads which fit into recesses cast in the pedestal. The pedestal is held in the proper position by the bolts PB, which pass through oblong holes in the pedestal to allow for longitudinal adjustment in either direction. This form of pedestal is suitable for journals from 5" in diameter up. Length of Bearings. The frictional resistance at the surface of the journal converts the mechanical energy into heat, and, unless the area of the journal is sufficiently large to allow the heat to radiate as fast as it is generated, the temperature will become great enough to destroy the lubri- cant, allowing the rubbing surfaces to come in contact and adhere to each other. The radiating surface would be en- larged by increasing the diameter of the journal, but the velocity of the rubbing surfaces would also be increased; therefore the frictional resistance "and the space through which it acts would be greater. Thus it will be seen that ,o add to the radiating surface without increasing the work r.t the surface of the journal we must increase the length of the bearing. In a paper read before the Manchester (England) Associa- 236 DRAWING AND DESIGNING. tion of Engineers, Professor Goodman stated that the area of a bearing should be such that not more than one thermal unit of heat is generated per square inch of bearing surface per minute. Let P total pressure in pounds; /t = coefficient of friction; .S = speed of circumference of journal in feet per TtDN minute = -- ; 12 N '= number of revolutions per minute; A = area of bearing in square inches, i.e., the diam- eter WX the length L\ D = diameter of journal in inches; L = length of journal in inches; W= width of the chord in contact, in inches. Foot-pounds of work done per minute at the circumfer- ence of the journal = PpS. The thermal units per minute P^SW f and A = 77 8) j from which L = ^, in inches. With steel journals running in bronze or white-metal bearings, having continuous lubrication, ju, the coefficient of friction may be taken at .0056. Exercise 77. fDesjgn a^^^lubricating pedestal for a shaft 6" in diameter, of the > ^^wn in Fig. 170, to carry a load of 35,000 pounds, ancFrun at a speed of 300 revolutions per minute. Show a HALF ELE.VATION, HALF-SECTIONAL ELEVATION, the plane of section passing through the centre of one of the lubricators, a HALF END ELEVATION and HALF TRANSVERSE SECTION, the plane of section passing through the pede/.tal at the centre, a HALF PLAN of the left-hand side of the pedes- tal, a QUARTER PLAN with the cover (C) removed, a QUAR- BEARINGS, SOLE-PLATES, AND WALL BOX-FRAMES. TER-SECTIONAL PLAN, the plane of section passing through the centre of the shaft. Scale 3" to the foot. Make also full-size drawings of the lower bush, showing a HALF ELEVATION and HALF-SECTIONAL ELEVATION, a HALF END VIEW, and a HALF TRANSVERSE SECTION, and a plan and elevation of the ring-joint as shown. All points are proportional to the diameter (D) of the journal, except those parts which are constant for journals of various sizes. CHAPTER VII. BELT GEARING. Belts Among the many different kinds of material used for belting are leather, cotton, gutta-percha, India-rubber, canvas, camel-hair, catgut, flat wire or hemp rope, steel bands, flat chains, etc. The most common in general practice are leather and cotton, the latter often found coated with India-rubber and known as gum belts. Leather is more durable than gum under most conditions, but for main driving the latter is superior, having an adhesion which is claimed to be one third greater ihan the former. Transmission of Motion by Belts. Motion may be transmitted from one pulley to another with uniform linear velocity by means of a belt, provided there is no slipping of the belt on the pulley; i.e., regarding the belt as inextensible every part of it will have the same velocity as the outside rim of the pulley. Referring to Fig. 171, let d l and d^ be the diameter ci the driver and driven pulleys respectively, and let N^ and N be their revolutions per minute and P'the velocity of the belt. The speed of the rim of the driver = ar "i allowing 70 Ibs. per inch width of belt, then 145 -T- 70 = 2.06, say 2j". Some Practical Rules for the Transmission of Power. Richards gives the following rule for the size of driving-belts, which he says is near enough for all cases that arise in ordi- nary practice. H.P.=^. . ... . (4) Where V = the velocity of the belt in feet per minute. W = the width of the belt in feet. A = the area given to suit different conditions in the following table : TABLE 30. ; -" LEATHER BELTS SINGLE THICKNESS. i H. P On smooth iron pulleys 80 ft. On wooden pulleys 65 ft. On covered pulleys 50 ft. GUM BELTS AVERAGE THICKNESS. i H.P. On smooth iron pulleys 60 ft. On wooden pulleys. 50 ft. On covered pulleys 35 ft. 244 DRAWING AND DESIGNING. Belts should be made as wide as possible ; they are often too narrow, but never too wide. Thickness of Belts. As belts increase in width their thickness should also increase. Double belts should be used on pulleys over 12" diameter. Large belts running at very high speeds, as in electrical work, should have slots punched through them in such manner and position as to prevent air cushion. The following proportions for thickness of belt and cor- responding working tension, based on a safe working stress of 320 Ibs. per sq. in. for laced joints, are given by Unwin : TABLE 31. Thickness of belt A i A Tff i T5 1* H' Working tension in Ibs. per inch of width . 60 70 80 100 120 140 160 1 80 200 220 240 For other rules and formulae see Kent's Engineers' Pocket Book, page 876. For a safe working tension under ordinary conditions, many authorities allow only 45 Ibs. per inch of width; but according to Mr. A. W. Smith, experiments have shown that a safe tension of 70 Ibs. may be had per inch of width of belt. Proportions of Pulleys (Figs. 173 and 174). a = centre of set-screw from end of hub = a l = centre of bolt from edge of flange = b = width of belt see Example 2. B pulley face = f (b + 0.4). (Unwin) . . , . (c) d shaft diameter. BELT GEARING. 245 246 DRAWING AND DESIGNING. BELT GEARING- 247 d l = diameter of set-screw in solid pulley = \d + iV'- (6) d^ = diam. of bolt in split pulley at rim and hub = eq. (6) d^ = set- screw for key = .2$d. D = diameter of pulley. E = centre of rim bolt from inside of rim = d^ + t t -f i" (7) V f = radius at end of arms = - g width of arm at rim = \Ii. h - width of arm at centre of pulley 8 BD 6 337A/~ sin g le belt - (Unwin.) .798 . /BD v - (8) h k = thickness of arm = - . / = length of hub = %B to B. n = number of arms = ^ + 4. The nearest number divisible by 2 should be taken. p = thickness of rib surrounding hub between arms = .31 d. t thickness of belt see Table 31. /, thickness of rim = .6/ + - OO 5 D- .... . (9) /, = inside taper of pulley rim = /, -r- 2. . 14 VlBD + i for single belt. (10) w = thickness of hub \ fi-'t double " (u) R = radius of pulley crown = from 3 to 5 b. Exercise 84. A fan revolving with a speed of 1800 rev. per min. develops 8 H.P. and has an 8" pulley on its shaft. Power is obtained from an engine fly-wheel running at 75 rev. per min. Diam. of fly-wheel = 5 feet. Determine the proper diameters of the intermediate pulleys and make a suit- 248 DRAWING AND DESIGNING. able working drawing of the largest of them, similar to Fig. 173 or Fig. 174. Scale 6" I foot. See Example 2, p. 241. Wood-split Pulley (Fig. 175). The Committee on Science and the Arts of the Franklin Institute, in report ing on the Dodge Wood-split Pulley with wooden bushings, stated that in most cases wood-split pulleys are better than iron pulleys. Some of the reasons given for this are as follows : (1) They are lighter than iron pulleys, lessening the weight on the line shaft and bearings and reducing friction. (2) The compression fastening of the wooden pulley on iron or steel shafts with wooden bushings will hold the pulley on the shaft quite firmly, dispensing with the use of keys. (3) The grip of a belt on a wooden pulley exceeds that on an iron pulley to an amount equal to at least 33 per cent. (4) The method of fastening the wooden pulley to the shaft neither mars nor weakens the shaft, and prevents any tendency to throw the pulley out of balance, as is the case when keys and set-screws are used. Construction. " They are built of wooden segments, the face being made of poplar. The two halves of the pulley are secured to the shaft with bolts. The bushings to fit different-sized shafts are made of hard wood, thoroughly air-dried, then bored and kiln-dried ; then each bush is counterbored to exact size of shaft, then carefully turned on the outside to fit the bore of the pulley. They are then cut transversely in halves." Exercise 85. Make complete working drawings of a wooden split loose pulley 14" diam., shaft 2" diam. Projections to be the same as shown in Fig. 175. Scale 9" = i foot. BELT GEARING. 249 250 DRAWING AND DESIGNING. All-wrought-steel Pulley. This pulley as manu- factured by the Am. Pulley Co. is shown in Fig. 176. In a paper on the subject by Mr. E. G. Budd before the Franklin Institute in June 1897, the following advantages are claimed for the all wrought- steel pulley: (1) They can be used in the heaviest service, clamped to the shaft without keys or set-screws, and never show a sign of slipping. (2) There is no machining required. The rims and arms FIG. 176. are cut with shears and pressed into shape with hydraulic pressure. BELT GEARING. 2$ I (3) Economy of material and symmetry of form, requiring no counterbalance. (4) Being made of the best and strongest material, it is fully as light as the wood pulley, and much more durable. Construction. Referring to Fig. 176 it may be seen that the rim is made up of four segments. It is divided once transversely and once longitudinally. The flanges on the rim at the centre of the face give a means of fastening it to the arms. The rim edges are rolled, giving a neat appearance and preventing the scraping of the belt in throwing it off or on. The hub is made of half cylinders of heavy steel, and is connected to the rim by a spider divided into four parts, two parts to each half of the pulley. The spider arms are flat and have the edges lying in the direction of rotation. The manner of fastening the arms to the hub and rim, and their corrugated section, as shown at A in Fig. 177, make them ex- ceptionally strong for their purpose. Exercise 86. Make a true working drawing of the all- wrought-steel pulley shown in Fig. 177 to the dimensions given. Scale 4." = / foot. Cone-pulleys In operating machine tools it is often necessary to change power and speed. This is accomplished most easily by means of cone-pulleys. The driven pulley has a series of steps whose diameters are proportioned so that the belt shall fit all pairs of steps with an equal tension, and when the belt is shifted from one pair of steps to another the velocity ratio will be changed. 252 DRAWING AND DESIGNING. BELT GEARING. 2$ 3 Length of Belts (Fig. 178). Let L = length of belt; D = diam. of large pulley; d = diam. of small pulley; /= distance becween centres of pulleys: . U = angle whose sine = -. fo-r crossed belts and D-d 2l for open belts. FIG. 178. From a table of sines find the angle 6 in degrees and COS0. Then for a crossed belt: . (12) and for an jpen belt 7f L = -(D + d) + B(D - d) + 2l cos ('3, 2 54 DRAWING AND DESIGNING. The length of the crossed belt is constant when D+d and / are constant ; therefore in designing a pair of cone-pulleys so that the crossed belt will have equal tension on all pairs, it is only necessary to use a pair of equal and similar cones taper- ing opposite ways. To design a pair of cone-pulleys for an open beltr Let AAAA and d.d^d^ = diameters of opposite pul- leys (Fig. 179). And using the graphical method given by Mr. C. A. Smith in the A. S. M. E., vol. 10, p. 296, let us suppose the following data to be known : (1) Diameters of D.D^D.D^ and d,. (2) /= distance between centres. Then let it be required to find the diameters of d& and d^ C and c are the centres of the opposite cones. Around centre C draw circles AAAA and at centre c draw d l to the diameters given. Draw tangent A^i Bisect Cc in the point E and erect a perpendicular EF. Make the distance EF = .314! found by experiment. With centTe F draw arc A tangent to Z>X- All lines drawn tangent to arc A will be a common tangent to a pair of cone steps giving the same belt-length as that of the given pair. So to find the diameters of the steps d^d^ and d< it is only necessary to draw tangents to D^ and arc A, A and arc A y A and arc A, and with centre c and radii = cd^ , cd z and cd^ respectively, draw the circles of the required steps. This method is an approximation, but close enough for all practical purposes. Exercise 87 Referring to Fig. 179: First, assume diam- eters A = 18", A = 14", A = 10" and A and d, = 6", and BELT GEARING. 255 find the corresponding diameters of the opposite steps accord- ing to Smith's graphical method just explained in connection with Fig. 179. Second, make complete working drawings of one of the cone-pulleys, showing half longitudinal cross-section and half side elevation combined, and also a half end elevation like Fig. 1 80. Scale 6" = i foot. PROPORTIONS OF CONE PULLEY. Let / = thickness of edge of rim = a-, h = thickness of hub = . 14 V 'BD l + J" from eq. (10) ; H length of hub = 1 . R = f ^ce radius = B. The remaining dimensions may be taken from the follow ing table. TABLE 32. (Dimensions in inches.) b 2 2| 3 4 5 6 8 IO 12 16 10 j a ft f | TV TV TV i i iV A e i i T\ 1 |^ 4 1 f g f 5 1 I 1 It I Ii H 4 if ?! 'I Rope Pulleys. Rope pulleys are made of cast iron with grooved rims, as shown in Figs. 181 and 182. The angle of the groove is usually 45. The grooves for guide pulleys are semicircular at the bottom, the radius of the curve being a little greater than the radius of the rope. The diameter of a 2 S 6 DRAWING AND DESIGNING. BELT GEARING. 257 FOLLOWER FIG. 180. 258 DRAWING AND DESIGNING. rope pulley measured to the centre of the rope should not be less than that given by the following rule : D l = (loD + 1 6) A where D 1 =. the smallest diameter of the pulley; D = the diameter of the rope. As in the case of belt gearing, the slack side of the rope should be on top wherever possible, so as to increase the arc of contact between the rope and the pulley. Fig. 181. This is the form of groove long used in Great Britain. It has flat sides inclined to each other at from 45 to 60. The general practice in America is to use the form of groove shown in Fig. 182, where the sides are curved. This form allows the rope to rotate in the groove, distributing the wear over the entire surface of the rope, making it last longer than it does in the flat-sided groove. Exercise 88. Make a drawing of the section of the rim of a rope pulley with five grooves, as shown in Fig. 181. Diam. of rope to be if". Scale full size. Take the other dimensions from the following table. TABLE 33. (Dimensions in inches.) D A B C E F G H I 7/16 5/16 I| I 13/16 3/4 9/16 T l 1/2 11/32 til I 31/32 15/16 11/16 \\ 9/16 3'8 2| 4 Ii i* 13/16 if 5/8 13/32 2 ] 7 ff If i-A IT 6 * 15/16 2 11/16 7/16 2l 2 'ft I 1 , *& 3 3/4 13/16 7/8 15/32 1/2 17/32 3 3? 3 t i \ 2| If iff iH i| tV 1 BEL 7 GEARING. *- G >j DKA WING AND DESIGNING. BELT GEARING. 26 1 Exercise 89. Make a drawing of the rope pulley rim section shown in Fig. 182. Diam of rope to be ij" Scale full size. Remaining dimensions may be taken from Table 34. TABLE 34. (Dimensions in inches.) D /i B c * .p c ^ / I 3/8 U Ij 1/4 3/4 7/8 3ii 31 I* 1/2 I T 7 ff 5/i6 15/16 4 4H 9/16 5/8 2?V 2! 3/8 7/i6 # J 5it 4 2 3/4 2| 2^ 1/2 4 61! 7i 2 i 7/8 2H 3i 9/16 2 a* 15/16 3 If 5/8 a 2 T 3 ff 8gf 9S I 3 A 4 11/16 4 9 CHAPTER VIII. TOOTHED GEARING. PROPORTIONS OF IRON TEETH. Fig. 183. / = circular pitch = k VP\ p' = diametral pitch (p X /) = 3- 1416; D = pitch diameter = T -- p' \ T = number of teeth = D X / ; / = addendum of tooth = .3/; /' = flank of tooth = .35^ to .4^; / = thickness of tooth = .48^ for cast-iron teeth, = .5/ for cut teeth; k = .04 for hand-wheels, = .05 for ordinary mill gears, = .06 for wheels of high velocity and mortise gearing; P = the total force transmitted by one wheel to another through a corner of the tooth = y 63020^-^.; V = the velocity of the pitch line in feet per second 2 X . 12 X 60 = -00873^; R the radius of the pitch circle in inches; N the number of revolutions of the wheel per minute; H the horse-power transmitted by the wheel. 262 TOOTHED GEARING. WOOD TEETH or cogs for mortise wheels are usually made thicker than for the iron teeth of the meshing wheel, jg ,; t' = thickness of iron teeth to mesh with mortise wheel / = thickness of wood cog = .6/. Exercise 90. (Fig. 183.) To construct the teeth for a spur gear of 15 teeth and rack, p' or diametral pitch = 2.5.1. Involute system, angle of action =15. Draw the centre line C, and compute the diameter of the pitch circle by dividing the number of teeth by/'. At the point a where the pitch circle cuts C draw line L, making an angle of 15 with the horizontal pitch line, and draw the base circle tangent to L. FIG. 183. To find /: Divide 360 by the number of teeth: the quotient will be the number of degrees in the arc/, which may be laid off with a protractor. Or divide the number of inches in the circumference of the pitch circle by the number of teeth : the quotient will be the pitch. Or divide a quadrant 264 DRAWING AND DESIGNING. of the pitch circle with the hair-spring divider into 15 equal parts, and from the point a mark every fourth division for the point where the outline of a tooth intersects the pitch circle. Next lay off the thickness of the tooth equal to half the pitch on the pitch circle of the wheel and the pitch line of the rack. Draw the addendum line of the wheel with a radius The root line of the rack is drawn tangent to the adden- dum line of the wheel, and the root line of the wheel is tangent to the addendum line of the rack. To describe the involute curve of the wheel-tooth: Take a piece of tracing-paper or thin celluloid, and trace upon it the straight line L, and make a small puncture at the point a with a needle. Now at the point where line L is tangent to the base line stick a needle, and rotate line L about it counter- clockwise until it intersects the base line; at the point of in- tersection stick another needle, and, removing the first needle, adjust the tracing until the line L becomes tangent to the base line at the second needle ; then through the puncture a in the tracing, with a 4H pencil sharpened to a conical point mark a point on the drawing-paper: this will be a point on the curve. Continue to find similar points until a sufficient number has been found to form the addendum of the tooth. It will be seen by the figure that the involute curve forming the addendum of the tooth extends below the pitch line to the base line; this part of the curve is generated in a similar way to the part above the pitch line, except that the generating line L must be rotated in the opposite direction. TOOTHED GEARING. 26 5 The addendum lines of the other teeth may be traced from the one just found. The rim of the rack, according to Reuleaux, should not be less than d in thickness, = .^.p -f- .125. Unwin gives .48/1 Low & Bevis give -47/. Use Unwin's proportion. When the curves have been carefully pencilled as above, they may be inked in with arcs of circles computed by means of the following odontograph table, taken from Geo. B. Grant's " Handbook on the Teeth of Gears" : ODONTOGRAPH TABLE INVOLUTE TEETH. CORRECTED FOR INTERFERENCE, INTERCHANGEABLE SET. Teeth. Divide by the Diametral Pitch. Multiply by the Circular Pitch. Face Radius. Flank Radius. Face Radius. Flank Radius. 12 2.70 .83 .86 .27 13 2.87 93 .91 30 14 3.00 .02 95 33 15 3-15 .12 1. 00 .36 16 3-29 .22 1.05 .40 17 3-45 31 1.09 43 18 3-59 .41 1.14 .46 19 3-7i 53 1.18 50 20 3-86 .62 1.22 53 21 4.00 73 1.27 57 22 4.14 83 1.32 .60 23 4.27 94 1.36 63 25 4.56 2.15 1-45 .70 28 4.82 2-37 1-54 77 31 5-23 2.69 1.67 .88 34 5-77 3-13 1.84 1. 00 38 6.30 3-58 2.OI 1.16 44 7.08 4.27 2.26 1.38 52 8.13 5.20 2.59 1.70 64 9.68 6.64 3.09 2.18 83 12. II 8-93 3-8? 2.90 H5 16.18 12 80 5.16 4-T5 200 25.86 22.3O 8,26 7-30 266 DRAWING AND DESIGNING. For any intermediate number of teeth proportionally intermediate values can easily be found by calculation. Example. A gear-wheel has 30 teeth, and the nearest number of teeth in the table is 31 ; then = 5.06, the number to be divided by/ 7 (1.25), making the true face radius = 4^" nearly. The flank of the tooth is radial, and it is joined to the rim. with a fillet whose radius is equal to the clearance. A special rule is provided for the rack-teeth: the flank and one half .the face is a straight line drawn at right angles- to line L ; the other half of the face is a circular-arc centre on the pitch line and a radius found by dividing 2.10" by/'. This rounding of the point of the rack-tooth is necessary when it is to mesh with a pinion having less than 28 teeth. The following tables will be found convenient for compar- ing the diametral pitch with the circular pitch ; they are from Grant's "Teeth of Gears": Cir. Pitch. Diam. Pitch. 6 52 si 58 5 .63 4? .70 4 78 si .90 3 3 05 2! 25 2 i .40 2 57 if .80 ij 2.10 If 2.50 i 3-14 1 4.2O 6.28 Diam. Pitch. Cir. Pitch. i 6.28 1 4.20 I 3-14 2.50 2.10 1. 80 2 1-57 2j 1.25 3 1.05 3* .90 4 78 5 63 6 52 7 45 8 39 9 35 10 3i TOOTHED GEARING. 267 Exercise 91. (Fig. 184.) To construct the teeth for a spur-gear wheel and pinion ; wheel to have 40 and the pinion 12 teeth. /' = 2.10. Walker system, non-interchangeable. FIG. 184. The curves of the teeth are epicycloids and epitrochoids, and are found by rolling the pitch circles on each other as. follows: For the addendum of the wheel-teeth draw arc A on a piece of tracing-paper or celluloid, and place it over the- drawing tangent to arc B at the point a. Through the point a on the celluloid make a puncture with a needle, and while holding the needle at a rotate the celluloid a small' distance to the right until arc A intersects arc B. At the point of intersection place another needle, and, removing the first needle, adjust the celluloid so as to make arc A tangent to arc B at the second needle, and through the puncture mark a point with the pencil ; this will be a point in the curve of the face edge. Other points maybe found in a similar way to complete the curves required. For the face edge of the pinion-tooth roll arc B on arc A* and the point a will describe the curve ab. 268 DRAWING AND DESIGNING. To draw the flank of the wheel-tooth: When arc A on the celluloid is tangent to arc B at a, trace curve ab on the celluloid and make a puncture through b\ then roll arc A to the lett on 8, and point b will describe the flank of the tooth. The flank of the pinion-tooth is then found by rolling arc B on arc A, when the point b' will describe the curve. TOO 7 H ED GEARING. 