UC-NRLF 
 
 B 3 75b SEE 
 
 EI.HALLOCK 
 
i 
 
 UNIVERSITY OF CALIFORNIA LIBRARY 
 
 THIS BOOK IS DUE ON TOE LAST DATE 
 STAMPED B^LOW 
 
 JUN 2 6 REC'D 
 
 
 5m-10,'22 
 
TRACTOR ENGINES 
 
 BY 
 
 EDWARD F. HALLOCK 
 
 OVER 140 ILLUSTRATIONS 
 
 A Complete Course of Lessons on the Construction 
 
 and Economical Operation of the Tractor 
 
 Engine; Ajustments and Repairs 
 
 Made Easy; How To 
 
 Aquire Maximum 
 
 Efficiency 
 
 192C 
 
 AMERICAN AUTOMOBILE DIGEST 
 CINCINNATI 
 
COPYRIGHT, 1920 
 EDWARD ROSENTHAL 
 CINCINNATI, OHIO 
 
CONTENTS. 
 
 CHAPTER I. PAGE 
 
 Engine Principles 1 
 
 CHAPTER II. 
 Features of Construction 13 
 
 CHAPTER III. 
 Major Engine Parts 43 
 
 CHAPTER IV. 
 Valves and Valve Mechanism 83 
 
 'CHAPTER V. 
 About the Fuel System 107 
 
 CHAPTER VI. 
 Lubrication of the Engine 149 
 
 CHAPTER VII. 
 Cooling 176 
 
 CHAPTER VIII. 
 Care of the Cooling System 187 
 
 CHAPTER IX. 
 Ignition System 193 
 
 CHAPTER X. 
 Care of Ignition System , 215 
 
 CHAPTER XI. 
 Engine Troubles 22S 
 
FOREWORD. 
 
 WITH the thought in mind that a clear con- 
 ception of the principles involved in the 
 operation of a piece of machinery helps consid- 
 erably in the matter of keeping the apparatus 
 in proper running condition, this little book on 
 tractor engines has been prepared. 
 
 First consideration throughout each of the 
 various chapters has been given to a complete 
 exposition of the basic principles on which the 
 matter treated with depends for its functioning; 
 with these principles firmly implanted in the 
 mind of the reader, we have felt better able to 
 make plain to him the points of divergence in 
 various constructions, and particularly the means 
 and the methods of effecting adjustments and 
 repairs. 
 
 It will be found, therefore, that each chapter 
 is a separate article, quite capable of standing 
 alone and dealing exhaustively with the subject 
 matter in hand. This arrangement, we have 
 felt, makes for coherence and clarity to the end 
 that the progress of the student tractor operator 
 or owner is furthered. 
 
 EDWARD F. HALLOCK. 
 
 NEW YORK, December 7, 1919. 
 
CHAPTER I. 
 
 Engine Principles. 
 
 Basic Principles on Which Engine Operation 
 
 Depends; Necessary Components and 
 
 Cycle of Operations of the 
 
 Practical Motor. 
 
 BROADLY speaking, the engine employed 
 for the operation of any tractor is a "heat 
 engine" a machine for taking energy in the 
 form of heat and converting it into useful work, 
 which is just another way of saying mechanical 
 energy. 
 
 The effect which heat considering it now as 
 a rise in temperature has on a congregation of 
 people is much the same as it exerts on matter 
 in general. If, for instance, we have a crowd 
 of folks huddled together under low temperature 
 conditions, and we suddenly elevate the tempera- 
 ture greatly, the individual members of the group 
 are going to get as far away from each other 
 as the degree of temperature demands in other 
 words, until each one obtains a fair measure 
 of comfort. In so doing, it will be appreciated 
 that the mass will spread out over a greater area 
 it will expand, in other words the expansion 
 of the whole being due to the individual move- 
 ment of the many people who make up the group. 
 
 We find that matter, be it solid, liquid or 
 gaseous as to state, acts exactly the same' under 
 the effect of heat or change in temperature. Heat 
 a bar of iron, for instance, and all the individual 
 molecules will exert themselves, and the result 
 will be the expansion of the bar exhibited as an 
 
2 Tractor Engines. 
 
 increase in length, width and depth in other 
 words, an increase in volume. 
 
 Expansion, of course, entails movement, and 
 movement is mechanical energy. The heat we 
 have put into the bar of metal, therefore, is not 
 lost; but it is converted into mechanical energy 
 and the metal bar is, in reality, a heat engine. 
 
 If now we take such a bar and hold one end 
 fast against all movement and to the other end 
 we attach a rod pivoted to the bar and with its 
 other end journaled on a crank, as shown by 
 Figure 1, it will plainly be seen that if we heat 
 
 FJG.l 
 
 Fig. 1. Elementary prin- 
 ciple of heat engine. 
 
 the bar to such an extent that it expands a dis- 
 tance equal to the throw or travel of the crank, 
 the crank will be turned, imparting rotary mo- 
 tion to the crankshaft. It, is also conceivable 
 that mounted on that shaft we can have a fly- 
 wheel or balance wheel which will store up suf- 
 ficient . energy to carry the crank over the "dead 
 center," so that when the flame is removed and 
 the bar begins to cool off, and thereby to con- 
 tract again and return to its original size, it will 
 carry the crank back once again, imparting rotary 
 motion to the shaft. We therefore obtain con- 
 
Engine Principles. 3 
 
 tinuous rotary motion simply by applying the 
 flame at the proper time and withdrawing it 
 when the outer end of the stroke is reached. 
 
 With such a simple heat engine there must be 
 encountered considerable loss of energy. There 
 is no means, for instance, of preventing direct 
 heat loss by radiation; at the same time there is 
 an indirect loss due to the fact that we are 
 taking advantage of the longitudinal expansion 
 of the metal only its expansion in the other two 
 directions takes place at the same relative rate 
 as the elongation under the change in tempera- 
 ture; but the potential power from this breadth 
 and depth expansion which entails the use of 
 heat to engender it, is lost to us. 
 
 It is not hard to appreciate, therefore, that 
 despite its beautiful simplicity, such an engine 
 must be very inefficient. Other drawbacks are 
 the element of time, for it needs a considerable 
 interval to raise the temperature of a piece of 
 metal, depending on the material itself and its 
 thermal capacity, its weight, size and shape and 
 the flame employed, and the length of bar neces- 
 sary to obtain sufficient enlargement under any 
 reasonable temperature change in order to make 
 a practical machine. 
 
 In order to make a practical heat engine which 
 will be sufficiently efficient to make its use de- 
 sirable from an economic standpoint, the expand- 
 ing medium we use must be capable of great 
 expansion on a comparatively limited change in 
 temperature ; must be capable of undergoing this 
 expansion with the utmost rapidity; and must 
 be of such nature that the forces obtained from 
 its expansion in all three directions are capable 
 of being resolved into a single force acting in 
 one direction without mechanical complication. 
 
 Let us consider for a moment the action of 
 
4 Tractor Engines. 
 
 gases under heat. We find that if we have a 
 vessel containing one quart of any true gas at 
 atmospheric pressure and degrees Centigrade, 
 and the vessel employed is gas tight and perfectly 
 flexible, and we heat the gas to 1 degree C, it 
 has expanded 1/273 of its original volume in 
 other words we now have in the vessel 1 1/273 
 quarts of gas. And for each increase of 1 de- 
 gree C. the gas will expand 1/273 of its volume 
 at degrees C. If, then, we heat the gas up 
 to 273 degrees C. we will have added 273/273 
 of a quart to the vessel that is, we will have 
 added .another quart of gas to the original quart, 
 or will have doubled its volume. 
 
 We nave considered in the above that there 
 has been no change in pressure it has remained 
 at atmospheric pressure throughout. 
 
 The example given is simply a concrete way 
 of expressing a well-known law of physics, known 
 as the Law of Charles. Given any true gas, its 
 volume will increase by 1/273 of its volume at 
 degrees Centigrade for every increase of 1 
 degree C., considering constant pressure through- 
 out the change. 
 
 If in the case of the vessel given above, in- 
 stead of being flexible it was perfectly tight and 
 inflexible so that it could not increase in capacity, 
 and we heated the air from degrees C., and 
 at atmospheric pressure to 273 degrees C we 
 would have, at the latter temperature, two quarts 
 of air forced into a one-quart vessel. Naturally, 
 its pressure would be increased, and whereas 
 the pressure was approximately 15 pounds to the 
 square inch at the lower temperature and smaller 
 volume, it would be approximately 30 pounds to 
 the square inch at the increased temperature. 
 
 In other words, had we taken the original quart 
 of gas and without change of temperature com- 
 
Engine Principles. 
 
 ASSEMBLY OF PISTON, CONNECTING ROD. AND CRANK 
 
 pressed it into a half-quart vessel, we would 
 have similarly doubled the pressure. In the 
 instance given above, however, by increasing 
 the temperature instead of holding it constant, 
 we doubled the quantity of gas contained in a 
 vessel without enlarging the vessel; and conse- 
 quently we doubled its pressure. 
 
 This concretely expresses a second law of 
 physics bearing on the behavior of gases, the 
 Law of Boyle : The pressure of a gas varies 
 inversely as its volume, considering constant 
 temperature. 
 
 We find that a gas will fulfill the conditions 
 
 set forth above for 
 an expansive me- 
 dium for employ- 
 ment in a practical 
 heat machine. Con- 
 trasted with solids 
 and liquids, its rate 
 of expansion per 
 degree of temper- 
 ature rise is great; 
 at the same time, 
 unlikft the solid, it 
 can be so confined 
 in a vessel that width and breadth expansion are 
 impossible, the expansion in these directions be- 
 ing resolved into increased length under the heat, 
 which is distinctly to our advantage. 
 
 Our simplest engine using a gas as the expand- 
 ing medium, then, would take the form- shown 
 in Figure 2. Here we have a cylindrical vessel 
 provided with a loose-fitting plug made just snug 
 enough in the smooth bore of the cylinder to 
 prevent leakage of the gas past the sides ; yet 
 sufficiently loose to permit of free up and down 
 movement of the plug itself, which in the engine 
 
 Fig. 2. The heat engine resolved 
 into its simplest elements. 
 
6 Tractor Engines. 
 
 we are pleased to call the "piston." Connecting 
 the piston to the crank on the shaft, whereby the 
 latter is set in motion, is a rod called the "con- 
 necting rod." The arrangement is such that 
 every time the piston moves outward in its cylin- 
 der bore, the crank is turned, and every time it 
 moves back, the crank 'is carried back, giving 
 rotary motion to the shaft. In order to carry the 
 crank past the dead center at each end of the 
 piston stroke, a balance or flywheel is mounted 
 on the shaft, which stores up sufficient energy 
 to carry on the motion when the crank has 
 reached its dead center. 
 
 Reference to the sketch will indicate that a 
 quantity of air is trapped in the space above the 
 piston in the cylinder. If, now, we apply a torch 
 or some other source of heat to the outside of 
 the cylinder, the trapped air within will be 
 warmed. Air, .of course, is a gas or rather a 
 mixture of gases and it will accordingly follow 
 the laws for expansion of gases under heat set 
 forth above, with the result that pressure is cre- 
 ated within the cylinder in exact accordance with 
 the increase in temperature of the air within. 
 The increase vgoes on until such time as the pres- 
 sure on the piston becomes sufficiently great to 
 cause it to move outward, turning the crank and 
 setting the engine in motion. 
 
 Such, in fact, is the principle on which the hot- 
 air engine operates. It is a slow-moving, low- 
 powered, inefficient engine; to. obviate its faults, 
 speed of action, whereby considerably greater 
 power is obtained with the use of the same 
 amount of machinery, is essential. 
 
 In the internal combustion engine, therefore, 
 instead of applying our heat to the outside of 
 the cylinder as a means of elevating the temper- 
 ature of the gases within, we intimately mix 
 
Engine Principles. 7 
 
 the fuel we are m'mg with the air which 
 is serving as the expanding medium, in ex- 
 actly the proper proportions to form a com- 
 bustible mixture. When we ignite this mix- 
 ture the burning of the fuel occurs almost 
 instantaneously; there is a sudden rise and a 
 great rise in temperature so that the air ex- 
 pands, causing pressure on the piston almost 
 immediately. 
 
 In order to make a practical internal combus- 
 tion engine, therefore, we must provide a cylinder, 
 piston and crankshaft assembly exactly as indi- 
 cated above; but we must also provide a means 
 of getting a fuel charge into the cylinder at the 
 proper time and mixed with the proper quantity 
 of air to form an explosive mixture. Also 
 we must provide a means of getting rid of 
 the burned gases after they have fully ex- 
 panded and performed their work on top of the 
 piston. 
 
 We have, leading into the cylinder or rather 
 into the combustion chamber, which is the space 
 in the cylinder above the piston when the latter 
 is at top stroke, in which chamber the actual 
 burning of the gases takes place an intake pipe 
 by means of which the mixture of gas (vapor- 
 ized gasoline or kerosene in the case of the trac- 
 tor engine) and air is introduced into the cham- 
 ber at exactly the proper time. This passage is 
 closed by means of a little valve shaped like a 
 manhole, and provided with a stem by means 
 of which the valve can be raised from its seat 
 and the passage opened for the reception of the 
 gases at the proper instant. This valve closes 
 tight against leakage of the pressure at all other 
 times and is normally held firmly to its seat by 
 a strong spring. It is called the "inlet" valve 
 or "intake" valve. 
 
8 
 
 Tractor Engines. 
 
 Also provided is a second passage closed by a 
 similar valve, which is opened at the proper time 
 for the expulsion of the burned gases, and kept 
 tightly closed against all leakage at all other 
 times. It is called the "exhaust" valve. 
 
 In diagrams in Figure 3, the placing of these 
 valves and passages and the action of these 
 valves in effecting the inlet and exhaust of the 
 gases at exactly the proper time with relation 
 to the piston stroke are indicated. In diagram A, 
 
 FIG. 3 
 
 Fig. 3. Indicating the four strokes in the cycle of operations 
 of the tractor engine. 
 
 as can be plainly seen, the piston is traveling 
 downward, and in doing so is acting like the 
 plunger of a suction pump, creating a partial 
 vacuum behind it. The inlet valve has been 
 opened, and this suction created by the piston 
 is relied upon to pull into the cylinder a full 
 charge of mixture of proper proportions for 
 firing from a mixing valve or a carburetor, as 
 the case may be. 
 
Engine Principles. 9 
 
 When the piston reaches bottom stroke so 
 that no more charge can be drawn into the cylin- 
 der, the inlet valve is closed and the cylinder 
 becomes a closed chamber. As the piston comes 
 up, carried on by the energy stored up in the 
 revolving flywheel, the charge is compressed. 
 Just about the time when the piston reaches its 
 top center and the compression is greatest, as 
 shown in diagram C, an electric spark is caused 
 to jump the gap of the spark plug, and from this 
 spark the mixture takes fire, burns, expands, 
 creates pressure within the cylinder which drives 
 the piston down, imparts energy to the. crank- 
 shaft arid to the flywheel; whereby power is 
 obtained. 
 
 It will be seen that on the compression stroke 
 of the piston and on the power stroke, both in- 
 take and exhaust valves have been kept tightly 
 closed ; this, of course, is to prevent the escape 
 of the fuel charge on the compression stroke and 
 of the forces of combustion on the power stroke ; 
 such loss would mean reduced pressure on the 
 piston and loss of power. 
 
 On the next upstroke of the piston, as shown 
 in diagram D, the exhaust valve is opened; and 
 since on the power stroke all the energy has been 
 taken from the expanding gases, they are blown 
 out by the ascending piston through the exhaust 
 valve, thereby clearing the cylinder for the re- 
 ception of a charge of fresh mixture. Imme- 
 diately the piston reaches its top center after 
 expulsion of the gases, the inlet valve is opened 
 again and the cycle of operations is repeated, 
 whereby continuous action is obtained. 
 
 It will be seen that in the accomplishment of 
 one complete cycle, the piston has made four 
 complete strokes lengthwise of the cylinder. It 
 went down once on the inlet or suction stroke; 
 
10 Tractor Engines. 
 
 up once on the compression stroke; down again 
 on the power stroke, and up once again on the 
 exhaust stroke. From the fact that four such 
 piston strokes are necessary, an engine operating 
 on this principle is called a "four-stroke-cycle" 
 engine, or in more common parlance, a four- 
 stroke engine. There are internal combustion 
 engines which operate on other cycles; there is 
 one, for instance, which accomplishes its entire 
 function in two strokes of the piston. But for 
 tractor service engines operating on any but the 
 four-stroke-cycle have made no progress, how- 
 ever serviceable they may be in other fields, 
 so that a description of their operation in a book 
 dealing strictly with modern tractor engine prac- 
 tice will serve no useful purpose. 
 
 The reader, in going over the diagrams pictur- 
 ing the cycle of operations, will also notice that 
 in going through one complete cycle the crank- 
 shaft made two complete revolutions. There is, 
 then, one power stroke to each four piston strokes 
 with a single cylinder engine of this type, and 
 the flywheel must be so proportioned as to carry 
 the piston through three idle strokes after each 
 power stroke before the piston is again in posi- 
 tion to impart power to the engine crankshaft. 
 
 If we were to actuate the valves directly from 
 the crankshaft, it must be evident that each valve 
 would open once for each revolution of the 
 crankshaft. As a matter of fact, as we can 
 prove for ourselves by referring once again to 
 the diagrams, the inLet valve opens only once 
 for each two revolutions of the crankshaft, and 
 the exhaust valve has a similar movement. The 
 exhaust valve is open for one-half of one revo- 
 lution, the inlet valve for the second half of 
 the same revolution, while for the second revo- 
 lution both are shut tight. 
 
Engine Principles. 
 
 11 
 
 It would not do, obviously, to open them di- 
 rectly from the crankshaft; we must interpose 
 a second shaft timed to rotate at half the speed 
 of the crankshaft in 
 order to obtain the 
 proper motion of our 
 valves relative to the 
 piston travel. The ar- 
 rangement of this shaft, 
 which we call the "cam- 
 shaft," is in- 
 dicated in 
 Figure 4. It 
 will be seen 
 that a gear 
 wheel is 
 mounted on 
 the crank- 
 shaft, engag- 
 ing with a second gear of twice the diameter 
 of th crankshaft gear mounted on the camshaft, 
 the relative sizes being such that the camshaft 
 rotates at half crankshaft speed. 
 
 FIC.4 
 
 Fig. 4. Showing how the camshaft 
 is driven at half crankshaft speed. 
 
 Fig. 5. Action of cam in opening the valve. 
 
 On the camshaft is mounted an irregularly- 
 shaped wheel a wheel with a hill on it and 
 called a cam for each valve. Every time the 
 
12 Tractor Engines. 
 
 hill on the cam comes around, it raises the valve 
 push-rod (see Figure 5), which in turn pushes 
 up against the bottom of the valve stem and ele- 
 vates the valve against the action of the valve 
 spring. When the hill passes, the valve spring 
 returns the valve to its seat. Where the valves 
 are of the overhead or "valve-in-head" type, the 
 push-rod is longer and transmits its motion to a 
 rocker arm or lever which bears down against the 
 valve stem, opening the valve at the proper time. 
 Naturally, the hill on the cam is exactly pro- 
 portioned to start opening the valve at the proper 
 time and to hold it open just long enough; and 
 the cams are so set on the camshaft as to time 
 their performance correctly with the piston travel. 
 
CHAPTER II. 
 
 Features of Construction. 
 
 Wkerein Multi-Cylindered Engines Excel for 
 
 Tractor AVork and tKe Standard 
 
 Types Offered. 
 
 IN the preceding chapter we have gained an 
 insight into the basic principles upon which 
 the tractor engine operates. In the employment 
 of these basic principles, all tractor engines are 
 identical in their details of construction, how- 
 ever, they differ radically from one another. It 
 is the purpose of the second chapter to go fully 
 into modern tractor engine construction, indicat- 
 ing the functions of the various parts and indi- 
 cating clearly wherein one engine differs from 
 the next and the reasons therefor. 
 
 We have had under consideration so far only 
 such engines as employ a single cylinder. It 
 must be evident that on a vehicle like a tractor, 
 where smooth progress is desirable, the produc- 
 tion of power in "jerks" such as we have seen 
 results from the single-cylinder construction, is 
 by no means ideal. It would be far better, for 
 instance, if instead of obtaining only one power 
 stroke for each two revolutions of the crank- 
 shaft, we could obtain two power strokes; still 
 better if we were able to get four power strokes, 
 or one for each half revolution of the crankshaft. 
 That means that we would obtain one power 
 stroke for every 180 degrees of crankshaft 
 movement. 
 
 It is quite impossible, of course, to obtain 
 such desirable results from a single-cylinder .en- 
 ds) 
 
14 Tractor Engines. 
 
 gine performing on the four-stroke cycle. It is 
 quite possible, however, to arrange two such 
 cylinders, or four such cylinders, to impart im- 
 pulses to a single crankshaft ; and by properly 
 arranging the crankthrows, and the cams, to 
 cause these cylinders to deliver their power to 
 the crankshaft at different times. 
 
 Such is the trend of modern tractor engine 
 practice ; single-cylinder engines which once were 
 almost universally used for tractor work are 
 fast becoming obsolete ; the' two-cylinder engine 
 still persists on several well-known makes of 
 tractors, but even it is giving way at the present 
 time to the four and six-cylinder types which 
 have made such great headway in the automobile 
 field and which are fast becoming standard' in 
 the tractor industry. 
 
 The four-cylinder engine is by far the most 
 popular at the present writing, there being very 
 few engines of a greater number of cylinders ; 
 and since the flexibility which we demand in the 
 passenger automobile is by no means essential to 
 tractor service, it seems altogether likely that 
 four cylinders will be the accepted standard of 
 the future tractor engine. It is worthy of note 
 that in only a single instance has a greater num- 
 ber of cylinders than six been adopted that is, 
 in the case of the Common Sense tractor pro- 
 duced on the Pacific Coast and which employs 
 a Herschell-Spillman engine with eight cylinders. 
 
 Indicative of the fact that for all the progress 
 made toward the multi-cylinder engine, the 
 single-cylinder type is not as yet a dead issue, 
 nor its production confined to the smallest manu- 
 facturers, are the accompanying photographs of 
 typical engines of that type produced by two of 
 the largest tractor builders in the country. 
 
Features of Construction. 
 
 15 
 
 Fig. 6. Single-cylinder horizontal engine 
 on 18-35 Rumely. 
 
 Figure 6 rep- 
 resents the 
 single - cylin- 
 der horizon- 
 tal engine 
 employed on 
 the model 
 18-35 tractor 
 produced by 
 the Advance- 
 RumelyTrac- 
 tor Co., La 
 Porte, Ind., 
 which has 
 given a re- 
 markable account of itself over past years, while 
 Figure 7 pictures a somewhat similar type of 
 engine, which is used on the 10-20 Mogul trac- 
 tor produced by the International Harvester 
 Corporation. 
 
 It will be noted in the case of the latter that 
 the valves are placed in the cylinder head, and 
 that. the engine is "hopper" cooled. A modified 
 "T"-head cylinder arrangement prevails in the 
 case of the Rumely engine. 
 
 Not always, 
 in the case of 
 the single-cyl- 
 inder engine, 
 is the horizon- 
 tal cylinder ar- 
 rangement ad- 
 hered to. Take, 
 for instance, 
 the B e e m an 
 garden t r a c- 
 tor, which is a 
 small hand- en g*. 7 ' Mogul 10 ' 20 single ' cylinder 
 
16 
 
 Tractor Engines. 
 
 operated machine, and a vertical cylinder engine 
 of this type is employed. 
 
 Two-cylinder tractor engines, which still are 
 commonly met with throughout the industry, 
 come in three different forms as to the arrange- 
 ment of the cylinders. The most commonly met 
 with is the "opposed" cylinder type, with two 
 horizontal cylinders facing each other on a sin- 
 gle crankcase. Such an engine is pictured in dia- 
 grammatic form in Figure 8, with the various 
 
 CAM GEARS- 
 CARBON STEEL 
 ACCURATELY 
 CUT TEETH 
 
 BRONZE BACK 
 
 NICK if BABBIT LINED 
 
 BEARINGS 
 
 lAsnv ADJUSTED 
 
 flG.8 
 
 Fig. 8. Two-cylinder opposed engine of the Bull Tractor. 
 
 parts indicated for the. convenience of the reader. 
 The engine in the figure is the one employed on 
 the Bull tractor, a three-wheeled type which is 
 held in great respect. 
 
