UC-NRLF UNITED STATES DEPARTMENT OF AGRICULTURE BULLETIN No. 300 Contribution from the Bureau of Public Roads THOS. ft. MacDONALD, Chief Washington, D. C, PROFESSIONAL PAPER Issued Nov. 10, 1915 Revised Aug. 22, 1922 EXCAVATING MACHINERY USED IN LAND DRAINAGE By Do L. YARNELL Senior Drainage Engineer CONTENTS Introduction 1 Development of Excavating Machinery . 1 Comparison of Kinds of Power .... 2 Determination and Analysis of Cost Data 9 The Floating Dipper Dredge 11 Page The Drag-Line Scraper Excavator. . . 29 The Dry-Land Dipper Dredge 44 The Dry-Land Grab-Bucket Excavator . 47 The Wheel Excavator 48 The Hydraulic Dredge 50 Machines for Cleaning Old Ditches. . 58 The Floating Grab-Bucket Dredge . . 28 Summary 59 WASHINGTON GOVERNMENT PRINTING OFFICE 1922 r/4? UNITED STATES DEPARTMENT OF AGRlCtlt.TilRE! | BULLETIN No. 300 Contribution from the Bureau of Public Roads THOS. H. MacDONALD, Chief Washington, D. C. PROFESSIONAL PAPER j^ed^g. 22. ml EXCAVATING MACHINERY USED IN LAND DRAINAGE. By D. L. YARNELL, Senior Drainage Engineer. CONTENTS. Page. Introduction 1 Development of < x c ;i v a ting ma- chinery 1 Comparison of kinds of power 2 Determination and analysis of cost data 9 The floating dipper dredge 11 The floating grab-bucket dredge 28 Page. The drag-line scraper excavator 29 The dry-land dipper dredge 44 The dry-land grab-bucket excavator. 47 The wheel excavator 48 The hydraulic dredge 50 Machines for cleaning old ditches 58 Summary 59 INTRODUCTION. The use of power machinery for the construction of drainage ditches and levees has become general in this country. Not only have new types of excavators been put on the market in recent years, but the older ones are being constantly improved to meet the re- quirements of drainage work. It is essential that the drainage en- gineer, upon whom rests largely the responsibility for the proper planning and execution of drainage undertakings, keep himself in- formed not only of the improvements constantly being made in ex- cavating machinery but also as to the special advantages and limi- tations of the various types of machines. Contractors usually are required, when submitting bids, to describe in a general way the machinery they intend to employ. Only by being familiar with such machinery will the engineer be able to decide as to its suita- bility for his project or to estimate intelligently the cost of the work. DEVELOPMENT OF EXCAVATING MACHINERY. Open drains were no doubt dug on wet agricultural lands during the early settlement of this country. Since only hand tools were then in use, the ditches were small. If the channel was too large 93127 22 1 4933-44 2* BULl!^TfN"300, U. S. DEPARTMENT OF AGRICULTURE. .*. ;!;.*. * .**,* ** .* ! "* "to permit thVm&ter&l to be dug and thrown out in one operation. it was necessary to rehandle the dirt with shovels or to carry it out in baskets or wheelbarrows. These methods were very slow and expensive. Although the ditches then constructed served their pur- pose for the small agricultural tracts, which were generally on high ground, the increase in population and the resulting spread of agri- cultural operations to the lower lands soon demanded the construction of larger channels. Teams and scrapers were then used where con- ditions permitted. If the material was hard it was first loosened with a plow and then removed by means of slip or wheel scrapers. This method, however, became too expensive when still larger ditches were required. Moreover, drainage channels must frequently be constructed on lands so wet and soft as to preclude the use of teams. The increasing demand for suitable excavating machinery engaged the attention of many men of mechanical bent, and the result has been the invention of modern types of machinery, the development of which has been rapid. By the use of modern machinery the cost of drainage work has been so reduced as now seldom to afford valid excuse for failure to drain. The early type of dipper dredge was equipped with the old-fash- ioned vertical spuds, and the hull was built wide to prevent tipping. The ditches desired at that time usually were small, and owing to the width of hull the operator was nearly always compelled to excavate more material than he was paid for. The bank spud, which runs directly from the side of the machine to the bank, was invented to do away with this unnecessary width of hull and consequent useless excavation. Although many delays and difficulties were encountered in the early stages of development, the cost of excavation by ma- chinery was soon reduced much below that by hand labor. That achievement marks an epoch in the progress of drainage in this country. In late years the so-called dry-land excavators of various types have been developed and have reduced the cost of excavation under con- ditions to which floating dredges are not adapted. The growth of the drag-line scraper excavator has been especially prominent. At present this machine probably has a wider field of usefulness than any other type of excavator made. COMPARISON OF KINDS OF POWER. Excavating machinery may be operated by steam or internal-com- bustion engines or by electric motors. Coal, woo.d, and crude oil are suitable fuels for steam generation. Internal-combustion engines operate with gasoline, kerosene, or distillate. Electric current must be conveniently available and low in cost if motors are used, and if EXCAVATING MACHINERY USED IN LAND ' DRAINAGE, the greater convenience and labor saving through' its use are to offset the increased cost of equipment. The selection is usually confined to steam and internal-combustion engines, because the work generally takes place out of reach of electric transmission lines. STEAM ENGINES. The determination of the economical fuel to use for a steam plant requires a knowledge of the heating qualities of fuels and of their costs delivered at the machine. Of the fuels wood-, coal, and oil, wood has the lowest heat value. The range in heating units is not as great in wood as it is in coal, because the ash and moisture contents of coal vary considerably. It is advisable to purchase coal containing as little ash as possible. Oils have a considerably greater heat value than either wood or coal. Some of them, such as Mexican oil, have a higher heating value than others, but are difficult to use on account of their greater viscosity. The following is a comparison 1 between bituminous coal and crude oil from Beaumont, Tex., containing 19,060 British thermal units per pound: Comparative evaporative power of oil and coal. 1. Pounds of evaporation per pound of coal with about 10 square feet of heating surface per boiler horsepower 7. 5 2. Pounds of evaporation per pound of Beaumont oil with about 10 square feet of heating surface per boiler horsepower 14. 8 3. Ratio of evaporation of oil to coal 1. 97 4. Number of barrels of oil equivalent to a ton of coal 3. 54 The coal used was measured by the gross ton of 2,240 pounds. It contained- 3 per cent of water and was representative of the bitumi- nous coal obtained from mines west of Ohio in the Central Western States. The oil weighed 7.66 pounds per gallon, or 322 pounds per barrel of 42 United States gallons. The figures give net evaporation after allowing for steam consumed to produce the forced draft necessary for burning the fuel. Authorities generally estimate that 2J pounds of dry wood are equivalent in evaporative power to 1 pound of good bituminous coal, or 0.6 pound of average fuel oil. The American Society of Mechani- cal Engineers has adopted for tests the ratio of 1 pound of wood to 0.40 pound of coal. Solid bituminous coal weighs approximately 84 pounds per cubic foot, while loosely broken bituminous coal weighs 49 pounds per cubic foot. Assuming a cord of wood to weigh 2,000 pounds, 2J cords are equivalent to 1 short ton of coal. In construct- ing channels in heavily timbered sections where the right of way 1 Denton, Prof. James E. Power, February, 1902, p. 8, 4. BULLETIN 300^ U. S. DEPARTMENT OF AGRICULTURE. must be cleared, it is frequently economical to use as fuel the wood cut in clearing. It is estimated that 1 pound of coal will convert from 7 to 10 pounds of water into steam, and that there are about 13,000 British thermal units in 1 pound of coal. The heat loss from a bare boiler containing steam at 125 pounds pressure on an ordinary summer day is about 1,200 British thermal units per square foot per hour. This, allowing for fire-box losses, is equivalent to about 1J pounds of coal per square foot of bare boiler surface per shift of 10 hours, or on a boiler having 226 square feet a heat waste of 339 pounds of coal. The economy of covering boilers with insulating material is seen from the following calculation: Boiler, 54 inches diameter by 16 feet long, contains 226 square feet surface. 