269 Exercise 92. (Fig. 185.) Draw the HALF ELEVATION, HALF PLAN, and HALF SKCTIONAL PLAN of a spur-gear wheel and pinion ; the wheel to have 60 and the pinion 15 teeth. / = 2.5- Draw all the teeth in one quadrant of the elevation, involute system. Fig 185 is the drawing of a spur-gear wheel 'made by Messrs. Robert Poole & Sons of Baltimore, Md., and presented to Sibley College for use as a model in the drafting-room. Exercise 93. (Fig. 186.) Draw ELEVATION, CROSS-SEC- TION, and PLAN of a bevel-gear wheel and pinion. The axes are to be at right angles to each other, and the wheel is to have 50 and the pinion 24 teeth, p' = 2.10. Radial flank system, non-interchangeable. Draw centre lines C and C' at right angles to each other, find the radii of the pitch circles, and draw D and D' at the proper distance from the axes. Draw E and E' at right angles to each other. F and F' are the developed pitch circles on which the teeth are drawn, the same as if they were for spur gears. And since the flanks are radial, the rolling circles A and B used to generate the face curves of the teeth are equal in diameter to the radius R and R' of the developed pitch circles of the pinion and wheel respectively. A model of this wheel will be found in the drafting-room for use in connection with this problem. Exercise 94. (Fig. 187.) Construct a worm-wheel and worm ; the wheel to have 50 teeth, and the worm-teeth to be drawn like those of the involute rack ; that is. the face edge will be drawn at right angles to line L, when line L makes 2/0 DRAWING AND DESIGNING. the angle of 15 with the horizontal pitch line H, as shown by the longitudinal cross-section in Fig. 187. The teeth of the wheel are made by a cutter similar to the worm, except that grooves are cut in the threads parallel to the axis, and the material is hardened steel. The worm itself is usually made of cast iron, but is sometimes made of wrought iron or malleable cast iron. TOOTHED GEARING. 271 The horizontal pitch line should be so placed as to bisect the cross-sectional area of the wheel-tooth at a\ otherwise the proportions of the teeth may be the same as those used for wheel and rack. FIG. 187. Exercise 95. (Fig. 188.) Design a cast-iron gear-wheel given the pitch-circle diameter 51", revolutions per minute 90, horse-power transmitted 280. First find the whole pressure of one wheel on the other = .00873 X 25.5 X 90 then = P= :L jr~i ( v =- find the circular pitch p = .0447 The number of teeth can now be found by multiplying the diameter of the pitch circle D X 3. 1416, and dividing by p __ : _ t^e nearest even number. DRAWING AND DESIGNING. FIG. 188. Let T represent the number of teeth ; then the velocity of the pitch line may be expressed as follows: pTN 12 X 1 6' and the pressure on the teeth is 550 X 12 X 60 X H H - = 396000 pTN TOO-THED GEARING. 2?$ Taking the width of the teeth into consideration, let t = .$6p for iron teeth when worn, = .45/ for wood teeth when worn ; h = .Jp for iron teeth, = .6p for wood teeth; then P= .O46#//for iron teeth, = .o84#//for wood teeth; and / = ^\/5 ^ ^ w ^ en ^ = width of tooth = from 2 to 4/, and in practice ki = .0707 for iron wheels, = .0848 for mortise wheels. When b = 2.5/, Unwin gives/ = .0447 VP Low & Bevis give/ = \f ^r. The dimensions of the teeth may be determined from the proportions already given : b = the breadth of face = 2.5/, etc. As the shaft for this wheel would probably have to resist a combined twisting and bending action, we can assume the diameter of the shaft to be 6", and the wheel fit 7". The width and breadth of the arms, the thickness of the rim, and the thickness and length of the hub, etc., can be easily determined by the proportions given in the following pages. 274 DRAWING AND DESIGNING. Arms of Gear Wheels. The usual shapes of arm cross- sections are shown in Figs. 189 to 192. Fig. 189 is mostly used for pulleys and light wheels; Fig, 191 shows another section that is com- monly used in light spur wheels, that in Fig. 192 for heavy spur gears, and that in Fig. 189 for bevel gears. When a = . = the thickness of 7 5 8 __ the teeth, Unwin gives // = VbR, Vn measured at the centre of the wheel. Taper J" in 12" on each side toward the rim. n = the number of arms; R = the radius of the wheel; b = the width of the cross-feathers, which may be = the breadth of the teeth as shown at b in Fig. 193, or f- the breadth of the teeth measured at the centre of the shaft and from f to |f at the rim. The ribs or feathers B do not add much to the resistance of the arms to bending in the direction of the driving force, but they are necessary to give lateral stiffness to the arms. Unwin gives B .3^). The feathers should be tapered to facilitate the removal of the pattern from the sand. To determine the number of arms in a wheel, Low & Bevis give -^ + 4. The nearest number divisible by 2 should be taken. TOOTHED GEA KING. 275 Unwin gives four arms for wheels not over 4 ft. in diameter, six arms for wheels of from 4 to 8 ft. in diameter, and eight arms for wheels from 8 to 1 6 ft. in diameter. Rims of Gear Wheels. The usual rim sections are shown in Figs. 193 to 204. The section shown in Fig. 193 is commonly used in light wheels. The following proportions agree closely with most au- thorities on the subject: d = the thickness of the rim at the edge = .48^ . The other proportions are shown in the figures. In the rims for bevel gears shown in Figs. 198 to 2OO the thickest part of the rim should be %d. Figs. 20 1 and 202 show examples of mortise gears for FIG. 197. FIG. 198. FIG. 199. spur and bevel wheels respectively; the mortise teeth are fixed either by wood keys as shown in Fig. 201, or by round iron pins as shown in Fig. 202. The proportions given in the figures agree closely with good practice. DRAWING AND DESIGNING. Shrouding. When the rim of a wheel is wider than the teeth and extends towards the point so. as to form an annular ring uniting the ends of the teeth, the teeth are said to be shrouded. Figs. 203 and 204 give two examples of shrouded teeth. By shrouding out to the pitch circle as shown in Fig. 203, teeth which are no thicker at the root than at the pitch circle can be strengthened about 100 per cent. In the pinion of a pair of gear wheels the shrouding may extend to the points of the teeth as shown in Fig. 204; this compen- sates for the weak form of the teeth in very small wheels, and prevents their failure from excessive wear. FIG. 200. FIG. 201. -f- FIG. 203 FIG. 204. Hubs of Gear Wheels. Figs. 205, 206, and 207 give examples of hubs to correspond to the examples of arms shown in Figs. 189, 191, and 192, respectively. The thickness of metal surrounding the bore of a gear TOOTHED GEARING. 277 wheel is given by Reuleaux = w = .4^ -f- .4" (when h = the width of the arm measured at the centre of the wheel). The keyway should be cut the full length of the hub, and the metal reinforced over the keyway if the wheel is in- tended for heavy duty. In large wheels the hubs are sometknes strengthened by wrought-iron rings shrunk on W both ends; the thickness is made = , and the thickness of the metal under the rings is b = width of teeth. FIG. 205. FIG. 206. FIG. 207. In heavy wheels with a large amount of metal surround- ing the bore, the hub is sometimes slotted across between the arms to give relief from initial strains due to unequal contraction in cooling; these slots are then filled with metal strips, and the divided hub is held firmly together by the iron or steel ring referred to above. CHAPTER IX. VALVES, COCKS, AND OIL-CUPS. Valves. A valve is a device for regulating the flow of a fluid through an opening. Prof. Unwin divides valves into three classes: (i) Flap- valves, or those which open with a hinge; (2) lift-valves, or those which rise perpendicularly to the seat; (3) slide-valves, or those which move parallel to seat. The valve-face is that part of the valve in contact with its seat when closed. Foot-valve and Strainer. Foot-valves are used to hold the water in long suction-pipes; otherwise the pump would have to be charged every time before starting. The strainer protects the valve from being choked with stones or other solids. The most common foot-valves are made of two cast-iron boxes, called the valve-box and strainer, bolted together by flanges, and having a leather clack-valve between them. The lower box is perforated with circular holes J" to \" diameter, and is called the strainer or snore- piece. In small foot-valves the suction is generally screwed into the top of the valve-box. Fig. 207 shows a vertical section and three half plans of a foot-valve for a 9" suction-pipe. VB is the valve-box, 5 the strainer, A is the valve-seat, B main valve, and C an auxiliary 2/8 VALVES, COCKS, AND OIL-CUPS. 2 79 FIG. 207. 280 DRAWING AND DESIGNING. valve on top of B. This style of clack is called a relief or break clack. Mr. Henry Teague, of Lincoln, England, in a paper read before the Inst. of M. E. of England, in 1887, reported having used a 15" main clack with a 5" supple- mentary clack for the purpose of reducing the very great con- cussion which was had by using the 15" clack alone, with the result that even when the hand or the ear was placed on the clack-box hardly a tremor or a sound was perceptible. D is the entrance to the suction-pipe. This double-valve feature gives almost complete freedom from shocks even in large pumps, and therefore works very quietly. The main valve, made of J" leather, forms the joint be- tween the valve-box and the strainer. E is the top and F is the bottom valve-plate, riveted together with f-inch rivets, and an opening in the centre equal to an area of about one half or one third that of the main opening. This auxiliary opening is fitted with the clack-valve C referred to above. It has an upper and a lower valve-plate, held together with the bolt H and fastened to the main valve with two screws at X, in plan and sectional elevation. The laps L should be made one tenth of the diameter of the respective valve-openings. Exercise 96. Make drawings of foot- valve and strainer shown in Fig. 207, and also an outside elevation of the valve- box and strainer. Scale 3" = i foot. India-rubber Valve. This valve (Fig. 208) consists of an india-rubber disk D, a brass grating or seat s, and a perfo- rated brass guard. The rubber guard and valve are attached to the grating by a stud-bolt B. The purpose of the guard VALVES, COCKS, AND OIL-CUPS. 251 < j FIG. 208. 282 DRAWING AND DESIGNING. FTG. 200. VALVES, COCKS, AND OIL-CUPS. 283 is to prevent the valve from rising too high. The perforations in the grating should not be large enough to cause much flexure of the rubber disk. The area of the grating should be such that when the valve is closed the pressure does not ex- ceed 40 Ibs. per square inch. The thickness of the india-rubber disk for large valves i.e., valves over 6" in diameter in condensers and pumps should be f" to f ". India-rubber valves are not good for pressures over 100 Ibs. per square inch. Exercise 97. Make a complete drawing of the india-rubber valve as shown in Fig. 208. Scale full size. The projection of the perforations in the conical guard is shown in Fig. 209. The following proportions represent good practice. Use the nearest T V". Unit = .19 \/^~ a = diameter of india rubber disk =15.5 of unit. b = thickness of the india-rubber disk = 1.6 " c = thickness of the grating-lip =: 1.75 " d= diameter of the valve. e = depth of seat-body = 2.75 " /= diameter of stud-body = 2.75 " g diameter of stud = 1.75 " h = diameter of holding-down bolt = 1.25 " k = depth of grating = 2.50 lc I =. thickness of grating-rib = .65 " m = width of seat-lip = .75 " n = diameter of guard = 12.00 " Exercise 98.- Make a complete drawing of an india-rubber disk-valve similar to Fig. 208. d io /r . Scale 9" = I foot. 284 DRA WING AND DESIGNING. FIG. 210. VALVES, COCKS, AND OIL-CUPS. 28$ Lift- or Wing-valves (Fig. 210). These valves are usu- ally made of brass. The essential' features are a circular disk and seat. The edges between the disk and seat are bevelled to the angle of 45, and are easily fitted and ground together. Springs or rods are used to close these valves when it is neces- sary to place them in a horizontal position. To give the valve a partial rotation and provide a new seating at each stroke the wings are curved slightly, as shown at Fig. 21 1. The curving is arbitrary, and may be projected as shown in the figure. The outside of the seat has usually a taper of J" in 12" ', but is sometimes driven straight. . The amount of the lift of the valve may be determined as follows: Let a = area of opening in seat ; d = diameter of opening in seat; L = lift of valve. Then a .7854^' and L = .35^. ..... (l) Taking a unit of proportion = .2 4/ = thickness of disk = 1.3 ; / = length of wings = 8 ; t = thickness of seat = I at small end. Exercise 99. Draw the valve as shown in Fig. 210 to the dimensions given. Scale full size. Exercise 100. Make drawing of the curved wing-valve as shown in Fig. 211. Scale full size. Spindle-valves (Fig. 212). These valves are guided cen- trally by means of a spindle and bridge ; otherwise they .are 286 DRAWING AND DESIGNING. \ * \ Jl -If- '-* T-1CM I V A . *-4 // ^ FIG. 211. VALVES, COCKS, AND OIL-CUPS. 28; FIG. 212. 288 DRAWING AND DESIGNING. similar to the wing-valve, but used for light work in pumps. The wing-valve and the spindle-valve are sometimes made with a flat seat and a leather face and also used for light duty in pumps, but have no advantage over the bevelled metal edges. Let W(Fig.2 io) = the width of the bearing-edges measured perpendicularly to the axis of the valve, p = the maximum dif- ference of pressure on the two sides of the valve ; then ~r r = nd yy the crushing pressure per square inch on the narrow bevelled edges of the valve and seat. The greatest safe pressure per square inch for phosphor- bronze is 3000 Ibs. ; for gun-metal, 2000 Ibs. ; cast iron, 1000 Ibs. ; and leather and india-rubber, 700 Ibs. Exercise 101. Make drawings of the spindle and valve as shown in F i ( . 212. Scale full size. Ball-valves (Fig. 213). These valves are much used in deep well-pumps and small fast-running pumps. To guide the lift of the ball it is surrounded by a cage with three or four ribs. The ribs should be as narrow as safety will per- mit, so as not to interfere with the free flow of the fluid above the valve-seat. Gun-metal is the best material for the balls. To lighten them they should be made hollow. The usual proportions for the ball-valves are given below: Unit = .2 Vd. a = diameter of ball = 1.34^. b = inside diameter of seat-casing = \.\2d. c = thickness of ball-guide = .9 times unit. e = distance between guides ss^-f-^.". VALVES, COCKS, AND OIL-CUPS. 289 . FIG. 213. DRAWING AND DESIGNING. f= length of seat-shank g = thickness of seat-flange h k I = lift of valve / = thickness of ball-shell = 3 times unit, = i = 1.2 = 1.2 These valves work best with a small lift. William M. Barr says that the lift of ball-valves should not exceed J". Exercise 102. Make drawings similar to those shown in Fig. 213. d \y . Scale i% full size. Flat India-rubber Disk-valves. Fig. 2 14 shows an ordi- nary example of this style of valve for cold water. The valve-seat and spindle are cast in one piece. The spindle is turned and polished, and the hole in the india-rubber disk is T V larger than the diameter of the spindle. This allows free action of the valve. The valve-seat is screwed into place with a pitch of eight threads to the inch, which maybe maintained for all sizes up to 4^'' diameter. Mr. W. M; Barr gives the following dimensions for india-rubber valves: TABLE 35. Diameter. Thickness. Hole. 2" 1 r r 2 i" TV' 4" 3" r yV 3*" n c 4 4-i 4*" " if- 5" ft if Springs give good results if made with No. 12 brass wire for 2" and 2\" valves; No. 10 wire for 3" and 3^" valves, VALVES, COCKS, AND OIL-CUPS. 2 9 1 1 FIG. 214. DRAWING AND DESIGNING. and No. 8 for 4" and 4^ valves. The outside diameter of the spring may be .5 that of the valve-disk. Five to six coils will give a suitable elasticity. Exercise 103. Make drawings for the india-rubber flat-disk valve, as shown in Fig. 214, to the dimensions given. Scale full size. Globe -valves. These valves are opened and closed by hand. The valve in Fig. 2 14 is for steam. When such a valve is used for cold water the valve-face is made of leather or india-rubbei, and when for hot water the india-rubber is mixed with graphite. The construction of the valve is so plainly shown in Fig. 215 that a description seems unnecessary. Exercise 104. Make drawings of globe-valve as shown in Fig. 215, and also a right-end elevation. Scale full size. Stop-valve (Fig. 216). This is another style of lift-valve controlled by hand. The particular valve shown in the figure is used as a throttle-valve by the Ball Engine Co., who kindly sent drawings. Let t = thickness of casing ; / = pressure in Ibs. per square inch; d diameter of the sphere in inches; /= safe bursting strength of material. Take 2000 for cast iron and 17,500 for yellow brass, and use a factor of safety 8, which gives 2500 for the former and about 2200 for the latter; then VALVES, COCKS, AND OIL-CUPS. 293 FIG. 215. 2 9 4 DRAWING AND DESIGNING. P-'H FIG. 216 VALVES, COCKS, AND OIL-CUPS. 2$$ The lift of the valve may be determined by formula (i) for winged lift-valves. The valve and its seat must pass through the valve-chest, so the opening should be made about J-" larger than the outside diameter of the valve-seat. The length of the thread on the valve-stem is equal to the length of the nut + lift of valve + J" for clearance. Exercise 105. Make drawings of the stop-valve as shown in Fig. 216. Scale 4." = i foot. Make the diameter of the inlet 6f" to the root of the thread, instead of 6" as shown in the figure. Boiler Check-valve. Fig. 2 1 7 shows working drawings of the Foster Safety Boiler-check. Fxercise 106. Make drawing of the Foster Boiler-check as shown in Fig. 217. Scale, full size. Cocks. Cocks are valves which operate with a rotary motion. The most common style of cock is that which con- sists of a plug made in the form of a truncated cone rotating in a seat of the same shape cast on a pipe. In Fig. 218 P is the plug, and C the casing or conical seat. O is the opening through the plug. By rotating the plug in one direction the openings are brought in line with the inlet A and outlet B of the pipe or casing. In this position the cock is open. Further rotation through 90 in either direction will bring the openings in the plug opposite the solid parts of the casing and close the valve. Exercise 107. Make drawings of the blow-off cook shown in Fig. 218, and in addition to the views given make a half sectional plan and half sectional end view. Scale, full size. In Fig. 219 is shown a blow-off cock which is really a wing-valve, opened and closed by a piston which in turn is op- 2 9 6 DRAWING AND DESIGNING. VALVES, COCKS, AND OIL-CUPS. 2 9 ; 298 DRAWING AND DESIGNING. VALVES, COCKS, AND OIL-CUPS. 299 crated by means of compressed air. The wing-valve Fis held on its seat by the steam-pressure in the boiler. When com- pressed air is introduced into the cylinder C through the pipe P the piston is pushed against the valve, opening it and allow* ing the contents of the boiler to blow through the cock into the discharge-pipe D. Exercise 108. Make complete drawings as shown in Fig. 219. Scale, full size. Oil-cups. There are many forms of oil-cups. Figs. 220 DRAWING AND DESIGNING. ow the construction of some of the oil-cups es of the Lehigh Valley Railway. ne of the simplest forms of oil-cups. The , cast in one piece. When charged, the reser- voir is filled with waste and oil. This cup is used on the link-hanger. Fig. 221 shows another simple form of oil-cup, used to oil the rocker-box and cross-head. VALVES, COCKS, AND OIL-CUPS. 301 Fig. 222 is a drawing of the oil-cup for the main rod, front end ; cross-wires prevent the waste from being thrown out. Fig. 223 shows another form of oil- cup used on the valve stem. The flow of the oil is regulated by the spindle S, and 167mS. W BE BRAZED FIG. 223. the duty of the spring is to hold it in position. This is made of .jig." brass wire J-" long when unloaded. Fig. 224 gives a form of oil-cup for the front end of the 302 DRAWING AND DESIGNING. r FIG. 224. VALVES, COCKS, AND OIL-CUPS. 303 MILLS, WTHDS. FIG. 225. 304 DRAWING AND DESIGNING. main rod on cross-head. It will be seen that in this case the flow of the oil is also mechanically controlled. Fig. 225 is a form of cup used on the guides. The flow of the oil is in this case also regulated by the raising or the lowering of the spindle by hand. Exercise 109. Make drawings, as directed by the in- structor, of one or more of the oil- cups illustrated in Figs. 220 to 225 when it is desired to fill unoccupied space on draw- ing-paper. Scale, full size. CHAPTER X. ENGINE DETAILS. The Plain Slide-valve The construction of all slide- valves must be such as to satisfactorily meet the following re- quirements: 1. To admit steam to one end only of the cylinder at a time ; 2. To allow the steam in the cylinder to escape from one end at least as soon as steam is admitted at the other end ; 3. To prevent steam from entering the exhaust-port from the steam-chest. During one revolution of the crank there are four princi- pal points reached and passed by the valve in the course of its travel : 1. ^^ point of admission, when steam begins to enter the cylinder. (See Fig. 236, Plate I.) 2. The point of cut-off, when steam is prevented from en- tering the cylinder. (See Fig. 233, Plate I.) 3. The point of exhaust, when steam is released from the cylinder. (Fig. 235, Plate I.) 4. The point of compression, when the exhaust is closed. (Fig. 234, Plate I.) 305 3 o6 DRAWING AND DESIGNING. In Fig. 226 is given a longitudinal section of a plane slide- valve, and also of the valve-seat S of the cylinder. The valve is shown in its central position, X and Kare the steam-ports and Z the exhaust-port. The valve-face is the under side of the valve with a length equal to F= 7J" + 2L. Outside Lap, or simply lap is the darkened portion L of FIG. 226. the valve which overlaps the steam-port when the valve is in its central position. Lap has no effect on compression or exhaust, but it hastens the cut-off, prolongs expansion, and shortens the time the port is open. Inside Lap, the smaller darkened portion / which over- laps the bridge between the steam- and exhaust-ports, pro- longs expansion, hastens and increases compression, retards ENGINE DETAILS. 