 The real virtue of a two-cylinder engine of 
 this type is the close approach to perfect balance 
 which the arrangement of the various parts per- 
 mits. It will be appreciated that with the single- 
 cylinder engine the sudden stopping and starting 
 
Features of Construction. 17 
 
 of the piston at each end of its stroke entails 
 considerable vibration, which is registered on the 
 entire tractor mechanism. With a view of elim- 
 inating this fault to the greatest possible degree, 
 makers of this type of engine attach counter- 
 weights to the crankshaft at points opposite the 
 crankpin in order to balance the weight of the 
 reciprocating members the piston and connect- 
 ing rod assembly. This arrangement is clearly 
 indicated in Figure 9, which shows a crankshaft 
 and piston assembly from an engine of this type. 
 
 Fig. 9. Counterbalanced single-cylinder crankshaft (Mogul 10-20). 
 
 In practice, however, it has been found im- 
 possible to achieve perfect balance of the recip- 
 rocating members by means of rotating counter- 
 weights, and while the latter do a measure of 
 good, the results obtained are by no means per- 
 fect. If, however, we apply to the crankshaft, 
 exactly opposite the crank, a reciprocating mass 
 exactly equal and similar to the piston and con- r\ 
 necting rod, the vibrations set up by this balanc- 
 ing mass will exactly counterbalance those 
 engendered by the piston movement, and smooth 
 operation of the engine will be promoted. 
 
 As can be seen by the illustration (Figure 8) 
 
18 
 
 Tractor Engines. 
 
 in the two-cylinder opposed engine, the piston 
 and connecting rod of the second cylinder are so 
 arranged as to take the place of this counter- 
 balancing mass, the crankthrows being set at 
 180 degrees apart. Hence, the vibratory forces 
 
 
 Top view of 12-25 
 H. -. motor. The 
 8-16 H. P. motor is 
 also built in this style. 
 
 Cam case on 12-25 
 H. P. motor. 
 
 Cam case on 25-50 
 H. P. motor. 
 
 K 
 
 Si maim 
 
 Top view of 25-50 H. P. motor. The 18-36 and 40-80 H. P. 
 motors are also built in this style. Note how narrow this four- 
 cylinder motor is and how strong in construction. 
 
 Fig. 10. . Some views which emphasize the features of A very 
 engines. 
 
Features of Construction. 19 
 
 set up by one piston occur at exactly the same 
 time, are equal to and in the opposite direction 
 from those. established by the other one, so that 
 they neutralize each other, a"nd perfectly smooth 
 operation is the result. It can plainly be seen 
 that the use of counterbalances on the crankshaft 
 of such an engine is needless. 
 
 In Figure 10 are shown similar views of the 
 Avery tractor engine of the opposed type in 
 both two-cylinder and four-cylinder types. The 
 main points of divergence between the Bull and 
 Avery two-cylinder engines are the employment 
 of L-head cylinders with direct acting thrust 
 valves on the former, as against the I-head 
 cylinder with valves in the head by the latter ; 
 also in the Avery a single camshaft is employed 
 to time the action of all four valves, while in the 
 Bull engine the employment of two camshafts is 
 indicated. 
 
 In connection with the Avery tractor it may 
 be said that this manufacturer has adhered to 
 the opposed type of engine* for many years and 
 developed that type to a point of refinement that 
 is hard to improve upon. In the four-cylinder 
 Avery job still another source of vibration is 
 eliminated. It will be noticed that in the two- 
 cylinder engine the cylinders are "staggered" 
 slightly, due to the arrangement of the throws 
 on the crankshaft. Because of this staggering it 
 is evident that the pull of one rod on the crank- 
 shaft, due to the piston stoppage, is delivered at 
 a different place from the pull of the other rod 
 and is opposite in direction. This will cause the 
 crankshaft to act somewhat like a lever, in- 
 fluencing it to rotate in a longitudinal plane about 
 a center midway between the points of attach- 
 ment of the two rods to the shaft. Since there 
 is a reversal of movement of the pistons twice 
 
20 
 
 Tractor Engines. 
 
 for each revolution of the shaft, and since such 
 reversal will cause a tendency for the longi- 
 tudinal rotation of the shaft to reverse also, we 
 have a source of an annoying vibration which 
 is very evident at high engine speeds. 
 
 If, now, we note the arrangement of the 
 crankthrows on the four-cylinder engine, we 
 find that those on the two outside cylinders are 
 on the same plane, while those on the two inside 
 cylinders are 180 degrees away, both rods, in 
 fact, attaching to the same pin. If we con- 
 sider the- action of the two outside pistons 
 
 at t h e mo- 
 ment of re- 
 ve r s al, we 
 find that both 
 are acting in 
 the same di- 
 r e c t i o n, so 
 that if the 
 shaft were 
 fulcrumed on 
 a center the 
 resulting 
 forces would 
 counterbalance each other and would not tend to 
 cause rotation of the shaft in a longitudinal plane 
 as with the two-cylinder engine. Likewise, the 
 forces which would tend to cause such rotation 
 from the . inside cylinders are exactly counter- 
 balanced. At the same time, the two pistons on 
 one cylinder block exactly balance those on the 
 other block, so that all reciprocating forces are 
 balanced, and an engine which is perfectly bal- 
 anced under all conditions results. 
 
 In Figure 11 is shown a photograph of still an- 
 other opposed two-cylinder engine, which is 
 fitted to the Ingeco tractor. It also is of the 
 
 Fig. 11. 
 
 type. 
 
 Ingeco engine of the opposed 
 
Features of Construction. 21 
 
 overhead valve type and its chief claim to 
 novelty is in the fitting of two carburetors, 
 whereby the necessity for a long intake mani- 
 fold entailing condensation under cold weather 
 conditions is done away with. Figure 12 gives 
 a side view of the two-cylinder Avery engine 
 making plain the use of long manifolds. In the 
 illustration a double-bowl carburetor is shown, 
 one bowl serving for gasoline and the other for 
 kerosene; the shift from the lighter to the 
 
 Fig. 12. Side view of the Avery double-cylinder type. 
 
 heavier fuel is made when the engine has become 
 sufficiently warmed up to handle the kerosene 
 properly. 
 
 It cannot be denied that the double-cylinder 
 horizontal engine has certain advantages in the 
 way of compactness over the opposed type, and 
 these advantages have led to its adoption in 
 preference to the opposed engine by several 
 tractor manufacturers. These advantages are 
 
22 Tractor Engines. 
 
 mainly a greater facility with which the various 
 fuel, water, oil and exhaust connections can be 
 made and the fact that such a cylinder arrange- 
 ment permits of the two cylinders being cast to- 
 gether in a single block, making for rigidity and 
 lessened cost of production. 
 
 Such an engine is the Titan 10-20, used on 
 one of the International Harvester models. It is 
 pictured in Figure 13 and like the Avery, is of 
 
 Fig. 13. Engine of Titan 10-20. 
 
 the overhead valve type. The chief drawback to 
 such an engine is the inability to obtain perfect 
 balance, or even a close approach to perfect 
 balance, if the firing intervals are made equal. 
 In order to bring about the latter condition, for 
 instance, on a two-cylinder engine, it is evident 
 that we will want one power impulse for each 
 crankshaft revolution, or 360 degrees of crank- 
 shaft movement. That means that both pistons 
 must be attached to the same pin or to pins on 
 the same plane, so that they will travel together, 
 
Features of Construction. 23 
 
 for if they were mounted 180 degrees apart, as 
 in the case of the two-cylinder opposed type, it 
 is evident that rotating the shaft 360 degrees 
 after the first cylinder has fired will result in the 
 second piston being at the bottom of its stroke 
 and in no position to fire. The only way to 
 have it in position to fire 360 degrees after the 
 first cylinder is to mount it on the same pin, and 
 this is the practice usually followed. 
 
 This practice, however, gives us two recipro- 
 cating masses 
 working 
 in unison and 
 not opposing 
 each other, 
 and it is evi- 
 d e n t, there- 
 fore, that the 
 vibration en- 
 tailed will be 
 twice as great 
 as in the case 
 of a single- 
 cylinder e n - 
 gine with the 
 same recipro- 
 cating masses 
 and turning 
 up at the 
 same speed. The means taken to offset this con- 
 dition, of course, are the attachment of counter- 
 balance weights to the crankshaft, as shown by 
 Figure 14, which illustrates a Rumely engine of 
 this type. The inability to obtain perfect bal- 
 ance by this method has been made clear before ; 
 it is evident that such an engine, due to its 
 tendency to vibrate badly, is suitable for low 
 rotative speeds only. 
 
 Fig. 14. A Rumely two-cylinder hori- 
 zontal type where balance has been sacri- 
 ficed to obtain even firing intervals. 
 
24 
 
 Tractor Engines. 
 
 FIG. IS 
 
 Fig. 15. Crank-case with cover removed 
 from Rumely 14-28 engine. 
 
 In the Rumely 14-28 engine the other alter- 
 native has been taken and even firing intervals 
 
 have been 
 sacrificed i n 
 order to at- 
 tain an en- 
 gine of better 
 balance. I n 
 this case 
 the crank- 
 throws are 
 set 180 de- 
 grees apart 
 so that one 
 cylinder fires 
 180 degrees 
 after the other, and then there is a complete 
 crankshaft revolution with no power impulse. 
 With this arrangement, which is shown in Figure 
 15, it is evident that the reciprocating mass of 
 one piston al- 
 most exactly 
 counter- 
 balances the 
 other ; there 
 is a slight 
 difference at 
 certain points 
 in the stroke 
 due to the 
 difference i n 
 rate of accel- 
 eration and 
 d e c e 1 e r a- 
 tion which 
 results from 
 the angularity 
 of the con- 
 
 Fig. 16. 
 motor. 
 
 Top view of the 14-28 Rumely 
 
Features of Construction. 25 
 
 necting rods ; however, balance in the line of the 
 cylinder axii is almost perfect. 
 
 It will be seen, however, that whereas with the 
 opposed type of engine it was simply necessary 
 to stagger the cylinders slightly to give clearance, 
 the side by side arrangement of the cylinders in 
 this case makes the points of attachment of the 
 two rods quite far apart much further than in 
 the case of the opposed type. Considering lon- 
 gitudinal balance with relation to the crankshaft, 
 therefore, the engine is greatly at a disad- 
 vantage. This fact has been offset in the engine 
 under consideration by the attachment of coun- 
 terweights on opposite ends of the crankshaft 
 and 180 degrees apart. The vibrations created 
 by these counterbalances tend to offset those 
 created by the piston movement and give a 
 smooth-running motor. 
 
 While the irregular firing of this engine is by 
 no means the ideal condition, in practice it has 
 not been found to work out greatly to the disad- 
 vantage of the unit as a whole. That this is 
 so is attributable to the fact that the flywheel 
 used is sufficiently heavy to carry the engine 
 shaft over at substantially constant speed, storing 
 up the energy from the two power strokes on the 
 first revolution and giving it back to the shaft on 
 the second revolution when there is no power 
 stroke. The two cylinders fire, of course, 180 y 
 degrees apart, there being a lapse of 360 degrees ' 
 after the second one fires before the first one 
 fires again. 
 
 The peculiarities of tractor design and the 
 total lack of standardization prevailing through- 
 out the industry have given rise to many con- 
 structions which either never were common 
 with the automobile engine, or at least never sur- 
 vived the experimental stage. One of these is 
 
26 Tractor Engines. 
 
 the four-cylinder engine, with the cylinders all 
 in a line and placed horizontally instead of 
 vertically. 
 
 The virtue of an engine of this type is, of 
 course, the fact that it lends itself readily to 
 proper placement in the frame of the tractor 
 without bringing any of the machine too high; 
 at the same time it makes an engine which is 
 very accessible, since not only the valve mechan- 
 ism, which is generally exposed and located on 
 top of the cylinders, but also the bearings can 
 
 Fig. 17. Four-cylinder horizontal engine of Aultman-Taylor 
 30-60 model. 
 
 be reached in a jiffy when it comes time to effect 
 adjustments or repairs. 
 
 That this is so is made evident by Figure 17, 
 in which is illustrated the engine of the Aultman- 
 Taylor 30-60 tractor. The facility with which 
 any part of the valve mechanism can be reached 
 as will be seen, the valve-in-head arrange- 
 ment is adhered to the ease with which the 
 cylinder heads can be removed from the two 
 cylinder blocks and, the otherwise generally ac- 
 cessible location of the engine parts and acces- 
 sories are plainly obvious. 
 
Features of Construction. 27 
 
 Figure 18, on the other hand, gives a very 
 fair indication of the facility with which every 
 bearing in the engine can be reached, giving am- 
 ple room for relining, taking up on slack bear- 
 ings or withdrawing the entire piston and con- 
 necting rod assembly when it is necessary to refit 
 piston rings, renew the pistons or otherwise cor- 
 rect faults or improve the operation of the 
 engine. The base or crankcase casting of the 
 engine is split diagonally, as shown, and simply 
 
 FI6.I8 
 
 Fig. 18. Showing the accessibility of the internal mechanism 
 of Aultman-Taylor 30-60 engine. 
 
 undoing the cap screws with which it is fastened 
 in place discloses the entire inner working 
 mechanism of the engine, and it all can be 
 reached from above; it is not even necessary to 
 drain the crankcase of the oil, as would be neces- 
 sary with the vertical cylinder engine. 
 
 The crankshaft employed is of the three- 
 bearing type which is commonly met with on 
 four-cylinder engines, both horizontal and ver- 
 tical cylinder types ; and it will be seen that the 
 
28 Tractor Engines. 
 
 
 
 two outside crankthrows are on a plane, and the 
 two inside on a plane 180 degrees away. The 
 effect is -that we have perfectly even firing in- j 
 tervals, one cylinder firing at each half revolu- 
 tion of the crankshaft, or at each 180 degrees ; 
 while at the same time we have a very close 
 approximation of perfect balance. It will be 
 seen, for instance, that the reciprocating masses 
 of the two inner cylinders are opposed to the 
 reciprocating masses of the two outer cylinders, 
 so that except for a slight difference in piston 
 velocities at certain crank positions, due to the 
 angularity of the connecting rods, both weights 
 and velocities are equal on the two sets, but the 
 direction of movement of one set is opposite that 
 of the other, so that balance is obtained. Con- 
 sidering longitudinal balance, the effect of the 
 two front-cylinder reciprocating masses is exactly 
 counteracted by that of the two rear .ones, so 
 that vibration from this score is done away with. 
 
 As tractor design progresses toward some ac- 
 cepted standard and such progress has been 
 marked over the past three years the vertical 
 cylinder type of four-cylinder engine, following 
 closely automobile practice, comes more and 
 more into its own. In fact, even the six-cylinder 
 vertical cylinder type is making some progress. 
 
 Doubtless there will always be quite some dif- 
 ference between the tractor engine and the ac- 
 cepted automobile standard ; difference which re- 
 sults from their different fields of . employment 
 and the widely divergent duties they are called 
 upon to perform. Chief among these differences 
 will be the weight, since it can easily be believed 
 that the tractor engine will, for at least some time 
 to come, represent a heavier construction for 
 equal power output than the automobile type 
 this difference being due to the fact that the trac- 
 
Features of Construction. 29 
 
 tor engine operates normally at three-quarters 
 load constantly throughout the day it is essen- 
 tially a constant-duty engine and, as such, prob- 
 ably always will be of the moderate speed type 
 and rather rugged in construction. 
 
 The automobile engine, on the other hand, is 
 called upon to deliver power at only one-quarter 
 its rated capacity throughout the greater part of 
 the day; but for brief intervals it may be taxed 
 to its limit or to any extent between maximum 
 and minimum power development possibilities. 
 It is essentially a variable load engine, and since 
 the vehicle it is used in connection with must be 
 capable of high speed and rapid acceleration, 
 light weight, in conjunction with great power, is 
 a prime essential. Quite as a matter of course, 
 the automobile designer has gone to high rota- 
 tive speeds in order to satisfy these conditions. 
 
 Flexibility and quick pick-up, on the other 
 hand, are not required of the farm tractor what 
 is wanted is a slow, steady pull with great dura- 
 bility. Hence we can logically expect that power 
 for power, the tractor engine will be weightier 
 and slower-moving than the automobile engine. 
 
 There are but a handful of tractor engines 
 which violate this condition. First and foremost 
 comes the Moline Universal, which employs a 
 four-cylinder engine of the high-speed type 
 which is comparatively light in weight, but withal 
 very rugged in construction. Second is the Ford- 
 son, also employing an engine which turns over 
 at a speed comparable with the average automo- 
 bile engine. But perhaps the most noticeable 
 exception to the rule is the Common Sense trac- 
 tor, which is a Coast production and which em- 
 ploys an eight-cylinder V-type engine, following 
 exactly automobile engine practice. 
 
 That ruggedness and heavy weight are the 
 
30 
 
 Tractor Engines. 
 
 rule, however, is made plain in some of the ver- 
 tical cylinder engines pictured herewith. Figure 
 19, for instance, illustrates the four-cylinder ver- 
 tical engine employed on the Emerson-Branting- 
 ham (Reeves) tractor, rated at 40 horse-power, 
 for belt work. Indicative of ruggedness is the 
 five-bearing crankshaft, a construction which has 
 all but disappeared from automobile practice, 
 and the employment of separately-cast cylinders. 
 The value of the latter construction on tractor 
 work is not to be minimized. The tractor engine 
 
 operates un- 
 der totally 
 different con- 
 ditions from 
 the automo- 
 bile engine 
 and the fact 
 that its work 
 is of the 
 hardest, and 
 long c o n - 
 tinued ; t h a t 
 its temper- 
 atures run 
 high and lub- 
 ri cat ion is 
 
 therefore difficult; and that sufficient attention 
 is, unfortunately, not always paid to the necessity 
 of keeping the air washer in prime condition, so 
 that no grit will get into the cylinders, results in 
 more frequent scoring of one or more cylinders, 
 necessitating either replacement or reboring. 
 With the individually-cast cylinders the correc- 
 tion can be made at greatly reduced cost, and in 
 much less time than when the cylinders are cast 
 in a single block, necessitating the removal or re- 
 
 40-65 
 
 . 19. Cross section of E-B (Reeves) 
 kerosene motor. 
 
Features of Construction. 31 
 
 placement of the entire block in accordance with 
 the amount of damage done. 
 
 This construction quite naturally gives a par- 
 ticularly long engine; -much longer than an en- 
 gine of the same cylinder dimensions but with 
 the cylinders cast in pairs or in block. But this ad- 
 ditional length is not an altogether bad feature. It 
 gives much greater clearance within the engine, 
 greatly facilitating the removal and the replace- 
 ment of the piston and connecting rod assem- 
 blies, etc. At the same time, considering again 
 the high prevailing temperatures, it is a well- 
 known fact that the individually cast cylinders 
 make possible the employment of cooling jackets 
 of substantially equal cooling capacity at all 
 points around the cylinder, so that warping of 
 the cylinders resulting in misalignment of the 
 working parts and greatly increased wear is, to 
 a greater or less extent, done away with. 
 
 In the engine under consideration, the cylinder 
 heads are cast with the cylinders and are not 
 separable ; and the valve arrangement is of the 
 L-head type. The sectional view of the two for- 
 ward cylinders clearly indicates the symmetry of 
 the water jackets as pointed out above. The 
 cylinders are provided with flanges at the lower 
 ends and through these flanges pass the cylinder 
 hold-down bolts by means of which the cylinders 
 are held firmly in place on the crankcase casting. 
 In tractor practice, due, of course, to the fact 
 that reduced weight is not of prime importance, 
 the ,crankcase is, in almost all cases, formed of 
 cast-iron instead of aluminum, which is usually 
 employed on automobile engines. This fact is 
 of greater importance in the case of an engine 
 fitted with individually-cast cylinders than is so 
 with the cast-in-block type, for the very good 
 reason that with the latter the cylinder block 
 
32 
 
 Tractor Engines. 
 
 
 Fig. 20. 
 oil engine. 
 
 7}4x9, four-cylinder Twin City 
 Valve side. 
 
 itself acts as 
 a stiffen- 
 ing truss to 
 give rigidity 
 to the entire 
 engine struc- 
 ture ; while 
 in the latter 
 case this 
 function must 
 be performed 
 in its entirety 
 by the crank- 
 case casting, 
 together with 
 the crankcase lower half. 
 
 It will be noticed also that the individually- 
 cast cylinder construction necessitates the em- 
 ployment of separate manifolds for the introduc- 
 tion of the mixture into the cylinders, for the 
 exhaust of the spent gases from the cylinders 
 and for the intake of the water to the jackets 
 and the outlet of the water from the jackets to 
 the radiator. 
 From this 
 s t andpoint 
 the construc- 
 tion is not 
 equal to the 
 cast -in -block 
 arrangement 
 wherein it is 
 perfectly pos- 
 sible to mold 
 the entire set 
 of gas and 
 water pas- 
 sages so as to 
 
 Fig. 21. 
 oil engine. 
 
 7^4x9 four-cylinder Twin City 
 
Features of Construction. 33 
 
 be incorporated within the single casting. While 
 the casting of such a block is quite a costly oper- 
 ation, machining is simplified, assembly greatly 
 simplified, and the number of parts greatly re- 
 duced, so that in the final analysis the cast-in- 
 block construction is undoubtedly the cheaper. 
 
 In Figures 20 and 21 are illustrated two views 
 of the Twin-City oil engine as employed on one 
 of these famous tractors. It will immediately 
 be noted that the construction of this engine is 
 not greatly different from that of the Reeves en- 
 gine just described, the most noticeable differ- 
 ence being 
 found in the 
 arrangement 
 of the mani- 
 folds. The 
 peculiar a r - 
 rangement, as 
 indicated o n 
 the Twin- 
 City engine, 
 has been 
 adopted pri- 
 marily with a 
 view of facilitating the burning of heavy fuel 
 such as kerosene; the arrangement is such that 
 some of the exhaust heat is utilized to effect 
 full vaporization of the heavy and less volatile 
 ends of the fuel so that a mixture which is 
 readily ignited and burns to completion is sup- 
 plied to the engine cylinders. As will be pointed 
 out in the chapter bearing on carburetion, it is 
 in the arrangement of the passages to effect this 
 purpose -that are discovered one of the chief lines 
 of divergence in tractor engine practice. 
 
 It was noted before that six-cylinder engines 
 were commonly met with in tractor work and 
 
 Fig. 22. 7 J4x9 six-cylinder oil engine. 
 
34 
 
 Tractor Engines. 
 
 the Twin-City line is one of several in which this 
 type of engine is employed. The Twin-City Six 
 is illustrated in Figure 22 and will immediately 
 be recognized as exactly the engine described 
 above with the addition of two more cylinders. 
 It is because the individually-cast cylinder ar- 
 rangement makes possible the expansion of a 
 four-cylinder engine into a six-cylinder job in 
 this manner with the use of parts which are 
 interchangeable, with a very few exceptions, 
 
 Fig. 23. The Tracklayer Motor is the valve-in-head type, long 
 established as the most powerful design of gas motor. . It is built 
 along simple lines to stand the test of work and time. 
 
 with those of the four-cylinder engine that many 
 tractor manufacturers prefer this construction. 
 All of the parts on this six-cylinder engine, for 
 instance, with the exception of the crankshaft, 
 crankcase, camshaft and manifolds, are perfectly 
 adapted to the four-cylinder engine. The crank- 
 shaft, of course, is of the 120 degree type, and 
 is mounted on seven bearings. 
 
Features of Construction. 
 
 35 
 
 FIG. 24 
 
 Fig. 24. Two views of the Flour City engine. 
 Above Showing camshaft side of motor. 
 Below Showing manifold side of motor. 
 
36 
 
 Tractor Engines. 
 
 Still another example of the individually cast 
 cylinder arrangement on a four-cylinder vertical 
 motor is given in Figure 23. This is the Best 
 Tracklayer engine employed on the larger of the 
 two models put out by the C. L. Best Tractor Co. 
 and is of clean-cut rugged construction. It will 
 be noticed that the valve arrangement is of the 
 valve-in-head type and that unlike the Reeves 
 and Twin-City engines, the cylinder heads are 
 cast separately and held in place by hold-down 
 bolts or cap screws. This not only facilitates 
 
 work inciden- 
 tal to the re- 
 moval of car- 
 bon when this 
 operation i s 
 necessary, but 
 it also makes 
 the frequent- 
 ly necessary 
 task of valve 
 grinding very 
 much easier. 
 