125 pounds gage pressure represents 352 F. temperature. Air temperature assumed to be 80 F. Coal cost at dredge assumed to be $11 per ton. Loss per square foot of bare surface per degree of temperature difference is 3 British thermal units per hour. (Authorities give this as from 2.7 to 3.) Assume that 1 pound of coal produces 7 pounds of steam. Latent heat of steam at 125 pounds gage 865 British thermal units. The total loss from the bare boiler per hour will then be 3.0 X (352-80) X 226 X $11. 00 865X7X2000 =$0.167 Thus the loss per shift of 11 hours would be $1.84 and the loss per month of 52 shifts would be $95.68. For a working pressure of 125 pounds per square inch, a boiler covering of about 2 inches should be used. In tests the efficiency of a 2-inch heat insulator has been found to be as high as 90 per cent. That means that by insulation 90 per cent of $95.68 can be saved or $86.11 per month. To cover a boiler, as described, costs about 60 cents per square foot. Thus, the boiler covering would be paid for in a little more than a month and a half of operation. The above calculations are based on an air temperature of 80 F. For lower air temperatures the saving would be correspondingly greater. For convenience in reckoning the temperature corresponding to the pressure in the boiler registered by the gage, Table 1 is given : TABLE 1. Steam temperatures at various pressures. Gage pressure per square inch. Steam tempera- ture. Gage pressure per square inch. Steam tempera- ture. Pounds. 10 25 50 75 OF 212 240 267 298 320 Pounds. 100 150 200 250 op 338 366 388 406 EXCAVATING MACHINERY USED IN LAND DRAINAGE. 5 The following formula 2 for determining. the latent heat of steam at various gage pressures is based on experiments made by M. Reg- nault : L (nearly ) =965.7 O.T (212) in which t is the steam temperature in degrees Fahrenheit to be ob- tained from the preceding table. It is convenient to remember that 1 horsepower per hour is equiva- lent to 2,545 British thermal units. Assuming 13,000 British thermal units in a pound of coal, the latter is equivalent to 5 horsepower- hours. From 18 to 20 pounds of bituminous coal per hour is burned with natural draft on 1 square foot of fire grate. Very frequently too small a boiler is used on a machine, and the boiler must be worked to its utmost capacity to furnish the necessary amount of steam. This results in great waste of fuel, which could easily be avoided by using a boiler of the proper capacity. On a certain 1-yard steam-operated drag-line excavator with a 50-foot boom the coal consumption per cubic yard was found to be 10 pounds. The boiler was replaced later with another of 35 per ce\it greater capacity, for which the fuel consumption was only slightly over 7 pounds per cubic yard. ELECTRIC POWER. The United States Reclamation Service used electrically operated drag-line excavators with IJ-yard buckets and 50-foot booms, mounted on caterpillars, in the excavation of 3,800,000 cubic yards. The ditches varied from 5 to 10 feet in base width, had 1| to 1 and 2 to 1 side slopes, and averaged 10 feet deep. The excavation per mile was approximately 40,000 cubic yards. Eighty-horsepower motors were used to move the machines while 40-horsepower motors operated the swinging drums. The average amount of current used was 0.88 kw. h. per cubic yard, including all line and transformer losses. In sandy -loam soil only 0.4 kw. h. per cubic yard was required. The transmission lines consisted of three No. 4 copper wires on 30-foot poles carrying current at 4,000 volts. This was transformed to 440 volts at the machines. The lines were torn down and rebuilt as the work progressed. 2 Kent's Mechanical Engineer's Pocketbook, 7th ed., p. 462. BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. i-5 (N IM' co * k JOt~>O-*OOOaOeOO'-'OCOOOi-i-iOOiOt^ us o> oowt* r- oo w* o oo po <* ci >o co Tj5 1^ eo 10 oo * co r^ o oi o ^ oo ' 01 o o c< o o o r>^ - f ,fU-Boft^ ,'2x/3"Machine Bolts (countersunk heads) of bottom p/anks are shown by dotted tines-' Top Timber 5"x IG"x 20' 0" Heart Pine. Bo11om Timbers 2'x/6'x20'0"HeartP/ne Cross Ties 6 H x8x8'0"SfdRR.Ties FIG. 1. Sectional track for a rotary-scraper excavator with skid and roller mounting. A drag-line excavator mounted on skids and rollers moves ahead by pulling on the bucket left partly filled in the earth to be excavated, the anchor blocks in front of the machine having been previously removed. There are instances where the surface material may be so soft as to preclude this method unless the top material is first excavated down to a stiff subsoil. To avoid this extra labor it is possible, after swinging the machine through 180, to hitch the bucket to a cable run through the bed of the machine and anchored to the track, and thus to move the machine by backing it up. The weight on the track of the machine that is being moved will ordinarily furnish sufficient anchorage. This method has been used successfully 32 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. in muskeg swamps, thus sparing the excavation of several feet of the soft surface to reach the underlying clay. The caterpillar or apron-traction mounting eliminates the track- men necessary with the skid-and-roller mounting. For small ma- chines two caterpillars (PL IV, Fig. 2) are commonly used. In one make of light drag-line excavator a combination of two wheels and two caterpillars is used. The heavier machines require four cater- pillars. A skillful operator can turn a drag-line excavator mounted on caterpillars in its own length. Large machines usually are mounted on four 4-wheeled equalizing trucks (PI. V, Fig. 1), though any size may be furnished with this mounting if desired. These trucks may all be nonpropelling, in which case the machine moves in the same way as i mounted on skids and rollers, or two of the trucks may be driven by power from the main engines of the machine. On the smaller machines one truck usually is mounted under each corner of the lower platform, while on the larger machines three of the trucks are generally mounted on an equalizing beam. This latter method is preferable, as by its use the weight of the machine is always evenly distributed, and thus the platforms are not subjected to severe stresses. There is another type of mounting in which a novel method of moving is employed. Attached to the upper platform and extending through the machine in a direction at right angles to that of the boom is a heavy steel shaft, on each end of which is a wheel segment (PL V, Fig. 2). The shaft also carries a large gear wheel which meshes with a pinion on the loading-drum shaft of the main engine. Sus- pended from the middle arm of each segment by means of a carrying beam and chains is a long shoe, which affords a bearing for the seg- ment as it rotates and propels the machine forward. To move in a given direction the excavator is rotated until the boom is pointing in the opposite direction ; the side shoes are lowered by rotating the shaft supporting the wheel segments, and the weight of the machine is thrown on to the side shoes; the segments cause the machine to rise and move ahead 8 feet. This excavator has an advantage over other types of self-propelling machines in that it can move in any direction. The machine can be walked at a rate of 25 to 30 feet a minute. When digging, the machine rests upon a large circular base. The average bearing pressure when working is from 3J to 4^ pounds per square inch. All self-propelling machines do without trackmen when working over reasonably stable ground. In soft ground extra bearing sur- face may be required to prevent the machine from sinking. On one occasion a 3-yard, 70-foot boom, walking, drag-line excavator, work- ing in unusually soft ground, required additional bearing surface. Eight pontoons were used, each 7 feet by 30 feet, the machine always Bui. 300, U. S. Dept. of Agriculture. PLATE III. FIG. I. RACK AND DOLLEY WHEELS. FIG. 2. MECHANISM FOR OPERATING PINION AND SWINGING DEVICE FOR RACK-AND-PINION TYPE OF DRAG-LINE EXCAVATOR. Bui. 300, U. S. Dept. of Agriculture. PLATE IV. D-3281 FIG. I. DRAG-LINE EXCAVATOR ON SKID-AND-ROLLER MOUNTING TRANSFERRING A SECTION OF TRACK AHEAD. FIG. 2. DRAG-LINE EXCAVATOR MOUNTED ON TWO CATERPILLARS. Bui. 300, U. S. Dept. of Agriculture. PLATE V. D-3322 FIG. I. DRAG-LINE EXCAVATOR MOUNTED ON FOUR 4-WHEELED TRUCKS. FIG. 2. WALKING DRAG-LINE EXCAVATOR MOVING AHEAD. Bui. 300, U. S. Dept. of Agriculture. PLATE VI. D-3198 FIG. I. ARRANGEMENT OF MACHINERY ON A STEAM-OPERATED DRAG-LINE EXCAVATOR. FIG. 2. TWO-LINE SCRAPER BUCKET OF THE SOLID TYPE. EXCAVATING MACHINERY USED IN LAND DRAIN ACE. 33 resting on three pontoons. With three pontoons the bearing pressure was 1-J pounds per square inch. MACHINERY AND EQUIPMENT. The power equipment of the drag-line excavator may be either steam, gasoline, or electric. On drag-line scraper excavators the internal-combustion engine has been used with success. In some places the quality of water obtainable for use in boilers and the ab- sence of electric power may determine the use of internal^combustion engines. The machinery for operating the drag-line excavator is placed on the upper platform. On excavators operated by internal-com- bustion engines the engine may be either gear-connected to the oper- ating drum or belt-connected. On steam-operated machines the main engines are of the double-cylinder, friction-drum type, mounted on a structural-steel base (PL VI, Fig. 1). The main engines operate the hoisting and loading drums. For rotating the excavators, separate engines of the double-cylinder type are used. The boilers may be either vertical or locomotive type. Tables 12 and 13 show the dimen- sions of engines, boilers, and accessories, average fuel consumption, and shipping weights of drag-line excavators of various capacities. 