307 the exhaust, but does not affect the admission or point of cut-off. The Travel of the valve is equal to twice the total dis- tance it moves from its central position in either direction ; or if the arms of the rocker are of equal lengths, then the travel of the valve is equal to twice the eccentricity of the eccentric. (See " Eccentric and Straps.") It is also equal to twice the sum of the width of the steam-port and lap plus the over- travel if any. The Lead Angle is the angle made by the centre-line of the crank with the centre-line of motion of the engine when the crank is at the point of admission. (See Fig. 236, Plate I.) The Lead is the amount which the valve has opened the steam-port at the beginning of the stroke. (See Fig. 231, Plate I.) To obtain smooth running, increased speed should have increased lead, and when the lead is increased every operation of the valve is quickened. The Angle of Advance of the eccentric is the number of degrees which the centre-line of the eccentric is over 90 ahead of the centre-line of the crank without a rocker, and with a rocker it is the number of degrees short of 90 behind the crank. The first case is illustrated in the diagram in Plate II, as follows: Let AO be the centre of the crank, CO a line 90 ahead of it, and OE the centre-line of the eccentric. Then COE is the angle over 90 ahead of the crank, and is therefore the angle of advance. For the case with a rocker let AO be the centre of the crank as before, and OD a line 90 behind it, and OF the centre-line of the eccentric. Then the angle DOF is the angle short of 90 behind the crank, and is therefore the angle of advance. 308 DRAWING AND DESIGNING. Inside Clearance is the opposite of inside lap, instead of the valve overlapping the bridge when on the centre; as- shown at / in Fig. 226, it shows a clearance between the in- side edge of the valve and the bridge. Inside clearance hastens exhaust, delays compression, but has no effect on the cut-off or admission. Overtravel is the distance the steam edge of the valve travels after fully opening the port, as shown in Fig. 232, Plate I. It increases the sharpness of the cut-off, retards compression, and gives a later release. Cylinder Clearance is all that space between the faces of the piston and the valve when the piston is at the beginning of the stroke. Piston Clearance is the distance between the piston and the cylinder-head. This clearance is to prevent the piston from striking either cylinder-head when the brasses on the connecting-rod wear and cause lost motion. Point of Cut-off is the point on the crank-circle which the centre of the crank reaches when the valve cuts off the live steam from the cylinder, and for the remainder of the stroke utilizes the expansive power of the steam. (See Fig. 233, Plate I.) Compression of the steam follows the closing of the ex- haust before the piston has completed its stroke. This is done to obtain a yielding cushion for the reciprocating parts to come to a full stop without shock before beginning the return stroke. Expansion begins at the point of cut-off and continues to the point of exhaust. (See Figs. 233 to 235 in Plate w ENGINE DETAILS. 309 During this period the valve travels a distance equal to the outside lap plus the inside lap. The Allen-Richardson Balance-valve This is one of the most popular combination slide-valves and is used on locomotives, stationary and large marine engines. Fig. 227 clearly shows the different parts used in the construction of this valve. The balance is effected by means of four rect- FIG 227. angular packing-strips 5 fitted into grooves on the top of the valve. Semi-elliptic springs Z are used to hold the packing- strips against the pressure-plate P when there is no steam irk the chest, but when steam is admitted to the chest it forces the strips against the pressure-plate and sides of the grooves, forming a steam-tight joint and preventing the steam from acting on that part of the top of the valve enclosed by the four packing-strips. 3IO DRAWING AND DESIGNING. Exercise no. Make drawings as shown in Fig. 227, and also a half plan of the top. Scale 8" = I foot. The Allen feature of this valve is the supplementary port shown at A just above the exhaust-arch. By means of this additional port steam is admitted to the same steam-port in the cylinder from both sides of the valve at the same time, thereby increasing the steam-supply with short cut-offs. The advantages of this valve over the plain slide-valve and the objections to it are discussed in the proceedings of the fol- lowing societies: A. S. M. E., vol. 20, May 1899; The Western Railway Club, March, 1897; Am. Railway M. M. Association, 1896; and in the " Locomotive up to Date " by Chas. McShane. * The American Balance Slide-valve. The American Balance is applied to any type of slide-valve. It consists of a steam-tight joint being formed between the valve and the under side of the steam-chest cover, thus excluding live-steam pressure from a given area. (See Fig. 228.) This joint is formed by a bevelled snap-ring which, when in place, is slightly expanded over a cone. The cone or cones are either cast with the valves or bolted to it, as circumstances require. The mechanical construction of the balance is: First, the cone or two cones, where necessity requires, are either bolted to or cast with the valve. The snap-rings, which are bevelled on their inner side to a corresponding degree with that of the cone, are bored smaller in diameter than their required work- ing diameter so that, by their being forced down on the cone by the placing of the steam-chest cover in position, the rings * The above description was furnished by Mr. J. T. Wilson, GeneraX Manager of The American Balance Slide-valve Co. ENGINE DETAILS. 311 themselves are under tension and are thus supported by their own elasticity when not under steam. The steam when admitted to the steam-chest exerts a pressv-re on the entire circumference of the ring, which has a tendency to close it or decrease its diameter, and owing to its bevelled face and the taper of the cone the steam also acts to lift it. By careful FIG. 228. consideration of the operation of this ring, now being held by the steam-pressure tightly against the face of the cone, it will at once be seen that all lateral wear is avoided, and the ring moves as a part of the cone or valve itself. It will also be noted that the ring is absolutely compelled to assume its work- ing position by the pressure on its circumference. When steam is shut off from the engine and the engine allowed to drift, as in locomotives, the valve is free to leave its seat until 312 DRAWING AND DESIGNING. the cone comes in contact with the cover. This affords per- fect and ample relief of the air which the piston is forcing from one end of the cylinder, and also a direct communication with the other end of the cylinder, in which a vacuum is being formed. The cylinders are therefore perfectly relieved by allowing the valve to lift \" off its seat. The bevelled feature in the ring renders the ring self-sup- FIG. 229. porting when not under steam, and supported by the steam- pressure when under steam, automatic adjustment for the wear, positive action under all conditions, and self-maintaining the steam-joint. It renders it possible also to duplicate the rings of respective size in repairs. Owing to the absence of lateral wear on the cones new rings can be duplicated at any future time. The greatest area of balance can be secured by this design, because it is least affected by back or upward pressure. The valve in order to ENGINE DETAILS. 3'3 leave its seat must first expand the taper ring against the chest-pressure acting on its circumference. The features enumerated all depend upon the taper. Fig. 228 is a double-cone balance-valve used on locomo- tives. The improved T ring, the invention of Mr. J. T. Wilson, is clearly shown in the figure. Fig. 229 is a single-cone balance-valve for use on com- pound stationary engines. A double-cone valve of this kind is in use on the Japanese cruiser " Chtose," the rings of which FIG. 230. are three feet ten inches in diameter, while that in Fig. 229 is only twenty inches diameter. Exercise in Make drawings of Fig. 230 as shown. Scale 6'' = i foot. The Bilgram Diagram. Among the many diagrams devised to determine quickly and accurately the position of the valve for any position of the crank, that due to Mr. Hugo Bilgram is one of the simplest and best. DRAWING AND DESIGNING. ENGINE DETAILS. $15 In Plate I let AB represent the valve circle, equal in di- ameter to the travel of the valve, and LI the centre-line of the crank rotating in the direction of the arrow. From B lay oft" the angle EOB, equal to the angle of advance. At E describe the arc bgk with a radius equal to the inside lap, and also the arc afd with a radius equal to the outside lap. Crank positions drawn tangent to these arcs at a, b, k, and d will give the points of cut-off, compression, release, and ad- mission respectively, as indicated in the figure. Let us follow the crank through one revolution, beginning with the dead-point A. In this position de is equal to the outside lead, and the valve has moved from its central posi- tion a distance Ee equal to the lap plus the lead. These relations are clearly shown in Fig. 231. c gives the distance which the valve has travelled from its central position, and at X the left-hand steam-port is shown open to steam an amount equal to the lead when the piston is at the beginning of its forward stroke, and the eccentric is connected directly to the valve, i.e., without a rocker. When the crank reaches the position L* perpendicular to OE the valve will have travelled from its central position a distance equal to EO. This is the extreme position of its xorward travel, as shown in Fig. 232. The maximum open- ing of the port X to steam is equal to Of, and the overtravel to mf t the actual width of the steam-port being = Om. As the crank leaves D the valve begins to return, and when the crank is at L* the distance of the valve from its central position is equal to the lap ab. Port X is now closed to steam, and cut-off is accomplished as shown in Fig. 233. When the crank is at L 1 the right-hand steam-port is DRAWING AND DESIGNING. closed to exhaust, and compression begins as shown at F, Fig. 234. When the crank reaches U the valve is on the point of opening port X, Fig. 235, to release the steam which was under compression during the time the crank moved from U to L l . At crank position L we find, as shown in Fig 236, that the valve is on the point of admitting steam to port F, and at B the backward stroke of the piston begins, the valve having opened the port an amount equal to the lead de, equal to the opening shown at X in Fig. 231. At crank position r and valve position Fig. 237 the valve has attained its maximum travel in the opposite direction to that shown in Fig. 232. At / 3 , Fig. 238, the valve cuts off steam from port F, and at A the new forward stroke begins. r FIG. 239. Exercise 112 (Fig. 239.) Given. Required Travel 5". Outside lap. Angle of advance. . . = 30. Inside lap. Cut-off = 8o# of stroke. Outside lead. Compression = 90$ of stroke. Inside lead. Width of steam-port = i J''. Maximum port opening. Overt ravel. ENGINE DETAILS. Draw AB and CO at right angles to one another. De- scribe the valve-circle arc ACB with a radius equal to half the travel or eccentricity of the eccentric = 2\" to the scale of twice full size. From B lay off the angle EOB equal to the angle of advance 30. Let AB represent the stroke, and from A lay off Al 80$ of a stroke of 24", and erect a perpendicular to cut the valve circle in /'. Draw OL* through r ; this is the crank position at the point of cut-off. Through E perpendicular to OL* draw Ea. With centre E and radius Ea describe the lap circle afd. From A lay off A2 = 90$ of the stroke, and erect a perpendicular to cut the valve circle at b. Through b draw OL*, which is the crank position at the point of compression. With E as centre and Eb as radius describe the inside lap circle. Draw OU tangent to bgk at point k. At O with a radius = the port opening describe the arc h. Then Ea is the required lap, Eb the inside lap, de the lead, ke the inside lead, (9/the maximum port-opening, and ///the overtravel. Exercise 113. (Fig. 240.) Given. Required. Cut-off = 8o# of stroke. Travel of the valve. Lap = \" . Angle of advance. Lead = i" '. Draw to a scale equal to twice full size AB and CO at right angles. Draw OL\ the position of crank at cut-off. Draw line I 2 parallel to AB at a distance above it equal to the lead ed. Draw line 3 4 parallel to AB at a distance equal to the lap plus the lead above it. With a radius equal to the DRAWING AND DESIGNING. given lap find by trial a centre on the line 3 4, and draw the lap circle afd tangent to OL*, and line i 2 at the points a and d. Then through E with centre O describe the valve circle ACB. AB is the travel of the valve, and EOB the angle of aa- vance. FIG. 241. Exercise 114 (Fig. 241.) Given. Required. Cut-off = 8o# of the stroke. Travel of the valve Admission = 90$ of the stroke. Lead. Maximum port-opening = Of (Fig. 240). Angle of Advance. Lap. ENGINE DETAILS. Draw AB and CO at right angles. Draw OL, the posi- tion of the crank at the point of admission. Draw OL*, the crank position at cut-off, and arc /with a radius equal to the given maximum port-opening. Bisect the angle LOD with the line OE. The centre of the lap-circle will be on this line. Draw fm perpendicular to OU, and make fn = fin. Through / draw fa parallel to nm, and aE parallel to mf. E is the centre of lap circle. Through E describe the valve circle ACB, and draw the line Ee at right angles to AB. Then AB is the travel of the valve, Ea the lap, BOE the angle of advance, and de the lead. Exercise 115. (Fig. 242.) Given. Required. Cut-off = 80$ of the stroke. Angle of advance. Lead = i". Lap. Maximum port-opening = Of (Fig. 240). Travel of valve. Draw AB and CO at right angles. Locate the crank position OL* . Draw the lead-line I 2 at a distance de from AB and parallel to it. With centre O describe arc 3 4 with a radius equal to the maximum port-opening. Find by trial the centre E of a circle that can be drawn tangent to OL 9 , arc 3 4, and line I 2. Through this centre draw OE. 320 DRAWING AND DESIGNING. Then BOE is the angle of advance, Ea the lap, and twice OE is equal to the travel of the valve. The Zeuner Valve Diagram In Plate II let AB repre- sent the stroke of the piston, the circle ACBD the path of the crank-pin, and L the centre-line of the crank. From C lay off OE equal to the angle of advance, and on OE as a diameter describe the valve circle equal to half the travel of the valve or eccentricity of the eccentric when no rocker is used. From centre O draw the arcs abc and gfk equal to the outside and inside laps respectively. At the beginning of the forward stroke the true position of the crank would coincide with AO, and the centre-line of the eccentric with OE. Now since the position of the point E is fixed for a given eccentricity and angle of advance, the point E will always be found on the circumference of the circle having OE as a diam- eter; and if the valve circle together with the crank be rotated around the centre O in a direction opposite to the arrow, its intersection with the line OB from O will be the distance which the valve has travelled from its central position after the crank has moved through any given angle. But instead of rotating the crank and valve circle let them remain fixed and rotate the line OB as an imaginary crank in the direction of the arrow, and the same results will be ob- tained in a much simpler way. Draw OL, the imaginary crank, through the point where the lap arc abc intersects the valve circle at the point c. The position of the valve will then be at the point of admission, because the valve will have travelled from its central position a distance equal to Oc, equal to the lap. ENGINE DETAILS. 321 322 DRAWING AND DESIGNING. This is clearly shown in Fig. 243. The valve is travelling in a direction opposite to the imaginary crank, and the steam edge / of the valve is on the point of admitting steam to the port X just 'before the beginning of the forward stroke. When the imaginary crank reaches the position OB the valve will have travelled a distance equal to Oc from its central position and, OB being a dead-centre, the valve will have opened the port X to steam an amount equal to the lead, and the port Y to exhaust an amount equal to pq, Fig. 244. When the crank has reached the position OE the valve will then have attained the extreme position of its travel. The shaded part bk shows the full opening of the steam-port, and ke the amount of overtravel, and at the same time the port Y is fully open to exhaust, as shown by the shaded por- tion fjj and JF is the exhaust overtravel (Fig. 245). The valve now returns and at R begins to close port X y until when the crank arrives at L* the port is fully closed and cut-off takes place, as shown in Fig. 246. When the crank is in the position L* at right angles to OE the valve is in its middle position, as shown in Fig. 247. At the crank position L n the valve has travelled a distance Og from its central position, and the port X is about to open to exhau. r ;t, as shown in Fig. 248. The port continues to open, unt.il at the position L 1 the port is fully open and con- tinues so until the crank reaches the position L 9 , when it begins to close, and is fully closed when the crank reaches L\ Now compression begins and continues through the angle L*OL. At L the valve has returned to the point of admission a little before the beginning of the new forward stroke. At crank position L* it will be seen from Fig. 250 that the ENGINE DETAILS. 323 port Fis fully open to steam, the port X fully open to exhaust, and that the valve has reached the extreme position of its travel for the backward stroke just the opposite of the posi- tion shown in Fig. 245. C FIG. 252. Exercise 116. (Fig. 252). Assume the same conditions as in Ex. 1 12 for the Bilgram diagram. Draw AB and CO at right angles. Make AB to any convenient scale equal to the stroke of the piston, and let ACB represent the path of the crank-pin. From C lay off angle OE equal to the angle of advance = 30, with a scale equal to twice full size. On Ok as a diameter, equal to half the travel of the valve, or 2 j-", de- scribe the valve circle Oakc. From B lay off Bl equal to 80$ of the stroke, and erect a perpendicular to cut the crank-pin arc in Z 3 . Draw OL*, the position of the crank at cut-off. Through the point a, where OL 3 cuts the valve circle, with O as centre describe the arc abc. From B lay off B2 equal to 90$ of the stroke, and erect a perpendicular to L*. Draw OL 9 , and through the point g, where OL 6 intersects the valve circle, with O as centre describe the arc gfh. From i> lay off bk equal to the width of the steam-port, and with centre O and radius Ok describe the arc 3^4. 324 DRAWING AND DESIGNING. Then Oa is the required lap, Og the inside lap, de the lead, $t the inside or exhaust lead, OE the maximum port- opening, and KE the overtravel. C O FIG. 253. Exercise 117. (Fig. 253.) Assume the same conditions as given in Ex. 113. Draw AB and CO at right angles. Draw OL\ the crank position at cut-off. From O describe arc abc with a radius equal to the lap, scale as before. Lay off de equal to the lead. Bisect Oa and Oc, and the point / where the bisectors intersect will be the centre of the valve circle which may now be drawn through the points aOe. Then OE is equal to half the travel of the valve, and COE is the angle of advance. Exercise 118. (Fig. 254.) Given. Point of cut-off. . . = 80$ of stroke. Point of admission = 90$ of stroke. Lead = ". Draw AB and CO at right angles, tions OL and OL\ Bisect the angle LOL* with the line OE. On OE assume any point as g, and draw gf perpendicular to OB, and gh perpendicular to OL. With center O and radius Oh describe the arc he. Required, Travel of valve. Lap. Angle of advance. Draw the crank posi- ENGINE DETAILS. $2$ Now the angles gOB and gOL are constant for a given admission and cut-off; therefore the lead will vary directly aa the eccentricity. FIG. 254. Let Og be an assumed eccentricity, then ef will bo its cor- responding lead, and the given lead is to the assumed lead ef as the required eccentricity is to the assumed eccentricity Of. Lay off Ol equal to the given lead, and O2 equal to ef. Draw 2g, and IE parallel to 2g. With a radius equal to Oe minus the given lead and centre O describe the arc abc. On OE as a diameter describe the valve circle Oaec. Then COE is the required angle of advance, OE the ec- centricity or half the travel of the valve, and Oa the lap. Exercise 119. (Fig. 255.) Assume the conditions as in Ex. 115. Draw AB and CE at right angles to each other. Draw OL\ the crank position at cut-off, Oa, the given lead, and Ob, the given maximum port-opening. At b erect the perpendicular bg. Through a draw ad&t right angles to OL\ Bisect the angle dee with the line Oc, and produce it to intersect fg at g. Join DRA WING AND- DESIGNING. draw cf parallel to Ob. With c as centre and cf as 'describe arc/, cutting ag in k. Join ck, and draw a O parallel to kc, cutting O^ in the point O t . Draw O^e parallel to O t A. \ Then Ock is the required angle of advance, O\a half the required travel of the valve, and O^e the lap. FIG. 255. Engine Frame or Bed-plate. Frames for horizontal engines are usually made of cast iron. This is the most suit- able material owing to the complicated sections found in most frames, and also because it gives the necessary rigidity. Figs. 256 to 258 show an engine frame of the " Tangye " type. It is that used by the Buckeye Engine Co. of Salem, Mass. Exercise 120. Make drawings as shown in Figs. 256 to 258. Scale li"-- I foot. ENGINE DETAILS. 