 As a com- 
 promise, not 
 a few manu- 
 facturers o f 
 four -cylinder 
 engines p r e- 
 fer to employ the cast-in-pair cylinder construc- 
 tion. Figure 24 illustrates both sides of the 
 Flour City tractor engine which is of this type. 
 It gives a very clean-cut engine, even despite the 
 fact that outside manifolds are necessary, while 
 at the same time the close-coupling of the two 
 pairs of cylinders makes possible the employ- 
 ment of a three-bearing crankshaft instead of the 
 five-bearing type called for by the individually- 
 
 Fig. 25. The cylinders of the Neverslip 
 engine are cast in pairs. 
 
Features of Construction. 37 
 
 '. 
 
 cast arrangement, and adds materially to the 
 stiffness of the construction, while at the same 
 time reducing production costs. In cases where 
 the cast-in-pair practice is adopted it is usual to 
 include in the line of engines a two-cylinder 
 model, a four-cylinder model and a six-cylinder 
 model, all using the same cylinder blocks. 
 
 Like the Best engine, the Flour City engine is 
 of the valve-in-head type, and is novel in that 
 very large inspection plates are provided on both 
 sides of the cooling jackets by means of which 
 
 cleaning of 
 the cooling 
 system can be 
 effected 
 to the entire 
 satisfaction 
 of the oper- 
 ator. 
 
 Another ex- 
 ample of the 
 pair-cast type 
 i s illustrated 
 in Figure 25. 
 This is the 
 engine employed on the Neverslip tractor, made 
 by the Monarch Tractor Co., Hartford,Wis. It 
 differs from the Flour City job materially, being 
 of the L-head type with valves, manifolds, mag- 
 neto, pump and governor all mounted on the one 
 side of the engine. 
 
 The clean-cut, staunch design made possible 
 by the cast-in-block arrangement is well illus- 
 trated in Figure 26, which pictures the four- 
 cylinder Kermath engine employed on the 
 smaller tractor put out by the Monarch Tractor 
 Co. under the style Lightfoot. The engine, 
 which is of the L-head type, is remarkably free 
 
 Fig. 26. Kermath engine used in Light- 
 foot tractor. 
 
38 
 
 Tractor Engines. 
 
 Fig. 27. 15 H. P. motor used 
 by Aultman-Taylor. 
 
 from complication in 
 so far as external ap- 
 paratus is concerned, 
 which, of course, is 
 distinctly a desirable 
 feature. 
 
 Contributing 
 greatly to this end is 
 the fact that the sin- 
 gle block casting, 
 coupled with the L- 
 head valve arrange- 
 ment, makes it quite 
 
 a simple matter to enclose the valve mechanism 
 entirely by means of a side plate or two as is 
 indicated in Figure 27, giving a view of one of 
 the Aultman-Taylor engines. In the illustration 
 the forward valve-enclosing plate has been re- 
 moved, disclosing the valve stems, springs and 
 tappet mechanism of the two forward cylinders. 
 Such enclosure is, of course, desirable from the 
 standpoint of cleanliness, which means reduced 
 wear; as well as from the standpoint of better 
 lubrication of 
 this important 
 part of t h e 
 engine mech- 
 a n i s m . In 
 most cases, 
 for instance, 
 the tappets 
 and the valve 
 stems are 
 lubricated by 
 an oil mist 
 conducted in- 
 to the valve 
 
 Fig. 28. 6^x8, four-cylinder Twin 
 City oil engine. Valve side. 
 
Features of Construction. 39 
 
 chamber from the crankcase through suitable 
 drillings or through holes bored in the hollow 
 tappets, providing a sufficient amount of oil for 
 the purpose. This, too, means reduced wear and 
 higher efficiency. 
 
 Contrasting the Twin City engine shown in 
 Figure 28 with those illustrated in Figures 20 
 and 21 shows clearly the trend of design. The 
 6j4 by 8 inch engine shown in the last figure is 
 a later production and incorporates many fea- 
 tures of design not found in the earlier types, 
 such, for instance, as the enclosed valves, the 
 block-cast cylinders and the separable cylinder 
 head. Quite naturally, the over-all length of the 
 engine, due to the compact cylinder arrangement, 
 is greatly reduced, as a comparison of the two 
 types offered by Twin City clearly indicates. 
 
 It might be well to point out at this stage that 
 the manufacturer of the Twin City line of trac- 
 tors is one of the most progressive in the indus- 
 try. The later models of the Twin City tractors, 
 which are giving a remarkable account of them- 
 selves in the field, and especially at the tractor 
 demonstrations throughout the country, are so t 
 far in advance as to be equipped with "double" 
 valves ; that is, two inlet valves and two exhaust 
 valves to the cylinder, closely following aviation 
 engine practice. Thereby greater area is ob- 
 tained than is possible with the single valve ar- 
 rangement, and the flow of the gases is corre- 
 spondingly facilitated. This, in turn, results in 
 a marked power increase and cooler operation ; 
 not the least important improvement in the oper- 
 ation, however, and one that is immediately ap- 
 parent and highly important, is the fact that 
 these- engines will throttle down and idle on 
 kerosene fuel in a manner that leaves but little 
 to be desired. It is lamentable, but true, that 
 
40 
 
 Tractor Engines. 
 
 this much cannot be said for all kerosene en- 
 gines employed in modern tractor construction. 
 Also reflecting modern practice to a marked 
 degree is the engine illustrated in two views in 
 Figure 29, employed on the Emerson-Branting- 
 
 
 MG.29 
 
 Figure 29. Emerson-Brantingham Engine. 
 
 Above Right side of E-B 16 H. P. kerosene motor, showing 
 carburetor and governor. 
 
 Below Left side of E-B 16 H. P. kerosene tractor, showing 
 magneto, pump and manifolds. 
 
 ham 16. It will be seen, in the lower view, that 
 the valves are fully enclosed by a single plate, the 
 valve arrangement being of the L-head type. 
 
Features of Construction. 41 
 
 Fig. 30. 
 side) 4^4 
 
 Buda Model "HU" (exhaust 
 in. (107.94x139.66 MM.) 
 
 One of the 
 factors which 
 has contributed 
 greatly to the 
 rapid advance- 
 ment of the 
 automobile was 
 the coming 
 of the parts 
 specialist the 
 manufacturer 
 with plant 
 equipped to 
 make motors, 
 and who concentrated on motors and developed 
 an engine that matched the best ; similarly the 
 manufacturer who specialized on transmissions, 
 axles, carburetors, magnetos, etc., etc. These 
 specialists could well afford to employ the best 
 of talent in their particular lines, talent that the 
 average automobile manufacturer could not begin 
 to hire; as a result, the industry as a whole pro- 
 gressed by leaps and 
 bounds. 
 
 It is not hard to 
 predict that the en- 
 trance of the specialist 
 into the field of tractor 
 production will have a 
 similar elevating effect. 
 At the present stage of 
 the industry, the special 
 manufacturer of en- 
 gines adapted particu- 
 larly for tractor service 
 has gained a firm foot- 
 ing and tractor engine 
 design is making 
 
 FIG. 31 
 
 Fig. 31. Buda Model "HU" 
 (end view) 4^ in. x Sy 2 in. 
 (107.94 x 139.66 MM.) 
 
42 
 
 Tractor Engines. 
 
 marked prog- 
 ress. 
 
 One of the 
 most impor- 
 tant stock en- 
 engine tnanu- 
 facturers is 
 the Buda Co., 
 of Harvey, 
 111. _ W ell 
 known also 
 as automobile 
 
 J FIG. 32 
 
 Fig. 32. Waukesha tractor engine. 
 
 engine manu- 
 facturers 
 and one of its typical tractor engine offerings 
 is illustrated in Figures 30 and 31. It is a four- 
 cylinder, block-cast, L-head job, clearly reflect- 
 ing the best that automobile engine practice 
 affords a*nd is being successfully used by dozens 
 of tractor manufacturers. Its clean-cut appear- 
 ance and apparent simplicity are its major appeal. 
 Figures 32 and 33 illustrate the Waukesha en- 
 gine, which is another of the stock engine jobs 
 which is a big factor in the industry. It 
 
 also is a four-cylin- 
 der, L - head engine 
 with the valves fully 
 enclosed ; the cylin- 
 ders, however, are 
 cast in pairs instead 
 of in a single block, 
 as was the case with 
 the Buda engine. 
 
 Some of the other 
 stock tractor engines 
 of prominence are the 
 
 Climax, Wisconsin, Buffalo, Beaver, Erd, Gile, 
 Doman, Westman and Midwest. 
 
 FIG.33 
 
 Fig. 33. Waukesha Motor 
 used in the Nilson Senior. 
 
CHAPTER III. 
 
 J/Lajor Engine Parts. 
 
 Their Construction, Functions, Care and Repair 
 Fully Described. 
 
 WHILE with some automotive engines in 
 applications other than tractor work, ma- 
 terial other than cast-iron or semi-steel may be 
 used for cylinder construction, in tractor prac- 
 tice these materials only are employed. The 
 reasons are not hard to find; the material 
 semi-steel is cast-iron with a certain proportion 
 of steel added to give it toughness is easily 
 cast, easily machined, and when suitably de- 
 signed and treated in manufacture will resist 
 any tendency to warp under the heat and will 
 carry all strains imposed upon it. It has still 
 another, and an all-important virtue. This is the 
 fact that there is present in cast-iron a certain 
 proportion of graphite in combination with the 
 metal itself. Under rubbing action the smooth 
 cylinder bore assumes a high polish and a tough 
 film forms which resists wear to a remarkable 
 degree. 
 
 In almost all cases, as was made plain in the 
 preceding chapter, the cylinder cooling jacket is 
 cast integral with the cylinder itself and the 
 modern tendency is to form all cylinders in a 
 single casting with integral jackets and mani- 
 folds. The removable cylinder head, however, 
 bolted to the top of the cylinder casting is taking 
 on a significance it never had before, and many 
 manufacturers ane incorporating it in their de- 
 signs. Such a cylinder casting with removable 
 
 (43) 
 
44 Tractor Engines. 
 
 head is shown in Figure 34, from one of the 
 Rumely models. 
 
 In the past it has been common practice to 
 rough-bore the cylinders and ream them to a 
 finish, which although not perfectly smooth, soon 
 assumed a polish under the piston action. This 
 practice, however, is fast giving way to the 
 grinding process, which leaves the cylinders with 
 highly polished and perfectly true round walls, 
 greatly facilitating fitting the pistons with the 
 proper clearance and checking any tendency for 
 oil pumping and gas "blow-by" when the engine 
 
 is in operation. With 
 a large number of the 
 stock engine manu- 
 facturers, it is also 
 common practice to 
 "weather" the cylin- 
 ders for some months 
 after the first machin- 
 
 Fig. 34. Rumely cylinders ing Operation. This 
 
 and cylinder head. 
 
 riG.34 
 
 ^ 
 
 ders are allowed to age in the open, which has 
 the effect of relieving any internal strains set 
 up as a result of the casting process and the 
 machining process, and which entail warping of 
 the cylinders and wear. / 
 
 Care of the Cylinders. Provided the engine 
 is treated with a fair degree of consideration, 
 especially as to proper lubrication, the wear on 
 the cylinders will be comparatively slight and 
 altogether negligible for the first season or two. 
 When the cylinders do show signs of wear, pro- 
 vided it is even throughout the length of the 
 bore, and on all sides such a condition is very 
 rare because of the variation in piston pressure 
 against the walls at different parts of the stroke 
 
Major Engine Parts. 
 
 45 
 
 correction can be effected by fitting oversize pis- 
 tons supplied by the manufacturer a few thou- 
 sandths of an inch larger than the ordinary piston. 
 
 To fit the new pistons 
 properly it will be nec- 
 essary to take the en- 
 gine down and lap the 
 cylinders with an ex- 
 panding lap, which can 
 be very easily made as 
 illustrated in Figure 
 35, from one of the old 
 pistons. The abrasive 
 material for this work 
 is a mixture of very 
 finely ground glass and 
 machine oil. It should 
 be used sparingly. The 
 proper lapping motion 
 is a combined twist and 
 up - and - down stroke 
 throughout the entire 
 length of the cylin- 
 der, so that all 
 parts of the 
 walls will be 
 evenly ground ; 
 the lap should 
 be turned from 
 time to time to 
 bring new sur- 
 faces into con- 
 tact. The lap 
 should be kept 
 expanded and 
 working until 
 
 the force re- Fig> 35> Illustrating construction 
 
 and use of an expanding lap for con- 
 tO turn ditioning the cylinder bores after wear. 
 
46 
 
 Tractor Engines. 
 
 or move the lap is practically constant through- 
 out the stroke. This shows that the cylinder is 
 perfectly round. Care should be taken to see 
 that all cylinder wall scores have been removed. 
 Where the cylinder walls are badly worn or 
 are scored, due to lack of adequate lubrication, 
 or the presence of some abrasive like sand, which 
 has damaged the cylinder wall surface, reboring 
 and fitting oversize pistons are necessary. Re- 
 boring a cylinder is a job which calls for special 
 tools and for a practiced machinist to operate 
 them in order to turn out creditable work. It is 
 highly inadvisable for the average tractor owner 
 or operator to undertake this work himself. The 
 best plan is 
 to send the 
 cylinder, or 
 the cylinder 
 block, as the 
 case may be, 
 to the nearest 
 service sta- 
 tion of the 
 tractor manu- 
 facturer or to 
 some compe- 
 tent tractor repairman 
 job of it. 
 
 Fig. 36. Cylinder cut out to show how 
 the Avery inner cylinder wall may be re- 
 moved. 
 
 who will make a proper 
 The Avery cylinder can be readily 
 relined as shown, in Figure 36. 
 
 It sometimes happens that the piston pin will 
 work loose and will chisel a slot in one or both 
 sides of the cylinder wall too deep to be removed 
 by reboring. Less frequently a piston ring will 
 break and produce a like result, the sharp broken 
 edge chiseling a groove in the wall. In such an 
 instance a recently-developed welding process, 
 called the Lawrence process, is invoked to fill up 
 the groove, the excess metal then being ground 
 
Major Engine Parts. 47 
 
 flush and lapped to a surface true with the bal- 
 ance of the cylinder wall. This also is a job 
 for the expert; when it is employed, unless the 
 cylinders are badly worn, it is usually not neces- 
 sary to fit oversize pistons. 
 
 In the case of a cracked cylinder, due to neg- 
 lect in winter, with consequent freezing of the 
 cooling water and cracking of the cooling jacket, 
 welding is the accepted means of effecting a per- 
 manent repair. Care should be exercised in the 
 selection of a competent welder for this work, 
 as a man who is inexperienced in handling his 
 torch will warp the cylinder or the block out of 
 shape and ruin it for further use. A good welder, 
 however, can make a very satisfactory repair 
 even on a very badly cracked cylinder. * 
 
 There are several compounds now on the mar- 
 ket for mixing with the cooling water which are 
 adapted to harden on contact with the air and 
 thus cement any cracks in the cooling system 
 through which they are carried by the water. 
 Any one of these compounds which is free from 
 solid matter may be employed as a temporary 
 means of repairing a cracked cylinder jacket 
 when it is not convenient to take the engine down 
 for welding ; in fact, in many instances this 
 method of repair has been found so satisfactory 
 as to preclude the necessity of a permanent repair. 
 
 With any tractor engine it will be necessary 
 to remove the accumulation of carbon from the 
 walls of the combustion chamber, the valve heads 
 and the tops of the pistons once or twice during 
 the season. The tendency to deposit carbon is 
 a chronic ailment with which all internal combus- 
 tion engines are afflicted to varying degrees, de- 
 pending on operating conditions, fuel used, pro- 
 portioning of the mixture, condition of the 
 engine especially as to piston and piston ring 
 
48 
 
 Tractor Engines. 
 
 fit, character and grade of oil used for lubri- 
 cation, etc. 
 
 When all is said and done, the best method 
 of removing the carbon is to take the engine 
 down far enough to get at the deposit, and then 
 scrape it off with special carbon-scraping tools 
 made up for this purpose and so shaped that 
 the blunt knife edge can be worked into every 
 nook and corner and the last trace of the trouble- 
 some carbon deposit removed. 
 
 With engines equipped with separable cylinder 
 heads this is not a hard job at all, for by unbolt- 
 ing the head (Figure 37) removing the neces- 
 sary parapher- 
 nalia, such as 
 water m a n i- 
 folds, ignition 
 cables, etc., and 
 after draining 
 the cooling 
 system the 
 entire combus- 
 tion chamber 
 is exposed. 
 Under any cir- 
 cumstances it 
 
 will be found that the employment of a steel wire 
 brush, or a piece of steel wool, will considerably 
 aid in removal of the deposit unless it be of the 
 "tacky" kind; then hard scraping is the only 
 resort. Where the cylinder heads are not sep- 
 arable, itis sometimes possible to employ flexible 
 wire carbon scrapers, getting at all parts of the 
 combustion chamber through the valve cap open- 
 ings, and finally blowing the accumulation of 
 carbon flakes out of the cylinder with an air 
 blast. Of course, on an engine of this type, if 
 an oxygen burning apparatus is available, a much 
 
 Fig. 37. Avery separable cylinder head. 
 
Major Engine Parts. 49 
 
 cleaner job can be effected by burning than by 
 attempting to scrape through the valve cap holes, 
 which at best is a makeshift method. 
 
 After thoroughly scraping the piston tops and 
 combustion chamber walls, in the case of the 
 separable head engine, before replacing the head 
 casting, see that there is no carbon on the valve 
 seats and make sure that the cylinder head gasket 
 is in good condition. Replace the gasket in 
 proper position; it is best to put it back without 
 shellac. Replace the cylinder head casting and 
 bolt it down in place, making sure to draw up 
 gradually on the bolts all around the casting so 
 as to distribute the strain evenly. Never tighten 
 up to the limit on one bolt with the others all 
 loose ; take a few bites on each and work them 
 in rotation until all are drawn up snugly. 
 
 With the engine all assembled, run it for a 
 while to warm the jackets thoroughly, and then 
 apply the wrench to the cylinder head bolts again 
 and draw them up, taking up all the slack which 
 has developed due to expansion under the heat. 
 
 Like the cylinders, the pistons are also made 
 of cast-iron and are carefully turned down to a 
 size wlfich permits of a slight clearance between 
 the piston and the cylinder wall. This clearance 
 varies with different engines, but it can generally 
 be accepted as one-thousandth of an inch for 
 each inch of diameter of the piston, the clearance 
 being measured on the skirt of the piston; the 
 skirt is the lower section. As a rule, the clear- 
 ance at the top of the piston will be somewhat 
 larger than this, due to the fact that the top of 
 the piston is subjected directly to the heat of the 
 burning gases and becomes considerably hotter 
 than the skirt, and as a result expands more. 
 
 The function of the clearance is quite obvious. 
 The piston, not being water-cooled like the cylin- 
 
50 
 
 Tractor Engines. 
 
 der walls, will reach a higher temperature under 
 operative conditions than the latter and will con- 
 sequently increase in diameter at a more rapid 
 rate than will the cylinder bore. The clearance 
 is left so that the piston, even when heated up to 
 maximum temperature, will always fit loosely 
 enough in the bore to slide freely, with no ten- 
 dency to bind or seize. Regardless of the tem- 
 perature attained, 
 however, some 
 clearance is always 
 present between the 
 piston and the cyl- 
 inder wall. 
 
 That being the 
 case, it is apparent 
 that there will be a 
 tendency for the 
 gases to rush past 
 the piston through 
 this space on the 
 compression and 
 power strokes ; 
 also for the air in 
 
 crankcase to 
 up into the 
 
 Fie;. 38. Section of piston show- 
 ing ring slots, bosses, webs, piston 
 pin and connecting rod eye. 
 
 the 
 rush 
 
 combustion cham- 
 ber on the intake 
 stroke. In order to 
 counteract this ten- 
 rush past the piston, 
 
 dency for the gases to 
 the pistons are slotted, as shown in Figure 38, 
 and into these slots, which are of uniform 
 depth all around the piston, are fitted expandable 
 rings, called piston rings. 
 
 The piston rings are cast-iron rings, generally 
 eccentric in form and slotted or split at the nar- 
 rowest point. The rings are turned down to the 
 
Major Engine Parts. 51 
 
 exact diameter of the cylinder bore on the out- 
 side before slotting. When slotted, therefore, 
 they expand slightly and can be sprung into posi- 
 tion in the slots on the piston. With most trac- 
 tor engines, three rings are fitted, although in 
 some cases four and even five are employed. 
 Their peculiar shape and the character of the 
 metal makes them springy and resilient, and the 
 gradually increasing section from the split or 
 slot to the largest section diametrically opposite 
 it insures equal tension at all points on the 
 periphery of the ring. 
 
 In position on the piston and with the piston 
 in the cylinder, the rings expand outward against 
 the cylinder wall, closing up the clearance space 
 left between the piston and the cylinder wall, 
 and thereby prevent the loss of the gases and the 
 blow-by of air. The rings also take a good part 
 of the wear, distribute the oil on the cylinder 
 walls, and check the passage of oil past the piston 
 and into the combustion chamber in excess ; they 
 tend to cushion the "cant" or "slap" of the piston 
 at each end of its stroke due to reversal of mo- 
 tion and the angle of the connecting rod. 
 
 The lower ring is usually called the "wipe" 
 ring, due to the fact that it scrapes off the excess 
 oil from the cylinder wall and returns it to 
 the crankcase chamber. Where the wipe ring 
 is fitted below the piston pin, it usually is posi- 
 tioned quite low on the piston, so that it just 
 overruns the counterbore at the lowest part of 
 the cylinder bore the counter bore is the tapered 
 section of the bore so formed as to facilitate 
 replacement of the pistons by compressing the 
 rings and preventing them from catching or jam- 
 ming. The reason for the wipe ring overrunning 
 the counterbore is so that the ofl it carries down 
 will have ample passageway back to the, crank- 
 
52 Tractor Engines. 
 
 case chamber and will not be returned to the 
 upper part of the cylinder wall by the upward 
 movement of the piston. 
 
 Where the wipe ring is positioned above the 
 piston pin, and in a few instances where it is 
 located well down on the skirt, this same func- 
 tion is performed in another manner. Immedi- 
 ately below the wipe ring is turned an oil relief 
 groove, generally triangular in cross-section. The 
 oil scraped off by the wipe ring collects in this 
 relief groove and is returned to the crankcase 
 chamber through a series of holes which carry 
 it to the inside of the hollow piston. 
 
 The piston is provided with two bosses on the 
 inside, into which is fitted a hollow steel pin 
 called the piston pin or "wrist" pin, and which 
 serves to connect the piston to the upper end of 
 the connecting rod. The pin is made of com- 
 paratively soft steel, but very tough in nature, 
 so that it is well adapted to stand up under the 
 constant shock encountered under the explosions 
 without becoming brittle and snapping, due to 
 crystallization. But as the piston pin must also 
 take a certain amount of heavy bearing wear, 
 due to the oscillation of the rod with the engine 
 in operation, it is obvious that its outer surface^ 
 must be well adapted to resist this wear. Con- 
 sequently, the pin, after being rough shaped to 
 size, is "cjase hardened" that is, it is subjected 
 to a heat treating process which leaves the outer 
 shell very hard and wear-resisting to a depth of 
 from two to five thousandths of an inch ; then the 
 pin is finished to exact size by grinding. This 
 hard shell takes the bearing wear, while the tough 
 core carries the brunt of the explosive pressure. 
 
 In some instances, the pin is clamped fast in 
 the upper end of v "eye" of the connecting rod 
 and allowed to find a bearing in the piston bosses ; 
 
Major Engine Parts. 53 
 
 in other cases, the pin is made fast in the bosses 
 by pinning or by a set-screw or other means of 
 locking and the bearing is in the eye of the rod. 
 In the latter case the eye is always bushed with 
 a bronze bushing which takes the wear. In the 
 first case, however, as a rule the bosses are not 
 bushed, since the cast-iron material of the boss 
 provides a fine wearing surface. In a few in- 
 stances, bronze bushes are fitted to the bosses. 
 
 Internally, most pistons are provided with webs 
 radiating from the piston head, and the function 
 of these webs is not so much to provide addi- 
 tional strength and support to the piston head, 
 although they do stiffen up the bosses, as it is to 
 assist in the radiation of the piston head heat to 
 the air in the crankcase chamber and thereby 
 maintain the piston at a moderate working tem- 
 perature. In some cases, also, the piston skirts 
 are provided with oil grooves just shallow slots 
 which serve, to hold a quantity of lubricant and 
 distribute it evenly over the cylinder wall surface. 
 