34 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. fe o at 2 S3 | Trucks, 245. - ::::::: 2 : ; o' - : : : j'jSd |^ : : 1 ,0,0 .2 S S ?1 c* p+ Tf O ,* -Sdd * "5 X ,_, S2 C**S? rH GC "5 1-T^T W | E^ , i tf O CM 1 CC ir 1 B : : : : : o ^ : : ^.e H > S? -00 iO o *->' N ^jg^ill i^sl s f. g IM H N : : \ '. : t- & '. '. : : : : : H : : S MH : : :^ ! : : ^ | CM J ! 1 o . : o r . , ; C ,,- c Length of boom, feet Digging-rope diameter, inche Standard length, feet Hoisting-rope diameter, incht Standard length, feet Main engines (double-cylinde Swinging engines (double-cy inder). Boiler dimensions Water-tank capacity, gallons Water consumption in 1 hours, gallons. Coal consumption in 10 hour tons. Shipping weight (skid moun c i i =1 2 w i! '"* | tr S9-S !-! bG C ^ ""iz ship. Shipping weight, ton; mounted on. Number of cars reauired t d i EXCAVATING MACHINERY USED IN LAND DRAINAGE. .11 M . 1 * 1 111 35 . . . . O O**~'oOcOcs*-'.*^.OO SHx25 .'OOSOi O5 S O 01 ^H r-, ^H N. CO CO 410) +^ M M O.QOO'O 00 CO Si ,=< r-H to i-l CT> :3 :&% : i :^ : .. P j S IS ' -o o MW 'O t^COOOGOOO'O . (N ^ t ' 36 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. BOOM. In the smaller drag-line excavators the boom is generally con- structed of two channels with cross bracing (PI. IV, Fig. 1), while in the larger machines two cross-braced lattice girders are used (PL V, Fig. 1). The lower ends of the two main members of the boom are spread apart to give stability, while at the upper end the two mem- bers are joined, and at that point one or more sheaves are placed. On some of the smaller machines the top of the boom is guyed to the top of the A frame, which is located near the front of the main'engine. The lower ends of the A frame are bolted to the platform ; the upper end is guyed to the rear corners of the platform. The length of the boom for drag-line excavators varies from 30 to 150 feet. On most machines it is suspended by a cable running to a drum on the plat- form. For raising or lowering the boom this drum may be operated either by power or by hand. BUCKET. There are various forms of scrapey buckets made for use with drag- line excavators. A type of bucket in common use is shown in Plate VI, Figure 2. This bucket can be operated with two lines, a loading and a hoisting line. For holding the bucket horizontal when hoist- ing, a patented device is used which consists of a cable secured to the top of the bucket at its front end, which, after passing through a sheave at the hoisting connection, runs down to the loading bail. With the loading line kept taut the bucket maintains a horizontal position. To dump the bucket, the loading line is merely released. The sizes, weights, and approximate prices of this bucket of stand- ard type are shown in Table 14. TABLE 14. Weights and prices of scraper buckets. Ca- pacity. Width of cutting edge. Weight without teeth. Price. Cu.yds. Inches. Pounds. 5 36 2,200 $660 1 45 2,500 698 11 45 2,800 780 li 48 3,200 862 2 51 4,850 1,043 2 57 5,850 1,191 3 60 6,550 1,357 3i 60 7,000 1,510 Many operators experience trouble with scraper buckets of the smaller sizes from their failure to clean themselves when working in sticky clay. To obviate this a skeleton scraper bucket has been made for very sticky clay. This bucket cleans itself more readily in EXCAVATING MACHINERY USED IN LAND DRAINAGE. 37 sticky material than the solid type. It is made in five-eighths cubic yard size only. OPERATION. It is impracticable to give exact figures on the time required to assemble a drag-line excavator, as the time will vary greatly with the make of machine, the length of boom, and the style of mounting. Operators generally agree that more time is required to assemble a machine mounted on caterpillars than one mounted on skids and rollers. In general, the time required for 8 men to assemble a drag- line excavator varies from 1 week for the small 1-yard walking type to 6 weeks for a 3|-yard caterpillar machine. The actual time con- sumed in erecting a 3-yard, 70-foot boom, walking, drag-line ex- cavator equipped with internal-combustion engines was 2,137 man- hours. The assembling by 12 men took 19 days. The machine made 26 wagonloads and was hauled from the siding to the project, a dis- tance of 3| miles, in 9 days. The fuel consumption for drag-line excavators depends on the character of the soil and the distance of hoisting. The average con- sumption of fuel for both steam and gasoline operated drag-line ex- cavators has been given (Tables 12 and 13). Cable expense is greater on drag-line excavators than on floating dredges. The life of cables depends largely on the nature of the work, regardless of the size of machine. Some operators consider the life of a digging cable as about 25,000 cubic yards and of a hoist- ing cable about 100,000 cubic yards. Other operators state the life in days of double-shift operation. In earth a digging rope will last from 2 to 3 weeks and a hoisting rope from 1 to 2 months, depend- ing on the number of shifts and the condition of the sheaves and drums. In cemented sand and. gravel a digging rope may wear out in 3 working shifts; usually in hard material its life is not longer than 10 shifts. The life of a cable is increased by proper lubrication. Incorrect lubrication or neglect of it results in increased wear within the rope. Even though the cable may appear bright and in good condition, this interior wear may be going on. The lubricant to be used de- pends upon the work which the cable is required to do. A hoisting cable which travels at considerable speed requires a different lubri- cant from track cables which move more slowly. Drag-line excavators with 50 to 60 foot booms operate more rapidly than machines with long booms of 90 feet or more. Therefore work which requires a short hoist and a small angle of swing can be done more rapidly than work which requires a long hoist and a large angle of swing. Rack-and-pinion swing machines have an advantage over 38 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. cable-swing machines in that when a swing of 180 degrees is re- quired the machine can complete the full circle and return to the loading point, whereas the cable-swing machine must be reversed with loss of both time and energy. A 3-yard, walking, drag-line excavator having an 80-foot boom was used to build a levee averaging 15 feet high. The machine traveled on the berm, taking dirt from the borrow pit, which did not exceed 10 feet in depth, and depositing the material on the levee site. The angle of swing was about 145 degrees. To fill the bucket required 30 seconds ; to hoist, swing, and dump took 25 seconds ; and 30 seconds were required to return to the borrow pit. The entire operation thus consumed 85 seconds. In the excavation of a ditch 36 feet deep in which the angle of swing was 90 degrees and the distance of hoist 60 feet, a 2-yard machine with a 75-foot boom was used. Filling the bucket required 25 seconds; to hoist, swing, and dump required 20 seconds ; and to return to fill the bucket consumed 20 seconds. Thus the entire time of one operation was 65 seconds. The output of drag-line excavators of various sizes will vary greatly with the length of boom, depth of cut, angle of swing, and character of digging. The figures given in Table 15 will serve as an approximate guide. TABLE 15. Output of drag-line excavators. Size of bucket. Length of boom. Economi- cal size of job.* Output per month, with double shift. Cu.yds. 9 f 11 Feet. 40 50 60 65 70 80 100 Cubic yards. 250,000 300,000 400,000 500,000 800,000 1,000,000 1, 500, 000 Cubic yards. 