327 23 A WING A*TD J Cylinder. Steam-engine cylinders are almost always made of a tough, close-grained cast iron as hard as can be safely worked. Diameter of Cylinder, D. Let P = the mean effective pressure of steam in pounds per square inch = M. E. P. ; L length of stroke in feet ; A = area of piston in square inches ; N= number of strokes per minute. PL A N Then - = I.H.P. or indicated horse-power, and I.H.P. X 33QOO A A is therefore = - ; so D = The mean effective pressure P may be found from the following formula : Let/ = the absolute initial pressure of steam, i.e., the gauge-pressure + J 5 Iks. i 7% f r l ss between boiler and cylinder. r = ratio of expansion = length of stroke in inches ~ distance travelled by piston in inches before steam is cut off. i + hyp. log. r Then P= - ^ -- back-pressure. Thickness of Cylinder, t. Let P l = boiler-pressure of steam per square inch in pounds; D = diameter of cylinder in inches. u Whitham " recommends the following formula for hor- izontal or vertical cylinders of large or small diameter where ENGINE DETAILS. provision is made for reboring and sufficient strength and rig- idity are secured : / = 0.03 V1\D. Length of Cylinder. The length of cylinder between heads = Stroke -[- thickness of piston -|- the sum of the piston clearance at both ends. Cylinder Head. The cylinder head or cover next to the crank is sometimes cast on the cylinder. The thickness of the cylinder head recommended by Prof. Seaton is 2OOO The thickness at the flange where the head is bolted to the cylinder should be -J- greater than this. Cylinder -head Bolts. The diameter of cylinder-head studs in locomotives is usually f ", and their pitch abour 4 times their diameter. For stationary and marine practice " Ripper " gives 4 where n = number of studs; d = diameter of studs; D diameter of cylinder; p maximum pressure of steam; /= 4000 to 5000. Steam-ports. The steam-ports which conduct the steam fro. /i the valve-chest to the cylinder should be as short and direct as possible, but large enough to prevent wire-drawing and of easy curvature. 33 DRAWING AND DESIGNING. The length of ports in locomotives is usually i" less than the diameter of the cylinder. In other types the length is generally made o. 8/7. The area of the steam-port is given by many authorities as follows : AV a =. , v where A = area of the piston in square inches ; v = velocity of steam through the port = 6000 feet per minute; V = velocity of piston in feet per minute (from 1000 to 1200); a = area of steam-port. Figs. 259 to 262 show the working drawings of a horizon- tal steam-engine cylinder made by the Buckeye Engine Co. Fig. 259 shows a longitudinal section through the centre of the cylinder, Fig. 260 a cross-section through the exhaust- passage, Fig. 261 a back-end view showing the opening for a valve-rod, and Fig. 262 a plan. Figs. 263 and 264 are the heads and covers suitable for this cylinder. When in position on the engine-frame the end of the cylinder, shown in Fig. 261, is bolted to the end of the frame shown in Fig. 261. Exercise 121. Make drawings of steam-cylinder as shown in Figs. 259 to 262. (Scale i\" = i foot.} Exercise 122. Make the design of a cylinder similar to that shown in Figs. 259 to 262 to develop 100 I.H.P. Stroke 30"; steam-pressure 90 Ibs. per square inch; cut-off at of the stroke. Number of strokes per minute 22o. ENGINE DETAILS. 331 33 2 DRAWING AND DESIGNING. Exercise 123. Make drawings of the cylinder heads shown in Figs. 263 and 264. (Scale /J" = i foot.) Pistons. A piston is that part of an engine or pump which slides to and fro inside a hollow cylinder either driven by fluid pressure or acting against fluid pressure they are usually of circular section and are made of brass, wrought iron, cast iron, or steel. A piston with valves which permit the fluid to pass from one side to the other is called a bucket and is used in pump cylinders. A single-acting piston, guided by the stuffing-box instead of the cylinder, is called a plunger and is also used in pumps. Steam-pistons. A steam-piston should be designed so as to prevent the steam from passing from one side of the piston to the other. The spring packing-rings should not press against the cyl- inder more than is necessary for steam-tightness. A piston should be no heavier than is necessary for strength. The weight of the piston should be distributed so as to prevent the excessive internal wear of the cylinder. The piston must be firmly connected to the piston-rod. Many different designs have been adopted to secure the above requirements. Fig. 265 is a plain box piston, used by the Southwark Foundry & Machine Company. It is cast in one piece; the core being removed by three holes, shown in the front, which are afterwards plugged up. The two small holes are for eye- bolts which are used to remove the piston from the cylinder when necessary. The packing consists of two cast-iron spring ENGINE DETAILS. 333 rings cut as shown in detail in the figure. The rod is forced into place by pressure and the ends riveted over. Exercise 124. Make drawings as shown in Fig. 265* (Scale 6" = I foot.) Fig. 266. This is another style of box pattern, used by the Ball Engine Company. The style of packing and the method of securing the piston-rod are plainly shown in the figure. FIG. 266. Exercise 125. Make drawings as shown in Fig. 266, and in addition make a half end section through the centre of the piston. (Scale 6" = I foot.) Fig. 267 shows a common built-up piston used largely in locomotives. It consists of a spider, S, a T ring, a follower, F, and two cast-iron spring-rings. The rod is forced into place and held by nut over which the end of the rod is riveted. Exercise 126. Make drawings of a built-up piston like Fig. 267 for an engine whose cylinder is 18'' X 24''. Take dimensions from Table 36. (Scale 6" = I foot.) Fig. 268, a cast-iron box piston used in the cylinder of the Empire State Express locomotive. Its construction is plainly shown in the figure. 334 DRAWING AND DESIGNING. Exercise 127 Make drawings of the piston shown in Fig. 268. (Scale 6" = / foot} Fig. 269 is a cast- steel box pattern cast in two parts and T 3 ' 15 16 18 19 20 22 $ 18 7/ FIG. 267. TABLE 36. 4i 81 t ENGINE DETAILS. 335 FIG. 268. 336 DRA WING AND DESIGNING. \ ENGINE DETAILS. 337 held together by rivets. This piston is made by the Baldwin Locomotive Works for the " Vauclain " compound locomo- tive. Exercise 128. Make drawings as shown in Fig. 269. (Scale 4" = i foot.) Fig. 270 shows the cast-iron pistons used in tandem stationary engines built by Mclntosh & Seymour. The packing is composed of cast-iron spring-rings cut and kept in place by the method shown in detail in the figure. The arrangement for securing the rod is shown in detail in Fig. 68, page 103. Exercise 129. Make drawings as shown in Fig. 270, (Scale 3" = i foot.) Fig. 271 is a built r_up piston for the Tangye stationary engines made by the Buckeye Engine Co. It consists of a spider, follower, and adjusting-screws. There are no springs; the screws act on an uncut junk-ring, so can only be used for centring, not for packing. The packing-rings are turned larger than the bore of the cylinder so as to pack by their own elasticity. They may or may not be turned eccentric, that is, thin where cut, and full thickness opposite the cut. If made eccentric, it is for the reason that they will be more nearly round when sprung into the cylinder. Exercise 130. Make drawings as shown in Fig. 271. (Scaled" = I foot.) Fig. 272 shows a water-piston suitable for cylinders under 9" diameter. The piston-rod is fitted to the head with a shoulder to drive the piston, and the rod is secured in place by a nut. The follower is also held by a nut and lock-nut. By this 338 DRAWING AND DESIGNING. ENGINE DETAILS. 339 means the follower and packing may be adjusted or renewed at will. The packing is made of layers of cotton cloth and sheet rubber. Exercise 131 Make drawings of water-piston as shown in Fig. 272. (Scale full size.} Connecting-rods. In steam and other engines the con- necting-rod connects the rotating crank with the reciprocat- ing cross-head. There are many styles of connecting-rods, and various methods are employed for taking up the wear of the brasses. Figs. 273 to 276 show good examples of rods used in station- ary, locomotive, and marine engines of the most modern types. Fig. 273 is the rod used by the Buckeye Engine Co. for their " Tangye " type of engine. The crank end is solid, the brasses are lined with babbitt, and adjustment for wear is had by means of a tapered steel block and screws. The cross- head end is called a strap end. The strap is firmly bound to the end of the rod with a cotter-key and gib, which also con- trols the adjustment for wear. . Fig. 274 has strap ends front and back. Keys are in- serted between the straps and the rod to prevent the shear of the strap-bolts. The construction of this rod and the method employed to take up the wear are plainly shown in the figure. The Erie City Iron Works use this rod on their stationary engines. Exercise 132. Make the drawings as shown in Fig. 273. (Scaled" = i foot.} Exercise 133* Make the drawings as shown in Fig. 274, 340 DRAWING AND DESIGNING. ENGINE DETAILS. 34' 34 2 DRAWING AUD DESIGNING. except that half of the plan shall be a section through XX. (Scale 6" = i foot.} Fig. 275 is the connecting-rod used by the Pennsylvania Railroad Company on their fast passenger-locomotives. The crank end of this rod is an improved design invented by Mr. A. S. Vogt, mechanical engineer of the company. . He ex- plains the improvements as follows: As before, the back end of the rod is forked, but the method of closing the open end of the fork is entirely differ- ent, and the key for closing the main brasses has been moved from the forward side of the brass to the rear, which has an- other good effect, viz., as the brasses in both front end and back end of the rod wear and are closed up to meet that wear, the actual length of the rod changes but very little, for the reason that the keying of both ends is in the same direc- tion, whereas in the old form of the rod the keying was in opposite directions, and as a matter of course the distance from centre of crank-pin to centre of crosshead pin increased gradually. The open end of the fork in this rod is closed > first, by a U-shaped block, the detail of which is marked A on Fig. 275; next, by the key which is marked B\ and last of all by a combined key and bolt marked C', this bolt clamp- ing the two members of the fork against the block A and forming an enclosed surface for the key to drive against. To prevent the slacking up of the nut C, a keeper-block is pro- vided at the bottom of the lower member of the fork. This is made with a recess into which the nut fits and a set-screw for locking the nut. The same keeper-block extends forward to the key B, which is also blocked by a set-screw in the block. It is quite evident that there is much less chance of shearing ENGINE DETAILS. 343 344 DRAWING AND DESIGNING. or offsetting of the bolt and the key in this than there was of the bolt in the former design ; but even if it should take place, which is not very likely, the whole thing can readily be dis- connected by, first, driving the key B out, unscrewing the nut on the bolt and moving the whole bolt slightly forward, when it can be lifted out at the top. Exercise 134. Make drawings as shown in Fig. 275. (Scale 6" = i foot.} This form of rod is called a marine connecting-rod be- cause it is often used on marine engines, but it is also largely used on stationary engines and is occasionally seen on loco- motives. The crank-pin end or stub is usually forged solidly on the rod, and all but the sides is finished by turning in the lathe. The sides are then planed and the bolt-holes drilled. The hole to receive the brasses may now be bored unless the top arid bottom of the brasses are to be thicker than the sides, in which event the hole will not be completed until after the cap or top end of the stub has been slotted off and bolted on again. It will be seen that the bolts are turned down to a diam- eter equal to the diameter at the bottom of the threads. This does not weaken the bolt, but makes it more elastic. The cross-head end of this rod is made forked to suit the cross-head, but it will be seen that each half of the forked end is constructed the same as in the large end. A detail drav/ing of the bolt and its locking arrangement is given in Fig. 65, page 96. Exercise 135. Make drawings as shown in Fig. 276. (Scale 2" = i foot.} ENGINE DETAILS. 345 Thrust of Connecting-rod. Assuming that a connect- ing-rod is equal to a pillar rounded or jointed at both ends, let D = diameter of piston in inches; L = length of stroke in inches ; 2.= length of connecting-rod in inches; P = maximum steam-pressure per square inch; T = thrust of connecting-rod. When the crank-pin is on a dead-centre and the connect- ing-rod is in line with the piston-rod, then T=-D*P = W, 4 the total load on the piston. But as the crank rotates the connecting-rod becomes inclined to the centre line of motion, and T increases as the angle of the connecting-rod increases until a maximum is reached at half-stroke, provided the steam is not cut off before. The value of T may be found for any position of the crank as follows : Let AB, Fig. 277, be the connecting-rod, and BC the crank. The forces acting at A are W, the maximum pressure on the piston, and R, the reaction of the guide on the cross- head, and T, the thrust along the connecting-rod. From the triangle of forces T AB and 7-= W= W , AC VAE'-AC'' 346 DRA WING AND DESIGNING. Diameter of Connecting-rod, Circular Section. Thurs- ton gives d = a V Dl, VP + C diameter at middle, where jo. a \ (o.< 15 for fast engines, 08 for moderate speed ; " for fast engines, " for moderate speed ; /, length of connecting-rod in feet, Seatons, Marks, and Whitham give d= 0.0275 8 FIG. 277. For the diameter at the crank-pin end Whitham gives 1. 08 times the diameter at the cross head end. The rod is larger at the middle and tapers about " to the foot. Sennett gives diameter at middle = " necks ^- 60 ENGINE DETAILS. 347 Locomotive Connecting-rods. The sizes of rectangular rods of uniformly tapered section are in practice as follows: Depth of Main Rod. On engines with cylinders 14" di- ameter or less the depth of the rod at the crank end is made '" less than the depth of the stub; over 14" diameter, -J" less. Depth of main rod at cross-head end = d^. Cyl. diam. 14" 15" 16" 17" 18" 19" 20" d, 2f" 2f" 3" 3" 3" 3" 3i" Thickness of main rod = /,. Cyl. diam. 14" 15" 16" 17" 18" 19" 20" t\ if" If" if" if" 2" 2" 2" Depth of Side-rods. The depth of the side-rod is made about " narrower than that of the stub end, and of uniform depth throughout. Thickness of side -rods = t y Cyl. diam. 14" 15" 16" 17" 18" 19" 20" 4 if" if" if" if" if" if" if" Pivot or Step Bearing. In this form of bearing the pressure is applied in the direction of the axis, and the load is carried entirely upon the end of the shaft. In lubricating a bearing of this type the oil should always be introduced be- tween the bearing surfaces from the under side and in the centre of the bearing, that the oil, under the influence of the DRAWING AND DESIGNING. centrifugal force, will be distributed over the entire rubbing surface. The best results are obtained from running the bearing in a bath of oil, as shown in Fig. 278, where the oil- basin surrounds the journal-box, which can be kept submerged in oil, thus insuring constant and efficient lubrication. In Fig. 278 the oil passes from the oil-basin OB to the journal- box through the hole h, and on to the under side of the shaft through the hole in the disk ED. To insure a continuous flow of oil through the holes, grooves are made on the under side of the journal-box, and upon the upper side of the projection upon which the disk BD is carried. To prevent lateral motion the end of the shaft is turned to fit the journal-box J t which is provided with a brass bush (B). The bush is secured against turning with the shaft by the projections E, which fit between lugs cast on the inner surface of the journal-box. The under side of the journal-box J is slightly spherical and rests upon a surface which is also slightly spherical. This allows the journal-box to be tipped over for a limited dis- tance by means of the set-screws 5 until its axis coincides with that of the shaft. The down pressure, of the shaft is carried upon a steel disk BD, which also rests upon a slightly spherical projection cast on the upper side of the journal-box bottom, allowing the whole of the shaft end to remain in con- tact with the disk although the bush B has become sufficiently worn to allow the shaft to have side motion, thus making the bearing adjustable, and capable of maintaining a perfect bear- ing over its entire surface under all ordinary working con- ditions. The disk BD is longer than the shaft diameter, and is prevented from turning with the shaft by the flat sides com- ing in contact with the lugs /. The journal-box is hexagonal ENGINE DETAILS. 349 35 DRAWING AND DESIGNING. in cross-section, and is tapered towards the top to allow it to tip the required distance without increasing the diameter of ^he oil-basin. It is held against turning with the shaft by the set-screws .S pressing against the flat faces. This form of pivot or step bearing is suitable for journals from \\" to 3^" in diameter. As the velocity ot the bearing surface varies from zero at the centre to a maximum at the circumference, and as the friction increases with the velocity, the wear will increase from the centre to the circumference. Thus it will be seen that the smaller the diameter D of the journal, within limits deter- mined by the pressure per square inch on the rubbing sur- faces, the more will the tendency to wear be reduced. D will be found by the formula _ T 4~ y from which 7854^ where P = intensity of pressure per square inch of projected area, which with this form of bearing running continuously may be taken at 300 Ibs. ; 7"= total load on the rubbing surface, which is the weight of the shaft and its attachments. Exercise 136- Design a bearing of the form shown in Fig. 278, to carry a load of 1450 Ibs. Show a HALF ELEVATION, a HALF SECTIONAL ELEVATION, a SECTIONAL END VIEW, the planes of section passing through the centre of the bearing, a HALF PLAN and a HALF SECTIONAL PLAN, the plane of sec- ENGINE DE7 AILS*. 35 1 rion passing through the bearing at the line ab. The unit of proportions = D + ''. The thickness t of the brass bush, and the bearing disk at the centre may be made = .o8Z> -f- T y '. The parts dimensioned in inches are constant for all sizes of j o u rnals. Scale full size. Crank-shaft or Main Bearings. The bearings carrying the crank-shaft of a vertical engine have the greatest pres- sure acting nearly vertically ; consequently the greatest wear will be above and below the shaft, and adjustment is effected by a two-part bearing, parted on the horizontal centre line, as in Fig. 170. The crank-shaft bearings of horizontal engines should be designed for horizontal adjustment to take up the side wear caused by the pull and thrust transmitted along the connecting-rod, and vertically to take up that caused by downward pressure due to the weight of the fly- wheels, etc. Vertical and horizontal adjustment can be obtained, with a two-part bearing, by parting the bushing at an inclination with the direction of both pressures. The inclination is generally 'mad 2 at 45. The frame-work con- nected with the crank bearings on horizontal engines is generally part of the engine frame, as in Figs. 2jg and 280. Three-part Bearing An example of this form of bearing is shown in Fig. 279, where the horizontal wear is taken up in one direction only, by screwing in the screws A, which move up the adjusting-gibs G against the shaft. The vertical wear is taken up by screwing down the cap C. In this design, as the bearings wear, the shaft will be moved forward and down, and can only be returned to its original position by renewing the babbitt strips. The cap is made to fit into the frame, and is also provided with projections which fit over the outside of 352 DRAWING AND DESIGNING. the frame, thus insuring that it will sit squarely upon its j )ur- nal. To keep the cap (C) from being screwed too far aad FIG. 279. clamping the shaft, it is provided with an adjusting-screw at each corner. The lubricator O consists of a pocket cast in the cap from which the oil is conveyed to the bearing through the holes // These are filled with cotton to keep the oil from flowing into the bearing too rapidly. This system of lubrication is efficient, ENGINE DETAILS. 353 but very wasteful unless the surplus oil flowing from the bear- ing can be caught and used again. This is done (Fig. 279) by casting a hollow projection OC on the frame under the bearing, from which the oil is drained off by the pipe OP to the bottom of the engine frame. Four-part Bearing. This form of bearing (Fig. 280) is parted on each quarter of the journal, which allows the wear, caused by the thrust and pull on the connecting-rod, to be taken up on either side. This is effected by screwing down the bolts A, which pull up the tapered wedges W, moving the gibs C forward toward the journal. To hold the bolts A against turning back, they are provided with a locking arrange- ment, shown, drawn to an enlarged scale, in Fig. 281. The vertical adjustment is obtained by screwing down the cap- bolts CB. The under side of the journal is carried upon a block LB, which is allowed to move transversely, thus allow- ing it to adjust itself to the journal, but is held against moving longitudinally by projections which fit over the raised part Fon the frame. The top bearing TB is held. in position by the screws 5, which also serve to hold the gibs (G) in position and keep the cap from being screwed down too tightly on the shaft. The lubricator O may be used for semi-liquid grease or by filling it with cotton saturated with oil. Length of Crank Bearing. To calculate the length of a bearing it is. necessary that we should know the amount and direction of the pressure to which it is subjected. The pres- sure on the crank-shaft bearings of a horizontal engine is uncertain in amount and direction. We can determine tne amount and direction of the resultant pressure caused by the thrust and pull of the connecting-rod and that due to the 354 DRAWING AND DESIGNING. weight of the: fly-wheels and shaft, but this pressure may be either augmented or relieved by the transmission of the power. A reliable rule, and one which is generally observed in this country, is to make the length of the bearing equal to TWICE THE DIAMETER OF THE SHAFT. The Cap. To relieve the cap as much as possible from the stresses the frame is carried up well around the bearing, and the cap (C) is practically a ;at plate. The upward pres sure of the cap caused by the angularity of the connecting-rod is found by the formula P r '~ This pressure may be augmented by the gearing which is used to transmit the power, and, to insure that the cap and cap-studs will have sufficient strength under the worst condi- tions, the value of / should be increased 100$. Then the maximum pressure p' on the cap will be found by the formala where P = total steam-pressure on the piston ; R ratio of length of connecting-rod to throw of crank. The length of connecting-rod is generally made equal to 6 times the throw of crank. The cap is in the condition of a beam on which the load is distributed over its entire surface. Then the bending moment is , and the moment of re- o LT* s'stance to bending is r~f- Therefore ENGINE DETAILS. 