 Care and Repair of Pistons. The pistons, like 
 the cylinders, are subject to wear. As was men- 
 tioned ujider the section dealing with cylinder 
 repair, the usual practice is to replace them with 
 new oversize pistons when they show wear to an 
 excessive degree or when scored, or when either 
 -of these two ailments have affected the cylinder 
 bore. This is necessary to secure a proper fit. 
 
 When the wear is not excessive, correction can 
 be made by removing the piston pin and detach- 
 ing the connecting rod and then heating each 
 piston to a cherry red and allowing it to cool 
 very slowly. The heat should be applied evenly 
 and the temperature mentioned should not be 
 exceeded; if the piston is cooled too quickly it 
 will warp out of shape. If properly done, the 
 effect will be to expand the pistons slightly, and 
 
54 Tractor Engines. 
 
 they will be enough larger than they were orig- 
 inally to permit of lapping down to a proper fit 
 in the cylinders. 
 
 The lapping is accomplished in the same man- 
 ner as described above, with the exception that 
 in this case the piston is lapped right into the 
 cylinder it is intended to use it in. The ground 
 glass and oil mixture is used sparingly and lap- 
 ping is continued until when dry and clean the 
 piston moves easily throughout the length of its 
 stroke without any tendency to stick or bind ; 
 .nor will it bind when twisted around. After 
 being perfectly fitted, it will be necessary to fit 
 new rings to the piston. 
 
 The piston ring grooves are likely to be worn 
 after long use. In such a case, it will be found 
 that the pistons themselves are no doubt badly 
 worn so that replacement is necessary. It never 
 pays to attempt to true up a ring slot by turning 
 it true to a larger size in the lathe. The best plan 
 is to get a new piston and fit standard size rings 
 to it in the manner outlined below. 
 
 Piston Rings. The piston rings will wear 
 both on their peripheries and on the upper and 
 lower edges, so that they will become a "sloppy" 
 fit in the ring grooves. This will not only permit 
 of the escape of the compressed gases on the 
 compression and power strokes, but will also . 
 permit the oil working past the rings or rather 
 in behind the rings and then up above them. As 
 a matter of fact, this sloppy condition of the 
 rings causes them actually to assist in elevating 
 the oil, for on the downward stroke of the piston 
 the rings work to the top of the grooves, leaving 
 all the space represented by the original clearance 
 left in fitting, and the subsequent wear, below the 
 under side of the ring, the lower edge of which 
 serves to scrape the oil from the cylinder walls 
 
Major Engine Parts. 55 
 
 and carry it through this space to the pocket in 
 behind the ring. When the piston starts on its 
 up stroke, the ring shifts to the bottom of the 
 slot, leaving the space at the top through which 
 the oil is pumped by the ring movement and 
 deposited on the cylinder walls above the ring to 
 work up eventually into the combustion chamber, 
 as indicated in Figure 39. 
 
 As a rule, when the engine is taken down, 
 unless it has seen unusually severe service, wear 
 with the cylinders and pistons will not be appar- 
 ent, or at least so appreciable as to make repairs 
 necessary. This, however, is not so in the case 
 of the piston rings. They will show wear in two 
 ways; the periphery which contacts with the 
 cylinder wall may be streaked with black lines 
 
 Types of piston rings showing how oil works upward. 
 Fig. 39. Showing oil pocket behind piston rings and how 
 sloppy" ring fit assists in oil pumping. 
 
 running in. a vertical direction, showing that- the 
 fit is poor and that the ring has not been in con- 
 tact with the cylinder wall all the way around, so 
 that the gases have "blown by" the rings, leaving 
 the black marks, or else the upper and lower sides 
 of the ring may be worn so that the .rings are a 
 loose fit in the ring grooves on the piston. In the 
 former case, unless the blow-by can be traced to 
 the use of incorrect grade of oil which has not 
 had sufficient body to maintain a perfect piston 
 ring seal under the heat, thereby preventing -the 
 escape of the gases, replacement of the rings 
 with the new ones will be necessary. 
 
56 Tractor Engines. 
 
 Sometimes, where it is found that even the 
 fitting of new rings does .not effect a cure, it 
 is well to increase the pressure per unit of ring 
 surface on the cylinder wall, and this is done by 
 the very simple process of fitting rings with a 
 groove, similar to an oil groove, all around the 
 periphery which cuts down the surface in actual 
 contact with the wall. As the total ring pressure, 
 or tension, is the same and the surface over 
 which it is distributed is smaller, it stands to 
 reason that the unit pressure is increased and 
 the ring will hold the gases to better advan- 
 tage. 
 
 The cost of new piston rings is so low that 
 when it is necessary to remove the rings from 
 the ring slots for any reason whatsoever, it 
 scarcely will be worth while to replace the old 
 ones ; it is much better to fit new rings all around. 
 Such being the case, there is scant reason for 
 wasting time endeavoring to remove the rings 
 whole; they are very brittle and can be broken 
 and readily removed. 
 
 If, however, it is desired to remove the rings 
 without breaking them, provide short strips of 
 
 sheet brass or steel, 
 about 22 or 2-i gauge, 
 one-half inch wide. 
 With a screwdriver 
 lift the end of the 
 ring and slip one of 
 these metal slips un- 
 der it, as indicated in 
 and """""Figure 40, working it 
 around to the back 
 with the aid of the screwdriver. Do the same with 
 one of the other slips, using the remaining slips 
 to carry the ends of the ring. For the top ring, 
 the use of the metal slips may be dispensed with 
 
 m 
 
 R6.40 
 
Major Engine Parts. 
 
 57 
 
 if you work gently and do not force the ring 
 too hard with the screwdriver; but for the lower 
 rings they are necessary in order to bridge -the 
 upper ring slots, so that the rings will not slip 
 into them when they are being removed. 
 
 Be careful in removing the rings, to so mark 
 them that they can be returned to the same ring 
 grooves. After removal, if the ring slots in the 
 piston are not worn, clean out the carbon deposit 
 with a blunt screwdriver, or, better still, with a 
 
 section of a broken 
 ring which has been 
 ground off to a chisel 
 edge as indicated in 
 Figure 41. Where 
 the rings are a 
 sloppy fit in 
 the grooves it 
 is essential that 
 they be re- 
 placed with 
 new ones 
 which should 
 be properly fit- 
 ted. A good 
 way to gauge 
 the fit is indi- 
 cated in Figure 40. Take the new ring and fit 
 it into the slot as shown. If it is a proper fit, 
 there will be just an appreciable play at the outer 
 edge of the ring diametrically opposite the point 
 of contact with the piston ; if there is more than 
 just an appreciable shake or movement, try an- 
 other new ring to this slot which may prove a 
 better fit. The ring should be rolled all the 
 way around in the slot and the fit determined 
 at several points. If it is found that the ring 
 is too snug a fit, rig up a trimming board, as indi- 
 
 Fig. 41. Cleaning ring grooves 
 sharpened section of broken ring. 
 
 with 
 
58 
 
 Tractor Engines. 
 
 cated in Figure 42, covering down a perfectly \ 
 true, smooth piece of board with very fine sand- 
 paper. The ring can be rubbed down to a proper 
 
 __ r _ . fit on this, pro- 
 
 1 vided that the 
 pressure is ex- 
 
 ^^g*./. I erted evenly on 
 
 all sides of the 
 ring, so as not 
 to cut more off 
 one side than 
 the other and 
 so disturb the 
 parallelism of 
 the edges. Af- 
 ter a ring has 
 been fitted to 
 a slot, mark 
 it so that you will be sure and place it in the 
 proper slot. When very close fitting is desired, 
 filing on a special ring^-holding board made up 
 with a few brads to hold the ring compressed, as 
 indicated in Figure 43, is efficacious. 
 
 New rings will be so large as to diameter^ 
 that when compressed, fully closing the gap, they 
 either will not fit into the cylinder' bore at all, 
 or else when 
 
 Fisj. 42. Trimming board and method 
 of using it to secure proper ring fit in 
 groove. 
 
 HG.43 
 
 they do enter 
 it they will 
 not leave a 
 proper joint 
 clearance.The 
 
 fit of the 
 
 rings to the 
 cylinder bore can be determined (Fig. 44) by 
 putting a piston without rings and from which 
 the piston pin and connecting rod have been 
 detached into the cylinder bore and pushing it 
 
 Fig 43. 
 
 ring " 
 
 Filing board for close fitting of 
 
Major Engine Parts. 
 
 59 
 
 far enough into the cylinder to leave room be- 
 neath it for a piston ring. The ring should be 
 sprung into this space, if possible, and the gap 
 clearance measured with a feeler gauge. . 
 
 The clearance should be just about .005 of 'an 
 inch. If too small, hold the ring between blocks 
 of soft wood in a vise, so as not to mar the 
 edges, and file off enough of the metal on the 
 ends of the rings to leave this clear- 
 ance, using a very fine mill-cut file 
 for this work. If a feeler gauge is 
 not at hand, it is well to 
 remember that the thick- 
 ness of a piece of 
 ordinary newspaper 
 is .003 of an inch, 
 so that if a double thick- 
 ness is used to determine 
 the clearance the result 
 will be entirely satisfac- 
 t o r y. Naturally, the 
 rings should be fitted to 
 the cylinders they are to 
 work in; not all to the 
 same cylinder. 
 
 Care must be taken 
 not to break the rings in 
 placing them back on the 
 pistons. The bottom 
 ring should be put on 
 first, using the four little 
 metal strips to bridge the upper ring slots and 
 facilitate the manipulation of the ring. After the 
 rings are placed on the piston, try them again to 
 make sure that they work freely, as a tight ring 
 may cause a scored cylinder; and even if that is 
 escaped, it is bound to leak and forestall our 
 purpose in placing it on the piston. Finally, slip 
 
 Fig. 44. Method- of de- 
 termining correct piston ring 
 gap clearance. 
 
60 Tractor Engines. 
 
 the rings around so that the slots or joints do 
 not fall in line; it is well, before replacing the 
 pistons in the cylinders, to space the joints at an 
 angle of 120 degrees with each other. This will 
 tend to check. leakage. 
 
 After new rings have been fitted, it will take 
 a run of at least several hours for them to have 
 worked into a perfect fit to the cylinder walls, 
 and it is well to see to it that the engine has 
 plenty of oil during this period. At the end of 
 that time the compression of the engine should 
 have improved considerably. 
 
 The connecting rod (Figure 45) in all modern 
 tractors is a very substantial drop forging, made 
 usually of vanadium steel or alloy steel of one 
 sort or another, which is adapted to provide the 
 
 greatest degree 
 of toughness 
 under the work 
 encountered. It 
 must be re- 
 membered that 
 
 sembTed 45 " Typkal connecting rod disas - the connecting 
 
 rod, like the 
 
 wrist pin, carries the full 'brunt of the explosion, 
 and that, moreover, it is subjected to a whipping 
 action and to pressure at an angle which taxes 
 its strength to the utmost. 
 
 It is obviously necessary to provide the great- 
 est degree of strength with the least possible 
 weight, and in order to accomplish this purpose, 
 not only has the engineer gone to the best of 
 material, but he also has gone to the best pos- 
 sible sectional shape to provide rigidity the I-- 
 beam. The rod as at present designed, is in 
 reality an I-beam girder, tapering from top to 
 bottom, and provided with a split bearing holder 
 
 FIG. 45 
 
 n 
 
 HiQ 
 
Major Engine Parts. 
 
 61 
 
 at the lower end, the cap being bolted to the rod 
 proper by either two or four special steel bolts. 
 It has been usual in tractor practice to line the 
 big end or 
 c r a n k p i n 
 bearing with 
 babbitt metal, 
 which is 
 
 OU red, * ^ t, 
 
 the rod while 
 
 Fig. 46. Jig for babbitting connecting rod. 
 
 molten and with a mandrel of substantially the 
 same diameter as the crankpin in place. A jig 
 for pouring such a bearing is indicated in Fig. 46. 
 When the metal has cooled, 
 the mandrel is removed, the 
 rough parts of the casting 
 smoothed out and the bearing 
 split with a saw along the 
 plane of the bearing cap face. 
 Then the bearing surface is 
 fi n i s h e d perfectly, first by 
 reaming and afterward by 
 blueing and scraping to a per- 
 fect finish. 
 
 Babbitt metal is used for 
 the bearing surfaces in both 
 main bearings and connecting 
 rod bearings, first, because it 
 stands up well under the fric- 
 tion and the constant pound- 
 ing due to the explosions ; and 
 Fig. 47. Typical secO nd, because it provides a 
 measure of safety. If, for 
 instance, the bearing should 
 become hot, due to lack of oil or some other cause, 
 instead of expanding and seizing the bearing pin 
 as a bronze bearing would do, and cutting the 
 pin surface badly, and at the same time severely 
 
 FfG.47 
 
 piston and connecting 
 rod assembly for 
 tractor. 
 
62 
 
 Tractor Engines. 
 
 Fig. 48. Detail of piston, piston pin and connecting rod of 
 Aultman-Taylor tractor. 
 
 straining the shaft, the babbitt bearing simply 
 melts and runs out, leaving the bearing 'perfectly 
 free. It immediately begins to give audible evi- 
 dence in the shape of a heavy pound, that some- 
 thing is wrong, and the operator is warned of the 
 necessity of shutting down the engine and mak- 
 ing the necessary repairs. In the case of the 
 bronze bearing under similar circumstances, the 
 pin would be so badly damaged that even if the 
 shaft were not sprung by the severe strain im- 
 posed by the seizure, regrinding of the pin to 
 bring it back to a perfectly smooth bearing sur- 
 face would be neces- 
 sary; that, of course, 
 entails removal of the 
 crankshaft. 
 
 As might be ex- 
 pected the crank- 
 shaft as the mem- 
 ber which carries the full load developed by 
 each of the cylinders, is made of drop-forged 
 steel of special analysis for toughness ; generally 
 chrome nickel steel, which resists crystallization 
 well, or vanadium steel, which also presents a 
 
 PfG.4? 
 
 Fig. 49. Piston and connect- 
 ing rod of Rumely tractor. 
 
Major Engine Parts. 
 
 63 
 
 Fig. 50. Three-bearing crankshaft 
 four-cylinder engine. 
 
 measure of protection from this score, is em- 
 ployed. After being roughly forged, the shaft 
 is trimmed down to approximate shape and the 
 pins for both main and crankpin bearings either 
 
 machined to a 
 finish or, as in 
 latter day prac- 
 t i c e , ground 
 for to a perfect 
 surface. The 
 number of bearings used will, of course, depend 
 entirely on the type of engine employed, the 
 number of .cylinders used, etc., as was made per- 
 fectly plain in the preceding chapter. The bear- 
 ings themselves are practically the same as the 
 crankpin bearings, being split with a bolted-on 
 cap and lined with babbitt metal. 
 
 In realization that, after all, pouring a bearing 
 is not a job to be undertaken by the layman 
 especially when it comes to fitting many tractor 
 engine manufacturers are giving up the poured 
 babbitt bearing in favor of the shell type of bear- 
 ing. Here we have a bronze shell of exactly 
 proper diameter to fit the bearing holder; this 
 bronze shell does not take the wear, but simply 
 serves as a support for the babbitt wearing sur- 
 face with which it in turn is lined ancl which 
 provides the ac- 
 tual bearing sur- 
 face. The bronze 
 shell is riveted, 
 or screwed,solid- 
 ly in place in the 
 bearing holder, 
 the rivet or screw heads being countersunk be- 
 low the bearing surface so that there is no chance 
 of their coming in contact with the pin surface. 
 
 Fig. 51. Two-bearing crankshaft on 
 Avery four-cylinder opposed engine. 
 
64 
 
 Tractor Engines. 
 
 With this type of bearing, replacement of the 
 bearing is greatly facilitated, for it is simply 
 necessary to remove and discard the worn shell 
 and fasten the new one firmly in place. Since 
 
 the shells are 
 made on the 
 limit system, 
 the shells fit 
 properly in 
 
 Fig. 52. Counterbalanced crankshaft on place and fit- 
 two-cylinder vertical engine. . , 
 
 ting is reduced 
 
 to a minimum. It will even be found that the 
 actual fitting of the bearing by blueing and scrap- 
 ing after the shells have been put in place, is 
 reduced to a minimum, and we not only get a 
 better fitting bearing when all the work is done, 
 but we also accomplish the work in a very short 
 space of time. 
 
 At one end, the crankshaft is provided with 
 a spur gear, which ,is sometimes formed integral 
 with the shaft and in other cases is formed sep- 
 arate and keyed, pinned or otherwise firmly 
 fastened in place. This gear meshes with a 
 second gear twice its 
 size, also fastened 
 firmly to the cam- 
 shaf t,the two compris- 
 ing the timing gear 
 train; the relation is 
 such that the cam- 
 shaft revolves at half 
 the crankshaft speed 
 for the proper opera- 
 tion of the valves, as 
 indicated in the first 
 chapter. 
 
 The Camshaft, like Fig. 53. Rumely crank 
 
 , < 1 1 r, case construction showing 
 
 the crankshaft, is ma in bearings. 
 
Major Engine Parts. 
 
 65 
 
 drop-forged of alloy steel, and the cams are 
 ground to exactly the proper contour, at the 
 same time the bearing pins are trued up and 
 ground to a proper finish. Generally, consid- 
 ering a four-cylinder vertical engine, the cam- 
 shaft will be supported in three bearings, two of 
 which will be of greater diameter than the maxi- 
 mum lift of the cams, so that the bearing, which 
 is not split as with the mainshaft bearings, can be 
 
 . 54. Method of testing the truth of connecting rod. 
 
 slipped over the cams into place. With the third 
 bearing at the front end, it is not necessary to 
 provide such a large diameter, since the shell need 
 not be slipped over the cams. These bearing 
 shells are generally of bronze. 
 
 Repairs to Connecting Rods, Etc. When mak- 
 ing a general overhaul of the engine, it is well 
 to check up on the alignment of the connecting' 
 rods, especially if the engine has been productive 
 
66 
 
 Tractor Engines. 
 
 of an elusive knock. The rod may be sprung 
 so that the piston is crowded at an angle with 
 the cylinder bore, or it may be twisted so that 
 the piston pin does not lie in the same plane as 
 the crankpin. The proper method of testing the 
 rod for these defects is indicated in Figure 54. 
 A mandrel of the same size as the crankpin is 
 supported in a vise and the rod is clamped tightly 
 to this by means of the crankpin bearing. A sec- 
 ond mandrel of a diameter the same as the piston 
 pin is clamped in place in the eye at the upper 
 end of the connecting rod. These mandrels 
 should be sufficiently long for their parallelism 
 to be tested. The illustration shows an easily 
 made and convenient gauge for testing their pa- 
 rallelism. By sighting along the mandrels it is 
 easy to determine whether there is a twist in the 
 rod, so that the mandrels do not lie in the same 
 plane. If either test shows the rod to be out 
 of truth, it can readily be sprung back by bend- 
 ing cold, simply by applying pressure in the 
 proper direction on the mandrel through the con- 
 necting rod eye. 
 
 Piston Pin. 
 The piston 
 
 pin itself will 
 
 give evidence 
 
 of wear after 
 
 long usage 
 
 and looseness 
 
 in the bush- 
 ings provided 
 
 for it in the 
 
 piston bosses 
 
 will give rise 
 
 to a sharp 
 
 metallic click Fig. SS. Removing piston and rod 
 
 i T assembly through inspection opening 
 
 Or knOCK. in O n Best engine. 
 
Major Engine Parts. 67 
 
 such a case, it will be necessary to replace the 
 piston pin with a new one, and in some cases 
 to rebush the cylinder bosses. Try the new pin 
 in the bosses, and if it is a good, snug fit with 
 no play, rebushing will not be required. If, how- 
 ever, it is loose, the old bushings can either be 
 reamed out to take an oversize pin which is a 
 comparative simple operation, or they can be 
 drifted out with a drift slightly smaller in diam- 
 eter than the outside measurement of the bush- 
 ing, care being taken "to hold the piston firmly 
 on a soft wood saddle while the bushing is being 
 
 Fig. 56. Lower crank case removed, showing main bearings, 
 connecting 'rod and bearing, and the ease with which piston is 
 removed in Waukesha engine. 
 
 driven out. The new bushings can be pressed 
 into place by means of a press or a vise, care be- 
 ing taken to pad the jaws of the press with a soft 
 wood block so as to mar neither the piston nor the 
 bushing. It will be necessary to ream the new 
 bushings to take the new piston pin, even though 
 it is not oversize. Extreme care should be taken 
 to clamp the pin firmly in the eye of the connect- 
 ing rod so as to guard against its working loose 
 and scoring the cylinder walls. 
 
68 
 
 Tractor Engines. 
 
 Where the pin is locked in the bosses and bears 
 in the rod eye, only one bushing at this point is 
 necessary. 
 
 Mainshaft and Crank pin Bearings. Both the 
 mainshaft and crankpih bearings are adjustable. 
 Evidence of looseness comes in the form of a 
 heavy pound or knock, which should be heeded 
 and the engine stopped immediately. In case a 
 crankpin bearing is suspected of being at fault, 
 drain the oil from the engine and remove the 
 plate from the bottom of the crankcase, which 
 
 will expose the 
 connecting rods 
 in the case of. 
 a vertical cyl- 
 i n d e r engine 
 (Figure 56). 
 Sometimes the 
 rods can .be 
 reached 
 through in- 
 spection plates 
 in the crank- 
 case. Taking 
 a firm hold on 
 the crankpin 
 bearing each 
 rod can be 
 tested in turn for looseness. In case appreciable 
 play is detected, take off the crankpin bearing 
 cap, hold it in a vise and draw file the ends 
 (Fig. 57), taking very little metal off and mak- 
 ing sure to take it off evenly all around and just 
 as much from one side as from the other. 
 
 Where the bearing is "shimmed" for adjust- 
 ment (Figure 58), removal of a thin shim on 
 either side will generally suffice, no filing being 
 necessary. 
 
 Fig. 57. Method of adjusting bearing 
 by filing off cap slightly. 
 
Major Engine Parts. 
 
 69 
 
 Replace the cap, being sure that the punch 
 marks correspond, and tighten up the crankpin 
 bearing bolts until the bearings fit the pin snugly. 
 Test the tightness of the bearing by turning 
 
 the engine over 
 with the start- 
 ing handle. 
 
 In the ordi- 
 nary course of 
 events, provided 
 the engine has 
 received decent 
 
 Fig. 58. Shimmed bearing. j 
 
 treatment and 
 
 care, especially as to correct lubrication, it will 
 be necessary to take up on all the crankpin bear- 
 ings slightly once every couple of months. Pro- 
 ceed as above, being careful not to get the bear- 
 ings too tight, as in that case they will cut out 
 rapidly. After adjusting the bearings, it is well 
 to idle the engine for a couple of hours before 
 taking the tractor into the field to run the bear- 
 ings in to a good fit. Do not forget to lock the 
 crankpin bearing bolt nuts when the bearings 
 have been properly fitted and set up. 
 
 Fig. 59. Rough spotting to determine where bearing surface 
 is high. 
 
70 Tractor Engines. 
 
 In case the wear is too great to be taken up 
 by the above method, or in case of bearing fail- 
 ure, the rod will have to be rebabbbitted. To do 
 a worth while job of repouring a bearing requires 
 ,not only proper equipment in the way of a jig, 
 but also experience in bearing pouring. The 
 best advice that can be given in a case of -this 
 sort, is to send the rod or rods off to the nearest 
 service station or the nearest competent repair- 
 man, who will rebabbitt the bearing at small cost. 
 
 With the rod relined with new babbitt, it is 
 
 Fig. 60. Illustrating correct method of scraping a bearing 
 after "spotting" to determine the high spots. 
 
 not a difficult job for the man with patience and a 
 limited amount of mechanical skill to spot and 
 scrape in the bearing to a good fit on the crank- 
 pin. Coat the surface of the crankpin with a 
 very thin film of Prussian blue; the thinner the 
 better, and it should be spread perfectly even. 
 After thoroughly coating the pin, mount the 
 bearing on it, clamping it firmly, but not so 
 tightly in place that it cannot be turned ; be sure 
 and apply it to the pin in the same position as 
 
Major Engine Parts. 71 
 
 it will be used in the engine when reassembled 
 (Fig. 59). Then turn the bearing around a couple 
 of times, undo the bolts and remove it. It will 
 be found that all the high spots on the bearing 
 surface will show up in blue both on the upper 
 half and the lower half. 'Now hold the bearing 
 in the vise, as shown in Fig. 60, and with a good, 
 sharp bearing scraper scrape a small amount of 
 metal off these high spots, and in fact from the 
 area just around them. When both top and cap 
 have been scraped, reclamp bearing on the pin 
 after spreading out. the blue again, and take 
 another impression. If the scraping has been 
 carefully done, the blue this time will cover a 
 much larger surface. 
 