18,000 25,000 30,000 35,000 40,000 50,000 70,000 1 By economical size of job is meant the yardage below which the machine can not be installed and operated without appreciably increasing the cost per cubic yard of excavation. These figures give only the average output, including all lost time ; they may be greatly exceeded in any particular month during con- tinuous operation. On one contract a 2-yard, 60-foot-boom drag- line excavator averaged 70,000 cubic yards a month with double snift while building a levee containing 1,100 cubic yards per station. In the excavation of quicksand great care must be used in handling the bucket. The hoisting line is kept taut, holding the back end of the bucket a foot or so above the sand, while the cutting edge, or lip of the bucket, is pulled into the material. The output of a ma- chine in quicksand is about one-fourth that in ordinary earth. EXCAVATING MACHINERY USED IN LAND DRAINAGE. 39 Cost. Table 16 gives the approximate cost of rack-and-pinion- swing. rotary drag-line excavators. TABLE 16. Costs of rack-and-pinion-swHng, rotary, draff-line, excavators, 1921. Size of bucket. Length of boom. Kind of power. Style of mounting. Approxi- mate cost. Cu.yds. Feet. 30 Oil engine Caterpillar $11 000 i 40 Steam do 14*800 | 40 Oil engine do 18* 650 40 do..'... Walker 15 700 li 45 Steam Skid and rollers 20 850 [I 45 do Caterpillar 29' 200 2 60 .do Walker 3l'oOO 2 60 do Skid and rollers 26 700 2 60 do Caterpillar 38 300 2 85 .do Skid and rollers. 38 ? 300 3 60 do Walker . . 36 500 31 100 do Skid and rollers 46 900 3* 100 .do Trucks 56 800 34 125 do do . 71 000 5 155 do do 97 500 To equip boilers for burning oil fuel costs from $450 to $550, de- pending on the size of the boiler. CABLE-SWING EXCAVATOR. A cable-swing, drag-line excavator (PI. VII, Fig. 1), with a 1-yard bucket and a 40- foot boom, has been placed on the market recently. The machine is mounted on four apron tractors and is operated by a 55-horse power, two-cylinder opposed-type engine. The weight is about 20 tons. The road speed is one-half mile per hour. The hoist- ing line is five-eighths inch and the loading line three-fourths inch. The machine costs $7,000, including the bucket. It can be operated by one runner and one oiler and consumes about 35 gallons of gasoline in 10 hours of operation. The bucket measures 35 inches wide. The over-all clearance of the machine is 10 feet 3 inches by 26 feet. The machine has a 10-foot turntable. The vertical distance from the ground to the fair lead sheaves is 5 feet 2 inches, and the horizontal distance from the boom pivot to the center of the turntable is 6 feet 9 inches. The machine can be shipped, assembled, on one car. Only the boom and A frame are dismantled for shipping. NONROTATING DRAG-LINE EXCAVATORS. A light drag-line excavator of the nonrotating type is being used rather extensively (PL VII, Fig. 2) . The machine is built entirely of steel. The main frame is 24 by 24 feet, but can easily be made wider or narrower if desired. The platform is 12 by 30 feet. The frame is mounted on four steel wheels, each 5 feet high and 3 feet wide. The boom is 40 feet long and can be extended 10 feet more if it is desired to use the machine for tile trenching or lowering large tile 40 BULLETIN 300, U.. S. DEPARTMENT OF AGRICULTURE. into place. A 45-horsepower, 2-cylinder, opposed-type oil engine is used for power. The bucket has a capacity of five-eighths cubic yard and is 43 inches wide. One man is required to operate the machine and one man to handle the track in soft ground. About 30 gallons of gasoline or 40 gallons of kerosene are required per 10-hour day. The machine is moved ahead by means of a cable attached to a dead- man or to stakes. The large wheels will travel over fairly firm ground without track ; no trackman is therefore needed, except in quite soft ground or swamp. The machine, complete, weighs 12 tons. When dismantled it can be loaded on one flat car or if transported by team will make 12 wagonloads. The heaviest load is the engine, which weighs 5,640 pounds. To assemble the machine takes five men four or five days. The same number can dismantle it in two days. The hoisting line is one-half inch cable 125 to 140 feet long. The loading line is three- fourths inch cable 60 feet long. In single-shift operation a loading cable will ordinarily last 10 days and a hoisting cable two weeks. The machine will excavate about 300 cubic yards per shift or about 15,000 cubic yards per month with double shift. The maximum ditch which it will dig at a single cut has a 42-foot top, 12-foot base, and 8-foot depth. The machine may be had in widths of 36 or 40 feet and costs approximately $5,500. In enlarging an old ditch averaging 6 feet deep so as to have a channel 13 feet deep with a 10-foot base, "a five-eighths yard non- rotating excavator, with a 40-foot boom, was used. The material re- moved averaged 10 cubic yards per linear foot. The angle of swing was 75 degrees, and the boom was suspended at an angle of 35. A direct-line swing was used, the swinging cables being attached di- rectly to the boom instead of running through sheaves on the boom and then back to the corner of the cross-frame. This kind of hitch gave a much quicker swing. A time study made of 75 dips gave the following information : To load the bucket took 8 seconds ; to hoist, swing, and dump, 8 seconds; to return the bucket to the ditch. 8 sec- onds ; the entire time to complete one dip was, therefore, '24 seconds. To move the machine ahead a distance of 9 feet required 9 seconds. Another type of nonrotating excavator has been developed which has a double boom with bull- wheel swing instead of pivot swing. The machine is made in two sizes, five-eighths yard and 1 yard. The smaller size can be furnished with either the caterpillar mount- ing or the regular sliding-track mounting, while the larger size is furnished only in the sliding-track mounting. The smaller machine has a five-eighths-yard bucket, 24-foot boom, and a 32-horsepower oil machine ; the machine, complete, weighs 32 tons. The track shoes are each 30 feet long and 30 inches wide, and Bui. 300, U. S. Dept. of Agriculture. PLATE VII. D-3320 FIG. I. CABLE SWING DRAG-LINE EXCAVATOR WITH CATERPILLAR MOUNTING. D-3078 FIG. 2. NONROTATING TYPE OF DRAG-LINE EXCAVATOR WITH WHEEL MOUNTING. Bui. 300, U. S. Dept. of Agriculture. PLATE VIII. D-3308 FIG. I. NONROTATING SCRAPER EXCAVATOR WITH SLIDING TRACK MOUNTING. D-3343 FIG. 2. WALKING DRY-LAND DIPPER DREDGE. EXCAVATING MACHINERY USED IN LAND DRAINAGE. 41 the spud feet are 12 feet long by 8 inches wide. The bearing pres- sure when working is about 3 pounds per square inch. The distance covered at each move of the spud feet is 5 to 6 feet, and it requires about 30 seconds to move the machine ahead this distance. The road speed is 1J miles in 10 hours. About 30 gallons of kerosene are re- quired per 10-hour shift. For operation three men are required- one runner, one craneman, v and one trackman. The machine can be shipped on one car and requires four men one day to assemble and the same time to dismantle. The average output is from 500 to 800 cubic yards in 10 hours. The ditch best suited for the small ma- chine is one with a 6-foot top and 4 feet of depth, although it can dig a ditch with a 20-foot top and 12 feet in depth. The machine costs about $12,000 with the sliding-track mounting and $15,000 with caterpillar mounting. The larger machine (PL VIII, Fig. 1) has a 1-yard bucket, 32-foot boom, and 45-horsepower engine, and weighs, complete, 45 tons. The track shoes are each 34 feet long by 40 inches wide, and the spud feet 2 feet wide and 12 feet long. The bearing pressure when work- ing is 2.8 pounds per square inch. The distance covered at each move of the machine is 5 to 6 feet, 45 seconds being required to make the move. The road speed is about three- fourths mile in 10 hours. About 40 gallons of kerosene are required per 10-hour shift. The machine requires three men for operation one runner, one crane- man, and one trackman. Two cars are needed to ship the machine. Four men can assemble it in five days and dismantle it in the same time. The average output is from 700 to 1,000 cubic yards per 10- hour shift. The size or ditch best suited for the machine has a 20- foot top and 7 feet in depth. It can, however, dig a ditch with a 35-foot top and 14 feet deep. The machine costs about $18,000. Over dry earth roads four men with four teams have hauled the large machine 4 miles in three days. The smaller machine can be shipped already assembled, whereas the larger machine must be dis- mantled for shipping. This type of machine when digging does not straddle the ditch, but works along the center line when a new ditch is being dug or on one bank when an old ditch is being enlarged or cleaned out. No earth " roll " is left on the bank to fall back into the ditch. On these machines the average life of a loading line is 15,000 cubic yards; of a hoisting line, 40,000 cubic yards ; of the track lines, 60,000 cubic yards. For the larger machines the minimum economical project is about 200,000 cubic yards with double-shift operation. For the smaller machines the job should have about 30,000 cubic yards. Contractors state that for the smaller machine they do not want to take a job costing less than $8,000. 