355 from which T -*' r x 8 X/' where L = length of cap ; T= thickness of cap; p' = total load on cap; /= distance between cap-studs; f= strength of the material, which may be taken at 5000 Ibs. Diameter of Studs. The maximum pressure (/') on the under side of the cap is resisted by the studs CB. There- fore their effective area will be found by the formula P' Area at bottom of thread = where n = number of studs ; ft = strength of material = 5000 Ibs. per square inch of area at bottom of threads. Having found the area at the bottom of the threads, turn to Table No. 8, page 66, from which take the nearest diameter of screw having the required area. The diameter of the adjusting-studs (A) and the set-screws (s) may be made -J" in diameter when the journal is 6" or less, and increased J" for every inch the journal is increased above 6" in diameter. The Gibs. The height of the gibs (G) should be f, and their thickness at t should be equal to \, of the shaft diameter. Adjusting-wedges. Instead of using three adjusting wedges and screws, as in Fig. 280, another arrangement is to DRAWING AND DESIGNING. use one wedge and one adjusting-screw with two guide-pins, as in Fig. 282. In the latter arrangement the wedge sup- ports the gib and is in contact with the frame its entire length. The thickness of the wedges at the top should be I J times the diameter of the screw (A) + i", and their width w when . 282. FIG. 280. three are used should not be less than % the length of the journal (L). The taper of the wedges may be made from I in 6 to I in 8. The screw A should be sufficiently long to enter the wedge W a. distance equal to its diameter when the wedge is full down. Top and Bottom Blocks. The thickness t at the thin- nest part of the bottom block should be equal to .23, and that of the top block .15, of the journal diameter. ENGINE. DETAILS. v-, 357 Exercise 137. Design a crank-shaft bearing of the form shown in Fig. 279, proportioned for a horizontal steam- engine, having a cylinder 9" in diameter, stroke 10", initial steam-pressure 200 Ibs. per square inch, and the diameter of the journal (D) 4". The bearing to have a vertical and hori- zontal adjustment of f". Show a HALF ELEVATION, A HALF SECTIONAL ELEVATION, a HALF END VIEW, a HALF SECTIONAL END VIEW, a HALF PLAN, and a HALF SECTIONAL PLAN of the right-hand side. Scale 8" to the foot. Exercise 138. Design a crank-shaft bearing of the form shown in Fig. 280, proportioned for a horizontal steam- engine having a cylinder 18" in diameter, stroke 30" long, and an initial steam-pressure of 220 Ibs. per square inch. The bearing to have a horizontal adjustment of J" in either direction and a vertical adjustment of $". Make D the diameter of the journal 9". Show an ELEVATION, PART PLAN, and PART SECTIONAL PLAN, the plane of section passing through the centre of journal. Scale 4." to the foot. Show also a detail drawing of the adjusting screws and wedges, as in Fig. 281. Scale 8" to the foot. Exercise 139 Design a crank-shaft bearing of the form shown in Fig. 280, substituting the adjusting-wedge arrange- ment shown in Fig. 282. Make the proportions suitable for the conditions given in Exercise 138. Scale 4." to the foot. Ball Bearings This device for reducing friction consists of perfect spheres placed between the journal and the bear- ing; the balls taking the place of the bush in supporting the shaft, thus substituting rolling for sliding friction. As the bearing areas are only slightly flattened points, the wear will DRAWING AND DESIGNING. be comparatively rapid ; so, to reduce the amount to a minimum, the balls and the surfaces upon which they roll are made of steel tempered as hard as possible. The different forms of ball bearings are designated accord- ing to ;he number of points that the balls have in contact with the surfaces upon which they roll. In a three-point bearing a line drawn through one of the points in the direction in which the load acts should pass midway between the other two points. Thus the form of bearing shown in Fig. 283 will give good results only when the resultant of all the pressures acts at an angle of 45, other- wise the balls will not revolve on a true axis, but will have a screw motion and therefore a considerable amount of friction. The design shown in Fig. 284 is suitable for a pressure in a vertical direction only. In a four-point bearing a line drawn through one of the points in the direction in which the pres- sure acts should pass through a contact-point on the other side of the ball (as in Fig. 285), then the balls revolve on a true axis and sliding friction is entirely avoided. Size of Balls. Steel balls rolling under pressure do not fail by crushing, their period of usefulness depending upon both speed and pressure. This would seem to indicate that the balls should be as large as possible, thus reducing the number of revolutions in proportion to those of the shaft, and increasing their strength ; but there is a practical limit to this owing to the fact that the larger the balls the fewer will be the number, and therefore the fewer the number of bearing points. The bearing would then fail by the balls crushing into the surfaces upon which they roll. There is a great di- versity of opinion as to the proper size of ball in relation to ENGINE DETAILS. 359 load and speed. The size given in Table No. 37 gives a fair average proportion of the diameter of the ball to the diameter of shaft used in practice for horizontal bearings. TABLE NO. 37. Shaf* 'Jiam. Ball Diam. Crushing Strength of Ball. Shaft Diam Ball Diam. Crushing Strength of Ball. \ &" i 3 3000 l" l| r > 20 000 | j- 5 ooo If 2 i > 30 ooo I A 7000 2| 3 t j- 40 800 I i| f > 1 2 OOO 3* 4 i 50 ooo 6OOOO Ball Races. The thickness (t) of the surfaces upon which the balls roll should not be less than tlu diameter (d ) of the ball, and the width W = ij times the ball diameter. The angles of the grooves are generally made 45. In every ball race a slight amount of clearance (c) is left between each pair of balls. This is necessary, first to get the balls into place, second to insure the free rolling of the balls. The amount of clearance is generally made from .002 to .004; it will there- fore be safe to assume .003 as good practice. Then taking the diameter I\ of the ball circle = D + 2t + d D + 2d. In 360 Fig. 285 the angle 0= ~ ~ = - 211 I 80 I 80 sin n n d+j: ~~~ From a table of sines find the angle 6 in degrees corre- sponding to x. Then i 80 and i8o c (4) The number of balls must be within .001 X n of being a whole number; if not, we must increase the diameter^,. Thus 30- DRAWING AND DESIGNING. supposing that formula No 4 gives n = 20.75, then we must increase D l to get in the next whole number of balls. Taking n = 21, we can find D^ by the formula />,= d+e I So 01 (5) sin Load on Bearings. As already explained, the life of a bearing is a function of both speed and load. Therefore if FIG. 283. FIG. 284. FIG. 286. FIG. 285. the speed is increased, the load must be corresponding!]/ de- creased or the life of the bearing will be shortened. Using the proportion of ball to the shaft diameter given in Table ENGINE DETAILS.. 361 37, the safe load in relation to the speed may be found by the formula __f c X N - , (6) where* L = total load on the bearing; f e = strength of ball; 5 = speed of the ball races in feet per minute ; N= number of balls carrying the load ; in horizontal bearings = i of the total number. Exercise 140 Design a lathe grinder of the form shown in *Fig. 286 provided with four-point ball bearings. Make the emery-wheel 6" in diameter xi" thick, belt drum ij" in diameter and length suitable for a ij" belt. The diameter of the shaft (D) = f ". Show an ELEVATION with one of the bearings partly in section, a HALF END VIEW and a HALF SECTIONAL END VIEW as shown in Fig. 286. Scale twice full size. Thrust Bearings._The difficulty experienced with the ordinary pivot or thrust bearing, due to the velocity increas- ing as the distance from the centre, is overcome by the application of balls to this type of bearing. The designs shown in Figs. 287 and 288 are made by the Boston Ball Bearing Co. and may be used on either vertical or horizontal shafts. The balls are held in place by the cage C, the use of which, although tending to increase rather than diminish fric- tion, facilitates the placing and removing of the balls, and by its use the balls can be placed at various distances from the centre cf the shaft, thus increasing the time the bearing will *un before wearing grooves in the plates PB. In Fig. 288 362 DRAWING AND DESIGNING. the balls are arranged in spirals ; thus every ball runs on a separate path, and the tendency to wear grooves is reduced to a minimum. The small cages are made in one piece, as in Fig. 287, and the balls are put into position by springing the cage, while in the large cages the top is fastened to the under side, by rivets, after the balls are in position, as in Fig. 288 The cages are made from -y" to " thick. The thickness (t) should not be less than the diameter of the ball, and the DR FIG. 288. FIG. 287. distance e should not be less than of the ball diameter. The centres of the ball races are J of a ball diameter apart. .The hub H is screwed to the shaft by means of one or more set-screws (5), the diameter of which may be made .2D, but not greater than ". L = 2t -f- 3^, but not less than %D. D' 2D when D is less than 2", and = 1.7 when D is 2" or over. The load and speed to which this type of bearing is subjected will determine the number of balls. Taking the size ENGINE DETAILS. of ball in proportion to the diameter of the shaft from Table No. 37, then from formula No. 6 Exercise 141. Design a thrust bearing of the form shown m Fig. '287 for a 4" shaft, to carry a load of 760 Ibs. and run at a speed of 600 revolutions per minute. Scale full size. Stuffing-boxes. To prevent leakage, when rods work through the walls of a chamber containing fluid, the rod is passed through a cavity filled with an elastic material which will adjust itself to any irregularities on the surface of the rod. Fig. 289 shows a stuffing-box suitable for a horizontal DR FIG. 289. steam-engine piston-rod, and Fig. 290 one arranged for a vertical steam-engine piston-rod. The stuffing-box SB may be made a separate piece and bolted to the cylinder-head, as in Fig. 289, or cast with the cylinder-head, as in Fig. 290. Part of the box SB is bored DRAWING AND DESIGNING. FIG. 290. ENGINE DETAILS., 365 larger than the diameter of the piston-rod PR, thus leaving a space S around the rod which is filled with packing consisting of a fibrous material saturated with oil or tallow. The pack- ing is pressed against the rod by screwing down the gland G, which is generally made of brass for rods under 4" in diam- eter, as in Fig. 289, and of cast iron lined with brass for the larger rods, as in Fig. 290. Proportions. The proportions of the stuffing-box are generally decided by the conditions under which it is used ; thus the box is generally made longer for a high than a low pressure. However, under any conditions, the longer the box the longer will the packing last. The following proportions are suitable for average pres- sures and speeds, and could be used for high pressure, but would require to be repacked comparatively often : L = 2D for rods 2" or less in diameter; L = \\D for rods between 2" and 3" in diameter; T __ jl/} << << << 3 // << A ff '' 4< L = D + \" for rods over 4" in diameter; /, = .75^; T '= ^D in nearest -fa; C= \\D-\-2d; =Z /=' = y , and that this value in marine and stationary engines may be exceeded to the extent that p' = 60000 -f- V. Then nd* ,_ R *v -*>*r 40000 40000 (Vn* i)" In many cases of ordinary stationary-engine practice, especially on engines having four-bar guides, the above formula would give a very short block, and as there is gener- ally no difficulty in providing large rubbing-surfaces, we find the areas increased as large as where V '= velocity of piston in feet per minute = (length of stroke X twice the number of revolutions per minute). The cross-head should always be designed so that the 37 DRAWING IND DESIGNING. resultant pressure (K) on the guides will have its point of resistance at the centre of the cross-head rubbing-surfaces, as shown in Fig. 292. "Wrist-pin. The connecting-rod is attached to the cross- head by the pin CP, Fig. 293. In this form of joint, as the velocity is low and the pressure constantly changing in direc- tion and magnitude, the allowable pressure per square inch is comparatively high, reaching in some designs as much as 1400 Ibs. per square inch. Seaton says that the pressure per square inch should never exceed 1200 Ibs. per square inch of projected area (d X /) When the total load on the pin is taken as the maximum load on the piston, i.e., the initial steam-pressure X area of piston, the length of the pin is generally made to equal from d to i . 3 T f bending moment is = -^ and the moment of resistance to bending = fZ. Where Z is the modulus of section, given in Table No. 29. The Length of Guide-bars between distance-pieces is = to the stroke -f- the length of the block -f- end clearance, which may be made = i" at each end. Four-bar Guide. The arrangement shown in Fig. 293 is that used on the cycloidal engine (Atlas Engine Works). _) 1 CP 3 ^* FIG. 294. With chis arrangement the pressure Pis equally distributed on each side of the piston-rod, which is guided laterally as well as vertically by the cross-head sliding on the inner surfaces of ENGINE DETAILS, 373 t"ne guide-bars G. The piston-rod PR is secured to the cross- head C by the arrangement shown in Fig. 294. To prevent the piston-rod from exerting undue pressure on the stuffing- boxes, should the axis of the piston-rod not coincide with that of the cross-head, the hole through the shank of the cross- head is made larger than the diameter of the piston-rod, which is adjustable and held in position by means of the set- screws 5. In this arrangement the breadth b of the bearing- surfaces on each bar is generally made equal to ^ their length. The area of the bearing-surfaces may be determined by formula No. 8. Then and 1' = . 4 b The form of guide-bar used in this design may be made of cast iron or steel, and proportioned in the following manner: Having determined the breadth b and the length Z, then calculating for a bar of rectangular section, secured at both ends and loaded at the centre, the height h of the bar at the centre will be found by the equation from which JR X L' X 6 b X/X 6' where / may be taken at 3000 for cast iron, and 6000 for steel. Take h' = .?$ h, then the area of the web will be = (h x b) (h'Xb), and taking the thickness t of the web = .4^. Then the height of the web at the centre will equal area of web -T- 4#. 374 DRAWING AND DESIGNING The greatest strain on the stud-bolts B which secure the guides to the engine-frame is due to screwing up. They may be made = i J" in diameter. To allow for any slight inac- curacy of workmanship, the holes through the bars are made T y larger than the diameter of the bolts B, and the bars are adjusted laterally by the screw 5'. The bars are adjusted vertically by means of the nut N, shown in Fig. 295 > which is screwed into the guide-bar blocks GB. The rubbing-sur- faces are lubricated by oil-cups screwed on to the upper guide- bars. The oil is transmitted to the lower bars through the holes O on the cross-head. Exercise 145, Draw the four-bar guide and cross-head arrangement shown in Fig. 293 suitable for an engine having a cylinder 12" in diameter X 15" stroke. Initial steam-pres- sure 75 Ibs. per square inch. Speed 300 revolutions per minute, and a connecting-rod four times the length of the crank. Scale 4" to the foot. Draw also details of the adjusting-nut TV and the cross- head pin, and show the arrangement of fastening the piston- rod to the cross-head, taking the diameter of the piston-rod = 2". Scale full size. Two-bar Guide. When two guide-bars are used they are arranged either one above and one below the piston-rod (in this case a cross-head of the type shown in Fig. 297 is used) or both guide-bars above the piston as shown in Fig. 296. The latter arrangement is one commonly used in locomotive construction. The pressure is on the upper guide, L7G, when the locomo- tive is running forward, and on the lower guide, LG, when running back ; and as the engine is generally run forward more E1V&INE DETAILS. 375 DRAWING AND DESIGNING. than back, the bearing-surface on the lower bar may be made smaller than that of the upper. In this design the cross-head C is of cast steel and provided with a brass slide-block SB which has strips of babbitt metal top and bottom. To fit and remove the piston-rod easily from the cross-head, the -shank is cut and, after .the rod is in position, it is gripped by screwing down the bolts CB and se- cured by driving a tapered cotter through it and the cross- head .shank, ^ The hole O is to allow for lubricating the cross-head pin. The guide-blocks GB are fastened to the cylinder at one end and to a guide-bar frame at the other. Exercise 146. Draw the cross-head and guide-bar arrange- ment shown in Fig. 296. Scale 3" to the foot. Also details of the 'slide-blocks SB, guide-block GB, cross-head pin CP, cotter C, and washer W. Scale half size. Cross-heads. Adjustments to take up the wear or for original setting may be accomplished by moving the guide- bars, as in Figs. 293 and 296, or the slide-blocks, as in Fig. 297. In this design the cross-head C is hollowed to receive the connecting-rod end, which works upon the pin CP. The pin is of case-hardened steel and is kept from turning by the ^-inch square-headed screw K. The piston-rod PR is screwed into the cross-head and se- cured by the nut LN. The socket into which the rod PR is screwed has flat surfaces on the top and bottom to give clear- ance 'for the mit N. The diameter at the end of the socket is equal to the dis- ENGINE DETAILS. 377 3/'8 DRAWING AND DESIGNING. tance across the flats, and tapers back j- of an inch to the larger diameter. The bearing-surfaces on the slide-blocks are turned, and the corresponding surfaces on the frame, upon which they fit, are bored to the same radius. The blocks are provided with grooves on the under sides, which fit over projections on the top of the cross-head, to prevent their lateral movement. To take up the wear, the slide-blocks move horizontally, on the inclined surfaces upon the top and bottom of the cross-head, for a distance equal to the length of the holes minus the diameter of the studs, and by this horizontal motion they move vertically T ^ of an inch. Exercise 147. l)raw a cross-head of the form shown in Fig. 297, showing a SIDE ELEVATION, END ELEVATION PARTLY IN SECTION, and a SECTIONAL PLAN, the plane of section passing through the centre of the cross-head pin. Scale full size. Construction. To find the inclination necessary to give the required vertical movement, mark off on the centre line ab the distance from the centre of the pin CP to the point C, and through C draw the line cd at right angles to ab and equal to the horizontal motion of the slide-blocks, and through d draw de equal to the vertical movement. The line drawn through the points ce will have the required inclination. Fig. 298 shows a form of cross-head used on the U. S. cruiser Olympia. In this design the wrist-pin CP is outside of the cross-head, and there are two bearing-surfaces on the connecting-rod end. The slide-blocks SB are secured to the cross-head C by the bolts B. To allow the removal of the ENGINE DETAILS. 379 slide-blocks while the cross-head is in position, one of the pro- jecting lips L on each block is removable and held in place by the bolts B. To 'facilitate the removal of the Apiece Z, it is provided with set-screws 5. The piston-rod PR is secured to the cross-head by the nut shown in Fig. 67, page 100. Fig. 299 is an isometric sketch of the complete cross- head. Fro. 299. /2/faa FIG. 298. Exercise 148. Draw a general arrangement of the cross- head shown in Fig. 299. Show a FRONT ELEVATION, a HALF PLAN, and a HALF SECTIONAL PLAN of the top, the plane of section passing through the centre of the wrist-pin. Scale 4. inches to the foot. Eccentrics. The eccentric is a form of crank in which the radius of crank-pin is greater than the sum of the radii of the crank and the shaft, as shown in Fig. 300, where the 380 DRAWING AND DESIGNING. crank is shown by dotted lines, and the eccentric by full lines. It is used for converting circular into reciprocating motion. For this purpose its action is identical with that of a crank, and as the eccentric absorbs rnore power than the crank (owing to the greater leverage at which the friction acts) it is used in preference only where the throw is comparatively FIG. 300. short. The eccentricity or throw of the eccentric is the distance r from the centre of the shaft to the centre of the sheave. The stroke of the reciprocating piece worked by the eccentric is equal to twice the throw. Fig. 301 represents an eccentric used for working the slide-valve of a locomotive engine. The eccentric proper is generally called the sheave o** pulley. When it cannot be passed on to position over the end of the shaft, the sheave is ENGINE DETAILS. 