 Scrape down the high spots again, being more 
 careful to take only a small amount of metal off.- 
 Use the flat of the scraper blade and give it a 
 twisting diagonal stroke in order to avoid ridg- 
 ing the comparatively soft bearing metal. After 
 several repetitions of this process, the blued area 
 will be found to very nearly cover the bearing 
 surface, provided the scraping has been discreetly 
 done. Then wipe bearing and pin clean, smear 
 it well with lubricating oil and adjust it to a snug 
 fit as indicated above. If it is found, when it 
 comes time to set up the bearing, that when the 
 bolts are screwed up tight the bearing grips the 
 pin too tightly, cut several shims of very thin 
 brass .002 to .004 of an inch and place an 
 equal number of these on each side of the bear- 
 ing between the two halves to provide a correct 
 adjustment when the bearing bolt screws are 
 pulled up tight. 
 
 In every case when it is found necessary to 
 reline a bearing, the pin should be carefully 
 examined for roughness or ridges ; it is well 
 also to test it for roundness with a micrometer 
 
72 Tractor Engines. 
 
 or a good pair of calipers if these instruments 
 are at hand. If the pin is at all rough, do not 
 attempt to fit a new bearing on it until it has 
 been smoothed up and put in good condition 
 again. If this precaution is not observed, all the 
 trouble and expense of putting in the new bear- 
 ing will come to naught, for it will quickly be 
 cut out again, making a repetition of the task 
 necessary. An experienced machinist can take 
 a pin that is not too badly scored and file it to 
 approximate condition, finishing it off by lapping 
 with a clamp and very fine abrasive. The best 
 plan, however, is to send the crankshaft that is 
 found to be scored as to the bearing pins to the 
 service station and have it reground and put in 
 first-class shape again. 
 
 In connection with the above, one of the lead- 
 ing tractor manufacturers says: 
 
 "Fitting connecting rod bearings is very im- 
 portant, and you should know that the rods fit 
 properly at all times. Do not allow them to run 
 loose and 'pound/ It is important to keep con- 
 necting rods tight and well-oiled at all times. 
 Bearings are constructed so that shims can be 
 removed to take up the wear. When bearings 
 are worn so badly that all shims have been re- 
 moved it is then necessary to use new bearings. 
 
 "The one-half bearing grooved for oil must be 
 fitted in lower one-half of connecting rod shell. 
 
 "The first operation is to fit the shells tight in 
 the connecting rod and the connecting rod cap 
 so they will have a full bearing back of the shell. 
 About the best way to get a good fit is to place 
 the shell on the crankshaft and then tap the cap 
 to place, as shown in Fig. 61. 
 
 "The next operation is to get a good bearing 
 fit to the crank. To do this, it is best to use 
 lamp black to 'paint' the pin or crankshaft, then 
 
Major Engine Parts. 
 
 73 
 
 set half of bearing on pin and work back and 
 forth ; the lamp black will show the high places 
 or where bearing needs to be scraped. Keep this 
 operation up until the bearings show a nice even 
 fit all over the surface before you put the rods 
 on the crankshaft to stay. 
 
 "The connecting rod bolts should be drawn up 
 tight, when the bearings are properly fitted and 
 bolts drawn up as tightly as possible, the connect- 
 ing rod bearings should almost sustain the weight 
 
 Fig. 61. Fitting bearing shell to rod bearing. 
 
 of the rod. If the cylinder is off and the rod 
 raised to the' top it should just 'ease' down of 
 its own weight. If it drops easily and loosely 
 it has not been fitted close enough. If the cylin- 
 der is not off, test it by turning fly-wheel. 
 
 "If the rod will not fall of its own weight, not 
 enough shims have been used. Do not back the 
 nut off until the rod will drop, but put in more 
 
74 
 
 Tractor Engines. 
 
 shims. The bolts should be tight, and edges of 
 bearings should be in close contact with shims. 
 It pays to fit the bearings properly. 
 
 "Every morning take off inspection plate and 
 examine the bearings and oil level, and see that 
 the connecting rod bolts are tight. Remember 
 the old adage, 'A stitch in time saves nine.' It 
 is mighty true with a motor. A little neglect may 
 cause an expensive break." 
 
 To take up on the mainshaft bearings, take off 
 the three babbitted caps from the mainshaft bear- 
 ings and clean the bearing surface with gasoline. 
 
 Apply Prussian blue or red lead to the crank- 
 shaft bearing surfaces, which will enable you, in 
 fitting the caps, to determine whether a perfect 
 bearing surface is obtained. 
 
 Place the rear cap in position and tighten it up 
 as much as possible without stripping the bolt 
 threads. When the bearing has been properly 
 fitted, the crankshaft will permit moving with 
 one hand.. If the 
 crankshaft cannot be 
 turned with m one 
 hand, the contact 
 between the bearing 
 surfaces is evidently 
 too close, and the 'cap 
 requires shimming up, 
 one or 'two brass lin- 
 ers usually being suf- 
 ficient. In case the 
 crankshaft moves too 
 easily with one hand, 
 the shims should be 
 removed and the steel 
 surface of the cap 
 filed off, permitting 
 it to set closer. 
 
 Fig. 62. Showing simple 
 means of adjusting Avery 
 mainshaft bearings. 
 
Major Engine Parts. 75 
 
 After removing the cap, observe whether the 
 blue or red "spottings" indicate a full bearing 
 the length of the cap. If "spottings" do not 
 show a true bearing, the babbitt should be scraped 
 and the cap refitted until the proper results are 
 obtained. 
 
 Lay the rear cap aside and proceed to adjust 
 the center bearing in the same manner. Repeat 
 the operation with the front bearing, with the 
 other two bearings laid aside. 
 
 When the proper adjustment of each bearing 
 has been obtained, clean the babbitt surface care- 
 fully and place a little lubricating oil on the bear- 
 ings, also on the crankshaft; then draw the caps 
 up as closely as possible the necessary shims, 
 of course, being in place. Do not be afraid of 
 getting the cap bolts too tight, as the shim under 
 the cap and the oil between the bearing surfaces 
 will prevent the metal being drawn into too close 
 contact. If oil is not put on the bearing surfaces, 
 the babbitt is apt to cut out when the motor is 
 started up before the oil in the crankcase can get 
 into the bearing. 
 
 It must be remembered that after scraping, the 
 bearings will not be a snug fit on the pins, but 
 will touch only at the high spots ; if the scraping 
 has been carefully done these high spots will be 
 very numerous, spread all over the bearing sur- 
 faces, and naturally be comparatively small. 
 After the bearing has been run in for a couple of 
 hours, provided it is given plenty of oil, it should 
 wear down "to a perfect fit on the pin, which 
 should eliminate arty tendency for it to bind. 
 
 After long use, especially if the crankcase oil 
 has not been changed at frequent intervals, the 
 bearing surface will contain embedded gritty 
 matter which will act as an abrasive and lap the 
 bearing pin somewhat. In order to correct this 
 
76 Tractor Engines. 
 
 condition, it will be necessary to scrape the sur- 
 face of the bearings, spot them in and refit them 
 to proper alignment. 
 
 Crankshaft. Aside from truing up the bear- 
 ing pins as outlined under the last heading, the 
 only repair that is ever called for by the crank- 
 shaft is to test it out for true running between 
 centers or on knife edgesi If it is found to be 
 sprung, unless the spring is comparatively slight 
 it should be discarded and replaced with a new 
 shaft. A slight spring can be taken out, but as 
 special jigs are necessary, the shaft should be 
 returned to the factory or to the nearest service 
 station for this treatment. 
 
 Camshaft. Repairs to the camshaft are in- 
 frequent, since it is not subjected to hard wear. 
 After several seasons' use, sufficient looseness 
 may be detected in the camshaft bearings to 
 make rebushing desirable; this is a simple mat- 
 ter of drifting out the old bushings and pressing' 
 in new ones, much as the piston pin bushings in 
 the piston bosses were refitted. It sometimes 
 happens also that the camshaft becomes sprung, 
 generally as a result of being hit with a broken 
 connecting rod or some similar mishap. If not 
 too badly sprung, this fault can be corrected by 
 blocking the shaft between two wooden 'blocks 
 and applying pressure with a lever or jack at the 
 high point to bring it back to shape; if badly 
 sprung, and especially if the cams show appre- 
 ciable wear, it is a better plan to replace the cam- 
 shaft with a new one. 
 
 Tools and Their Use. To properly care for 
 a piece of machinery, certain tools are necessary 
 in order to do the job quickly and correctly. 
 
 One of the chief causes of serious tractor 
 troubles is that the adjusting or repairing is not 
 
Major Engine Parts. 
 
 77 
 
 done when it should be done, and very often on 
 account of the lack of proper tools or not know- 
 ing what tools to have on hand. 
 
 \&**&** m 
 
 "tj YfS. 
 
 - O 
 
 Fig. 63. Useful tools for tractor operators. 
 
 The following list of tools will be found about 
 all that are necessary for doing all kinds of ad- 
 justing and repairing on your tractor, and from 
 
78 Tractor Engines. 
 
 time to time one will get other handy and useful 
 tools: 
 
 One 1^2 -pound ball pene hammer. 
 
 One screwdriver, 10-inch. 
 
 Two 24-inch flat cold chisels, and 
 
 One- fourth round nose chisel. 
 
 Two oil groove chisels. 
 
 No. 41 S wrench (semi-finish). 
 
 No. 37 S wrench (semi-finish). 
 
 8-inch crescent wrench. 
 12-inch monkey wrench. 
 18-inch pipe wrench. 
 
 Two round punches, j^-inch and %-inch. 
 Hack saw frame and 10-inch blades. 
 Pair tinner's snips. 
 Carpenters' bit brace. 
 Flat files, such as 10 and 14-inch. 
 Half-round file (14-inch). 
 Round file (^-inch). 
 Combination square with 18-inch blade. 
 Pair of good pliers. 
 A carpenters' pinch-bar. 
 One 10-inch and 14-inch babbitt scraper. 
 Two pieces of ^-inch square hemp packing, 
 
 18 inches long. 
 Two spring clamp rings. 
 Carborundum stone. 
 Soldering' iron and solder. 
 A whisk broom. 
 A good bench vise. 
 
 The oil groove chisels are for cutting oil 
 grooves in bearings, and you should own two of 
 them, one with about y&" cutting edge and 3-16" 
 on the other, so that grooves can be cut proper 
 size in both large and small bearings. 
 
 The No. 41 S wrench fits standard size nuts 
 of ft" and 1", and the No. 37 fits $/&" and 
 
Major Engine Parts. 79 
 
 24" nuts, these four sizes being standard, and 
 you will find most of the bolts and nuts on your 
 tractor about that size. The 8" crescent wrench 
 will take all sizes from y%" down as well as 
 cap screws. The 18" pipe wrench is about right, 
 since it will take all sizes of pipe used on your 
 tractor. 
 
 The hack saw is a very handy tool when doing 
 all kinds of repair work where a saw can be used. 
 
 A pair of tinner's snips are necessary when 
 making new shims for bearings, etc. 
 
 Flat files can be purchased in all sizes to suit 
 the needs. A half-round and a. round file will 
 be found very useful when enlarging bolt holes, 
 etc., about implements. 
 
 The combination square with 18-inch blade 
 will be found very handy when lining and squar- 
 ing up bearings for babbitting, etc. 
 
 A short carpenter's pinch-bar will be used very 
 much around the farm and on the outfit. 
 
 When babbitting bearings the most important 
 tools for such work are your babbitt scrapers. 
 A set of good scrapers can be made out of a 
 10-inch and a 14-inch half-round file by grinding 
 off all the teeth on an emery wheel and then 
 finish up smooth on a grindstone. Be careful 
 when grinding on emery wheel so as not to draw 
 the temper out of edge of file by allowing to get 
 too hot. Continually dip file in water to keep 
 it cool while grinding. The flat side should be 
 ground out hollow, since in such shape it will 
 sharpen easily and quickly. 
 
 The carborundum stone is for the purpose of 
 keeping the edges of your scraper sharp so it 
 will cut babbitt. You will find that a sharp 
 scraper will cut babbitt and also brass very easily. 
 
80 Tractor Engines. 
 
 When dull it is almost impossible to touch it by 
 scraping. You should make a case for your 
 scraper out of paper, cloth or wood, so as to 
 protect its edge when not in use. 
 
 The two pieces of half -inch square hemp pack- 
 ing are used to make a tight joint around shafts 
 or hubs of gear when babbitting, and the spring 
 clamp rings are used to hold the hemp up tight 
 in place. 
 
 A soldering iron and some solder are very 
 useful. when mending oil cans, pipes, and such 
 parts as can be repaired by soldering. The flux 
 used when soldering is commercial muriatic acid 
 with as much zinc put into it as it will dissolve, 
 and have all surface to be soldered clean and 
 bright. 
 
 A whisk broom is one of the handiest articles 
 with which to keep a tractor clean. It will be 
 found that if the operator will from time to time 
 brush off all the dirt and trash which settles on 
 a tractor he will be able to keep it clean with a 
 very small amount of time spent with the whisk 
 broom. For the purpose of wiping up grease 
 and oil, old gaudy sacks cut up, or cotton waste 
 should be used. 
 
 A bench vise attached to the rear platform of 
 tractor will be found handy all the time and 
 should be one of the tools first purchased. 
 
 The equipment for handling lubricants for 
 tractor use are as follows : 
 
 The can in which hard oil is carried on the 
 tractor for all hard oil compression cups should 
 not be larger than five or ten-pound capacity, 
 and should have a tight cover, one which will 
 keep out all grit and dirt. 
 
 When taking out grease, to fill a grease cup, 
 use a short paddle which can be carried in the 
 
Major Engine Parts. 81 
 
 grease can and remove the grease from on top 
 of grease in can. Do not dig a hole in the center 
 of the grease and continue it to the bottom of 
 pail or can. By digging out the middle and 
 having such a cavity in grease, helps to collect 
 grit and trash which may fall into can unnoticed 
 and thus get mixed with the grease, and thus 
 goes into a bearing, where it does a great amount 
 of harm, even more than the operator believes 
 possible. Keep grease clean. 
 
 The can in which you carry gas engine cylinder 
 oil should be about two or three gallon capacity. 
 A five-gallon can is too clumsy and hard to 
 handle. In a short time more oil will be spilled 
 than the cost of two or three smaller cans. Keep 
 the can closed up tight with a screw top or corked 
 with a cork of solid material such as wood or 
 lead. Never use a corn cob, as it breaks up 
 easily and drops into the oil can; from there it 
 gets into the lubricator and stops it up, thus again 
 causing considerable delay and possibly damage. 
 
 Keep your oiling equipment clean. x A small 
 funnel with a medium fine screen should be used 
 when drawing oil from the barrel into the can, 
 so as to catch all chips from the bearings which 
 get into a barrel when tapping for faucet, and 
 also can be used when filling lubricator on trac- 
 tor. Keep the funnel clean so no dirt gets into 
 oil by first lodging on funnel. 
 
 The oil which is taken out of the splash basin 
 of your motor from time to time can be filtered 
 through a filter. Take a fifteen or twenty-gallon 
 can or barrel and cut several small holes in its 
 bottom and fill about half full of cotton waste 
 or gunny sacks. The oil is poured into top of 
 can and passes slowly through filter and is caught 
 in another receiver below filter. This oil can 
 
82 Tractor Engines. 
 
 be used for gear oil or on other machinery. 
 Never use it in motor again. 
 
 Whenever a man visits a tractor, and he looks 
 inside of the tool-box and sees a heap of scrap 
 iron, broken bolts, nuts, earth and tools mixed 
 together, and then glances at the oil-handling 
 equipment and sees an oil can wide open covered 
 with dirt, and grease can without a cover and 
 jammed into all kinds of shapes, he will not need 
 to look over the tractor to tell just what kind of 
 shape it is in. An operator can be judged by the 
 apearance of the oiling equipment and tool-box/ 
 
CHAPTER IV. 
 
 Valves and Valve Mechanism. 
 
 How They Differ and the Advantages of EacK 
 Type Proper Care and Adjustment. 
 
 TAKEN all in all, there is no system of the 
 several which go to make the complete 
 tractor engine that is of more importance to the 
 correct functioning of the motor than the valve 
 system. As a matter of cold fact, it is doubtful 
 if there is any other feature of engine design 
 that has been given as much careful considera- 
 tion and experimental work as has the design 
 and the arrangement of the various parts which 
 have to do with the functioning of the valves. 
 
 We have alluded, in chapters ahead, .to vari- 
 ous valve arrangements ; particularly the L-head 
 and the valve-in-head types. In all, there are 
 five distinct valve arrangements commonly em- 
 ployed in internal combustion engine work, as 
 follows : T-head, in which the cylinder is pro- 
 vided with two cylinder pockets so that in cross 
 section it resembles a Capital T, one valve being 
 located in each of these pockets. Such a con- 
 struction gives a very accessible engine ; however, 
 it entails the use of two camshafts, while at the 
 same time the presence of cylinder pockets to 
 any greater degree than is absolutely necessary is 
 by no means desirable. This is due to the fact 
 that the pocket provides additional surface for 
 the radiation and loss of the heat of the explo- 
 sion, which, as we learned in the first chapter, is 
 the real source of our power, and the efficiency 
 of the engine is impaired as a consequence. Also 
 
 (83) ' 
 
84 Tractor Engines. 
 
 the presence of a pocket, or two pockets, con- 
 siderably retards the speed with which full com- 
 bustion of the fuel charge can be effected, and 
 by so doing we have a second cause of power 
 loss. 
 
 The second type is the L-head type, with both 
 valves positioned in a single cylinde'r pocket and 
 operated from a single camshaft. This arrange- 
 ment has the virtue of compactness and ex- 
 treme simplicity, as to valve operating mech- 
 anism, and for these reasons it is typical of 
 present-day tractor engine practice. The single 
 pocket is not a great drawback and many manu- 
 facturers consider the accessibility and the sim- 
 plicity which it gives rise to of greater import- 
 ance than the slight power increase which can 
 be attained by eliminating the pocket altogether. 
 
 The third system, and the one which at the 
 present time is making the greatest progress in 
 the tractor industry, is the valve-in-head type, 
 in which 'both the valves are located in the cylin- 
 der head and operated by means of long push 
 rods and tilting levers or rocker arms from a sin- 
 gle camshaft. The virtue of this system 'is that 
 it provides a combustion chamber which is a 
 very close approach to the ideal spherical shape ; 
 there are no pockets in the cylinder and the com- 
 bustion chamber presents less wall area for heat 
 radiation in proportion to capacity than with any 
 other type ; at the same time, the location of the 
 spark plug is such that we obtain the fastest pos- 
 sible speed of the flame rapid flame propaga- 
 tion, as we term it with no pocket of dead or 
 partially dead gas to retaAl it. 
 
 It has the disadvantage of introducing some 
 complication into the valve operating mechanism ; 
 more parts to wear and need adjustment. But 
 in the modern valve-in-head engine, these 
 
Valves and Valve Mechanism. 85 
 
 !*is 
 
 to 1 
 
86 Tractor Engines. 
 
 little points have been so well worked out that 
 no trouble on the score of wear and lack of ad- 
 justment are chargeable against the valve-in- 
 head engine, provided it is given at least as good 
 treatment as any of the other types. 
 
 The two other types are by no means a factor 
 in the tractor industry and we will dismiss them 
 with a word. They are the F-head system with 
 a single valve the inlet located in the cylinder 
 head, and the exhaust valve located in the single 
 cylinder pocket ; and the Knight sleeve valve 
 type, in which the functions of the valves are 
 performed by two sliding sleeves surrounding 
 the piston. In the F-head type, we can obtain 
 very large valve areas with a very small cylinder 
 pocket, much larger than can be obtained with 
 the L-head type, and also much larger than can 
 be obtained with the, valve-in-head type. An 
 engine with this valve arrangement, therefore, is 
 particularly powerful despite the presence of the 
 small valve pocket ; however, the complication of 
 the valve mechanism has stood in the way of the 
 development of the type for tractor service, al- 
 though in automobile application it is making 
 marked progress. The Knight engine is not 
 used for tractor service. 
 
 In Figure 64 the assembly of the cylinders, pis- 
 tons, crankshaft, etc., with the camshaft and the 
 valve mechanism on a typical four-cylinder en- 
 gine of the ve'rtical L-head type indicates clearly 
 the relation of the various parts and the func- 
 tioning of each. The valve proper, which is 
 pictured in Figure 65, is made of tungsten steel 
 in most modern motors, although quite a few 
 manufacturers employ a cast-iron head with a 
 ste.el stem welded in place. The cast-iron stands 
 the heat well, which is of great importance, es- 
 pecially in the case of the exhaust valve,' which 
 
Valves and Valve Mechanism. 87 
 
 is constantly subjected to the intense heat of the 
 exhaust gases ; tungsten steel has been found 
 even more efficacious from the heat-resisting 
 standpoint, while at the same time the all-steel 
 valve is not particularly subject to warping. 
 
 The valve head is shaped like a manhole and 
 has a beveled edge which seats on a similarly 
 shaped seat formed in the cylinder, so that when 
 the valve is closed no leakage can occur around 
 the seat and through the port, provided the valve 
 is in good condition. The valve is ground to a 
 gas-tight fit with the cylinder seat when the en- 
 gine is as- 
 sembled at the 
 factory. 
 
 The valve 
 is positioned, 
 with relation 
 to the port 
 which it con- 
 , t r o 1 s , by 
 means of a 
 valve stem 
 guide in 
 which the 
 stem of the 
 valve finds a bearing. This guide is usually 
 formed of cast-iron similar to the cylinder, and 
 in fact in some instances, is formed integral with 
 the cylinder casting. The usual practice, how- 
 ever, is to make the guide separate and press it 
 into place, so that when wear occurs the ill re- 
 sults occasioned by it can be remedied by remov- 
 ing the worn guide and fitting a new one. 
 
 It will be seen that the cam does not act 
 directly against the bottom of the valve stem; a 
 mushroom-shaped cam follower, push rod or 
 tappet, as it is variously called, is interposed 
 
 f 16.65 ' 
 W 
 
 Fig. 65. Showing the valve and cam fol- 
 lower assembly and how the cam follower 
 is actuated by the cam. 
 
88 Tractor Engines. 
 
 between the cam and the valve stem and it finds 
 its bearing in a tappet guide formed in the shelf 
 on the upper half of the crankcase. These cam 
 followers are also case hardene4 to prevent 
 rapid wear. 
 
 The shape of the valve tappet is not always 
 the same. In some engines the tappet is fitted 
 with a roller which bears on the cam to reduce 
 wear and noise. 
 
 The valve stem is surrounded by a valve 
 spring, helical in shape, which bears against the 
 under side of the valve pocket in the cylinder, 
 being centered by the valve stem guide, and 
 which is held on the stem by means of a washer 
 and a short key or pin passing through a hole in 
 the lower end of the valve stem. Other locking 
 arrangements, such as horseshoe washers, fitting 
 into recesses on the valve stems, are sometimes 
 used. 
 
 This spring is sufficiently strong to return the 
 valve rapidly to its seat when the cam follower 
 rides off the hill on the cam. It is also suffi- 
 ciently strong to prevent the exhaust valve open- 
 ing under the suction or reduced atmospheric 
 pressure in the cylinder on the inlet stroke. 
 
 Due to the arrangement of the crank throws 
 on the crankshaft, it is not possible to fire the 
 cylinders in exact rotation starting with number 
 one which is always the cylinder at the timing 
 gear end of the engine and working back in 
 numerical order. On the four-cylinder engine 
 shown in Figure 64 the firing order is 1, 2, 4, 3. 
 Just what is happening in each of the cylinders 
 when -any particular one is firing is made plain 
 by reading across in the following tabulation. 
 Reading down shows the order of the strokes'in 
 any one cylinder : 
 
 ,A~ 
 
Valves and Valve Mechanism. 89 
 
 Cylinder No. 1 No. 2 No. 4 No. 3 
 
 Power Compression Intake Exhaust 
 
 Exhaust Power Compression Intake 
 
 Intake , Exhaust Power Compression 
 
 Compression Intake Exhaust Power 
 
 In other words, when cylinder No. 1 is firing, 
 No. 2 is on the compression stroke getting ready 
 to fire next. No. 4 is on the intake stroke and 
 No. 3, having just fired, is exhausting. 
 