42 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. ACCESSORY EQUIPMENT. For housing men employed in the operation of drag-line excavators many contractors use camp wagons, consisting of portable houses mounted on wagons. The most common size is 8 feet wide by 18 feet long. The structure costs about $200 and a wagon with 4-inch tires about $100. SELECTION OF SCRAPER EXCAVATOR. In selecting a scraper excavator, the purchaser, in addition to choosing the most desirable kind of power and the means of moving RCACH Of BOOM IN FCCT FROM CENTER OF BOOM LUC AT VARIOUS A HOLES. A . To Tfiit Dittanct add "A" trhtrt Distance from Cenler of Machine is required -Diagram of scraper excavator showing relation between the length of boom and the effective reach of machine. over the ground best suited to his particular case, must determine the length of boom best suited to his needs. Figure 2 is a diagram showing the relation between the length and angle of elevation of the boom and the effective reach of the machine. In this diagram all distances are referred to the heel of the boom. If it is desired to refer horizontal distances to the center of the machine, the correction A must, of course, be added; this distance varies somewhat with the different makes of machine. The distance B of the heel of the boom above the ground likewise varies slightly in different machines. To determine the maximum clearance of the bucket above the ground for different lengths and positions of boom the distance B must be added to the vertical heights given on the right-hand margin of the diagram, and from this sum must be subtracted the distance C EXCAVATING MACHINERY USED IN LAND DRAINAGE. 43 which depends upon the kind of bucket used. Thus for a 70-foot boom elevated at a-n angle of 35 degrees the horizontal distance from the center of the machine to the bucket would be 57+ A, and at that position of the boom the bucket would just clear a waste bank of the height 4Q+B-C. In using the diagram for nonrotating excavators the distance A is not added, since the boom of this type of machine swings at its pivot. Table 17 gives the approximate distances A and B in figure 2 for the various sizes of machines on the different styles of mountings. The distances will vary slightly for different makes of excavators. TABLE 17. Limitations of operation of (Iran-line excavators. SLe of bwkot. Length of boom. Diameter of turntable. Type of mounting. Distance A.i Distance B.i Cu.y.'s. i Feet. 30 Feet. in. 4 7 Caterpillar Feet. in. 2i-3 Feet. in. 4-41 1* 40 11 3 Walker " G 4 3 5 J 42 7 Caterpillar 4 3 5 6 1 40 7 Skids and roller.? 3 3 4 5 14 45 9 6 Caterpillar 7 5 9 5 45 9 (') Skids and rollers 7 5 7 4 9 J GO 14 Caterpillar 7 5 9 5 2 60 14 Skids and rollers 7 5 G 5 2 50 15 do 9 G G 6 2 50 15 Walker 10 4 G 2 1 85 20 Skids and rollers 12 2 7 8 2V 85 20 Trucks 12 2 11 G 3 GO 17 Walker 10 8 4 9 3 GO 17 Skids and rollers 11 8 7 3V 80 20 do 12 6 8 3* 100 24 do 12 2 7 10 sl 125 24 Trucks 12 10 13 4 80 24 Skids and roller.; . . 12 6 8 4 100 24 do . . . 15 8 6 Bee figure 2. The clearance distance C (Fig. 2) varies with the size of bucket and size of sheaves used. Table 18 gives the approximate values of C for the various sizes of bucket' shown in Plate VII, Figure 1. TABLE IS. Clearance of buckets for draff-line excavators. Size of bucket. Distance C. 1 Size of bucket. Distance C. 1 Cu. mis. 1 Feet. 12 Cu. yds. Feet. 15i to 16 I 124 3i 15^ to 16J 1 12 to 12!* 4 "1 li 12i to 13 4J 18J 2 14* to is 5 19 to 23 2J 14i to 15J 1 See figure 2. The factor governing the size of the ditch which a certain machine can dig is not ability to excavate, but, rather, to dispose of the mate- rial excavated, especially where the ditch is deep and the yardage per linear foot relatively large. An experienced runner can drop 46 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. 1 to 2 miles in 10 hours. It is very useful on projects where the yardage per 100-foot station is small and where there are many short laterals. A dry-land dipper dredge made of steel but equipped with a dif- ferent device for walking than the machine just described is illus- trated in Plate IX, Figure 2. The machine when working rests on two skids, each 3 feet wide by 30 feet long. The auxiliary skids each measure 3 feet wide by 28 feet long. When being moved the weight of the machine is shifted to the auxiliary skids, and the ma- chine is skidded ahead. The auxiliary skids are then pulled forward. The machine will move either forward or backward. It is made with various widths of span from 14 feet up to 45 feet and in three sizes, f , 1, and 1^ cubic yards. The length of boom varies for the different sizes from 25 feet to 55 feet. A dry-land dipper dredge which employs the same method of walking as the machine illustrated in Plate VIII, Figure 2, but which is equipped with a different type of bucket, is used to some extent on drainage work. This machine (PI. X, Fig. 1) is built almost en- tirely of wood, longleaf yellow pine being used, as this wood has greater resiliency than fir. The boom is of wood reinforced by truss rods. This machine as ordinarily built will span a ditch with a top width of 28 feet. It has a 40-foot boom and a If-yard dipper. Booms of 30 or 50 feet can be used. For power a 60-horsepower internal-combustion engine is used. The dipper or scoop (PL X, Fig. 2) is 5 feet wide at its cutting edge. By virtue of the peculiar shape of the scoop, 2f cubic yards are easily removed at each dip. This excavator is mounted on six shoes or feet, one at each corner of the platform and one on each side of the machine at the center. The four corner shoes are attached directly to the framework of the machine and move with it. The machine moves by shifting its weight to the center feet and sliding forward on the four corner shoes. The center feet are then pulled forward by means of chains attached to a drum. The machine in operation weighs 160 tons, but on account of the large bearing surface of the shoes the pressure per square inch is slightly less than 10 pounds. The front shoes are 6 by 10 feet ; the rear shoes, 6 by 9 feet ; while the middle shoes are 7 by 14 feet; these sizes, of course, can be varied. When operating, the entire weight is on the four corner shoes. To dismantle or assemble an old machine of this type takes 15 men about 30 days. To build an entirely new machine would take the same number of men from 60 to 90 days. The machine can be shipped on four cars. For this machine the minimum economical yardage of any one job is 1,000,000 cubic yards. The machine will excavate an average of EXCAVATING MACHINERY USED IN LAND DRAINAGE. 47 60,000 cubic yards a month with double shift ; with steady running it will greatly exceed this amount. Its operation requires 4 men 1 runner, 1 craneman, 1 engineman, and 1 oiler. The runner handles the hoisting and backing lines, the craneman the swinging and dump- ing lines. The amount of fuel required per shift is 75 gallons of kerosene and 1 gallon of gasoline. About 5 gallons of cylinder oil are used per 24 hours, or two shifts. The ditch for which this ma- chine is best adapted is one with a 14-foot base, 1 to 1 side slopes, and 7 to 8 feet deep. From a motion study made of the time of operation of this ma- chine the average time for 50 dips was obtained. To fill the bucket required 10 seconds ; hoisting, swinging, and dumping, 9 seconds ; re- turning to the channel to dig, 8 seconds ; entire time for one complete operation, 27 seconds. Moving ahead a distance of 6 feet required about 18 seconds. THE DRY-LAND GRAB-BUCKET EXCAVATOR. Dn-land grab-bucket excavators of both the rotary and nonrotat- ing types are used to some extent in drainage reclamation. A ma- chine of the former type having an orange-peel bucket is illustrated in Plate XI, Figure 1. The excavator moves on skids and rollers or is mounted on four trucks which move on a track built in sections so that it can be taken up and relaid ahead of the machine as the work progresses. In the revolving type this shifting of track is done by the machine itself. The machine illustrated is operating a 2^-yard orange-peel bucket on levee work. The boom is 90 feet long. The main engines are 12 by 16 inches and the boiler, vertical in type, 74 inches in diameter. The track gauge of the machine is 26 feet from center to center; the rotation speed is 2 revolutions per minute. A type of dry-land grab-bucket excavator which has been used on rice plantations and on marsh lands along the eastern coast for dig- ging ditches and building small levees is shown in Plate XI, Figure 2. This machine is made in four sizes, with either automatic or bull- wheel swing. The general dimensions, weight, and price for each size of machine and each type of swing are given in Table 20. 