381 made in two parts, P and P f , parted on a line passing through the centre of the shaft and at right angles to the horizontal centre line of the eccentric, and held together by studs. That the strain may come on the stronger part, P', the key and set- screws used in fastening the sheave to the shaft are placed on that part. The eccentric-rod ER is secured to the strap 5 by 382 DRA WTNG AND DESIGNING. the bolts B,B^B Z . The hole through the strap, for the centre-bolt B^ , is elongated that the rod ER may be adjusted when setting the valve. Proportions. The thickness / of the sheave may be \D ", with a minimum of \" . The diameter of the sheave will then = D + 27- + 2t. The breadth B of the sheave may be found by the formula L B = D' x/ where L = load driven by the eccentric ; D' = diameter of the sheave; p allowable pressure per square inch of projected f t = area, which should have a maximum of 100 Ibs. Thickness of key = . iD. Breadth of key = ij times the thickness. The size of the strap-bolts SB should be proportioned to resist the load driven by the eccentric. ~ X 2 X /, where d l = diameter at the bottom of the threads ; L = load driven by the eccentric ; ft = safe strength of bolts, which may be taken at 2000 Ibs. per square inch. The size of the rod-bolts, assuming the load is resisted by the two fitted bolts, may be found by the formula *. ' L 4 X2X/ ENGINE DETAILS. 383 f may be taken at 3000 for wrought iron. The distance C between centres may be made = $d. The parts marked in decimals are proportional to B, the breadth. Exercise 149. Draw the arrangement of eccentric-sheave and strap shown in Fig. 301, proportioned to carry a load of 2300 Ib's., taking the pressure per square inch of projected area = 50 Ibs. Draw the views shown in Fig. 301 ; also a SECTIONAL END VIEW looking' towards the right, the plane of section passing through the eccentric at the line cd. Make the eccentric-rod 3i" X i". Scale half size. COURSE II. ELEMENTARY MACHINE DRAWING INCLUDING DETAIL WORKING AND ASSEMBLY DRAWINGS, CONVENTIONS FOR DIMENSIONING, INDICAT- ING FINISH, NOTES, BILL OF MATERIAL, TITLE, STYLE OF LETTERING, ETC. Prerequisites before Beginning Course II. Students must have completed Course I as contained in Reid's Mechanical Drawing, or an equivalent course consisting of Lettering, Geo- metrical Drawing, Orthographic Projection, Developments, In- tersections, Isometrical Drawing and W T orking Drawing. ELEMENTARY MACHINE DRAWING. MINIMUM NUMBER OF PLATES AND MAXIMUM NUM- BER OF HOURS ALLOWED TO COMPLETE EACH DIVISION OF THE WORK. FIRST SEMESTER. PLATES i AND 2. Consisting of screws, bolts, rivets and riveting and bolt fastenings, must be completed and handed in on or before Friday, October 9, 1908. (26 hours.) PLATES 3, 4, AND 5. Consisting of anchor bolt and locking devices, knuckle and cotter joints, and shaft couplings, must be finished according to directions and handed in on or before Friday, November 20, 1908. (36 hours.) PLATES 6 AND 7. Consisting of universal shaft coupling and pipe couplings, must be finished and handed in on or before Friday, December 18, 1908. (24 hours.) PLATES 8 AND 9. Consisting of post bearing and pedestal bearing, must be finished and handed in not later than Friday, Jan- uary 29, 1909. (24 hours.) Students failing to finish any of the divisions of the work within the time specified, because of excused absences, may make arrangements with the Instructor to work in one or more extra periods. Students doing more work than is required in the given time will, other things being equal, receive a higher mark. END OF FIRST SEMESTER. 387 388 DRAWING AND DESIGNING. NOTE. Registered Freshmen conditioned in Machine Draw- ing will be required to complete satisfactorily the following plates of this course in addition to the plate shown in Fig. 302 : i, 2, 5, 8, 10, and 13, according to the directions given in the text. Con- ditioned students must work at least six hours per week. When the above plates are finished, work on the regular Freshman Machine Drawing may be commenced. SECOND SEMESTER. PLATE 10. Consisting of pulley and spur gear, must be completed and handed in on or before Friday, February 19, 1909. (15 hours.) PLATES n AND 12. Consisting of disk valves and globe valve, must be finished and handed in on or before Friday, March 19, 1909. (21 hours.) PLATE 13. Consisting of marine cross-head, must be finished on or before April 9, 1909. (18 hours.) PLATES 13 AND 14. These plates must be finished and handed in on or before May 21, 1909. (36 hours.) Students failing to complete any of the divisions of the work satisfactorily within the time allowed (for good reasons) may make arrangements with the Instructor to work in one or more extra periods. Students doing more than the required amount of work in the given time will receive a higher mark, other things being equal. END OF SECOND SEMESTER. ELEMENTARY MACHINE DRAWING. STUDENTS' CONDUCT IN CLASS. Students will be expected to give strict attention to their drawing work during the full time of each drawing period. //V fT MflK WCSS FT /A/ TWO /V;r />* TO B. G/^e\f //V /NCHES ft AD// /NO/GATE O By /? COMPLETE 0/A /< THUS O/MEHS/OHS Of Z^T-SS 7^4/ THUS - A/Or THUS ) ,k :# !r <*1- fcl ^-Kr /*r r|^^ A Materials and instruments must not be put away until the warning bell rings. Nothing should be brought to the drawing table that is .not needed for the drawing work in hand. If a student expects to be absent from the class he should endeavor to get excused by the Instructor and make arrange- ments for making up the work. 390 DRAWING AND DESIGNING. A student coming late to class should report at once to the Instructor, otherwise he will be marked with an unexcused absence. A report from the Instructor concerning the deportment of each student in class is expected by the Dean every two months. When a student is absent from class through an unforeseen cause, he should at the next regular period fill out an absence blank, giving date and cause of absence, sign it, and hand to the Instructor. The work of all absent periods must be made up by arrange- ment with the Instructor. PLATE i. Fig. 35, Exs. 29, page 131, 32, page 142, and 4, page 58. This plate should be laid out similarly to that shown on page 391. See Fig. 304 for standard bill of material. Di- mensions for standard title are given in Fig. 304. Use a 6 H pencil sharpened to a long wedge-shaped point and draw the figures with fine light lines, beginning at the upper left-hand corner of the sheet. In planning the positions of the different exercises take into account the space required for the title and the bill of material. All the exercises should be com- pleted in fine pencil lines and submitted to the Instructor for approval, after which the drawing is to be cleaned and all the given and required lines are to be relined in strong lines with a 4 H pencil sharpened to a long conical point, not too sharp. The dimension lines may now be placed to the best advantage, using a fine sharp line drawn with the 6 H pencil. Care should be taken when locating dimensions never to place figures on top of a line or even too near a line when it can be avoided. The dimensions should stand out on the clear paper to avoid con- ELEMENTARY MACHINE DRAWING. 391 fusion. Great care should be taken in pencilling in the title and bill of material to see that it is neatly and correctly lettered. The above directions will apply to the pencilling of all draw- ings in this course. Plate i will be a finished pencil drawing, 39 2 DRAWING AND DESIGNING. and only the title and bill of material together with the border line are to be inked. The width of the inked border line should be one thirty-second of an inch. PLATE 2. Exs. 9, 10, n, 12, and 13, pages 70 to 77. This plate is to be finished in pencil as in Plate i, and when signed _;!*_ *<* $~&1LL-OFMA TERIAL **ggf BBK NAME- . SOL MIL 1BEBAHKS Sir IZ'_ ^NCHDBTBDLT "7ST WT- 5TELJHO5 *i% 2 K , *-^- 7V3CVF r r- -, ^- /&- ' 1 1 1 1 L FIG. 304. by the Instructor it is to be traced on cloth and blue-printed. The proportions for the different styles of bolt-heads that are not U. S. standard will be found on page 75. The plan of the square nut in Ex. 9 and the hexagonal nut in Ex. 10 are to be omitted, but space should be provided for a plan of the hook bolt, omitting the nut and washer. In Ex. 13 show me hexago- nal nut across corners. ELEMENTARY MACHINE DRAWING. 393 PLATE 3. Exs. 17 and 22, pages 85 and 104. This plate is to be finished in pencil only. Read the text carefully, de- scribing the different kinds of foundation bolts, viz., the rag bolt, the Lewis bolt, and the anchor bolt. Study also the require- 394 DRAWING AND DESIGNING. ments of the problems and the given data. Before commencing the drawing for Ex. 22 the student should study the text de- scribing the different styles of nut-locking devices. Locate the drawing for Ex. 22 in the upper right-hand corner of the sheet and use only half of the plan shown. In Ex. 17 assume D the diameter of the washer at 6J" and draw to scale given. PLATE 4. Exs. 23, 24, and 26, pages 108 and 120. Use only Fig. 84 of Ex. 26. Joints to be made of wrought iron. Finish in pencil. PLATE 5. Exs. 44 and 50, pages 167 and 178. In Ex. 44 place the longitudinal elevation at left end of sheet and the end elevation to the right of the front elevation and draw also a plan above the latter, showing the upper half removed. Make square key J of the diameter of the shaft. In Ex. 50 assume D at 17^". This plate is to be finished in pencil and traced. PLATE 6. Ex. 53. Page 185. Make detail working draw- ing. All the parts are to be separated and fully dimensioned. Finish in pencil. PLATE 7. Exs. 56, 58, and 64, pages 191, 194, and 202. In Exs. 56 and 58 make the inside diameter of pipe 6". Make elevations and sections for all three problems the same as given in Ex. 55. Make finished pencil drawing with title and bill of material as usual. PLATE 8. Exs. 70 and 109, pages 214 and 304. Use Fig. 225 in the latter exercise. In addition to the two views given in the text-book, show a plan above the main elevation. Make finished pencil drawing and trace on cloth. Blue print. ELEMENTARY MACHINE DRAWING. 395 PLATE 9, Ex. 76, page 232. Make detail drawing showing all necessary views of each part of the problem. Make finished pencil drawing. Scale 4" = i ft. PLATE 10. Exs. 84 and 92, pages 247 and 269. In Ex. 84 assume the following dimensions : Diam. of shaft 2" ', diam. of pulley 20", width of belt 3^". Scale 6" = i ft. In Ex. 92 make scale 4" = ! ft. Make finished pencil drawing and trace on cloth. PLATE n. Exs. 99, 101, and 103, pages 285, 288 and 292. Make finished pencil drawings as directed. PLATE 12. Ex. 104, page 292. Make detail assembly draw- ing. Draw two assembly views, half section and half elevation on each. Next take the valve apart and make working draw- ings of each part. Scale as given. PLATE 13. Ex. 147, page 378. In addition to the views shown draw a longitudinal cross-section. Finish in pencil and trace. PLATE 14. Ex. 130, page 338. Make a complete detail working drawing and trace. Scale to suit. PLATE 15. Ex. 133, page 339. Make assembly drawing as directed, also details of each part fully dimensioned. Finish in pencil. PLATE 15 A. Ex. 149, page 383. Make deta'il working drawing. Finish in pencil. Scale to suit. COURSE III. ELEMENTARY MACHINE DRAWING FRESHMAN YEAR. PREREQUISITES. In Mechanical Drawing, Course I, Plates i to 6 inclusive, 10, u, 12, 14, 17, 19, 21 and 22. In Machine Drawing, Course II, the drawing shown on page 389, together with Plates i, 2, 5, 8 and 10. The above, or its equivalent, will be required of all students before commencing Course III. Student Conduct in Class. Read carefully the directions given on page 389, COURSE III. ELEMENTARY MACHINE DRAWING. MINIMUM NUMBER OF PLATES AND MAXIMUM NUMBER OF HOURS ALLOWED TO COMPLETE EACH DIVISION OF THE WORK. FIRST SEMESTER. PLATES 1-6 INCLUSIVE. Consisting of freehand lettering; must be completed and handed in on or before October i6th. (26 hours.) All lettering in regular periods will then stop and the work in Machine Drawing will begin. PIATE 7. Must be finished according to directions and handed in not later than October 3oth. (12 hours.) PLATES 8 AND 9. Must be finished as directed and handed in not later than November i3th. (12 hours.) PLATES 10 AND n. Must be handed in completed on or before December i8th. (27 hours.) PLATES 12 AND 13. To be finished and handed in not later than January i5th. (12 hours.) PLATE 14. To be finished and handed in on or before January 2Ojth. (12 hours.) 399 400 DRAWING AND DESIGNING. Lettering, Fig. 305, page 400. Use the 4 H rpened to a long conical point, not too sharp. X' x It Locate the lower point of the first guide-line 12 squares from top and 7 squares from left-hand edge of cross-section pad. ELEMENTARY MACHINE DRAWING. 401 Guide-lines should.be sketched lightly with a downward stroke and allowed to remain until letters are approved. i? ^ So iy ^ rr N X in 3 ^ O kj 5 k: k &*J, tf S N 13 X ?! O - a K v .7! rt K ' fa s?^ S ^i> ^^K < rv- ^ S$ K si ^ <: ^ IH I C2 ^ i? ^ *'L ^^5 ^ ^ tafciu >'** &W A .1* A* to l*lfvj lU^ !^ i\ Ij ^t ^ -j' ij S Q^J j^ *J^| |si|| || ^ *$ \ . ^ SI m N K in." fr ?J- K feft ^^ * S V S C .41 ^$r. <^ ,,J- 5 S2S U? ?>!"' SS- ^S 6 ^^ Lit Vs^U^ S^ Q:^ ^ > iy i < s .v v'S b- yi ^^ r 8r 8U SS Ml ^ i \ % s8^ v l v k ^ 5^ toUjiDrifl 1 ? IU^100 ^ i " 111 ^ UlK'g jpo ft ^ HjR ^ I. A ft. I,. ^ T > ^ ^\ ^fr 1 S NJ f P - fc I ^^^xll^hi ^ S Nl ff X ^^S i-ifl ill ^ ^-i S^il M^?l| il^ fe i ^V >^> lit Ux y-' |p |||ic 3j |p| |^ ^iOrs ^ S ^ V g h . '; ^| S Q-K^ ^ U) Q:^^^^ w . | 1^5$: ^ ; *0 ^) Vj to to ^i^^SJ ^ Cyjfo^'^^a OQQQ ^fo^^to^O) j K HI vv v\ Ch Q) ft) 0) 01 CM oi ^ cu ^ to to Q 0) h 00 M! ^ ^ ^o to 9) Q ^ > ^ to^O^ K V)^ CHr ^V)^(oq) fNv sm. C\t fw I v)Q\ A ) ^ 'o to ^) ^) fK/^_ ^^D^'Oto^^ ^ ^ ^0 (c Q ^ C\| (V) ^ ^ ^ OQ ^ ^ ro ^ ^ ^ co ^ C\i ) ^ ^ ^> ^0 Q) ELEMENTARY MACHINE DRAWING. 405 Pencil three words only of the small letters at first and submit for criticism before going on with the others. Use Ball pen, No. 506, to ink large letters and No. 516 for small letters and figures. PLATES 3-6. In the next three letter plates the directions for guide-lines, form, slope, spacing of letters, and for width of small letters should be carefully observed. PLATE 6.* While a substantial majority of the leading drafting rooms in the United States are in favor of using Gothic Capitals exclusively for notes and titles, there are a number using a combination of Gothic Capitals and Lower Case letters. So it is deemed wise to introduce one plate of Lower Case letters to give the student some knowledge of their form, proportion and construction. This plate should first be pencilled and after approval, inked. In addition to the "Ball" pen, No. 516, for large letters, the small letters should be inked with Gillott's No. 303. All pens when new should be "exercised" a little before beginning to letter. The form and proportion of these letters as given by the largest letters in Fig. 310, on page 407, should be adhered to as closely as possible. In general these letters should be made with down strokes of a uniform pressure. The only exceptions are the letters r * All letters and figures should have uniform slope. Letters and figures of one square high should have a full half square slope. Each plate must be signed by Instructor in charge, in pencil before inking and jn ink when plate is finished. Plates not so signed will be rejected. When plates are finished and signed they will be retained by the student until the six plates on lettering are completed, when they are to be bound with paper binders and handed to the Instructor. 406 DRAWING AND DESIGNING. K V*5 q> 0) (0 \ . c$i *,* *'<* S'OKK i; 5 O^vL ^ to v^ K.K \Lw (Krv\ v ^ IN v Vv H) M& U I v ^ ^ y N> K ^ ^ ^) 4) O fX ft\v V\ ^ 1^. K. \Jfc \{. fX MA ^ ? CQ ">) ^ 'fyw QQ njft) KK |\^ ) ") KK ^ Al CS) Qj Or) P) KK f/v ri ) l!l 5 KK ^\f^vj QO) ^ ") KK x) "0 ") (*) ft) m ELEMENTARY MACHINE DRAWING. 1 i 3 n ^ ** ' 5 407 ^ 45 i ^ I ^ I *o f I 1 x? ^ i^ s 1 t fill 408 DRAWING AND DESIGNING. and u. The curved part of the r may be made with an up stroke curved only at the top. The u is made with two down strokes I * * I IV I ^ I ^ <: & fcS? * ^ CQ <*: *M ij KUib^S $ kju) N ^ K ^ N ^ ^ Vj V) 0\ ^ m T Ui K > > ^ K R ^ U ^ ^ > * $ % ^ * V r\ (f\ Or 0" M 8 i ..?-* ^ I i 111 9 v < ^ ^ ^ Hi HI ^S Hj^ ^^ T<0 $ Q $ J L* $ii oG S i N trvi^^^N^MlU X IV S S ^ i/ < Q 5 < Hi 2 Sp ? 1 ' 3 a MUro . f 'M;iririfiP9 i ) 5 $ Q ^^ ^ ^S ^ g :Sl^^io . ^r^s* ^^^ -Q- ^ N ^ ?>;~ <&. x $ ^? ^li ^T S 5 ^ '(A Hi .^^^ io^^5 S^ ^S^S^^o^ioL 9 S ^^^ s^u^Qr N ^N>^< ^vsUiHjHi^S *j- *tt ^^Q: t ^^ l OC\^^ ^^NlJ* ^IK^^I^^^^^^O^I!! and the bottom curve filled in with a stroke to the right and upward. The m, n, and h should be formed with nearly sharp upper curves. ELEMENTARY MACHINE DRAWING. 409 This plate will have to be repeated until the desired results have been obtained. PLATE 6A, Fig. 311. This is an extra lettering plate for those students who may finish the required plates ahead of time. The extra plate will increase the grade mark. PLATE 7. Problem i. Make working drawing of automobile crank axle, as shown in Fig. 312, page 410. Problem 2. Make working drawing for top bracket for planing machine as shown in Fig. 312, page 410. Project also right end view of bracket. Begin by laying off border line and space for title. Locate all center lines of axle and bracket. Use 6 H pencil, sharpened as directed on page 8. Draw fine, clear, clean cut lines. When drawings of bracket and axle are complete and approved, strengthen all the object lines with a 4 H pencil, conical point. Draw all dimension lines. Put in arrow-heads and dimensions, beginning at the upper left-hand corner and work down toward the lower right-hand corner. Letter all notes very carefully. When the drawing is properly finished in pencil and signed by the Instructor, it will be ready to be traced on cloth. Use the "dull" side of the cloth and begin tracing with the spring-bow pen. Ink all arcs of circles, circles and irregular curves if any, before inking any straight lines. Ink dimension lines. Ink arrow-heads and dimensions in consecutive order, thus: left-hand arrow-head, dimension, sign of inches, and right- hand arrow-head. Ink hatch lines and center lines last of all. For weight and character of lines see "Conventions," page 419. 4io DRAWING AND DESIGNING. ELEMENTARY MACHINE DRAWING 411 PLATE 8. Problem i. Make a careful freehand sketch of either the i|jj" drop hanger or the post hanger to be found in the drafting room. Use orthographic projection and sketch on 8"X 10" cross- section . pad with 4 H pencil. Use only one side of the paper. Sketch three views of body and detail of link. All dimensions notes, title, and finish marks must be neatly placed on sketch. Begin the sketch by drawing all the center lines for the front and end elevations and the plan. Sketch center line for detail of link. Make size of sketch to suit size of paper. Lines should be sketched very lightly at first and when sketch is approved the lines may be strengthened. Put on all dimension lines before measuring the object. Sufficient dimensions must be placed on sketch to enable the draftsman to make a working drawing for the pattern maker without having recourse to the object, after the drawing is commenced. Sketch must be signed by the Instructor. Callipers may be had at the office. PLATE 9. Problem i. Make working drawing from the drop or post hanger, as the case may be, from the sketch made in Plate 8. Make finished pencil drawing scale 6" = i foot. See Fig. 156, page Z2Q, and Fig. 159, page 224, for similar hangers. PLATE 10. Problem i. Make freehand sketch for water cylinder of steam pump without the adjacent parts. Make longitudinal section through the center of cylinder, plan of top, half cross- 412 DRAWING AND DESIGNING. section, and half end view combined, also cross-section through supply and delivery ports. Scale about half size. Large circles may be drawn with compass. Follow directions given for Plate 8. Problem 2. Make sketch of upper valve seat of water cylinder. Show top and bottom views and turned section through center. Put on dimensions, notes, finish marks, and title on all freehand sketches unless otherwise directed. Problem 3. Make freehand sketch of valve chest cover for water cylinder, showing top and bottom views and turned section through center. Problem 4. Make freehand sketches of the following remain- ing details of the water cylinder of steam pump: 1. Piston and rod. 6. Valve seat. 2. Stuffing-box. 7. Valve disk. 3. Gland. 8. Valve spring. 4. Ring. 9. Valve cover. 5. Air chamber. 10. Valve spindle. i, 2, 3, 4, and 5 may be sketched on one sheet, using another sheet for 6, 7, 8, 9, and 10. Make all necessary views and com- plete as before. See sample sketch, Fig. 313, page 413. PLATE n. Problem i. Make assembly drawing for water cylinder for Steam Pump from sketches in Plate 10. Put on the principal dimensions, notes, title, and bill of material. Make finished pencil drawing and trace on cloth. Scale 8" = i foot. ELEMENTARY MACHINE DRAWING. 413 414 DRAWING AND DESIGNING. PLATE 12. Problem i. Make freehand sketches of either globe or safety valve in detail on one sheet as follows: 1. Globe valve body, longitudinal section, half cross-section and half end view combined. 2. Valve stuffing box and bonnet, half elevation and half section combined, and plan. Problem 2. 3. Valve spindle, one view. 4. Valve spindle nut, half elevation, half section and plan .5. Hand wheel, half elevation, half section, and plan. 6. Valve, half elevation, half section, and plan. 7. Valve nut, half elevation, half section, and plan. 8. Stuffing box cap, half elevation, half section, and plan. Problem i. 1. Safety valve casing, half elevation, half section combined, and plan. 2. Valve seat, half elevation, half section combined, and plan 3. Ring, half elevation, half section combined, and plan. Problem 2. 4. Valve spring, elevation and plan. 5. Valve spindle, one view. 6. Adjusting screw, two views. 7. Valve disk, two views. 8. Spring washer, two views. 9. Adjustable screw bushing, two views. 10. Lock nut, two views. ELEMENTARY MACHINE DRAWING. 415 PLATE 13. Problem i. Make detail assembly working drawing of either the globe or safety valve from sketches made in Plate 12. FIG. 314. This drawing must be fully dimensioned and contain all notes, title, and bill of material. Finish in pencil only. Scale to suit. 416 DRAWING AND DESIGNING. PLATE 14. Problem i. Make iso metrical drawing of layout of piping shown in Fig. 314, page 415. FIG. 315. Samples of couplings and piping will be found in the drafting room. See Fig. 315 for sketch of J" globe valve. Diameter ELEMENTARY MACHINE DRAWING 417 and thickness of pipes, length of screw, etc., can be obtained from Table 7, page 57. Fig. 316, page 416, shows the isometric layout of the center lines of the piping. Arrange on sheet to best advantage, allowing space for title and bill of material. Letter all notes very care- fully using lower case letters and Gothic caps. Make caps one FIG. 316. third higher than small letters. Scale 4" = i foot. Finish in pencil and trace. PLATE 15. If any student has time and desires to increase his mark, he may make as an extra plate an assembly detail working draw- ing of a chain oiling bearing similar to that shown in Fig. 161, page 226, except that it shall be designed for a ijf" shaft to 4 i8 DRAWING AND DESIGNING. suit either the drop or post hanger of Plate 9. Scale = full size. Finish in pencil and trace on cloth, or a design for a donkey pump, similar to that shown in Fig. 317, according to directions and data to be given by the Instructor. PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS AND METHODS IN MAKING PRACTICAL WORKING DRAWINGS. SUMMARY REPORT OF AN INVESTIGATION MADE BY THE WRITER WITH THE AUTHORITY OF THE ARMOUR INSTITUTE OF TECHNOLOGY, CHICAGO, ILL.