 In Figure 64 cylinder No. 2 is shown on the 
 power stroke and naturally both valves will be 
 closed. Reference to the tabulation will show 
 that No. 1 should be on the exhaust stroke and 
 it will be evident that the exhaust valve on No. 1 
 cylinder is raised in the figure. No. 3 should be 
 on the intake stroke ; the lifted inlet valve in the 
 illustration proves the correctness, while No. 4 
 should be on the compression stroke with both 
 valves closed; it is found to be so. 
 
 There is one other possible firing order on a 
 four-cylinder engine with this type of crank- 
 shaft, and, in fact, it is the more commonly met 
 with. It is 1, 3, 4, 2. 
 
 In the preceding chapter it was pointed out 
 that the time of opening and closing of the 
 valves was of great importance. While in seek- N ^ 
 ing to obtain an insight into the principles of the \ 
 engine it is well to consider that the valves open 
 and shut exactly on the top and bottom dead 
 centers, as the case may be, and remain open 
 exactly one piston 'stroke up or down or 180 
 degrees of crankshaft movement; as a matter of 
 fact in the practical engine such is not the case 
 by a large margin. 
 
 As a rule, the inlet valve does open, or begin to 
 open, when the piston is very near the top dead 
 center just starting down on its intake stroke. 
 
90 Tractor Engines. 
 
 
 The downward travel of the piston is completed 
 in a very short space of time a fraction of a 
 second when the engine is turning over at its 
 rated speed and in order for the new charge of 
 gas to enter the cylinder through the inlet piping 
 in sufficient quantity to fill the cylinder, its 
 velocity through the constricted passages must, 
 be high. 
 
 It is true that all bodies in motion acquire 
 momentum that is, a tendency to persist in 
 motion. The momentum is measured" by the 
 velocity at which the body is traveling multiplied 
 by the weight of the body. It follows that a 
 cannon ball weighing only a pound but traveling 
 at very high speed can ' have a momentum nu- 
 merically as great as a locomotive weighing 
 thousands of pounds more than the cannon ball 
 but traveling at a greatly reduced pace. 
 
 And so it is with our column of incoming mix- 
 ture; its weight is only a little bit, but its speed 
 is very high, so that the momentum it has ac- 
 quired during the intake stroke 1 is appreciable. 
 We find it worth while to take advantage of this 
 momentum by holding the inlet valve open for a 
 brief interval after the piston has passed bottom 
 dead center, the momentum of the rapidly mov- 
 ing gas column carrying more fuel into the cylin- 
 der and giving us a fuller charge. 
 
 Just how much "lag" is given the closing of 
 the inlet valve with relation to the 'bottom dead 
 center depends upon the size and the speed of the 
 engine, the size of the valves and the design of 
 the inlet port and gas passages. It varies con- 
 siderably in ^different engines. 
 
 In a comparatively few instances this same 
 principle is applied in the case of the exhaust 
 valve; it is held open for a brief interval after 
 top dead center is passed so that the momentum 
 
Valves and Valve Mechanism. 91 
 
 of the gases passing through the exhaust piping 
 will aid in clearing the cylinder and will tend 
 to create a partial vacuum behind it which helps 
 to pull in the fresh gas charge when the inlet 
 valve is opened. Sometimes the inlet valve ac- 
 tually begins to open before the exhaust valve 
 is fully closed, but this is rarely encountered in 
 anything except very high speed racing engines, 
 since it tends to make the engine hard starting 
 and interferes with smooth operation when 
 throttled do\vn for low speed and idling. As a 
 rule, as was said before, the exhaust valve is de- 
 signed to close on top dead center and the inlet 
 valve to open just at that point or a shade 
 afterward. 
 
 But it is of very great value to thoroughly 
 clear the cylinder of all the burned gases after 
 the power stroke. And it is true also that as the 
 piston starts down on the power stroke the 
 effective pressure of the gases drops off very 
 rapidly, so that when the crank is nearing the 
 bottom dead center the pressure is not really 
 worth while taking advantage of. It. is found 
 much better, in the way of smooth operation and 
 economy, to open the exhaust valve while the 
 piston has considerable distance still to travel 
 on the power stroke so as to give ample time for 
 .the spent gases to escape; this also tends to 
 make for cooler running, since the lower sec- 
 tion of the cylinder is not exposed to such in- 
 tensely hot gases. The "lead" which the exhaust 
 valve opening is given on the bottom dead center 
 varies greatly in engines of different design just 
 as the "lag" given the inlet valve opening varies. 
 
 The timing of the valves is a matter with 
 which the tractor owner or operator -has prac- 
 tically nothing to do. The timing determined on 
 by the factory engineer is brought about by the 
 
92 
 
 Tractor Engines. 
 
 design of the cams themselves, the mounting of 
 the cams "with respect to each other on the cam- 
 shaft and the mesh of the timing gear wheels. 
 This latter point is important to the owner, since 
 if the engine is taken apart and the timing gear 
 mesh disturbed, it is important that in putting 
 the engine together again they be properly 
 meshed or else none of the valves on the engine 
 will be timed to open or close at the proper time 
 with relation to the piston travel. 
 
 The exact set- 
 ting of these tim- 
 ing gears is in- 
 dicated both in 
 Figure 64 and in 
 Figure 66. It 
 will be found that 
 on the larger 
 camshaft wheel 
 
 F1G.66 
 
 Fig. 66. Method of meshing tim- 
 ing gears to time engine correctly. 
 
 there is a punch 
 mark on the wheel 
 rim adjacent one 
 of the hollows in- 
 to which the teeth 
 of the pinion fit. 
 On the crank- 
 shaft pinion one 
 tooth will be simi- 
 larly marked with 
 a punch mark. The proper mesh of the gears 
 is accomplished when the punch-marked tooth is 
 caused to mesh with the punch-marked hollow 
 on the camshaft gear. Once this relation is 
 established, all the valves on all the cylinders will 
 be perfectly timed, for it will be remembered 
 that all the cams are forged integral with the 
 camshaft. 
 
 It is well, in taking the engine apart, to make 
 
Valves and Valve Mechanism. 93 
 
 sure that the timing gears are punched. If not, 
 punch-mark them as outlined above before un- 
 meshing them so that they can be put back in 
 proper mesh. This applies to other gears as well. 
 
 A point that should be borne in mind is that 
 there is always a clearance left between the 
 lower end of the valve stem and the upper sur- 
 face of the push rod or tappet; this point is 
 made clear by referring to Figure 65. The rea- 
 son for this clearance is that the valve stem is 
 going to expand under the heat and if it we're in 
 actual contact with the tappet, due to this expan- 
 sion, the head would be raised slightly from the 
 cylinder seat and this would result in leakage. 
 It is highly important that there be a clearance 
 at this point and also important that the clearance 
 be maintained within certain definite limits. If 
 it is too small, the expansion, especially in the 
 case of the exhaust valves, which get tolerably 
 hot, will be sufficient to wipe it out. and the valves 
 will ride on the tappets and leak. If it is too 
 large, the tappet will not come in contact with 
 the valve stem as quickly as it should and the 
 valve will open late as a consequence. By the 
 same token, when the valve is being closed, the 
 tappet will reseat the valve too quickly so that 
 the valve*will not stay open as long as it should 
 and a loss of power and a tendency for the en- 
 gine to overheat will be one result; noisy oper- 
 ation due to the slap of the tappets against the 
 ends of the valve stems will be another annoying 
 result. 
 
 The tappet clearance, as it is -called, should be 
 between 1/16 and 1/32 of an inch, .preferably 
 as close to the smaller dimension as possible. It 
 will vary on different engines, but this is a fair 
 average. It is measured by inserting a slip of 
 metal of the proper thickness between the tappet 
 
94 Tractor Engines. 
 
 top and the valve stem (Figure 67). The clear- 
 ance is properly adjusted when the engine leaves 
 the factory, but it will be affected both by wear 
 of the tappet, cam and valve. stem, causing en- 
 largement, naturally, and by valve grinding, 
 which lowers the valve with relation to the cylin- 
 der and causes a diminishing of the clearance. 
 
 Attention to Valves The valves require more 
 or less regular attention. It is essential that they 
 
 
 
 
 n 
 1 1 >P 
 
 EiLL, IB ; " 
 
 Fig. 67. Adjusting tappet clearance on Waukesha engine. 
 
 seat properly in the cylinder seats in' order to 
 prevent leakage of the compressed gases on the 
 compression stroke and the explosive pressure on 
 the power stroke, for leakage means impaired 
 power and loss of snap and "pep" in the opera- 
 tion of the engine. 
 
 Valve grinding on any engine is not a diffi- 
 cult matter. To accomplish it, first drain the 
 engine, then remove the cylinder head in the 
 same manner as indicated for carbon removal 
 under cylinder repairs, exposing the top or heads 
 
Valves and Valve Mechanism. 95 
 
 of the valves where possible. On the left side 
 of the engine will be found two valve covers; 
 pressed steel plates held in place with two thumb 
 screws. They should be removed, exposing the 
 valve springs and upper ends of the cam fol- 
 lowers. Now with a valve lifting tool, with 
 fork placed under the valve stem and. chain or 
 link fulcrum adjusted so that you get a good 
 purchase (Figure 68), lift the valve spring, hold- 
 ing down the valve head. Holding the spring 
 in the raised position, pull out the pin passing 
 
 Fig. 68. Tools for removing valve cups and valves. 
 
 through the lower portion of the valve stem 
 and which holds the valve spring washer on the 
 stem. Release the spring and lift out the valve 
 which will then be free. 
 
 It is well to remove all the valves at once; 
 they are numbered, and the cylinder seats are 
 numbered to correspond, so that no difficulty will 
 be experienced in getting them back in proper 
 order. Now take some coarse valve grinding 
 paste and apply a thin coating of it evenly all 
 around the bevel surface of the valve and re- 
 place it in position. Then with a valve grinding 
 tool, which is a brace-like tool with a head pro- 
 
96 
 
 Tractor Engines. 
 
 vided with two prongs which are adapted to fit 
 into the two holes formed in the valve head 
 (sometimes the head is slotted to take a screw- 
 driver bit) rotate the valve back and forth from 
 a quarter to a half revolution, Figure 69. Do 
 not rotate it to the full revolution, as it is apt 
 to cause scratching of the valve and its seat. 
 After half a dozen twists of this nature, lift the 
 valve from its seat and put it in another position 
 and repeat the operation. 
 
 Continue this process 
 for a while, then wash off 
 the valve, wipe off the 
 seat and note the condi- 
 tion. When the valve is 
 right, the bevel surface 
 should show a ring of 
 contact with the seat ex- 
 tending entirely around 
 the valve, of oxidized sil- 
 ver appearance, free from 
 pit marks and black lines 
 and free from scratches 
 and ridges. The seat 
 should also be free from 
 pits and scratches. When 
 this result has been 
 achieved, wash off the 
 coarse paste and 
 
 f^f/IVG rc> 
 
 Fig. 69. Method 
 grinding valve to seat. 
 
 of 
 
 the fine or finishing paste and grind for a while 
 to remove any slight marks resulting from the 
 use of the coarse paste. 
 
 When all the valves have been ground in, put 
 them back in the cylinder and proceed to put on 
 the valve springs, washers and pins by the same 
 method as they were r.emoved. Then replace the 
 cover plates and the cylinder head, water pipe 
 and plug cables. 
 
Valves and Valve Mechanism. 97 
 
 Fig. 70. Valve grinding shown in picture. 1st. Remove valve 
 plug, by using a short flat bar. 
 
 Care should be taken in grinding in the valves 
 to see to it that none of the grinding paste gets 
 into the cylinders or the valve stem guides. If 
 only a little paste is used at a time, and wash- 
 ing off the valve and valve seat is carefully 
 done, there will be no trouble on this score. An- 
 
 Fig. 71. 2d. Remove valve spring by turning engine over until 
 the spring is compressed to its utmost. Place a short piece of 
 gas pipe (sawed as per illustration) between the spring and crank 
 case to hold spring in a compressed condition, then turn motor 
 over until the key can be removed from the valve stem. It is 
 not necessary to remove the spring when grinding. . 
 
98 
 
 Tractor Engines. 
 
 other point to watch is to make sure that the 
 
 "erindTJ V ree from the cam when 
 
 are grinding. Sometimes the valve will " he 
 
 shghtly raised by the cam, when, of cour e aH 
 
 he grinding in the world will no i put th e valve 
 
 n good condition, since it is simply rotating on 
 
 the valve stem and not on its seat 
 
Valves and Valve Mechanism. 99 
 
 Figures 70 to 74 illustrate the method to fol- 
 fow in an engine with horizontal cylinders and 
 heads not removable, while Figure 75 shows 
 the method to pursue with a valve-in-head 
 engine. 
 
 If the valves are very badly ridged and the 
 valve seats are in poor condition, reseating must 
 
 Fig. 74. 6th. Use a wide-faced screwdriver-shaped iron, in a 
 common brace. 7th. Press valve against valve sear and give 
 a turn to the right, release pressure, then press again and turn 
 to the left. Keep this up until a good seat is made. 8th. When 
 the grinding is finished, remove the valve and clean away all the 
 valve grinding compound so it does not get down into the 
 combustion chamber and get to cutting the cylinder rings or 
 piston. 
 
 be resorted to. A reseating tool can be obtained 
 at any supply store ; it is simply a tapered 
 reamer. Care should be exercised in using it 
 not to take too deep a cut, which may affect the 
 clearance between the valve stem and the tappet 
 and make' shortening the valve stem necessary. 
 A valve truing tool is made for putting the valves 
 into good condition ; it acts in a manner similar 
 
100 
 
 Tractor Engines. 
 
 to the reseating tool except that instead of fitting 
 into the seat and being turned around, the valve 
 fits into the tool and is rotated against several 
 cutting edges which correctly bevel it. After 
 reseating the cylinder seats and trimming down 
 the valves properly, they must be ground in to a 
 perfect fit as indicated above, since the cutting 
 tools do not leave them in condition to seat 
 perfectly. 
 
 If a good, true lathe is handy, there is no need 
 
 . for using a 
 
 special tool to 
 trim down the 
 valves, since 
 they can be 
 mounted in 
 the chuck of 
 the lathe and 
 rebeveled 
 with little or 
 no trouble. 
 Care should 
 be exercised 
 to set the 
 slide rest on 
 the lathe to the correct angle to insure a perfect 
 fit of the bevel surface on the valve with the 
 bevel of the cylinder seat ; care should also be 
 used not to mar the valve stems when mounting 
 them in the lathe chuck. 
 
 If, when the valves have been removed, it is 
 found that the head is warped so badly that trim- 
 ming down the valve will not bring it into proper- 
 shape, the best plan is to discard it and replace it 
 with a new valve. Sometimes it will be found 
 that the head is not perfectly true with the stem. 
 This can generally be corrected by replacing the 
 valve in the cylinder, making sure that it is off 
 
 . - "iinnr 
 
 COMPOUND 
 
 Fig. 75. Grinding valves on "valve-in- 
 head" engine. 
 
Valves and Valve Mechanism. 101 
 
 the cam, and giving it a good sharp whack in the 
 middle, using a soft drift of brass or mild rolled 
 steel to take trie actual hammer blow and protect 
 the cylinder against damage should the hammer 
 _ aim be poor. Where the valve stem is found to 
 be badly bent, it is best to insert a new valve and 
 not to bother with the old one, as it is very likely 
 to stick in its guide and render the cylinder in- 
 operative. When grinding the valves and before 
 
 replacing them, re- 
 move all the car- 
 bon deposit from 
 both the upper and 
 lower sides of the 
 valve head and 
 clean the valve 
 stem, removing any 
 carbonized oil and 
 roughness with a 
 strip of emery cloth 
 used as shown in 
 Figure 76. The 
 emery cloth should 
 be carefully used 
 so as not to take 
 
 too much off the valve stems, for it is essential 
 that they be a comparatively tight fit in the valve 
 stem guides. There should just be freedom 
 enough for them to slide up and down easily 
 without any tendency to stick; the looseness 
 . should not be appreciable. 
 
 If any of the valve springs are found to. be 
 weak and not of the same length as the average 
 spring, it is well to replace the poor ones with 
 new springs. A weak spring, especially on an 
 exhaust valve, will have a tendency to cause the 
 engine to lag and run unsteadily, the cause of 
 which sluggish action is difficult to locate. 
 
 FIG. 
 
 Fig. 76. Method of polishing 
 the valve stems. 
 
102 
 
 Tractor Engines. 
 
 Generally, valve grinding and carbon removal 
 are done at the same time, since both will be 
 necessary at about the same intervals and both 
 require disassembling the engine to about the 
 same degree. It is well, therefore, to count on 
 grinding in the valves each time the engine 
 taken down for carbon removal. 
 
 While the method of checking up on the tim- 
 ing of the valves will differ with every individual 
 make of engine, as indeed the' timing of the 
 valves will differ, if the method to be followed in 
 any one engine is applied to other makes, the 
 tractor operator will not be far from wrong. It 
 .is a fact that with most engines the timing of 
 the valves with relation to the crankshaft is in- 
 dicated by distinct markings on the flywheel 
 which show exactly when a valve should open 
 and close, and give indication of wrong timing 
 in case loss of power cannot be attributed to any 
 other cause. The following method applies to 
 the Twin City tractor engine and indicates clearly 
 the procedure on similar motors : 
 
 Markings on the Flywheel The diagram, 
 Figure 77, shows the points at 
 which the valves in one cylin- 
 der open and close. It must 
 always be remembered that it 
 takes two complete revolutions 
 to complete a four-cycle phase. 
 
 Now suppose the center 
 mark on the flywheel is in line 
 with the pointer located on the 
 center line of the motor. By 
 rotating the flywheel to the 
 right, the first mark indicates 
 the point at which the exhaust 
 valve just closes-. 
 
 The next mark is the point 
 
Valves and Valve Mechanism. 103 
 
 Fig. 78. Timing diagrams for Twin City engines. 
 
 at which the intake valve is just commencing to 
 open and remains open (which is the suction 
 stroke) until the intake closing mark is reached, 
 which is located past bottom dead center or op- 
 posite the intake opening mark. Continuing to 
 rotate compresses the charge until the top center 
 mark is reached, when the electric spark ignites 
 the charge. 
 
 When starting a motor the spark is retarded 
 or takes place after piston is on top center, but 
 when motor is up to speed and the maximum 
 power is required, the spark takes place before 
 top center is reached, which is the advance posi- 
 
 Fig. 79. Timing diagrams for Twin City engines. 
 
104 Tractor Engines. 
 
 tion. This can be done because the high speed 
 makes it possible to reach top center and past 
 before the gas is really ignited and expanded. 
 
 Advancing the spark too far will make the 
 motor pound, which is caused by the explosion 
 taking place too early and the full force is ap- 
 plied when the piston is still compressing the 
 charge. 
 
 Continuing to rotate until the next point is 
 reached is the exhaust just commencing to open. 
 This will remain open until the exhaust closing 
 point is again reached. 
 
 To place any one piston at the top center, ro- 
 tate the flywheel until the intake closes and the 
 center mark on the flywheel next reached will 
 bring that piston in the top center position. 
 
 The position of the marks on the flywheel, 
 measuring along the circumference, is as follows : 
 
 T. C.40&60 T. C.25 T. C. IS 
 
 Intake opens past top center 3^ 3>y 2 1^4 
 
 Intake closes past lower center. . 4%2 2 2 %2 
 
 Exhaust opens before lower center 9 l Vs2 T 7 A 6%6 
 
 Exhaust closes after top center.. 2%4 ! 31 /&2 U /LQ 
 
 These are illustrated graphically in Figures 
 78 and 79. 
 
 EXACT SETTING OF VALVE FOR PROPER TIMING 
 ON MOTOR OF BULL TRACTOR. 
 
 Set so that exhaust valve opens 36 before 
 center. 
 
 Set so that exhaust valve closes 8 after center. 
 Set so that intake valve opens 14 after center. 
 Set so that intake valve closes 20 after center. 
 
 INCHES ON FLYWHEEL. 
 
 36 8 5 / 32 inches. . 8r=l 13 / 16 inches. 
 14=3 3 /i6 inches. 20=4 1 V 32 inches. 
 
Valves and Valve Mechanism. 105 
 
 Fig. 80. Timing of Bull tractor engine. 
 
 Time of 
 opening or 
 closing, stated 
 as before and 
 after center, 
 refers to di- 
 rection of 
 motor rota- 
 tion. 
 
 All opening 
 and closing 
 distances 
 shown should 
 b e measured 
 on flywheel 
 
 rim only and from center arrow. Never remove 
 flywheel from crankshaft without marking posi- 
 tion so you will get it back just as it was before 
 rempved. 
 
 Crankshaft and camshaft gears are marked 
 and set as follows : 
 
 Short or R. H. shaft set to marks Nos. 1. 
 Long or L. H. shaft set to marks Nos. 2 
 (Figure 80). 
 
 After the valve grinding operation, of course, 
 it always will be necessary to readjust the valve 
 
 tappet clear- 
 ance to bring 
 it back to the 
 manufacturer's 
 specifications. 
 Like the valve 
 timing check- 
 ing, the method 
 to be followed 
 in effecting 
 this adjustment 
 will depend to 
 
 Fig. 81. Adjusting 
 overhead valve engine. 
 
 push rods on 
 
106 Tractor Engines. 
 
 a greater or less extent on the type of engine, 
 and especially on the type of valve arrangement 
 employed. 
 
 Figure 67 indipates clearly the method to be 
 followed in effecting the adjustment on an L- 
 head engine, a rule or stick being employed to 
 determine the position of the piston with rela- 
 tion to the stroke and a feeler gauge used to de- 
 termine the proper clearance. The adjustment 
 of the tappets is made by opening the locknut 
 holding the tappet adjusting screw, in place on 
 top of the tappet and unscrewing the screw 
 slightly to take up some of the clearance in case 
 of wear, or screwing it down in case the adjust- 
 ment is too tight. Figure 81 shows how the ad- 
 justment is made in the case of an overhead 
 valve engine, the picture illustrating the method 
 of adjustment used in the case of the Case 
 10-18 model. 
 
CHAPTER V. 
 
 About the Fuel System. 
 
 Some Thoughts on the Fuel Burned in Tractor 
 Engines and the Means for Obtain- 
 ing Best Results. 
 
 WHILE in the automobile field we find that 
 gasoline is the universal fuel, and that 
 practically every make of car and truck is 
 adapted to burn this light hydrocarbon fuel and 
 none other, this standardization of fuel is by no 
 means apparent in the tractor industry. 
 
 The reason is not hard to find. The tractor 
 engine, operating as it does on almost full load 
 throughout the en- 
 tire day, consumes 
 considerable fuel 
 (Fig. 82) ; if, then, 
 we employ a low- 
 cost fuel as against 
 
 a hicrh-rnct nrf Fi S- 82 - The gasoline tank 
 
 ne ' tells the story. Exact relative 
 
 Other thing's being" size of gasoline and oil fuel tanks 
 
 i rr 6 r on the 14-28 Oil Pull Tractor. 
 
 equal, the cost of 
 
 operation of the tractor is greatly reduced. 
 
 As has been repeatedly pointed out in the case 
 of the tractor engine, flexibility is not required 
 to anywhere near the same extent as with the 
 automobile engine ; the use of kerosene, therefore, 
 is not at all objectionable, always provided the 
 means for handling it are sufficiently well carried 
 out so the engine will idle while hitches are being 
 made, and other adjustment effected preparatory 
 
 (107) 
 
108 Tractor Engine's. 
 
 to starting in on the hard work, and immediately 
 pick up and carry the full load without faltering 
 or loading up. 
 
 Where kerosene has failed as a motor fuel for 
 tractor service, the fault has been that idling 
 was generally followed by bad operation, due to 
 the reduction of temperatures, so that when the 
 throttle was opened to give the fuH load, the 
 heavy fuel was not properly handled. 
 
 An internal combustion tractor motor to per- 
 form the function of burning kerosene in the 
 most successful and advantageous manner must 
 embody in its design and construction the fol- 
 lowing elements: 
 
 1.* A double carburetor with one side con- 
 nected to the gasoline supply tank, which can 
 be properly adjusted and used for starting and 
 heating up the engine. 
 