48 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. TABLE 20. Dimensions and costs of dry-land grab-bucket excavators icith oranye-pcel bucket fitted with butt-wheel and automatic swing. Bucket capacity. 9 cubic feet. 15 cubic feet. 21 cubic feet. 1 cubic yard. Common dimensions: Boom, length, feet 30 21 6 10 15 9 11 8 6 10 9 28 9 10,500 2,300 ,5,470 8 26 9 8,500 2,200 $4, 410 11J 40 26 3 15 17 6 17 8 20 11 38 6 11,000 3,950 $6, 630 * 18 10 36 4 9,000 3,750 $5, 280 16 50 33 5 18 25 21 10 30 15 47 15,000 7,400 $8, 760 27i 13 45 13,000 7,000 $7, 480 26^ 54 33 5 18 25 21 12 40 15 52 17,000 7, 6GO $0,725 31* 13 50 15, 000 7,200 $8, 855 30 Size of platform- Length, feet and inches Width, feet ... .. A frame- Height above bottom of skids, feet and inches Extreme overall width of machine, feet and inches Bull- wheel diameter , feet Engine,interna 1 combustion type with two friction drums, tandem horse power Bull-wheelswing: Clearance under bucket, feet .... Radius of swing from center of A frame, feet and inches Weight, including drums and swinging gear, pounds Timber to build machine, feet b. m Approximate price not including timber of machine Tota 1 weight set up for work, tons Automatic swing: Clearance under bucket, feet Radius of swing from center of A frame, feet and inches Weight, including drums, pounds Timber to build machine, feet b. m Approximate price, not including timber Tota 1 weight of machine set up for work, tons . . . THE WHEEL EXCAVATOR. There is a type of wheel excavator which has a steel frame which supports on the front end the power equipment and on the rear end a pivoted steel framework holding the digging wheel (PI. XII, Fig. 1). The steel frame is mounted on two broad-tired wheels at the front end and on two apron tractors at the rear end. The large bearing surface permits the machine to operate in soft, swampy ground. The power equipment may be either a steam or an internal- combustion engine. The latter is used the more extensively. The excavating wheel revolves upon antifriction wheels placed just outside its rim. The excavating scoops or buckets are placed on the circumference of the excavating wheel. The front of each scoop is provided with a cutting edge which takes a thin slice from the face of the trench as the wheel rotates. When the bucket reaches the top of the wheel the earth falls onto a belt conveyor, which deposits it on the waste bank at one side of the ditch. Table 21 gives general data concerning each size of machine, the dimensions of ditch each will dig, and the approximate cost of the various machines. Bui. 300, U. S. Dept. of Agriculture. PLATE IX. D-26G FIG. I. DRY-LAND DIPPER DREDGE MOUNTED ON TRACK. D-4094 FIG. 2. WALKING DRY-LAND DIPPER DREDGE WITH SKID WALKING DEVICE. Bui. 300, U. S. Dept. of Agriculture. PLATE X. D-3074 FIG. I. WALKING DRY-LAND DIPPER DREDGE WITH DOUBLE BOOM AND SCOOP BUCKET. FIG. 2. SCOOP BUCKET OF DRY-LAND DREDGE Bui. 300, U. S. Dept. of Agriculture.' PLATE X!. FIG. I. DRY-LAND ROTARY GRAB-BUCKET EXCAVATOR. FIG. 2. NONROTATING DRY-LAND GRAB-BUCKET EXCAVATOR. Bui. 300, U. S. Dept. of Agriculture. PLATE XII, FIG. I. NONCONVERTIBLE TYPE OF WHEEL EXCAVATOR. FIG. 2. CONVERTIBLE TYPE OF WHEEL EXCAVATOR. EXCAVATING MACHINERY USED IN LAND DRAINAGE. TABLE 21. Data pertaining to the wheel excavators. 49 Clearance length of machine, feet. . 35 44 46 43 50 52 52 55 55 Clearance width, feet 13i 4iX3 10X3i 30 27 3 to 12 18 2 6 3 $7,200 18 5X4 12X5 40 36 4 to 16 21 4 6 3 6 $8, 300 21} 5X4 12X5J 50 45 4 to 16 25 6 4 6 $10,000 23| 6X5 12X5 50 45 3 to 15 28 7 5 2 $11,500 25 6X5 14X6 60 50 3 to 15 32 8 5 6 $13, 200 28 6X5 14X7 75 60 2 to 12 38 9 5 6 $15, 400 28 6X5 16X7 80 70 2 to 12 42 10 5 6 $16,300 30 6X5 16X7 90 80 2 to 12 46 11 5 6 $17, 100 32i 6X5 16X8 100 90 2 to 12 50 12 5 6 $19,300 Size of front wheels, feet Size of apron wheels, feet Engine, horsepower. ... Gasoline consumption in 10 hours, gallons Cutting speed, feet per minute Weight, tons Top width of ditch, feet and inches Depth of ditch, feet and inches Approximate price ... . The road speed of all sizes of the above machine is about 1 mile per hour. Two cars are required for shipping. Four men can unload and assemble one of these machines in three to five days. There is a wheel type of trench excavator so designed that by adding side knives a ditch Avith sloping sides can be dug. This machine is illustrated in Plate XII, Figure 2. A series of buckets attached to two parallel chains travel over the circumference of a wheel which is supported by a central shaft. The cutting knives slice the earth from the sides of the ditch, the dirt falling into the path of the buckets. The excavator is made in two sizes. The smaller size will dig a ditch 5 feet deep and 3 feet in bottom width, with side slopes 1 to 1. The larger size will dig a ditch 6 feet deep and 5 feet in bottom width, with 1 to 1 side slopes. The machine is mounted on caterpillar tractors. For the small size, 4 by 6 foot tractors are used; the large machine requires 4J by 11 foot tractors. Either steam or gasoline power is employed, the latter being more popular. The smaller excavator weighs 15 tons and requires a 24- horsepower engine ; the larger machine weighs 20 tons and is oper- ated by a 40-horsepower engine. Both types of wheel excavators when equipped with internal- combustion power require two men to operate. If the work is in extremely soft ground two or more additional men are required. In addition a team and teamster are needed for hauling fuel and other supplies. No average operation figures can be given as to the amount of work per shift that a wheel excavator will accomplish, as these vary greatly with the character of the soil, the conditions under which the work is being done, and the operator. In one of the Gulf States a wheel excavator equipped with a 30-horsepower gasoline engine, digging a ditch 4 feet deep, 4 feet wide at the top, and 2 feet wide 93127 22 4 50 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. at the bottom, made an average distance of 2,250 linear feet in 10 hours. The soil was a hard, yellow, sandy clay, overlain by a tnrfy muck varying in depth up to 2J feet. The total length of ditches dug was 165 miles, two machines of the same size being used. The maximum distance dug in 10 hours was 6,600 feet. The fuel con- sumption per shift of 10 hours was 50 gallons of gasoline. On another project a wheel machine of the same size was used. The soil was a silt loam, firm and uniform, but not tenacious. The average length of ditch cut per day was 800 feet, while the maximum was 1,950 feet. The total length of ditch cut was 117,000 feet. Wheel excavators are adapted to the excavation of ditches in soils free from stumps, buried timbers, bowlders, or rock. They have been used extensively in the Gulf States on flat, swampy prairie lands. THE HYDRAULIC DREDGE. The hydraulic dredge has been used only to a limited extent in the construction of drainage ditches, due to the fact that nearly all such ditches are too small to be dug economically by this method. Hydraulic dredges are suitable for digging ditches 800 or more square feet in cross section, for building levees under favorable con- ditions, and especially for building up tidal flats and lowlands. The principal parts of the hydraulic dredge are a centrifugal pump, the power machinery to drive the pump, and the hull on which the machinery is mounted. When the dredge is operating the material to be excavated, mixed with water, is drawn in through the suction pipe and discharged where desired through a line of pipe sometimes several thousand feet long. Coarse sand, gravel, muck, and silt are easily handled in this way, and by the use of a rotary cutter on the end of the suction pipe comparatively hard clay can be removed. The machine does not work well where there are stumps, logs, large stones, or other such obstructions. The dredge must be moved frequently. This is usually accom- plished by cables operated by a hoisting engine and attached to deadmen on the shore or, if working in a large stream, to anchors dropped into the stream. Either one or two spuds are arranged at the stern of the dredge, which hold that end of the hull in position. By swinging the head of the dredge the amount of material de- livered to the pump can be regulated so that the dredge will handle the maximum percentage of solids. To determine whether the dredge is working properly a vacuum gauge is attached to the suction pipe and a pressure gauge to the discharge pipe. The operator by means of the vacuum gauge can tell when the pump is handling the proper amount of material, as EXCAVATING MACHINERY USED IN LAND DRAINAGE. 