*, INTO THE PRESENT PRAC- TICE OF THE LEADING DRAFTSMEN IN THE UNITED STATES, IN THE USE OF STANDARD CONVENTIONS AND METHODS WHEN MAKING COMMERCIAL WORKING DRAWINGS. A circular letter accompanied by a list of thirty-five questions was submitted to two hundred leading firms in the United States, embracing nearly all kinds of engineering practice. The returns have been exceedingly gratifying, and especially so has been the spirit with which the " Questions" have been received and answered. Many requests have been received from chief draftsmen for a copy of the returns. The questions submitted and the answers received are given somewhat in detail below. 419 420 DRAWING AND DESIGNING. Q. i. Do you place complete information for the shop on the pencil drawing, such as all dimensions, notes, title, bill of material, scale, etc. ? Complete information is placed on drawing before tracing. 57 Complete information is placed on tracing only 42 Principal dimensions and title only on pencil drawing 2 Draw directly on bond paper 10 Did not answer this question 10 Sometimes 7 Reasons given for making the pencil drawing complete: To arrange notes. To save ime. The tracing is not usually made by the draftsman who makes the pencil drawing. Q. 2. Do you ever ink the pencil drawing? Never ink the pencil drawing 91 Generally ink the pencil drawing 7 Sometimes ink the pencil drawing 8 Sometimes ink the pencil drawing and shellac it for shop use . i Use bond paper 10 Make pencil drawings on dull side of tracing cloth .. 2 Ink center lines of assembly drawing i Ink center lines of pencil drawings in red 2 Q. 3. Do you trace on cloth and blue print? Always trace on cloth and blue print 102 Blue print from bond paper 10 Blue print from bond paper occasionally . . , i Sometimes make " Vandyke " prints for shop use i Sometimes use paper drawings in shop for jigs and fixtures. i Q. 4. Do you use blue prints entirely in the shop ? Use blue prints altogether in shop . 105 Sometimes use pencil drawings or sketch 21 PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS. 42! Sometimes use sketches made with copying ink i Sometimes use prints from " Vandyke " i Use white prints mounted on cardboard and varnished i Use blue prints mounted on cardboard i Use sketches for rush work i Q. 5. When tracing do you use uniform wide object lines? Ever use shade lines ? Use uniform, thick object lines. Never use shade lines 100 Sometimes use shade lines 21 Use shade lines on small details 5 Always use shade lines 14 Experts in the use of shade lines may do so to make drawings clear i Shade rounded parts i Q. 6. What kind of a center line do you use ? Long dash, very narrow, and dot, thus : 42 Long dash and two dots, 29 Very fine continuous line, 19 Very fine dash line, long dashes, - 8 Long dash and dot in red, - 3 Continuous fine red line, - 8 Long dash and three dots, - i Long dash and two dots, thus: - i Q. 7. What kind of dimension line do you use ? Continuous fine line, broken only for dimension - 52 Fine long dash line, - 32 Fine long dash line and dot, - 13 Fine continuous red line, - 8 Fine continuous blue line, - 4 Fine continuous green line, - i 422 DRAWING AND DESIGNING. Same character of line as center line, , 32 Dotted line, - i Long dash and two dots, 2 Heavy broken lines, i Q. &. What style of lettering do you use ? Sloping ? Vertical ? Free-hand? All capitals of uniform height? or capitals and lower case ? Free-hand sloping 52 Free-hand vertical . . 45 Free-hand capitals, Gothic, uniform height 61 Free-hand capitals, and lower case . . 40 All caps, initials slightly higher 5 Lettering left to option of draftsman 2 Mechanical lettering, all caps . 3 Not particular, the neatest the draftsman can make free- hand 4 Mechanical lettering, all caps, sloping 2 Give great latitude in lettering, only insist it be bold and neat i Roman, caps and lower case, free hand 2 Large letters Aths, small ^\ds and Jth 2 Q. 9. Are your titles and bills of material printed or lettered by hand? Lettered by hand 79 Standard titles printed and filled in by hand 12 Bill of material table printed and lettered by hand 12 Lettered by hand, contemplate having them printed i B. of M. typewritten on separate sheet and blue printed. . . 8 Titles partly printed and filled in by hand & Use rubber stamp for standard title, fill in by hand 6 Standard title, bill of material lithographed on tracing cloth.. 8 PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS. 423 Q. 10. Do you use a border line on drawings? Always use border lines 97 Never use border lines 13 Use border lines on foundation plans, to send out i No border lines on detail drawings i Intend to discontinue the use of border lines i Border lines used only on design drawings i Only on drawings to be mounted on cardboard i Only used for trimming blue print 2 On assembly drawings only i Width of margins reported: i", J", f", i", and J". Q. ii. When hatch-lining sections, do you use uniform oi symbolic hatch lines ? Standard symbolic lines 59 Uniform hatch lines for all materials 44 Shade section. part with 4H pencil and note name of material 4 Symbolic hatch lines and add name of material 3 Uniform hatch lines for metal only i Uniform on details, symbolic on assembly drawings 4 5 Pencil hatch on tracings and note material other than cast iron i Uniform hatch lines, sometimes solid shading i No uniform system i Sections tinted with water colors representing the metals.. i Q. 12. Is the pencil drawing preserved? Is the tracing stored or do you make " Vandyke" prints for storing away? Store tracings only 96 Pencil drawings preserved for a time 30 Pencil drawings preserved 13 White prints made and bound for reference i Tracings kept in office for reference, blue prints stored 9 " Vandyke " prints stored i 424 DRAWING AND DESIGNING. Use " Vandyke " as substitute for tracing 2 Arrangement drawings preserved, detail drawings destroyed after job is completed. Pencil drawings used for gasket paper i Original pencil drawing inked and stored i Assembly drawings and layouts preserved 4 Patent office drawings preserved i Tried " Vandyke " but found it unserviceable, tearing easily. i Q. 13. Do you use 6H grade of pencil for pencil drawings or what? 6H 73 4H, mostly for figures and letters 52 5H 16 Ranging from 2H to 8H 53 Q. 14. Do you use plain orthographic projection for free-hand sketches? Ever use perspective or isometrical drawing for sketches ? Plane orthographic 3d angle projection 99 Isometrical drawing for sketches 25 Perspective for sketches . i Isometric for piping layouts and similar work 8 Perspective and isometric for catalogue work 2 Isometric sometimes 6 Never use free-hand sketches 6 One says, "When we run into other than orthographic, men are too timid and not sure of themselves. In perspective drawings when work is cylindrical, workmen get mixed up on center lines. Q. 15. What sizes of sheets do you use for drawings? 9"Xi2" .w-v.;- 13 ., 16 PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS. 425 i8"X24". ...... .......... .......................... 20 ......................................... .. 19 There seems to be little uniformity in the sizes of shop drawings, about 67 firms reporting different combinations. A few have no system but simply make the size of sheet to suit the object to be drawn. Q. 16. Do you use red ink on tracings? Never use red ink on tracings .......................... 57 Recently discarded the use of red ink ..... . ............. 2 Use red ink for pattern figures ......................... i Use red ink for center and dimension lines ............... 8 Use red ink for check marks . . . . ....................... i Use red ink for existing work on studies ................. i Use red ink sometimes ........................... ..... 2 Use red ink on occasions when it is desired to show old work in red and new work in black (use carmine) ........... i Use carmine for brick ................................. i Qs. 17 and 27. How indicate finished surfaces on drawings? When finished all over? When "file finished," ground, planed, bored, drilled, etc. ? Finished surfaces indicated as in Fig. i ................. 65 Finished surfaces indicated as in Fig. 2 .................. 16 Finished surfaces indicated as in Fig. 3 .................. 8 Finished surfaces indicated as in Fig. 4 .................. 2 Finished surfaces indicated as in Fig. 5 .................. 2 Bound the surfaces with red lines ................. ...... 2 Bound the surfaces with dotted lines .................... 2" Name the finish by note in full . ........................ 68 Do not specify machinery method ...................... 6 (See drawing.) 426 DRAWING AND DESIGNING. Q. 18. Do you use horizontal or sloping lines for convention in screw threads ? Sloping lines, see Fig. 6 94 Horizontal lines, see Fig. 7 12 f/G. X F/G.2. j r _f ' . J Finish only third line from top FIG. 6. FIG. 7. FIG. 8. FIG, 9. FIG. 10. Horizontal lines, see Fig. 8 13 Both 7 Neither, but as shown in Fig. 9 i Neither, but as shown in Fig. 10 i PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS. 427 Q. Ly. When a large surface is in section do you hatch-line around the edges only ? Hatch-line edges only 62 . Sometimes - 3 Hatch section all over 54 Do not use hatch lines; shade the whole surface with 4H pencil 3 Usually show a broken surface line i F/G.//. Q. 20. Do you section keyways in hubs or show by invisible lines ? Section keyways as shown in Fig. 1 1 73 Show key way by invisible lines, see Fig. 12 40 Keyways in hubs left blank i Q. 21. In dimensioning do you prefer to place the dimension upon the piece or outside of it? Outside whenever possible 92 Upon the piece 13 428 DRAWING AND DESIGNING. Both, according to size and shape of part 19 No rule i Commenting on placing dimensions outside of piece one says, "It entails less confusion to workman." Another says: "So as to make detail stand out." Q. 22. Do you use feet and inches over 24 inches? Yes 69 Use feet and inches over 36" 4 Use feet and inches over 24" on foundations and outlines . . 2 Use feet and inches over 48" 6 All inches 21 For pulleys use inches up to 48" i Inches up to 10 feet 2 Start feet at 24" thus: 2-0" 2 Usually, but not always 2 Yes, except pitch diameters of gears, which are all given in inches 2 Yes, except in boiler and sheet iron work 3 , Use feet and inches over 1 2" 6 Inches up to 100" 3 Inches up to 60" i Q. 23. How do you indicate feet and inches? Thus 2 ft. 4", or thus 2-V ? 2-4" 97, 2 4" 5, 2 FT. 4" 2, 2ft. 4" 13. Both 2ft. 4" and 2-4" i, 2FT. 4 IN. i, 2' 4" 8, 24^ i. Q. 24. Do you dimension the same part on more than one view? One view : : ; 94 More than one view as check 46 PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS. 429 Q. 25. When several parts of a drawing are identical would the dimensioning of one part suffice for all, or would you repeat the dimension on each part? One part only . . , 82 Would repeat or indicate by note 39 " Left to judgment of draftsman " i " When it is evident that several parts are identical the dimensioning of one part would suffice, 'Would never leave room for doubt.'" Q. 26. Do you write R for radius or RAD. ? D. for diameter or DIA. ? RAD . . 35 Rad . . .47 R .... 32 rad. . . i r 3 DIA .. 41 Dia . . 48 D. ... 15 d . . . . 3 dia . .. 4 DIAM .... i Diam. 3 diam 5 Do not use R. or RAD., dimension only i Q. 28. Do you always give number of threads per inch? When you do how are they indicated ? Only give number of threads when not standard 67 All others always indicate number of threads in a great variety of ways. A few of the different styles of noting the threads are given below: J" 10 Thr. 5THDS. PER i". Sthds. 4 threads per inch. Mach. . Screw 10-24, il" XII, 16 P. RH. Vth. U. S. S. XVIII, r "-8- U. S. S. i" TAP, 8 PITCH, 3 TH'D R. H. SQ. DOUBLE, 5"-i8 THDS. R. H. OWN ST'D io thds. per inch. For pipe tap thus, J" P.T., etc., etc. Q. 29. How do you "Mark" a piece to indicate on the bill of material ? Number it on drawing and put a circle around it 34 430 DRAWING AND DESIGNING. By name or letter 35 By pattern number 2 By symbol and number 14 Castings, I, II, III, Forgings, i, 2, 3. Q. 30. When a working drawing is fully dimensioned why should the scale be placed on the drawing ? For convenience of drafting room 25 Check against errors 1 1 Not necessary 18 Scale not placed on shop drawings 18 For convenience in calculations and planimeter work i To give an idea of over-all dimensions when these are not given. " We never saw a drawing so fully dimensioned as to warrant leaving off the scale " 2 " If a drawing is to scale the scale should be on the drawing, whether it is needed or not." " It gives every one interested a better conception of the proportions of the piece, and there are frequently portions of a design which do not require a dimension for the shop to work to, and which it is interesting to scale from an engineering point of view." "To get approximate dimensions not given on drawing." "Impractical to dimension all measurements for all classes of work." "Scale will tell at a glance, dimensions would have to be scaled." "To obtain an idea of relative size of parts without scaling the drawings." "To sketch on clearance." "To proportion changes." "When erecting to measure over-all sizes." " In case a dimension has been left off, the scale will help out." " This is a question of opinion ; some will not have the scale, others insist on it." "We always give the scale." PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS. 431 "It is an immense help and time saver in the drawing room." " Generally no reason. In our work we combine standard apparatus by ' fudge ' tracing, and it is convenient to know scale so all parts will surely be to same scale." "In discussing alterations, additions, clearances, etc., it is con- venient to know the scale instantly." "For convenience in drafting room. We often put an arbitrary scale on with a reference letter indicating scale to draftsman." " To give toolmaker an idea of the size of the finished piece." "As an aid to the eye in reading." Above are some of the reasons given for placing the scale on the drawing. Below are given a few of the reasons why some do not place the scale on the drawing. " Scale should never be used in shop," says one. "Not necessary. Sometimes drawing is made out of scale." "Not advisable, on account of workmen getting into the habit of working to scale instead of to the figures." " Know of no good reason at all." " Believe it best to leave scale off." " Should not. Drawing should never be scaled." "Know of no good reason why it should be." "Should not be given on drawing." " Do not object if left off, not needed." Q. 31. Do you use the glazed or dull side of tracing cloth? Dull side ... 66 Glazed side. 32 Both 4 "Dull side, because it lies flat better in drawers." " Dull side, so that changes which may be necessary while work is under construction, can be made easily in pencil and later in ink." " Dull side so tracings may be checked in pencil." "It prevents curling." " Both, although the glazed side when traced on lies better in the drawer." 432 DRAWING AND DESIGNING. "We use cloth glazed on both sides, work on convex side, so that shrinkage of ink will eliminate camber." " Dull, except for U. S. Government, who requires the glazed side to be used." Q. 32. How do you place pattern numbers on castings? Pattern number with symbol or letter is placed on or near the piece, e.g., PATT.-D-478-C 36 This question was not happily stated; most answers gave "raised letters cast on," while the question like all the others refers to the marking of the drawing. Q. 33. How do you note changes on a drawing? On tracing with date 32 New tracing and new number 17 Put a circle around old figure and write new figure beside it with date 8 Make new tracing 5 Red ink with date .' 8 Use rubberstamp " Revised" with date, and indicate changes on record print 28 Use change card system i Special forms for purpose. Change -made in a book with date. New prints made to replace. In place at title with draftsman's initials and date 8 Q. 34. Do you place dimensions to read from bottom and right hand, or all to read from bottom, or how ? Bottom and right hand . ..' 103 From bottom only 2 No fixed rule 2 From R to L and bottom to top i PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS. 433 Q. 35. Do you always make a table to contain the bill of material ? Yes 49 No 25 Not always. . 5 Usually . i Use separate bill 32 Bills on general drawings only. On details number is marked on piece. "No, but it is advisable to do so." "Have abandoned that system." INDEX. Aluminum, 33 Angle, Lead, 307 Area of a bearing, 200 B Babbitt metal, 33 Ball bearings, 230 Base plates, Adjustable, 230 Bearing, Adjusting wedges for, 355 Bearing, Area of a, 206 Bearing, Cap of, 354 Bearing, Chain lubricating, 225 Bearing, Crank-shaft or main, 351 Bearing, Four-part, 353 Bearing, Gibs for, 355 Bearing, Length of, 235 Bearing, Load on ball, 360 Bearing, Pedestal or pillow-block, 230 Bearing, Pivot or step, 347 Bearing, Post, 214 Bearing, Solid journal, 207 Bearing, Self-adjusting, 217 Bearing, Three-part, 351 Bearing, Thrust, 361 Bearings, Blocks for, 356 Bearings, Diameter of studs for, 355 Bearings, Divided, 210 Belt gearing, 238 Belting, Rules for, 240 Belts, Length of, 253 Belts, Transmission of power by, 240, 213 Bolt, Anchor, 82 % Bolt, Hook, 76 Bolt, Lewis, 80 Bolt of uniform strength, 91 Bolt, Rag, 78 Bolt, Square-headed, 67 Bolt, Stud, 68 Bolt, Tap, 75 Bolt, Tapered, 77 Bolt, T-headed, 74 Brass, 32 Bronze or gun-metal, 32 Bushes, steps or brasses, 227 C Calking, 126 Case-hardening, 34 Castings, Malleable, 32 Castings, Shrinkage of, 44 Cast iron, 30 Cast iron, Specific gravity of, 40 Cast-iron water-pipe, Thickness of, 43 Cast steel, 32 Cementation process, 35 Chilled castings, 31 Clearance, Cylinder, 308 Clearance, Inside, 308 Clearance, Piston, 308 Compression, 308 Cock, Blow-off, 295 Cocks, 295 Connecting-rod, Thrust of, 345 435 INDEX. Connecting-rods, 339 Connecting-rods, Buckeye Engine Co., 341 Connecting-rods, Diameter of, 346 Connecting-rods, Erie City Iron Works, 341 Connecting-rods, Marine, 344 Connecting-rods, Penn. Railroad Co.'s, 343 Connecting-rods, Proportions of loco- motive, 347 Constructions, 26 Conventions, Standard, 20 Copper, 32 Cotter and gib, 120 Cotter locking arrangement, 122 Cotter, Taper of, 117 Cotters, 116 Couplings, Box or muff, 165 Couplings, Cast-iron pipe, 190 Couplings, Converse pipe, 197 Couplings, Flanged shaft, 178 Couplings for brass and copper pipes, 203 Couplings, Frictional, 174 Couplings, Hill plate, 171 Couplings, Jaw clutch, 181 Couplings, Loose flange, 195 Couplings, Pipe, 190 Couplings, Propeller shaft, 185 Couplings, Rigid, 164 Couplings, Screwed flange pipe, 198 Couplings, Screwed socket, 200 Couplings, Sellers clamp, 171 Couplings, Shaft, 164 Couplings, Spiral jaw, 181 Couplings, Spigot and socket pipe, 193 Couplings, Split muff, 167 Couplings, Stuart's clamp, 176 Couplings, Universal joint, 185 Couplings, Wrought-iron and steel- pipe, 196 Cross-heads, 376 Cross-head blocks, 368 Cross-heads and guides, 368 Cross-sections, 26 Cylinder flange fastenings, 69 Cylinder, Diameter of steam, 328 Cylinder, Length of steam, 329 Cylinder, Steam, 328 Cylinder, Thickness of steam, 328 Cylinder head, 329 Cylinder steam-port, 329 D Design, Elementary machine, 29 Design of spur gear, 271 Eccentrics, 379 Eccentrics, Proportions of, 382 Eccentric, Throw of, 380 Elasticity, 37 Elasticit) r , Modulus of, 37 Elastic limit, 37 Engine details, 305 Engine-frame or bed-plate, 326 Expansion, 308 Figuring, 19 Factor of safety, The, 38 Frame, Drop-hanger, 218 Gearing, Belt, 238 Gearing, Toothed, 262 Gears, Bevel, 270 Gears, Involute toothed, 263 Gears, Spur-wheel and pinion, 268 Gears, Walker system of, 267 Gears, Worm, 271 Gear-wheels, Arms of, 274 Gear-wheels, Hubs of, 276 Gear-wheels, Rims of, 275 Gear-wheels, Shrouding of, 276 Guide, Four-bar, 372 Guide, Two-bar, 374 Guide-bars, 370 Guide-bars, Length of, 372 Guides, Strength of, 372 INDEX. 