 2. The other carburetor connected to the 
 kerosene or distillate supply tank and properly 
 adjusted so that the intake air lines to the motor 
 may be instantaneously switched from communi- 
 cation with one carburetor to the other, as the 
 circumstances may require. 
 
 3. The pipe lines from the kerosene or dis- 
 tillate tank must be through some portion receiv- 
 ing heat from the exhaust that will raise the 
 temperature of this low-grade fuel to a point 
 not above 90 degrees F., nor_below 75 degrees F. 
 
 4. The kerosene carburetor must have its 
 inlet connected to a housing around the exhaust 
 pipe so that . when the exhaust pipe becomes 
 heated 'the air passes into the carburetor at a 
 temperature not below 80 degrees. 
 
 5. With the air and the fuel at the respective 
 temperatures above given, meeting in the carbu- 
 retor, the mixture is readily formed. 
 
About the Fuel System. 109 
 
 6. The mixture thus formed must be turned 
 into gas (air-charged kerosene is not yet a gas). 
 Therefore, in traveling through the intake pipe, 
 it must be brought into contact with the surfaces 
 of the intake pipe, made hot on the exhaust pipe 
 (called a gasifier Figure 83). Passing over 
 these heated corrugated surfaces in a circular 
 path and finally traveling upwards into the cylin- 
 der, the centrifugal action throws the heavier 
 particles of kerosene against the heated wall, and 
 
 the heat transforms 
 the kerosene - charged 
 air into a dry gas 
 which will instantane- 
 ously fire and burn 
 quickly and completely. 
 
 7. In the passage- 
 way between the gasi- 
 fier and the intake 
 valve, a valve must be 
 provided through 
 which outside air can 
 be taken in, which will 
 temper this gas mix- 
 Fig. 83. Cross-section of the. tUre and re <J UCG th <T 
 
 Avery gasifier. temperature of it, and 
 
 A-Fuei mixture coming from thereby prevent the 
 
 carburetor and entering gasifier. 1 QSS thrOUgh expansion 
 
 B Fuel mixture thoroughly & 
 
 gasified and entering cylinder. due tO the temperature 
 
 .J-Exhaust coming from cyl- re q uired to gasify the 
 
 grMitS?- fure. - m 
 
 8. Provision for in- 
 jecting water (Fig. 85) with the kerosene and 
 low-grade fuels is necessary to prevent carbon 
 deposits and knocking due to preignition. It is 
 not necessary to start the water for a few min- 
 utes, and under some conditions of temperature 
 very little water is required. When preignition 
 
110 
 
 Tractor Engines. 
 
 takes place, water is required, but only just in 
 sufficient quantity to prevent the knock. Too 
 much water is indicated by a white vapor through 
 the exhaust of the engine. 
 
 9. The thermo-syphon system of circulating 
 
 INTAKE ^^M OIF OLD 
 
 f/G. 84 
 
 Fig. 84. Section through Buckeye-Deppe Integrator, showing 
 carburetor arrangement for heating the fuel and air and the me- 
 chanical atomizer in the form of a whirling fan placed above the 
 special center-opening throttle. 
 
 the cooling water is beneficial in the matter of 
 burning kerosene, because it automatically starts 
 the water circulating as soon as sufficient heat 
 has been generated within the engine for burn- 
 ing the heavy fuel. A circulating pump is not 
 
About the Fuel System. Ill 
 
 so desirable, because at certain seasons of the 
 year the cooling water is circulated too fast for 
 the temperature prevailing and keeps the tem- 
 perature of the water top low for good operation, 
 causing condensation in the cylinders; and when 
 the mixture is not thoroughly gasified, or be- 
 comes condensed, passage of the fuel by the 
 pistons is sure to be the result. 
 
 While kerosene is greatly used in the tractor 
 field, its increasing price, bringing it well up 
 
 into the price class 
 with the lighter gaso- 
 line, coupled with the 
 fact that certain diffi- 
 culties have resulted 
 in a good many in- 
 stallations, because 
 the principles on 
 which the proper op- 
 eration of a kerosene 
 engine depended have 
 not been fully under- 
 stood, have' resulted 
 in many tractor engi- 
 neers retaining the 
 gasoline fuel in pref- 
 erence to the kerosene. 
 Both gasoline and 
 kerosene are more or 
 less volatile liquids obtained' from the distillation 
 of crude petroleum. This heavy, black, smelly 
 oil, which i$ drawn from wells which flourish in 
 several parts of the United States and in many 
 foreign countries, is put into a still and the tem- 
 perature raised until certain of the lighter con- 
 stituents contained in the crude oil boil off. 
 
 The first vapors to pass off are too light for 
 use as motor fuel, and the general process is to 
 
 Fig. 85*. Aultman-Taylor heavy 
 fuel carburetor showing water 
 injection apparatus. 
 
112 Tractor Engines. 
 
 condense them and pass them back into the still, 
 where they assist in breaking up the heavier con- 
 stituents, producing the lighter hydro-carbons 
 which are adaptable for internal combustion en- 
 gine use. After all the light vapors have passed 
 off, the temperature is elevated slightly and boil- 
 ing again takes place, and we have another yield 
 of vapor which, when condensed in a cooling coil 
 outside % the still, is found to possess a boiling 
 point somewhat higher than the first fraction to 
 come over on the starting process. 
 
 This process of boiling off all the liquid that 
 will distill at a given temperature and collecting 
 the condensed liquid, then elevating the tempera- 
 ture slightly, causing the next fraction to distill 
 over and piping the distillate into another tank, 
 is continued until nothing is left in the still ex- 
 cept residue. Roughly, the process yields gaso- 
 line, naphtha, benzine, kerosene, distillate, heavy 
 fuel oil, light lubricating oils, medium lubricating 
 oils, heavy Jubricating oils, petroleum jelly, paraf- 
 fin wax or asphaltum, when the crude oil is of 
 asphalt instead of paraffin base. 
 
 This classification is very rough. As a matter 
 of actual fact, the number of liquids with dif- 
 ferent boiling points that can be separated from 
 the crude oil is almost indefinite, so that any one 
 of the above-mentioned oils really consists of a 
 large number of oils of different boiling points, 
 with these boiling points falling within a given 
 range. 
 
 Good gasoline will consist of liquid^ with boil- 
 ing points between 100 degrees F. and 350 de- 
 grees F. ; its specific gravity weight of a cubic 
 inch of gasoline at a given temperature compared 
 with an equal volume of water at the same tem- 
 perature or its Baume reading, which gives a 
 similar comparison by another standard or scale, 
 
About the Fuel System. 113 
 
 has no bearing on its value as a fuel, a point 
 which the average operator finds it hard to be- 
 lieve. 
 
 What we really want in a gasoline motor fuel 
 is one which will vaporize readily; that is, one 
 in which the whole body of the fuel will vaporize 
 within a comparatively short temperature range. 
 We can have such a fuel, and its gravity as given 
 by Baume reading may be 56 degrees; but pro- 
 vided the boiling points of its various constituents 
 are within a comparatively short temperature 
 range, and the maximum temperature is not so 
 high as to preclude ready vaporization of the 
 fuel at ordinary temperatures, it will be a good 
 fuel. 
 
 If, on the other hand, we have a fuel made 
 up of one distillate say, for instance, kerosene 
 with high boiling point and low gravity and 
 some other hydro-carbon such as first comes over 
 from the still with very low boiling point and 
 high "Baume test, the average or mean Baume 
 test of the two mixed together may stand as 
 high as 70 or 75 degrees Baume and the fuel 
 will not be as good for motor use as the first 
 with lower Baume test. The reason is easily 
 found; the lighter portion of the fuel will va- 
 porize readily, making the engine easy to start, 
 but will 1'eave behind the heavier portion of the 
 fuel, not so readily vaporized, which will be 
 troublesome. 
 
 It is readily seen, therefore, that it is fallacious 
 to attempt to judge the quality of gasoline by 
 the specific gravity or Baume tests, either of which 
 tests are carried out with an instrument called 
 a hydrometer, differently graduated in accord- 
 ance with which standard is adopted. The only 
 reliable test to determine the value of a fuel is 
 the distillation test, which gives the range of the 
 
114 
 
 Tractor Engines. 
 
 boiling points of the constituents of which the 
 fuel is composed. 
 
 In the case of kerosene fuel, we have not the 
 real need to worry over the distillation curve or 
 any other form of test, for it is a fact that any 
 engine adapted to handle kerosene properly will 
 work well with any kerosene which the present 
 market affords. 
 
 . ' THROTTLE STOP*'. 
 THROTTLE LEVEft "--- s 
 
 NEEDLE VALVE 
 
 BiNOiN'G NUT 
 CHOKE VALVE -LEVER 
 
 TTLE STOP SCREW 
 
 AIR VENT 
 
 FLOAT VALVE PLUG 
 
 TAKE OUT SCREW 
 fO REMOVE. FLOAT 
 
 CONNECTION 
 TO TANK 
 
 . 86 
 
 Fig. 86. Carburetor from Case 10-18 tractor. 
 
 % 
 
 While, as indicated above, there are some 
 special conditions to be taken into consideration 
 when kerosene is the fuel used, in the broadest 
 sense the principles upon which the vaporization 
 of the fuel depends does not vary. With either 
 fuel in tractor application, we employ a carbu- 
 retor (Figure 86) to assist in the operation. 
 
 The purpose of the carburetor is three-fold. 
 It is a fact that no substance, be it air or solid, 
 will take fire and burn until converted into the 
 
About the Fuel System. 115 
 
 gaseous state. The quicker the substance is con- 
 verted into the form of a gas, the more rapid 
 will the combustion be. It stands to reason, 
 therefore, that in order to obtain very rapid com- 
 bustion of our fuel we must convert it to a state 
 where it will be very rapidly transformed into a 
 true gas which will readily take fire and in burn- 
 ing liberate' the desired quantity of heat to ac- 
 complish the work on the top of the piston. 
 
 That is the primary function of the carburetor. 
 It is so arranged that it divides the liquid into 
 an infinite number of very fine particles ; breaks 
 it up, pulverizes or atomizes it so that the fuel, 
 being held in suspension in the air after emerg- 
 ing from the carburetor where it has undergone 
 this treatment, is in fine condition to be readily 
 converted into a true gas. This result is brought 
 about in very much the same manner as perfume 
 is sprayed from an atomizer. In the carburetor 
 there is a nozzle which corresponds to the spray 
 nozzle of the atomizer, and the rush of air across 
 the orifice of this nozzle occasioned by the suc- 
 tion of the cylinders when the pistons are going 
 down on their intake strokes, causes the fuel to 
 flow from this nozzle in the form of a fine spray, 
 whic^h is taken up by the passing air column and 
 carried into the cylinders. 
 
 It is also a fact, that any substance which is 
 burning combines in definite proportions with 
 oxygen gas which is present in the air. For 
 complete combustion of any fuel a given amount 
 of this gas must be supplied for a given amount 
 of the fuel ; if the oxygen is drawn from the air 
 a fixed amount of the air sufficient to supply the 
 required amount of oxygen must be supplied or 
 else the combustion will not be complete. 
 
 It so happens that with gasoline, in order to 
 supply sufficient oxygen, 16 times as much air 
 
116 Tractor Engines. 
 
 by weight is required as of gasoline. Such a 
 mixture of gasoline and air, with the fuel 
 thoroughly vaporized, would be the theoretically 
 perfect mixture. There is present in the air, 
 however, an inert or inactive gas called nitrogen, 
 which retards the speed with which the mixture 
 will burn, and in order to counteract the slowing 
 up effect of this inert gas it is necessary to 
 supply a greater amount of fuel than one part 
 to sixteen, and so the usual carburetor, when in 
 good adjustment, is set to supply approximately 
 ten times as much air by weight as of fuel ; this 
 is the practical ideal mixture, while the 16 to 1 
 mixture is the theoretical ideal one. 
 
 The second function of the carburetor is to 
 proportion the amount of fuel to air to maintain 
 this correct mixture throughout every condition 
 of speed and power. If the carburetor does not 
 maintain this mixture correct, it is evident that 
 at some speeds we will have a mixture with an 
 excess of fuel present which will be slow- 
 burning, sluggish and wasteful of fuel and we 
 will not get full power from the engine. At 
 other speeds we will get a mixture with an ex- 
 cess of air, whicrj also will be slow-burning and 
 from which we will not get sufficient heat and 
 pressure to cause the engine to develop *full 
 power, while at other speeds we will get a per- 
 fect mixture and the engine will perform well. 
 
 The modern carburetor has been developed to 
 a point where it will maintain this most necessary 
 constancy of mixture proportions throughout the 
 entire speed range of the engine, giving us flex- 
 ible operation, economy from the fuel standpoint 
 and maximum power but above all, perfectly 
 steady and reliable operation, with no tendency 
 for the engine to falter, stop or stall. 
 
 The carburetor is one other important func- 
 
About the Fuel System. 117 
 
 tion to perform which is sometirries overlooked. 
 It incorporates in its makeup a shutoff valve 
 applied to the passage, by which the mixture 
 leaves the carburetor and finds its way to the 
 intake manifold, through which it is conducted 
 to the cylinder. This is the throttle valve, and 
 its purpose is to control the amount of mixture 
 delivered to the cylinders and consequently the 
 power developed by the engine and the speed or 
 pulling ability of the engine. 
 
 It will be well, perhaps, to give some thought 
 to basic principles on which carburetors as a 
 whole depend. In order to eliminate complica- 
 tions, for the present, let us consider that the 
 throttle valve is missing and that the carburetor 
 consists of a simple nozzle or jet protruding into 
 an air passage connected with the cylinders. If 
 we neglect the friction of the air piping, it is 
 evident that the amount of air which will pass 
 through the pipe will be proportional to the speed 
 of the engine. In other words, the engine acts 
 as a pump ; at a given number of revolutions per 
 minute it will pump a certain amount of air, de- 
 pending on the piston displacement ; at double that 
 speed it will pump very nearly twice as much air. 
 
 The force which is actually causing the air 
 to flow into the cylinders is the pressure of the 
 atmosphere. The pistons are drawing the air 
 out of the manifold, reducing the pressure in 
 the manifold from about 15 pounds per square 
 inch, or atmospheric pressure, to something less 
 than that amount, depending on the speed of the 
 engine. Let us suppose that at the lower speed 
 cited in the case above, the pressure in the mani- 
 fold was reduced to 10 pounds per square inch ; 
 then at the air opening on the carburetor we 
 have an effective pressure of five pounds per 
 square inch, causing the air to enter and 'flow 
 
118 Tractor Engines. 
 
 through the tubing or piping to the cylinders. 
 If now we double the speed of the engine we 
 still further decrease the pressure in the mani- 
 fold, let us say, to five pounds per square inch, 
 so that we have a pressure of ten pounds per 
 square inch forcing the air through the piping; 
 and naturally its flow will be somewhere near 
 double the rate at lower speed and approximately 
 twice as much will pass through in a given time. 
 
 This reduced air pressure in the manifold is 
 important, as is also its variation with the speed 
 of the engine. In the nozzle which projects into 
 the air pipe we have the fuel, the level controlled 
 so that it stands just at the top of the jet. When 
 the air pressure is reduced in the manifold, since 
 "we have the pressure of the atmosphere acting 
 on the other end of the fuel line leading to the 
 noaele, w % e naturally have a pressure exerted to 
 , force the fuel out of the nozzle into the mani- 
 fold where it mixes with the rapidly moving air 
 column. The fuel is atomized by passing through 
 a comparatively fine nozzle, sometimes of special 
 shape. This atomization is furthered by the 
 rapid movement of the air column. 
 
 Naturally, at higher speeds, with the manifold 
 pressure reduced, we are going to have more 
 pressure action on the liquid column, tending to 
 cause it to flow at faster pace and in greater 
 quantity into the manifold. If the laws govern- 
 ing the flow of air through tubing under reduced 
 pressure and those governing the flow of liquids 
 through nozzles under reduced pressure were the 
 'same, it is evident that from this simple arrange- 
 ment we would get a constant mixture of gasoline 
 and air at all speeds. k 
 
 Such, however, is not the case. The flow of 
 liquid through the nozzle increases more rapidly 
 with the falling off in manifold pressure than the 
 
About the Fuel System. 119 
 
 flow of the air through the pipe so that at high 
 speeds we get a mixture with an excess of fuel, 
 or, as we say, an over-rich mixture. 
 
 If, therefore, we adjust the fuel nozzle so as 
 to give us the correct mixture at low speeds, it 
 is evident that at high speeds we are going to 
 get a rich mixture. If, on the other hand, we 
 adjust it to give us the correct mixture at high 
 speeds, at low speeds the mixture is going to be 
 
 <BE:. _., _ BINDING NUT 
 
 SECONDARY ' ^mEPPS '- J^ CHOKE VALVE 
 
 AIR VALVE 
 
 REMOVABLE FLOAT 
 VALVE SEAT 
 
 .Fig. 87. Sectional view of carburetor. 
 
 lean there will not be enough fuel for the 
 amount of air supplied. This result is due to the 
 difference in flow between the air and the liquid 
 columns under the differing manifold pressures. 
 If we bear this relation distinctly in mind, we 
 will not have the slightest difficulty in thoroughly 
 grasping the construction and the principles 
 of operation of the carburetor applied to almost 
 any tractor engine. One from a Case 10-18 
 
120 Tractor Engines. 
 
 tractor is shown in cross-sectional form to make 
 its construction plain, in Figure 87. The fuel 
 enters from the tube leading from the tank at 
 the point marked "Float valve" and flows down 
 into the bowl of the carburetor. In this bowl 
 there is a cork float in the shape of a ring to 
 which is attached a small lever hinged or ful- 
 crumed to the top of the float chamber. The other 
 arm of this lever is arranged to press against the 
 gasoline intake needle. As the float rises with 
 the level of the incoming gasoline, it gradually 
 brings the lower or pointed end of this needle 
 into contact with a valve seat, clearly indicated 
 in the figure, and closes off the gasoline so that 
 no more can enter the bowl. This float mechan- 
 ism is so arranged as to maintain a constant level 
 of the fuel in the float chamber at all times. 
 
 The air. enters the carburetor through a hori- 
 zontal passage on the side marked "Air intake," 
 and this passage is bent downward to form a 
 well, an4 at the same time its diameter is de- 
 creased so that at the deepest section of the well 
 the area of the passage is at a minimum. Just 
 at this point is located a needle valve passing 
 through the well and closing the gasoline passage 
 between the well and the float chamber. Nor- 
 mally, this valve is opened just enough to provide 
 sufficient gasoline for full power operation of 
 the engine. The needle valve, however, permits 
 of very accurate regulation of the amount of fuel 
 which can enter the air passage from the float 
 chamber. 
 
 Coming up from the well, the air passage 
 broadens out again and takes a vertical path, and 
 just where it enters into the comparatively broad 
 mixing chamber is placed a hinged valve, called 
 the secondary air valve. It will be appreciated 
 that this valve will be fully closed, due to its 
 
About the Fuel System. 121 
 
 own weight, which is carefully proportioned to 
 the conditions obtaining on the Case engine, so 
 that the passage of the air is stopped or nearly 
 stopped. 
 
 Reference to the diagram will show that the 
 needle valve proper is surrounded with a cylin- 
 drical passage or air bypass, by means of which 
 a certain limited quantity of air can pass into the 
 mixing chamber from the well even with the 
 secondary air valve, closed. When the suction 
 on the manifold increases, due to increased work 
 being done by the engine, as when the throttle 
 is opened, the air valve opens automatically, per- 
 mitting an increased amount of air to enter the 
 mixing chamber. 
 
 The "float valve is so arranged that it main- 
 tains the mixture exactly at the proper level to 
 permit a slight overflow into the well, maintain- 
 ing a puddle when the engine is not in operation. 
 Considering now that the engine is cold, the 
 operator will turn the engine over and the enter- 
 ing air will rush through the well at very high 
 velocity, due to the constricted passage. The 
 high velocity, however, entails a drop in pressure, 
 so that at the spray nozzle controlling the en- 
 trance of the fuel into the well we will have a 
 partial vacuum formed. The flow of gasoline 
 into the well will, therefore, be started auto- 
 matically the instant the engine is turned over, 
 and the amount flowing will depend on the veloc- 
 ity of the air and the suction which it creates in 
 the constricted passage. 
 
 The entering air will impinge on top of the 
 puddle and supply the excess amount of gasoline 
 to air mixture in order to provide a rich mixture 
 for starting while the engine is cold; after the 
 first few revolutions, however, the well will be 
 sucked dry and all the gasoline supplied will 
 
122 Tractor Engines. 
 
 come through the needle valve and the spray 
 nozzle. But at the spray nozzle the air passage, 
 considering low speeds, is greatly narrowed, forc- 
 ing the air to* assume very high speeds through 
 the cylindrical bypass around the needle valve. 
 The high velocity entails great suction so that 
 sufficient gasoline is drawn through the needle 
 valve in- order to provide the constant mixture 
 for low throttle operation. 
 
 The opening of the secondary air valve pro- 
 portions the amount of air flowing directly into 
 the mixing chamber to the amount flowing 
 through the bypass, and consequently regulates 
 the suction on the needle valve in exact accord- 
 ance with the amount of air flowing to provide 
 just the correct gasoline flow to determine a 
 constant mixture. 
 
 From the carburetor the mixture passes into 
 the inlet manifold, which is a branched pipe 
 leading the mixture to the intake port on each 
 cylinder; the amount of mixture entering the 
 manifold is controlled by the throttle valve, which 
 is simply a disc of brass of a diameter substan- 
 tially equal to the internal diameter of the mix- 
 ture passage in the carburetor and mounted on 
 a horizontal spindle which when turned by the 
 lever sets the disc either to close the passage or 
 open it, or to give any desired intermediate open- 
 ing as required by the operating conditions and 
 the amount of power it is desired to take from 
 -the engine. As a matter of fact, the throttle 
 valve never comes to a fully closed position when 
 the carburetor is in correct adjustment; there is 
 always a slight opening maintained by a screw 
 adjusted stop on the throttle lever so that even 
 when the throttle control lever is fully closed, 
 sufficient fuel will pass the valve to keep the en- 
 gine running at low speed idling, as it is termed. 
 
About the Fuel System. 123 
 
 A second butterfly valve is placed in the air 
 intake pipe on the carburetor ; it is called a choke 
 valve and is operated by a lever. Normally, with 
 the engine running, regardless of speed, this 
 valve stands fully open and is held so by a spring. 
 In starting, however, especially in chilly weather, 
 it is desirable to provide a rich mixture ; consid- 
 erably richer than the running mixture, because 
 with cold air the gasoline is harder to convert 
 into a true gas; less of it is so converted and 
 more must be supplied to make up for the 
 
 deficiency. Instead of 
 supplying more gaso- 
 line by opening the 
 needle valve further, 
 the choke valve is 
 partially closed so 
 that less air is sup- 
 plied, which also has 
 the effect of reducing 
 the atmospheric pres- 
 sure in the mixing 
 chamber of the carbu- 
 retor so that there is 
 a large flow of fuel 
 into the well, the com- 
 bined strangulation of 
 the air and increased flow of gasoline giving 
 the necessary rich mixture for starting. 
 
 The cup or bowl of the Linga carburetor 
 (shown in Figures 88 and 89) has three com- 
 partments for gasoline, kerosene and water. 
 Each compartment has a float. 
 
 The 'gasoline, which is used for starting, and 
 the kerosene are both supplied to the engine 
 through a common opening controlled by the fuel 
 needle valve (8). The water is fed through the 
 water needle valve (11). 
 
 Fig. 88. The Linga Vaporizer. 
 
124 
 
 Tractor Engines. 
 
 To change from gas- 
 oline to kerosene, or 
 the reverse, it is only 
 necessary to tilt the 
 fuel switch (12) from 
 one side to the other. 
 When tilted to the 
 right it holds the kero- 
 sene needle (10) down 
 on its seat, which 
 closes the opening be- 
 t w e e n the kerosene 
 compartment and the 
 fuel needle valve. In 
 this position the gaso- 
 line needle (9) is lifted 
 and gasoline is admit- 
 ted to the fuel needle 
 valve. 
 
 If the fuel switch (13) 
 is tilted to the left the 
 gasoline passage closes 
 and that of kerosene 
 opens. If the switch 
 (13) is placed in a 
 vertical or middle po- 
 sition the vaporizer 
 will feed a mixture of 
 half gasoline and half, 
 kerosene. 
 