51 the reading on the gauge is greater when pumping solid material than when pumping water only. The reading on the pressure gauge varies with the length of the discharge pipe used and with the elevation to which the material is pumped. An experienced operator, however, can tell when the operations are being carried on properly. The reading in inches on the vacuum gauge can be reduced to the equivalent head in feet by multiplying the number of inches by 1.13. The reading on the pressure gauge, in pounds per square inch, can be reduced to the equivalent head in feet by multiplying the gauge reading in pounds by 2.30. The practical maximum discharge pressure is from 45 to 55 pounds, depending somew r hat upon the size of the pump. For extra high heads, relay or booster pumps are used ; that is, the first pump delivers the ma- terial through a certain length of discharge pipe into the suction line of the relay pump. An auxiliary pump is often used to dis- charge water continuously into the shell of the dredging pump to aid in moving the material pumped. , The suction head is the distance from the surface of the water to the center of the pump plus pipe friction and losses of head through the rotary cutter and at the entrance of the suction pipe. The total suction head should not ordinarily exceed 25 feet, a condition easily met by the hydraulic dredge. The discharge head is the difference in level between the pump shaft and the point of discharge, plus the friction in the discharge pipe. For priming the pump a small centrifugal pump is commonly used. The method is to raise the suction pipe until its end is higher than the dredging pump and prime until priming water discharges from the suction pipe; the suction pipe is then dropped into the water and the dredge pump started. SELECTION OF EQUIPMENT. In order to select the proper equipment several ruling factors must be considered. The character of the material to be excavated, the maximum depth of water from which the material is taken, the maximum elevation at which the material is to be deposited, and the maximum and minimum length of discharge pipe to be used, are conditions which must first be determined. Likewise the quantity of material to be excavated per shift must be decided upon, as well as the type of power equipment and method of drive. The percentage of solids moved depends upon the character of material pumped and the velocity in the discharge pipe. In mud or silt 20 per cent or more solid material may be handled with the water ; in sand and gravel probably not more than 10 per cent. Light 52 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. silt or fine sand are easily carried in suspension, and for these a larger diameter of discharge pipe with a lower velocity may be used than for coarse sand and gravel. The maximum velocity of dis- charge is reached when the friction head begins to increase too rapidly. The velocity at which the abrasive action on the internal surface of the discharge pipe begins to be serious occurs at about 12 feet per second for pipes 20 inches in diameter. The gain in the proportion of solids transported at high velocity may be offset by the cost of more frequent renewals of discharge pipe. Discharge pipes having a diameter of 15 inches and a thickness of wall of eleven-sixty-fourths inch, and containing from 0.5 to 0.6 per cent of carbon and from 0.6 to 0.7 per cent of manganese, have passed more than 300,000 cubic yards without wearing out. Since the wear is chiefly along its bottom, the pipe may be marked and rotated a quarter turn occasionally to insure even wear. The smaller the diameter of the discharge pipe the higher the velocity for a given discharge, and the greater the percentage of solids which will be transported. The larger the discharge pipe the greater the volume of mixture carried for a given amount of power. The amount of power must be determined that will give sufficient velocity to carry the material in suspension and deliver the maximum amount of solids. With 6-inch pipe or less, sand mix- tures will flow well with a pipe velocity of 5 feet per second. In a 20-inch pipe it has been found that a velocity of 10 feet per second will transport sand. The smaller pumps, 12 inches and under, may be either belt-driven or direct-connected to the power unit. The larger pumps are usually direct-connected to the power unit, this method of drive being the most economical. When there happens to be great variation in the length of discharge pipe it is advisable to have impellers of differ- ent diameters one of large diameter when long discharge pipes are used and a smaller impeller with a short discharge pipe. By using the proper size of impeller the engine is better able to main- tain its normal speed. DETERMINATION OF SIZE OF PLANT. To determine the amount of power required to operate the pump the following factors must be considered: (1) diameter of suction and discharge pipe; (2) kinds of pipe and length of each kind; (3) character of end connections ; (4) static head; (5) efficiency of pump and engine (which may vary from 30 to 70 per cent) ; and (6) nature of material and percentage of solids transported. EXCAVATING MACHINERY USED IN LAND DRAINAGE. 53 The required horsepower of the engine may be obtained by multi- plying the weight of the mixture transported by the total head in feet, and .a coefficient dependent upon the combined efficiencies of the pump and engine. Efficiencies over 50 per cent are rarely obtained in a hydraulic dredge pump. Table 22, compiled from data pub- lished by manufacturers of hydraulic dredges, gives the capacities and required power for pumps of various sizes. TABLE 22. Capacities and required poiver of hydraulic dredges. Solids pumped per hour. Approxi- Diameter mate of horse- suction and discharge pipes. Normal capacity. 10 per cent. 15 per cent. 20 per cent. power required for each foot of head. Gallons per Cubic Cubic Cubic Inches. minute. yards. yards. yards. 4 450 12 18 24 0.4 5 700 20 30 40 .6 6 1,000 30 45 60 .8 8 1,800 50 75 100 1.5 10 2,800 90 135 180 2.5 12 4,000 130 195 260 3.0 15 6,300 200 300 400 5.0 18 9,000 300 450 600 7.0 20 13, 000 375 560 750 8.0 24 17,000 500 750 1,000 10.0 Suppose it is desired to select pump and power equipment for a hydraulic dredge to be used in building a levee with a top elevation 20 feet above the water surface, the maximum length of discharge pipe to be 2,000 feet, the material to be pumped being sand which it is desired to pump at the rate of 130 cubic yards of solids per hour. In pumping sand it is assumed that 10 per cent of the discharge is solids. Table 22 shows that a 12-inch pump will deliver the required amount of material. To determine the size of the power unit to work the pump effi- ciently it is necessary to determine the head against which the pump is to operate. This includes static head, entrance loss, and friction in suction and discharge pipes. Table 23 shows the velocity of flow and friction head per 100 feet for water in clean iron pipe, as given by pump manufacturers. To obtain the friction head for the mix- ture pumped by a hydraulic dredge, the figures given in Table 23 should be increased from 40 to 75 per cent, depending upon the character of the material pumped. 54 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. TABLE 23. Friction head per 100 feet and velocity of flow of water in clean iron pipe. Gal- lons per min- ute. Inside diameter of pipe in inches. 4 5 6 8 10 12 14 15 18 20 22 24 450 750 1,000 1,800 2,500 3,000 4,000 6,000 7,500 10,000 12,500 14,000 17,000 Friction head, feet. Velocity, feet per second. Friction head, feet. Velocity, feet per second. Friction head, feet. Velocity, feet per second. Friction head feet 13.9 11.4 *4.6 7.3 11.3 12.2 1.9 5.1 5.1 8.4 9.0 11.3 1.2 4.8 2.2 6.4 0.74 4.0 6.92 11.5 13.3 15.9 2.3 7.4 4.39 10.2 6.3 12.2 0.94 5.1 1.78 7.09 2.55 8.5 4.65 11.5 Velocity, feet per second. Friction head feet 0.84 5.2 1.19 6.3 2.10 8.9 4.8 13.4 Velocity, feet per second. Friction head, feet. Velocity, feet per second. Friction head feet 1.45 7.2 2.9 10.8 4 4 Velocity, feet per second. Friction head, feet. Velocity, feet per second. Friction head, feet 1.43 8.2 2 18 1 30 Velocity, feet per second. Friction head, feet. Velocity, feet per second. | Friction head feet 13.5 10.3 3.67 13.7 8.26 2.25 11.0 3.06 13.0 4.25 15 4 1.39 9.0 1.87 10.5 2. 