437 Instructions, Introductory, I Instruments, 7 J Joint, Forms and proportions of cot- ter, 118 Joint, Knuckle, 106 Joint, Lap, -143 Joint, Locomotive steam-pipe ball, 200 Joints, Riveted, 125 Journals, 206 K Key-heads, 114 Key, Flat, no Key, Round, 112 Key, Saddle, 109 Key, Sliding feather, 113 Key, Sunk, no Key, Woodruff, 113 Keys, 109 Keys, Fixed, 112 Keys, Strength of, 114 Lead, 307 Lead angle, 307 Lettering, 194 Load, 365 Locomotive dome connection, 156 Locomotive fire-box ring, 154 Locomotive plain slide-valve, 305 Locomotive tube-setting, 155 M Malleable castings s 32 Materials, 30 Materials, Strength of, 36 Metallic packing, 366 Metallic packing, United States, 366 Muntz metal, 32 N Nut convention, 63 Nut, Hexagon, 60 Nut, Jam, 92 Nut locking devices, 92 Nut-lock, Circular, 99 Nut-lock, Spring washer, 94 Nut-lock, Wile's, 95 Nuts locked with set-screws, 96 O Oil-cups, 299 Overtravel, 308 Pedestal, Self-lubricating, 232 Pin-joint, Knuckle, 106 Pins and pin-joints, 104 Pins, Split, 104 Pins. Taper, 105 Pipes, 189 Pipes, Thickness of, 189 Piston, Ball Engine Company's, 333 Piston, Buckeye Engine Company's 338 Piston clearance, 308 Piston, Locomotive, 334 Piston, Macintosh & Seymour's, 336 Piston, Water, 340 Pistons, 332 Pistons, Steam, 332, 335 Point of cut-off, 308 Pressure on rubbing surfaces, 369 Projection of India-rubber valve- guard, 282 Proportions of India-rubber valve- guard, 283 Pulley, All wrought-steel, 250 Pulley, Cone, 251 Pulley, Rope, 255 Pulley, Wood split, 248 Pulleys, Proportions of, 244 Pulleys, Proportions of cone, 255 R Resistance, 37 Riveted butt-joint, Double, 144 Riveted butt-joint, Triple, 148 Riveted joint, Calculation of, 136 Riveted lap-joints, Double, 139 438 INDEX. Rivet-head, Proportions of, 130 Rivet-heads, Form of, 128 Riveting, Chain, 139 Rivets and riveted joints, 125 Rivet-shank, Length of, 130 Rivets, Pitch of, 136 Screw, Cap, 85 Screws, Collar, 85 Screws, Holding power of, 88 Screw-thread, Buttress, 55 Screw-thread, Knuckle, 55 Screw-thread, Seller's or U. S. stand ard, 51 Screw-thread, Square, 55 Screw-thread, Standard pipe, 56 Screw-thread, Whitworth, 53 Screw-threads, Conventions for, 59 Shade lines and shading, 15 Shaft, To find diameter of steel, 159 Shaft-couplings, 164 Shafting, Deflection of, 162 Shafting, Line, 157 Shafts, Hollow, 163 Sole-plates, 229 Steel, Bessemer, 34 Steel, Siemens-Martins, 34 Steps, 227 Stuffing-boxes, 363 Strain and stress, 36 Strength of cast iron, 38 Strength of steel, 39 Strength of wrought iron, 39 Strength, Proof, 38 Strength, Ultimate, 37 Table of ultimate and elastic strength, 40 Table of tenacities of metals, 40 Table of weights and measures, 41 Table of wrought iron welded tubes, 44 Table of different colors of iron, 45 Table of decimal equivalents of one inch, 45 Table of the melting-point of metals, etc., 46 Table of the weight of various sub- stances, 46 Table of the weight of timber, 46 Table of the circumferences and areas of circles, 47 Table of screw threads, 70 Table of saddle and flat keys, no Table of rectangular sunk keys, in Table of single-riveted joints, 135 Table of single-riveted joints, 136 Table of double-riveted joints, 141 Table of double-riveted lap-joints, 144 Table of double-riveted butt-joints, 147 Table of triple-riveted butt-joints, 149 Table of Sellers clamp couplings, 174 Table of flanged shaft couplings, 180 Table of jaw clutch couplings, 183 Table of standard cast-iron pipe flanges, 192 Table of Pope pipe couplings, 196 Table of steam-pipe connections, 206 Table for brass, copper, and wrought- iron pipes, 204 Table of sections, 205 Table of thickness of belting, 243,244 Table of proportions of cone pulleys, 255 Table of proportion of rope pulleys, 258, 261 Table, Odontagraph, 265, 266 Table of India-rubber disk valves, 290 Table of locomotive-piston propor- tions, 334 Table of thickness of pipes, 189 Table of thickness of India-rubber valve disks, 283 Table of thickness of steam-cylinders, 328 Valve, Allen-Richardson balance, 309 Valve, American balance, 3iv, INDEX. 439 Valve, Angle of advance of slide, 307 Valve, Ball, 288 Valve, Boiler check, 295 Valve, Cocks and oil cup, 278 Valve diagram, The Bilgram, 313 Valve diagram, The Zeuner, 320 Valve, Flat India-rubber disk, 290 Valve, foot and strainer, 278 Valve, Globe, 292 Valve, India-rubber, 280 Valve, Inside clearance of slide, 308 Valve, Lead of slide, 307 Valve, Overtravel of slide, 308 Valve, Lift or wing, 285 Valve. Plain slide, 305 Valve, Point of admission of slide, 305 Valve, Point of cut off of slide, 308 Valve, Point of exhaust of slide, 305 Valve, Point of compression of slide, 305 Valve, spindle, 285 Valve, stop, 292 Valve, Travel of, 307 W Wall box frames, 211 Wall brackets, 216 Wall or post hanger, 223 Weights of cast-iron water-pipes, 42 Wooden teeth or cogs, 263 Woods used in construction, 35 Working drawings, 17 Wrist-pin, 370 Wrought metals, 33 Wrought iron, Specific gravity of s 40. Wrought-iron welded tubes, 44 SHORT-TITLE CATALOGUE OF THE PUBLICATIONS OP JOHN WILEY & SONS, NEW YORK, : CHAPMAN & HALL, LIMITED. ARRANGED TINDER SUBJECTS. Descriptive circulars sent on application. Books marked with an asterisk (*) are sold at net prices only. All books are bound in cloth unless otherwise stated. AGRICULTURE HORTICULTURE FORESTRY. Armsby's Principles of Animal Nutrition 8vo, $4 oo Budd and Hansen's American Horticultural Manual: Part I. 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Stresses in Simple Trusses 8vo, 2 50 Part II. Graphic Statics 8vo, 2 50 Part III. Bridge Design 8vo, 2 50 Part IV. Higher Structures 8vo, 2 50 Morison's Memphis Bridge Oblong 4to, 10 oo Sondericker's Graphic Statics, with Applications to Trusses, Beams, and Arches. 8vo, 2 oo WaddelTs De Pontibus, Pocket-book for Bridge Engineers. ..... i6mo, mor, 2 oo * Specifications for Steel Bridges I2mo, 50 Waddell and Harrington's Bridge Engineering. (In Preparation.) Wright's Designing of Draw-spans. Two parts in one volume 8vo, 3 50 HYDRAULICS. Barnes's Ice Formation . 8vo, 3 oo Bazin's Experiments upon the Contraction of the Liquid Vein Issuing from an Orifice. (Trautwine) 8vo, 2 oo Bovey's Treatise on Hydraulics 8vo, 5 oo Church's Diagrams of Mean Velocity of Water in Open Channels. Oblong 4to, paper, i 50 Hydraulic Motors 8vo, 2 oo Mechanics of Engineering 8vo, 6 oo Coffin's Graphical Solution of Hydraulic Problems i6mo, mor. 2 50 Flather's Dynamometers, and the Measurement of Power , . i2mo, 3 oo Folwell's Water-supply Engineering 8vo, 4 oo Frizell's Water-power 8vo, 5 oo Fuertes's Water and Public Health i2mo, i 50 Water-filtration Works i2mo, 2 50 Ganguillet and Kutter's General Formula for the Uniform Flow of Water in Rivers and Other Channels. CHering and Trautwine) 8vo, 4 oo Hazen's Clean Water and How to Get ft Large i2mo, i 50 Filtration of Public Water-supplies 8vo, 3 oo Hazlehurst's Towers and Tanks for Water- works 8vo, 2 50 Herschel's 115 Experiments on the Carrying Capacity of Large, Riveted, Metal Conduits 8vo, 2 oo Hoyt and Grover's River Discharge 8vo, 2 oo Hubbard and Kiersted's Water- works Management and Maintenance 8vo, 4 oo * Lyndon's Development and Electrical Distribution of Water Power. . . .8vo, 3 oo Mason's Water-supply. 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Non-metallic Materials of Engineering and Metallurgy 8vo, 2 oo Part TI. Iron and Steel 8vo, 3 50 Part III- A Treatise on Brasses, Bronzes, and Other Alloys and their Constituents 8vo > 2 SO Tilbon's Street Pavements and Paving Materials 8vo, 4 oo Turneaure and Maurer's Principles of Reinforced Concrete Construction.. .8vo, 3 oo Waterbury's Manual of Instructions for the Use of Students in Cement Labora- tory Practice. (.In Press.) 9 Wood's (De V.) Treatise on the Resistance of Materials, and an Appendix on the Preservation of Timber 8vo, 2 oo Wood's (M. P.) Rustless Coatings: Corrosion and Electrolysis of Iron and Steel Svo, 4 oo RAILWAY ENGINEERING. Andrews's Handbook for Street Railway Engineers 3x5 inches, mor. i 25 Berg's Buildings and Structures of American Railroads . . .4to, 5 oo Brooks's Handbook of Street Railroad Location i6mo, mor. Butt's Civil Engineer's Field-book i6mo, mor. Crandall's Railway and Other Earthwork Tables Svo, Transition Curve i6mo, mor. * Crockett's Methods for Earthwork Computations Svo, Dawson's "Engineering" and Electric Traction Pocket-book i6mo r mor. 5 oo Dredge's History of the Pennsylvania Railroad: (1879) Paper, 5 oo Fisher's Table of Cubic Yards Cardboard, 25 Godwin's Railroad Engineers' Field-book and Explorers' Guide. . . i6mo, mor. 2 50 Hudson's Tables for Calculating the Cubic Contents of Excavations and Em- bankments Svo, i oo Ives and Hilts's Problems in Surveying, Railroad Surveying and Geodesy i6mo, mor. i 50 Molitor and Beard's Manual for Resident Engineers i6mo, i oo Nagle's Field Manual for Railroad Engineers i6mo, mor. 3 oo Philbrick's Field Manual for Engineers i6mo, mor. 3 oo Raymond's Railroad Engineering. 3 volumes. Vol. I. Railroad Field Geometry. (In Preparation.) Vol. II. Elements of Railroad Engineering Svo, 3 50 Vol. III. Railroad Engineer's Field Book. (In Preparation.) 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(Thompson) 8vo, 3 50 Moyer's Descriptive Geometry 8vo, 2 oo Reed's Topographical Drawing and Sketching 4to 5 oo Reid's Course in Mechanical Drawing 8vo, 2 oo Text-book of Mechanical Drawing and Elementary Machine Design. 8vo, 3 oo Robinson's Principles of Mechanism 8vo, 3 oo Schwamb and Merrill's Elements of Mechanism 8vo, 3 oo Smith's (R. S.) Manual of Topographical Drawing. (McMillan) 8vo, 2 50 Smith (A. W.) and Marx's Machine Design 8vo, 3 oo * Titsworth's Elements of Mechanical Drawing Oblong 8vo, i 25 Warrgn's Drafting Instruments and Operations i2mo, i 25 Elements of Descriptive Geometry, Shadows, and Perspective 8vo, 3 50 Elements of Machine Construction and Drawing 8vo, 7 50 Elements of Plane and Solid Free-hand Geometrical Drawing i2mo, i oo General Problems of Shades and Shadows 8vo, 3 oo Manual of Elementary Problems in the Linear Perspective of Form and Shadow i2mo, i oo Manual of Elementary Projection Drawing i2mo, i 50 Plane Problems in Elementary Geometry i2mo, i 25 Problems, Theorems, and Examples in Descriptive Geometry 8vo, 2 50 Weisbach's Kinematics and Power of Transmission. (Hermann and Klein) 8vo, 5 oo Wilson's (H. M.) Topographic Surveying 8vo, 3 50 Wilson's (V. T.) 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(Merriam) I2tno, i 25 Dawson's "Engineering" and Electric Traction Pocket-book . . . . i6ino, mor. 5 oo Dolezalek's Theory of the Lead Accumulator (Storage Battery), (von Ende) i2mo, 2 50 Duhem's Thermodynamics and Chemistry. (Burgess) 8vo, 4 oo Flather's Dynamometers, and the Measurement of Power 121110, 3 oo Gilbert's De Magnete. (Mottelay) .8vo, 2 50 * Hanchett's Alternating Currents I2mo, I oo Bering's Ready Reference Tables (Conversion Factors) i6mo, mor. 2 50 * Hobart and Ellis's High-speed Dynamo Electric Machinery 8vo, 6 oo Holman's Precision of Measurements 8vo, 2 oo Telescopic Mirror-scale Method, Adjustments, and Tests .... Large 8vo , 75 * Karapetoff's Experimental Electrical Engineering 8vo, 6 oo Kinzbrunner's Testing of Continuous-current Machines. 8vo, 2 oo Landauer's Spectrum Analysis. (Tingle) 8vo, 3 09 Le Chatelier's High-temperature Measurements. (Boudouard Burgess). .i2mo, 3 oo Lob's Electrochemistry of Organic Compounds. (Lorenz) 8vo, 3 oo * London's Development and Electrical Distribution of Water Tower 8vo, 3 oo 11 * Lyons's Treatise on Electromagnetic Phenomena. Vols. I. and II. 8vo, each, 6 oo * Michie's Elements of Wave Motion Relating to Sound and -Light 8vo, 4 oo Morgan's Outline of the Theory of Solution and its Results I2mo, I oo * Physical Chemistry for Electrical Engineers I2mo, i 50 Niaudet's Elementary Treatise on Electric Batteries. (Fishback). . . .I2mo, 2 50 * Norris's Introduction to the Study of Electrical Engineering 8vo, 2 50 * Parshall and Hobart's Electric Machine Design 4to, half mor. 12 50 Reagan's Locomotives: Simple, Compound, and Electric. New Edition. Large i2mo, 3 50 * Rosenberg's Electrical Engineering. (Haldane Gee Kinzbrunner). . . .8vo, 2 co Ryan, Norris, and Hoxie's Electrical Machinery. 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(Truscott and Emory). .12010, 2 oo * Ludlow and Bass's Elements of Trigonometry and Logarithmic and Other Tables 8vo, j oo Trigonometry and Tables published separately Each, 2 oo * Ludlow's Logarithmic and Trigonometric Tables 8vo, i oo Macfarlane's Vector Analysis and Quaternions 8vo, i oo McMahon's Hyperbolic Functions 8vo, i oo Manning's Irrational Numbers and their Representation by Sequences and Series I2mo, i 25 Mathematical Monographs. Edited by Mansfield Merriman and Robert S. Woodward Octavo, each i oo No. i. History of Modern Mathematics, by David Eugene Smith. NQ. 2. Synthetic Projective Geometry, by George Bruce Halsted. No. 3. Determinants, by Laenas Gifford Weld. No. 4. Hyper- bolic Functions, by James McMahon. No. 5. Harmonic Func- tions, by William E. Byerly. No. 6. Grassmann's Space Analysis, by Edward W. Hyde. No. 7. Probability and Theory of Errors, by Robert S. Woodward. No. 8. Vector Analysis and Quaternions, by Alexander Macfarlane. No. 9. 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Large i2mo, 3 50 Sinclair's Locomotive Engine Running and Management i2mo, 2 oo Smart's Handbook of Engineering Laboratory Practice i2mo, 2 50 Snow's Steam-boiler Practice 8vo, 3 oo Spangler's Notes on Thermodynamics i2mo, i oo Valve-gears , , 8vo, 2 50 Spangler, Greene, and Marshall's Elements o Steam-engineering 8vo, 3 oo Thomas's Steam-turbines : 8vo, 4 oo Thurston's Handbook o> Engine and Boiler Trials, and the Use of the Indi- cator and the Prony Brake 8vo, 5 oo Handy Tables 8vo, i 50 Manual of Steam-boilers, their resigns, Construction, and Operation..8vo, 5 oo 15 Thurston's Manual of the Steam-engine 2 vols., 8vo, 10 oo Part I. History, Structure, and Theory 8v:>, 6 oo Part II. Design, Construction, and Operation 8vo, 6 oo Steam-boiler Explosions in Theory and in Practice i2mo, i 50 Wehrenfenning's Analysis and Softening of Boiler Feed-water (Patterson) 8vo, 4 oo Weisbach's Heat, Steam, and Steam-engines. (Du Bois) 8vo, 5 oo Whitham's Steam-engine Design 8vo, 5 oo Wood's Thermodynamics, Heat Motors, and Refrigerating Machines . . . 8vo, 4 oo MECHANICS PURE AND APPLIED. Church's Mechanics of Engineering 8vo, 6 oo Notes and Examples in Mechanics 8vo, 2 oo Dana's Text-book of Elementary Mechanics for Colleges and Schools. .i2mo, i 50 Du Bois's Elementary Principles of Mechanics: Vol. I. Kinematics 8vo, 3 50 VoL II. Statics 8vo, 400 Mechanics of Engineering. Vol. I Small 4to, 7 50 Vol. II. Small 4to, 10 oo *Greene's Structural Mechanics 8vo, 2 50 James's Kinematics of a Point and the Rational Mechanics of a Particle. Large I2mo, 2 oo * Johnson's (W. W.) Theoretical Mechanics i2mo, 3 oo Lanza's Applied Mechanics 8vo, 7 So * Martin's Text Book on Mechanics, Vol. I, Statics i2mo, i 25 * Vol. 2, Kinematics and Kinetics . .i2mo, 1 50 Maurer's Technical Mechanics 8vo, 4 oo * Merriman's Elements of Mechanics I2mo, i oo Mechanics of Materials 8vo, 5 oo * Michie's Elements of Analytical Mechanics 8vo, 4 oo Robinson's Principles of Mechanism 8vo, 3 oo Sanborn's Mechanics Problems Large I2mo, i 50 Schwamb and Merrill's Elements of Mechanism 8vo, 3 oo Wood's Elements of Analytical Mechanics 8vo, 3 oo Principles of Elementary Mechanics lamo, i 25 MEDICAL. * Abderhalden's Physiological Chemistry in Thirty Lectures. (Hall and Defren) 8vo, 5 oo von Behring's Suppression of Tuberculosis. (Bolduan)... i2mo, i oo * Bolduan's Immune Sera i2mo, i 50 Davenport's Statistical Methods with Special Reference to Biological Varia- tions i6mo, mor. i 50 Ehrlich's Collected Studies on Immunity. (Bolduan) 8vo, 6 oo * Fischer's Physiology of Alimentation Large i2mo, cloth, 2 oo de Fursac's Manual of Psychiatry. (Rosanoff and Collins) Large i2mo, 2 50 Hammarsten's Text-book on Physiological Chemistry. (Mandel) 8vo, 4 oo Jackson's Directions for Laboratory Work in Physiological Chemistry. ..8vo, i 25 Lassar-Cohn's Practical Urinary Analysis. (Lorenz) i2mo, i oo Mandel's Hand Book for the Bio-Chemical Laboratory I2mo, i 50 * Pauli's Physical Chemistry in the Service of Medicine. (Fischer) i2mo, i 25 * Pozzi-Escot's Toxins and Venoms and their Antibodies. (Cohn) i2mo, i oo Rostoski's Serum Diagnosis. (Bolduan). '. I2mo, i oo Ruddiman's Incompatibilities in Prescriptions , 8vo, 2 oo Whys in Pharmacy I2mo, i oo Salkowski's Physiological and Pathological Chemistry. (Orndorff) 8vo, 2 50 * Satterlee's Outlines of Human Embryology I2mo, i 25 Smith's Lecture Notes on Chemistry for Dental Students 8vo, 2 50 16 Steel's Treatise on the Diseases of the Dog 8vo, 3 50 * Whipple's Typhoid Fever Large i2mo, 3 oo Woodhull's Notes on Military Hygiene i6mo, i 50 * Personal Hygiene i2mo, i oo Worcester and Atkinson's Small Hospitals Establishment and Maintenance, arid S ggestions for Hospital Architecture, with Plans for a SmaU Hospital i2mo, i 25 METALLURGY. Betts's Lead Refining by Electrolysis 8vo, 4 oo Holland's Encyclopedia of Founding and Dictionary of Foundry Terms Used in the Practice of Moulding i2mo, 3 oo Iron Founder i2mo, 2 50 " " Supplement i2mo, 2 50 Douglas's Untechnical Addresses on Technical Subjects i2mo, i oo Goesel's Minerals and Metals: A Reference Book i6mo, mor. 3 oo * Iles's Lead-smelting i2mo, 2 50 Keep's Cast Iron 8vo, 2 50 Le Chatelier's High-temperature Measurements. (Boudouard Burgess) 12010, 3 oo Metcalf's Steel. A Manual for Steel-users i2mo, 2 oo Miller's Cyanide Process i2mo, i oo Minet's Production of Aluminium and itsjndustrial Use. (Waldo) . . .i2mo, 2 50 Robine and Lenglen's Cyanide Industry. (Le Clerc) 8vo, 4 oo Ruer's Elements of Metallography. (Mathewson) (In Press.) Smith's Materials of Machines i2mo, i oo Thurston's Materials of Engineering. In Three Parts 8vo, 8 oo Part I. Non-metallic Materials of Engineering and Metallurgy . . . 8vo, 2 oo Part II. Iron and Steel 8vo, 3 50 Part HI. A Treatise on Brasses, Bronzes, and Other Alloys and their Constituents 8vo, 2 50 Ulke's Modern Electrolytic CopperRefining 8vo, 3 oo West's American Foundry Practice '. ! i2mo, 2 50 Moulder's Text Book i2mo, 2 50 Wilson's Chlorination Process ' 12 mo, i 50 Cyanide Processes ramo, i 50 MINERALOGY. Barringer's Description of Minerals of Commercial Va!ue Oblong, mor. 2 50 Boyd's Resources of Southwest Virginia 8vo, 3 oo Boyd's Map of Southwest Virginia .Pocket-book form. 2 oo * Browning's Introduction to the Rarer Elements 8vo, i 50 Brush's Manual of Determinative Mineralogy. (Penfield) 8vo, 4 oo Butler's Pocket Hand-Book of Minerals i6mo, mor. 3 oo Chester's Catalogue of Minerals 8vo, paper, i oo Cloth, i 25 * Crane's Gold and Silver 8vo, 5 oo Dana's First Appendix to Dana's New " System of Mineralogy. ." . .Large 8vo, i oo Manual of Mineralogy and Petrography zarno 2 oo Minerals and How to Study Them i2mo, I 50 System of Mineralogy Large 8vo, half leather, 12 50 Text-book of Mineralogy 8vo, 4 oo Douglas's Untechnical Addresses on Technical Subjects i2mo, i oo Eakle's Mineral Tables 8vo, i 25 Stone and Clay Products Used in Engineering . ( In Preparation. ) Egleston's Catalogue of Minerals and Synonyms 8vo, 2 50 Goesel's Minerals and Metals : A Reference Book i6mo, mor. 3 op Groth's Introduction to Chemical Crystallography (Marshall) i2mo, i 25 17 * Iddings's Rock Minerals 8vo, 5 oo Johannsen's Determination of Rock-forming Minerals in Thin Sections 8vo, 4 oo * Martin's Laboratory Guide to Qualitative Analysis with the Blowpipe. 12010, 60 Merrill's Non-metallic Minerals: Their Occurrence and Uses 8vo, 4 oo Stones for Building and Decoration 8vo, 500 * Penfield's Notes on Determinative Mineralogy and Record of Mineral Tests. 8vo, paper, 50 Tables of Minerals, Including the Use of Minerals and Statistics of Domestic Production Svo, i oo * Pirsson's Rocks and Rock Minerals I2mo, 2 50 * Richards's Synopsis of Mineral Characters.. I2mo, mor. i 25 * Ries's Clays: Their Occurrence, Properties, and Uses 8vo, 5 oo * Tillman's Text-book of Important Minerals and Rocks 8vo, 2 oo MINING. * Beard's Mine Gases and Explosions Lar^e i2mo, 3 oo Boyd's Map of Southwest Virginia. Pocket-oook rorm 2 oo Resources of Southwest Virginia 8vo, 3 oo * Crane's Gold and Silver 8vo, 5 oo Douglas's Untechnical Addresses on Technical Subjects i2mo r oo Eissler's Modern High Explosives Svo, 4 oo Goesel's Minerals and Metals : A Reference Book . . , , i6mo, mor. 3 oo Ihlseng's Manual of Mining 8vo, 5 oo * Iles's Lead-smelting I2mo, 2 so Miller's Cyanide Process i2mo, i oo O'Driscoll's Notes on the Treatment of Gold Ores Svo, 2 oo Peele's Compressed Air Plant for Mines Svo, 3 oo Riemer's Shaft Sinking Under Difficult Conditions. (Corning and Peele) . . .8vo, 3 oo Robine and Lenglen's Cyanide Industry. (Le Clerc) Svo, 4 oo * Weaver's Military Explosives Svo, 3 oo Wilson's Chlorination Process izmo, i so Cyanide Processes ' i2mo, i 50 Hydraulic and Placer Mining. 2d edition, rewritten i2mo> 2 50 Treatise on Practical and Theoretical Mine Ventilation 12 mo, i 25 SANITARY SCIENCE. / Association of State and National Food and Dairy Departments, Hartford Meeting, 1906 , Svo, 3 oc Jamestown Meeting, 1907 Svo, 3 oo * Bashore's Outlines of Practical Sanitation i2mo, i 25 Sanitation of a Country House i2mo, i oo Sanitation of Recreation Camps and Parks i2mo, i oo FolwelTs Sewerage. (Designing, Construction, and Maintenance) Svo, 3 oo Water-supply Engineering Svo, 4 oo Fowler's Sewage Works Analyses i2mo, 2 oo Fuertes's Water-filtration Works.. I2mo, 2 50 Water and Public Health i2mo, i 50 Gerhard's Guide to Sanitary House-inspection i6mo, i oo * Modern Baths and Bath Houses Svo, 3 oo Sanitation of Public Buildings 1 2mo, i 50 Hazen's Clean Water and How to Get It Large i2mo, i 50 Filtration of Public Water-supplies Svo, 3 oo Kinnicut, Winslow and Pratt's Purification of Sewage. (In Press.) Leach's Inspection and Analysis of Food with Special Reference to Stats Control Svo, 7 oo Mason's Examination of Water. (Chemical and Bacteriological) i2mo, i 25 Water-supply. (Considered Principally from a Sanitary Standpoint) . . Svo, 4 oo 18 * Merriman's Elements of Sanitary Engineering.. . .- 8vo, 2 oo Ogden's Sewer Design nmo, 2 oo Parsons's Disposal of Municipal Refuse 8vo, 2 oo Prescott and Winslow's Elements of Water Bacteriology, with Special Refer- ence to Sanitary Water Analysis i2mo, 50 * Price's Handbook on Sanitation . i2mo, 50 Richards's Cost of Food. A Study in Dietaries 12 mo, oo Cost of Living as Modified by Sanitary Science 1 21110, oo Cost of Shelter i2mo, oo * Richards and Williams's Dietary Computer 8va, 50 Richards and Woodman's Air, Wa^rj^aa^Food from a Sanitary Stand- point ,.^<^\^. " . . . :vy. 8vo, oo Rideal's Disinfection and the^nre^vatjojj of Fjiod 8vo, oo Sewage and Bacteria'l^ifipdtw*r of ^ettage 8vo, 4 oo Soper's Air and Ventilatic^p SuawaJ*. . . -^/l Large 12010, 2 50 Turneaure and Russell's Public 'vfQMTj&iptifa.ex. 8vo, 5 oo Venable's Garbage Crematjuges u^kmencaQ //. 8vo, 2 oo Method and Devices for Bkcte4al)rj^tment of Sewage 8vo, 3 oo Ward and Whipple's Freshvliater BiwteySr (In Press. ) Whipple's Microscopy of DnnlnSg^ater 8vo, 3 50 * Typhod Fever Large i2mo, 3 oo Value of Pure Water Large i2mo, i oo Winslow's Bacterial Classification. (In Press.) Winton's Microscopy of Vegetable Foods 8vo, 7 50 MISCELLANEOUS. Emmons's Geological Guide-book of the Rocky Mountain Excursion of the International Congress of Geologists Large 8vo, i 50 Ferrel's Popular Treatise on the Winds 8vo, 4 oo Fitzgerald's Boston Machinist i8mo, i oo Gannett's Statistical Abstract of the World 24mo, 75 Haines's American Railway Management I2mo, 2 50 * Hanusek's The Microscopy of Technical Products. (Winton) 8vo, 5 oo Ricketts's History of Rensselaer Polytechnic Institute 1824-1894. Large i2mo, 3 oo Rotherham's Emphasized New Testament Large 8vo, 2 oo Standage's Decoration of Wood, Glass, Metal, etc 12010, 2 oo Thome's Structural and Physiological Botany. (Bennett) i6mo, 2 25 Westermaier's Compendium of General Botany. (Schneider) 8vo, 2 oo Winslow's Elements of Applied Microscopy I2ir o, i 50 HEBREW AND CHALDEE TEXT-BOOKS. Green's Elementary Hebrew Grammar i2tno, x 23 Gesenius's Hebrew and Chaldee Lexicon to the Old Testament Scr.ptures. (Tregelles) Small 4to. half mor. 5 oo 19 iff 1 1 t : ;.'' I