04 12 6 1.25 9.0 1.79 10.79 2..6 13.1 Velocity, feet per second. (Friction head, feet. Velocity, feet per second. Friction head feet 3.8 15.3 Velocity, feet per second. The loss of head due to an elbow in a 12-inch pipe line may be esti- mated at 2 feet. The entrance loss is usually considered equivalent to 2 or 3 feet of head. The minimum velocity that will transport sand in a 12-inch pipe has been found by experience to be approxi- mately 8 feet per second. Table 23 shows that for clear water the friction loss per 100 feet of 12-inch and 14-inch pipe is 4.65 feet and 2.10 feet, respectively, and that the velocity of flow is 11.5 and 8.9 feet per second, respectively. As the velocity in the 14-inch pipe is sufficient to transport the 10 per cent mixture to be pumped, this size of pipe should be used, because there is less friction than with the 12-inch pipe. The 2,000 feet of discharge pipe would therefore develop a friction head of 20 by 2.10 feet, or 42 feet, with clear water ; with a 10 per cent sand mixture this head should be increased at least 50 per cent, or to 63 feet. EXCAVATING MACHINERY USED IN LAND DRAINAGE 55 If the pipe lines make four elbow turns and the friction loss in the suction pipe, which is seldom more than 25 to 40 feet long, is omitted, the total head to be pumped against is as follows : Feet. Static head (difference in elevation of water surface and top of levee) 20 Friction loss in 2,000 feet of 14-inch discharge pipe ^ C3 Loss of head in 4 elbow turns 8 Entrance loss 2 Total head to be pumped against 93 Table 22 shows that approximately 3 horsepower is required for each foot of head to make a 12-inch centrifugal pump deliver 130 cubic yards of solids per hour in a 10 per. cent mixture. It would, therefore, be necessary to have 279 horsepower available to pump against the required head of 93 feet. As it is advisable to have ample power available, a 300 or preferably a 350 horsepower engine should be used. If electric power is used, a 400-horsepower motor should be installed, as electric equipment can not successfully be subjected to overload as can steam equipment. In determining the size of plant required it is important to provide ample reserve power and capacity. This is necessary because of the many variable and unknown factors entering into the operation of hydraulic dredges. A choked suction pipe, pump, or discharge pipe can frequently be corrected without serious loss of time if ample reserve power is available. OUTPUT. The amount of material pumped in a unit of time and the fuel consumption per cubic yard pumped vary, of course, with the kind of material pumped and the conditions under which operations are conducted. The information given in Table 24 is representative of this type of dredge. In the operation of hydraulic dredges there is considerable lost time, due to delays caused by such items as changes in discharge pipe, choked suction pipe, pump, or discharge pipe, repairs, and renewals. Not more than 50 to 75 per cent of the time will be spent in actual operation. 56 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. TABLE 24. Operating data for United States liydmiilie dredges? Diameter of dis- charge pipe. Material. Average gauge pressure in dis- charge pipe. Average vacuum in suc- tion pipe. Total head. Average output per hour of pump- ing. Coal used per cubic yard pumped. Total excavation. Inches. 10 Sand Pounds per square inch. 14 Inches. 15 Feet. 49 Cubic yards. 89 Pounds. 13.3 Cubic yards. 163 288 12 9 20 43 97 15 63 9 172 12 Sand , gravel , shells 18 10 53 199 6.5 16, 889 12 Sand 18 12 55 107 6.35 55 131 12 Sand and gravel 14 9.7 42 76 14.4 123, 959 12 do 10 14 39 105 12.6 165 028 12 Mud. 16 15 54 181 4.22 376, 079 15 * Mud, clay, sand 12.6 16.9 48 141 9.8 230, 257 15 Gravel and sand 12 20 50 257 6 79 310 370 15 Silt, clay, and sand 22 18 71 172 8.64 488, 875 15 Mud and silt 18 12 55 293 3.2 792 807 15 Mud, clay, and sand 3.5 11 21 309 2.71 1, 078, 2S5 15 Sand, mud, and shells 16 7 45 551 3.35 1. 298, 597 18 Sand and mud 14 18 53 113 15 228 263 18 20 Sand and mud, some rock Sand and rock 22 15.4 9 16 61 54 286 336 6.7 5.27 1, 045, 689 365, 433 20 Mud, sand, and shell 28 14 80 1.130 4.31 444, 665 20 20 Sand, mud, and stiff clay Mud and clay 25 28 12 18 71 85 180 685 8.41 2.45 527, 360 636, 417 20 Mud snd sand 32 12 87 503 7.33 1,270,703 20 Mud and clay 21 15 65 827 2.48 1, 341, 835 20 Silt, quicksand 32 12 87 369 3.75 1, 687, 476 20 Mud, sand, clay 26 g 69 1 016 3.07 3 697 875 24 Sand and gravel 9 13.5 36 542 10.4 59, 702 1 Annual Report, Chief of Engineers, United States Army, Floating Plant (1915). USE IN LEVEE CONSTRUCTION. The hydraulic dredge can be used successfully in constructing levees where water and soil conditions are suitable and where there is sufficient yardage to pay for the installation of such a machine. Suitable soils are those largely composed of sand with some silt or clay. If a large amount of silt or clay is present there is a tendency for the material to remain in suspension for considerable time and it is difficult to form the levee. Plate XIII, Figure 1, illustrates the method of forming the desired slopes by means of steel boards. These boards, made of No. 14 gauge steel, about 18 inches wide and 10 feet long, with angle-iron top, are light enough to be easily moved by .one man. They may be placed in a continuous single line along the intersection of the side slope with the natural slope at the end of the fill, or they may be placed in a staggered line along the slope as shown. Several men equipped with shovels are necessary to dis- tribute the material evenly and to move the slope boards ahead as the levee is built up. A hydraulic dredge (PI. XIII, Fig. 2) with hull 90 by 24 by 5J feet, having a centrifugal pump with 12-inch suction pipe, 14-inch discharge pipe, a 250-hersepower tandem compound engine, and a locomotive-type boiler nominally rated at 150 horsepower, was used in constructing a section of levee along the Mississippi River near Bui. 300, U. S. Dept. of Agriculture. PLATE XIII. D-3079 FIG. I. BUILDING A LEVEE BY MEANS OF STAGGERED SLOPE BOARDS. D-3080 FIG. 2. HYDRAULIC DREDGE BUILDING LEVEE. \ D-3077 FIG. 3. A TYPE OF CUTTER HEAD USED ON THE HYDRAULIC DREDGE. Bui. 300, U. S. Dept. of Agriculture. PLATE XIV. FIG. I. DISCHARGE PIPE OF HYDRAULIC DREDGE SHOWING MATERIAL PASSING THROUGH OPENINGS IN BOTTOM OF PIPE. FIG. 2. DISCHARGE PIPE OPENING WITH SHUTTER. FIG. 3. RELEASE VALVE IN DISCHARGE PIPE. EXCAVATING MACHINERY USED IN LAND DRAINAGE, 57 Muscatine, Iowa. The material was sufficiently hard to require a cutter head (PL XIII, Fig. 3). The mechanism for running the cutter head was operated by a vertical two-cylinder steam engine. For moving the dredge a 6 by 9^ inch double-cylinder, three-drum hoisting engine was used, the cable being secured to a deadman on the shore at one end and to a heavy anchor in the river at the other. One drum was used to raise and lower the suction pipe. The hoist- ing engine used steam from the main boiler. For operating the pump a rope drive was used, the rope being four-strand and 1J inches in diameter. Rope transmission is believed to be less affected by moisture than leather belting; moreover, there is less slippage with rope drive. The discharge pipe was carried from the dredge to the shore on barges, each 40 by 14 by 2 feet. The material was deposited on the levee through 4 by 6 inch openings in the bottom of the discharge pipe (PL XIV, Fig. 1). The openings were equipped with shutters (PL XIV, Fig. 2), so they could be opened or closed as desired. The discharge pipe was divided into 25-foot lengths, each of the last 10 lengths being equipped with three openings or gates. The pump became clogged occasionally with masses of roots, and to prevent damage to the discharge pipe from the resuction in the pump a joint of pipe having a release valve which allowed air to enter (PL XIV, Fig. 3) was inserted in the pipe. Resuction will cause a 14-inch dis- charge pipe of 14-gauge material to collapse unless release valves are provided. The pump was equipped with pressure and vacuum gauges to enable the operator to gauge the working of the dredge. The operating crew for one shift consisted of a foreman, an op- erator, a fireman, and a deck hand. From 5 to 10 men were required at the end of the discharge pipe, depending upon whether an old levee was being enlarged or a new levee built. The coal consumption averaged from 4 to 5 tons per 11-hour shift. When the condenser was not used about three-fourths ton more fuel per shift was needed. With steady running the dredge pumped from 2,000 to 2,400 cubic yards in 11 hours; on the job as a whole, however, the average was from 1,000 to 1,200 cubic yards per shift. The open type of impeller with five blades was used on the dredge described. This impeller has adjustable shoes which can be replaced when worn. To build a hull for a dredge of this description takes 8 men 6 weeks; to assemble the machinery, 6 men about 6 weeks; to build a coal barge 75 by 16 by 5 feet, and 5 pontoons, each 40 by 14 by 2 feet, will take 8 men G weeks. The cost of the dredge complete is about $30,000, including barges and pipe. In excavation where many roots are encountered, it has been found that the inclosed impeller having two blades works exceptionally Pamphlet Binder Gaylord Bros. Makers Syracuse, N. Y. PAT. JAN 21, 1908 4933-li TA T3 Y5 UNIVERSITY OF CALIFORNIA LIBRARY