 The kerosene needle 
 valve has a stronger 
 spring than the gaso- 
 line needle, so ordinar- 
 ily the kerosene pas- 
 sage will remain open 
 and close the gasoline 
 passage. For starting 
 
 n<3. 39 
 
 Fig. 89. Sectional view of 
 Linga Vaporizer. 
 
 Linga. Vaporizer Parts. 
 
 1. Bowl with three compart- 
 ments. % 
 
 2. Vaporizer Body. 
 
 3. Auxiliary Air Valve. 
 . 4. Auxiliary Air Valve. 
 
 5. Valve Cage* 
 
 6. Drip Bell. 
 
 7. Nut. 
 
 8. Fuel Needle Valve. 
 
 9. Switch Needle. 
 
 10. Switch Needle. 
 
 11. Water Needle Valve. 
 
 12. Packing Nut. 
 
 13. Fuel Switch. 
 
 14. Fuel Switch Nut. 
 
 15. Throttle Valve. 
 
 16. Throttle Lever. 
 
 17. Throttle Stud. 
 
 18. Throttle Nut. 
 
 19. Connecting link or throttle 
 lever shoulder. 
 
 20. Spring. 
 
 21. Spring. 
 
 22. Float Valve Screw. 
 
 23. Float Needle. 
 
 (Bronze Balls are used on 
 some sizes). 
 
 24. Float Arm. 
 
 25. Float. 
 
 26. Stud. 
 
 27. Compression Coupling. 
 
 28. Throttle Screw. 
 
 29. Drain Cock. 
 
About the Fuel System. 125 
 
 on gasoline the fuel switch must be tilted to the 
 right and held there by fastening the thumb nnt. 
 
 The air intakes are at the bottom. The ini- 
 tial air (about one-fifth of the total) is drawn 
 through the nozzle tube in the center. This is 
 the hot air taken from a jacket around the ex- 
 haust pipe. The fuel is drawn into this hot air 
 jet and evaporated. 
 
 The auxiliary air is admitted through the two 
 annular slots around the center tube. The valves 
 are two annular rings of such weights as will 
 insure the best running of the engine at high 
 and low speed. 
 
 The governor on the engine acts directly on 
 the butterfly valve of the carburetor. You will 
 notice a little projection or shoulder fastened to 
 the butterfly valve lever by means of a nut. 
 When the engine is running idle or empty the but- 
 terfly valve or throttle closes and this little shoul- 
 der strikes the fuel switch, tilting it just a trifle 
 and thus admitting a small amount of gasoline 
 with the kerosene. Thus the full flexibility of 
 the engine is preserved. 
 
 The carburetor is very simple. After remov- 
 ing the hot air intake, the bowl of the carburetor 
 can be removed by turning off the large thumb 
 screw at the bottom. A screwdriver is the only 
 tool required to remove the floats and valves tp 
 allow cleaning the fuel passages. 
 
 The Rumely carburetor used on the Model 
 14-28 tractor is very simple, and is free from 
 floats, springs and internal automatic mechanism 
 or complicated parts, requiring frequent adjust- 
 ment, or changing to suit damp or dry weather. 
 It consists simply of a vertical tube of peculiar 
 internal shape, surrounded by three divided 
 chambers for kerosene, water and gasoline, each 
 having a needle valve. Below the fuel cham- 
 
126 
 
 Tractor Engines. 
 
 bers the throttle valve is placed, which is coupled 
 direct to the governor and accurately measures 
 and proportions each charge of mixed fuel, air 
 and water that goes into the cylinders. 
 
 The gasojine chamber is used only in starting, 
 and as it has no other use, there are no auto- 
 matic means for getting gasoline into it. A 
 bronze plunger pump working off the camshaft 
 lifts kerosene and water to the carburetor, the 
 surplus draining back through overflow pipes. 
 
 A jacket on the' exhaust pipe heats the intake 
 air with means for regulating the amount of 
 heat. This is necessary in 
 cold weather only. 
 
 The air first goes through 
 a cleaner where the dust and 
 grit are removed, and then 
 enters the top of the carbu- 
 retor, passes through the ven- 
 turi and mixes with the kero- 
 sene and water, the relative 
 quantity of each being regu- 
 lated by the governor con- 
 trolled throttle valve located 
 in the lower part of the car- 
 buretor. From here the mix- 
 ture goes direct to the com- 
 bustion chamber of the motor to be consumed. 
 In appearance it is merely a cylindrical tube 
 surrounded by the fuel chambers. In outward 
 appearance it follows general lines of carburetor 
 construction, as practiced by builders of internal 
 combustion engines. The internal construction, 
 however, of the 14-28 carburetor, is radically dif- 
 ferent from that of carburetors of other builders, 
 as Figure 90 fully explains. 
 
 Figure 90 shows a cross-section of the 14-28 
 carburetor. It will be noted that the central 
 
 Fig. 90. Sectional 
 view of 14-28 car- 
 buretor. 
 
About the Fuel System. 127 
 
 cylindrical passage has a restricted portion form- 
 ing a venturi tube. The oil fuel nozzle is located 
 in the under portion of the venturi, while the 
 water nozzle is located above. 
 
 Due to the peculiar shape of this passage and 
 the relation of the nozzles to it, the proper quan- 
 tity and proportions of fuel and water are 
 automatically fed to the engine at all times, 
 regardless of load. 
 
 The action of the engine piston produces a 
 partial vacuum in the carburetor passage, and 
 this relative vacuum in the zone marked A varies 
 with the load, so that the correct proportion of 
 fuel is always exactly suited to the existing load. 
 
 In the zone above the venturi marked B, a rela- 
 tively strong vacuum prevails during the heavy 
 loads, but decreases very rapidly as the load is re- 
 duced. At the low loads the vacuum is reduced to 
 such an extent in this zone that no water is fed. 
 
 Thus we have a means whereby the fuel mix- 
 ture is automatically fed under governor control 
 in correct proportions at all loads the water 
 being automatically supplied in correct propor- 
 tions for the higher loads only and none at all 
 being admitted for the light loads. 
 
 The Secor-Higgins carburetor used on the 
 18-35 and 30-60 Rumely OilPull sizes, as may 
 be seen in Figure 91, is divided into upper and 
 lower sections, the upper section being again 
 divided into three compartments. The compart- 
 ment farthest to the right is for the kerosene, 
 the middle one for water and the one farthest 
 to the left for gasoline. All open into the lower 
 section. 
 
 The lower section is the mixing chamber. In 
 the bottom of this are three rectangular open- 
 ings. The two openings on the left hand side 
 admit air to the mixing chamber; the one on 
 
128 
 
 Tractor Engines. 
 
 the right is the opening to the manifold through 
 which the mixture of kerosene, water and air 
 passes directly into the cylinder. A plate which 
 is controlled by the governor slides back and 
 forth over these openings. The openings in this 
 plate are arranged so that when it is pulled to 
 the right the outlet to ,the cylinder is made 
 smaller, while the air inlet is also reduced to a 
 
 Fig. 91. Secor-Higgins carburetor, another automatic type 
 used by Rumely. 
 
 lesser extent through the uncovering of the open- 
 ing at the left hand of plate/ 
 
 Needle valves in the kerosene and water cham- 
 bers control the maximum amount of fuel and 
 water to be fed. These need be set only once 
 at full load, and the carburetor under governor 
 control then takes care of the adjustment for 
 all other loads. 
 
About the Fuel System. 129 
 
 As a general rule, with the tractor engine the 
 fuel is gravity fed from the tank to the carbu- 
 retor, the tank being located well above the lever 
 of the carburetor, so that there is little chance 
 of failure even when the machine is working 
 on a steep incline. While with most -tractors of 
 the kerosene burning type two separate tanks are 
 provided, one for the small amount of gasoline 
 needed in order to facilitate starting and to run 
 the engine long enough to warm it up to a point 
 where it will handle the kerosene fuel, in some 
 instances, as for instance the Case, a double 
 compartment tank is provided, the smaller com- 
 
 partment being 
 used for the 
 gasoline. The 
 arrangement 
 of the Case 
 tank is made 
 very plain by 
 Figure 92. 
 . TO CARBURETOR Itwillbesccn 
 
 Fig. 92. Fuel connections and strain- that the COn- 
 ers on Case 10-18. 
 
 nections are 
 
 such that the kerosene can be shut off at will and 
 the engine run on gasoline; likewise the latter 
 can be shut off and the engine operated on the 
 kerosene. The usual practice is to shut off the 
 kerosene and switch on the gasoline a few mo- 
 ments before shutting down at the completion of 
 the day's work so that the gasoline will have, a 
 chance to fill the carburetor bowl in preparation 
 for an easy start next morning. 
 
 In almost every instance a strainer of one sort 
 or another is included in the fuel line to prevent 
 passage of sediment into the carburetor, where it 
 is bound to clog up the nozzle and affect the run- 
 ning of the engine. The arrangement of the two 
 
130 
 
 Tractor Engines. 
 
 strainers on the Case fuel supply line one for the 
 gasoline tank and the other for the kerosene tank 
 is indicated in the figure. It is important that 
 they be cleaned frequently. 
 
 Carburetor Adjustment. The proper adjust- 
 ment of the carburetor is, of course, a matter 
 which will have to be determined for each indi- 
 vidual make of carburetor and engine as well. 
 There are no hard and fast rules for effecting 
 adjustment which will fit all cases, or even a 
 majority of cases. If we study the following 
 
 principles, however, 
 we will find that they 
 apply to all carbure- 
 tors, all engines, and 
 all fuels common to 
 tractor practice, and 
 will aid us much in 
 carrying out the terse 
 directions generally 
 given for carburetor 
 adjustment in the 
 tractor instruction 
 book furnished by the 
 manufacturer. 
 
 The first thing to 
 do, in attempting to 
 attain the adjustment 
 of any carburetor 
 wherein the fuel supply is adjustable by means 
 of a needle valve, is to bring the needle valve 
 gently, but fully, to its seat so as to shut off all 
 the flow through the jet or nozzle. Care should 
 be exercised in effecting this, not to jam the valve 
 down on its seat and cause deformation of either 
 the needle or the seat, as if this is done it will 
 be almost impossible to attain a correct adjust- 
 ment of the carburetor without replacing the parts 
 
 Fig. 93. Cross section of pat- 
 ented Mogul mixer and cylinder, 
 showing adjustments. 
 
About the Fuel System. 131 
 
 with new and perfect ones. Then turn the needle 
 back one or two turns depending on the carbu- 
 retor and the size of the engine and turn the 
 engine over to start it, priming the cylinders if 
 necessary. 
 
 Where priming is not necessary it will be well 
 to close the choke valve on the carburetor to pro- 
 vide a good rich mixture for starting. With the 
 engine running, even though it is running badly, 
 
 do not attempt to ob- 
 tain a final adjust- 
 ment on the carbure- 
 tor until the whole 
 mechanism has 
 warmed up. Be sure 
 that the choke valve 
 is opened again im- 
 mediately after the 
 engine has started, 
 for if it is held closed 
 the over-rich mixture 
 supplied will choke 
 the engine and cause 
 it to stop. 
 
 After thoroughly 
 warming up the en- 
 gine, retard the spark 
 fully and open the 
 throttle sufficiently to 
 allow the governor to 
 control the engine speed. Then adjust the needle 
 valve carefully, first to limit the amount of gaso- 
 line supplied, noting the effect on the operation 
 of the engine. Continue until the speed begins 
 to fafl off, and then turn the other way until the 
 smoothest possible running is obtained. 
 
 Now close the throttle, and advance the spark 
 quarter way. The engine should run evenly and 
 
 Fig. 94. View of Verosene 
 mixer and water injector, show- 
 ing adjusting devices. 
 
132 Tractor Engines. 
 
 at low speed, well throttled down. The speed 
 can be regulated by resetting the stop screw on 
 the throttle lever. 
 
 If the engine shows a tendency to backfire or 
 "pop" in the carburetor when the throttle is 
 opened quickly, it is evidence of a lean mixture, 
 which should be corrected by opening the needle 
 valve very slightly until this tendency is no longer 
 apparent. 
 
 If the engine is hard to start and will not idle, 
 or knocks as if afflicted with carbon or spark 
 knock when the throttle is opened quickly, it is 
 further evidence of lean mixture and should be 
 corrected by opening the needle valve adjustment 
 slightly. Rich mixture will make itself apparent 
 by fhe presence of black smoke issuing from the 
 exhaust, which is characterized by a pungent 
 odor, unmistakable to the trained engine oper- 
 ator. Blue smoke, on the other hand, has noth- 
 ing whatever to do with the carburetor adjust- 
 ment, resulting solely from an overabundance 
 of lubricating oil. Likewise a white haze issuing 
 from the exhaust, in the case of a kerosene- 
 burning engine, indicates that the supply of water 
 through the injector is slightly too much for the 
 amount of fuel being burned and the load being 
 carried, and the water supply should be cut down 
 slightly. 
 
 Further evidence of a -rich mixture is sluggish 
 action of the engine, which sometimes is accom- 
 panied by a heavy pound which is quite irregular 
 and which, therefore, can readily be distinguished 
 from a bearing knock ; and by a marked tendency 
 for the engine to overheat, causing boiling away 
 of the cooling water. The best way to verify the 
 conclusion that the mixture is over-rich is to 
 turn off the fuel with the throttle set to produce 
 an engine speed slightly under the governed 
 
 
About the Fuel System. 133 
 
 speed of the engine ; if the engine picks up speed 
 after a minute or two, due to lowering of the 
 fuel level in the carburetor and consequent weak- 
 ening of the mixture, it is evident that the mix- 
 ture has been too rich, and correction should 
 be made by closing the needle valve slightly to 
 provide good operation as outlined in the tests 
 above. 
 
 Repairs. If it is found impossible to obtain a 
 satisfactory setting of the carburetor, it is likely 
 that the device is out of order 
 and in need of some slight re- 
 pairs. The first thing to look 
 for is correctness of the fuel 
 level. In most tractor carbure- 
 tors the fuel level is correct 
 when the fuel just rises enough 
 
 1- GALLON 
 OILCAN 
 
 nG.95 
 
 Fig. 95. Simple means of determining the correct adjustment 
 of the float in the carburetor. 
 
 to overflow the shoulder surrounding the nozzle 
 in the mixing chamber so that ^he well is full of 
 fuel for starting. If the level does not reach this 
 point, hard starting and the inability of the en- 
 gine to idle will be the result due to weak mix- 
 ture. The float lever should be bent very 
 slightly and the carburetor tested to see if the 
 correct level has been attained ; this may have to 
 be repeated several times in order to effect a cure. 
 Figure 95 shows a hook up for tesjting the level. 
 If the fuel level is much above this point, we 
 will have a sluggish engine due to rich mixture. 
 It may be caused either by wear of the gasoline 
 
134 Tractor Engines. 
 
 
 inlet valve pin or its seat, causing leakage, so 
 that the operation of the float does not stop the 
 flow of gasoline into the carburetor bowl. The 
 correction is to fit new valve needle and seat and 
 so adjust with the float as to permit of the cor- 
 rect fuel level being attained. A bit of dirt on 
 the valve seat will have the same effect. The 
 float may have become "water-logged" ; that is, 
 it may have absorbed so much of the fuel that 
 it has lost some of its buoyancy and will no 
 longer close the valve fully. In this case replace- 
 meet with a new float affords the best cure, and 
 care should be taken to see to it that the float 
 is coated with shellac varnish (except where 
 alcohol is used as fuel) to protect it from the 
 action of the fuel causing a repetition of the 
 trouble. 
 
 The adjustment of the float operating lever 
 may be such that it does not close the needle 
 valve quickly enough so that a higher level than 
 correct is attained. Correction is made by bend- 
 ing the lever away from the float slightly to 
 permit earlier closing of the needle valve. 
 
 The carburetor may have dirt or grit in it 
 which will stop up the jet or nozzle, retarding 
 the fuel flow, or it may have a drop or two of 
 water, which will have the same effect. In this 
 case it is well to take the carburetor off and 
 clean it thoroughly. Then remove the gas line 
 from the tank and blow through it to clean out 
 thoroughly, making sure at the same time that 
 the sediment bulb is clean and free from water. 
 To prevent recurrence of the trouble, drain a 
 teacupful of gasoline from the sediment bulb on 
 the tank frequently to prevent dirt from reaching 
 the carburetor, and at least once a week drain 
 the carburetor by means of drain cock provided 
 on bottom of the bowl; this will wash it out 
 
About the Fuel System. 135 
 
 thoroughly and eliminate any sediment or water 
 which has escaped through the sediment bulb and 
 strainer provided on the bottom of the fuel tank. 
 
 Wear of the needle valve and its seat will re- 
 sult in a condition where it is no longer possible 
 to obtain a correct carburetor adjustment. In 
 such a case, the proper thing to do is to replace 
 the worn parts with new ones. Likewise wear 
 of the throttle disc will prevent idling of the 
 engine unless the mixture is altogether too rich 
 for good operation under full load conditions. 
 The disc clearance should be about .008 of an 
 inch with the disc closed; if it is appreciably 
 more than that, replace it with a new disc. The 
 clearance of the throttle spindle should be no 
 more than .005 of an inch; where it is greater 
 it will permit of air leaking in to thin the mix- 
 ture, producing irregular operation and inability 
 to throttle the engine down. This is also the 
 case if any of the joints of the intake manifold 
 or intake piping are not tight; there are several 
 of them in some instances. In most cases they 
 are made tight with copper asbestos gaskets. 
 
 To detect leakage at these points, start the en- 
 gine and have it running with the throttle closed 
 as far as possible. Squirt lubricating oil from a 
 hand oil can around the joint. In case of leak- 
 age, the oil will be sucked into the manifold at 
 the place where such leakage occurs. Correction 
 can be made by tightening the hold-down nuts 
 by means of which the manifolds are held in 
 place, or in the case of a bad leak, by replacing 
 the gaskets with new ones and setting the hold- 
 down nuts up tight. 
 
 Doubtless it will prove helpful to the oper- 
 ator, regardless of the make of machine, to digest 
 the following complete instructions for the care 
 of the fuel system, which have been prepared 
 
136 Tractor Engines. 
 
 to cover the Twin City line, which is one of many 
 equipped with the Bennett carburetor: 
 
 Fuel from the small gasoline tank flows to 
 the carburetor by gravity. 
 
 Fuel after being placed in the main supply tank 
 is pumped from there to the overflow cup, above 
 the motor, and flows from the cup to the motor 
 by gravity. After switching to the main supply 
 tank, if the pump does not bring fuel to the 
 overflow cup, look for the following causes: 
 
 Empty supply tank. 
 
 Leak in pipe between pump and tank. 
 
 Dirt under check valves. 
 
 Pump needs repacking. 
 
 A fuel strainer is placed in the pipe line 
 where it joins the carburetor. This should be 
 opened occasionally and the dirt, if any, removed. 
 
 There are two check valves located in the line 
 leading from the fuel tank to the pump, and in 
 case of trouble these should be examined. 
 
 If the pump gradually fails to pump and dis- 
 charges a stream of bubbles into the overflow 
 cup, it indicates that there is a leak in the pipe 
 line between the pump and the tank, or that the 
 tank is empty. 
 
 Leaks in the pipe line are easily caused by 
 fittings working loose, and in such a case they 
 should be unscrewed and the threads covered 
 with shellac or common laundry soap; then re- 
 assemble. Care, should be taken not to strain 
 valves or checks in screwing them together. 
 
 In case the pump is not working tighten the 
 gland which forces the packing around the 
 plunger. Never use any sticky or gritty material 
 for packing. Drop a little lubricating oil around 
 the plunger after the gland is tightened. Do not 
 force this gland too tight or it will bind the 
 plunger and break the pump from its fastenings. 
 
About the Fuel System. 137 
 
 If the fuel leaks around the pump plunger, the 
 pump should be repacked. In placing the new 
 packing, unscrew the cap, lift the gland out of 
 the pump barrel and remove all the old packing, 
 replacing it with new. Common laundry soap is 
 a good lubricant for this purpose, and it is well 
 to mix a little of it with the new packing. After 
 rep^cing the gland, screw the cap down fairly 
 tight; then loosen it until you are sure the pump 
 plunger works freely. 
 
 A good method of packing the pump is to 
 make two rings of No. 315 3/16-inch Anchor 
 brand braided packing and place in the packing 
 space and fill up the rest with lamp-wicking. 
 
 The fuel supply must be kept .clean. If the 
 pump suddenly starts and then stops pumping, 
 it indicates that there is dirt coming through the 
 check valves. Any dirt that happens to get into 
 the fuel tank is liable to be drawn up into the 
 check valves or carburetor and cause trouble. 
 To prevent dirt or water from getting into the 
 fuel, it should be filtered through chamois skin, 
 or, in any case, should be strained through a fine 
 screen. 
 
 If there is plenty of fuel in the overflow cup 
 and the engine misses, first throwing out black 
 smoke when the needle valve is opened far 
 euough so that it will run at all, and then pop- 
 ping back through the carburetor, and no ad- 
 justment of the fuel valve will stop it, the indi- 
 cations are that there is dirt in the pipe leading 
 from the overflow cups to carburetor, which has 
 clogged the needle valve or supply pipe, so that 
 the fuel does not flow into the carburetor fast 
 enough to keep up the supply. Dirt may also 
 lodge in the carburetor float valve. This usu- 
 ally causes the carburetor to overflow and drip 
 from the bottom. The only remedy for this 
 
138 
 
 Tractor Engines. 
 
 Fig. 96. Shows the 
 enclosed type of Ben- 
 nett carburetor as 
 used on the Twin City 
 motors. 
 
 is to take the pipes and carburetor apart an 
 clean them. 
 
 If the exhaust has a weak muffled sound, and 
 shows black smoke, too much 
 fuel is being fed through the 
 carburetor. If it back-fires or 
 coughs back through the car- 
 buretor, the mixture is not 
 rich enough and needs more 
 fuel. 
 
 To adjust the enclosed type 
 Bennett carburetor (Fig. 96). 
 Turn fuel needle "A" clock- 
 wise as far as possible, and 
 then unscrew about one full 
 turn. Start motor, and by 
 screwing air valve "B" clock- 
 wise, let as much air in as 
 possible without making the 
 
 motor miss or backfire. Do 
 not open water needle "D" 
 unless engine is using kero- 
 sene. 
 
 To adjust the open type 
 Bennett carburetor (Fig. 97). 
 Open fuel needle two full 
 turns, and when motor is run- 
 ning cut down to iy 2 turns. 
 It will not be necessary to 
 touch the air valve, but in 
 case the motor smokes too 
 Fig. 97. shows the much and the fuel is cut 
 open type as used on down to good running:, loosen 
 
 all Twin City motors / ,, , 
 
 except the 4^x7 size, nut L and use a screw- 
 driver to turn screw "B" 
 clockwise. This will supply more air. 
 
 It may be necessary to give a little more fuel, 
 but for best economy the carburetor should be 
 
About the Fuel System. 139 
 
 adjusted to use as little fuel and as much air 
 as possible. 
 
 To USE KEROSENE AS FUEL. 
 
 There are two fuel tanks used in the opera- 
 tion of Twin City Motors. 
 
 One is a small tank for gasoline, mounted 
 higher than the motor from which the fuel flows 
 by gravity to the carburetor, and the other is a 
 large tank from which the fuel is pumped to a 
 glass overflow cup and thence flows to the car- 
 buretor by gravity. 
 
 The engine must be started on gasoline. After 
 the bowl of the carburetor is hot, shut off the 
 gasoline and turn kerosene into the carburetor. 
 
 After the kerosene starts into the engine, it will 
 sputter and choke, and the fuel needle valve will 
 have to be opened one-quarter turn on the open 
 type, and one full turn on the enclosed type. 
 
 After the engine runs a little there may be 
 heard a metallic knocking or pounding, which is 
 caused by preignition. In order to eliminate this 
 the water injector valve should be opened and 
 a little water sprayed into the intake pipe. This 
 will cut down the heat, and the knocking will 
 cease. 
 
 It will be necessary to retard the spark from 
 that used for gasoline. 
 
 The engine will operate best on kerosene when 
 the least possible water is injected. Just keep 
 the adjustment so that the engine will not knock. 
 
 It is advisable to shift the carburetor back on 
 to gasoline when the motor is idle a great deal, 
 as the bowl of the carburetor will not continue 
 to be hot unless some load is kept on the engine. 
 
 Caution. Be sure and turn off water valve 
 when engine is not running. 
 
 It is a good plan to shut off both fuel pipes, 
 
140 Tractor Engines. 
 
 drain carburetor, and leave drain open when 
 the engine is not running, as this gives the 
 float a chance to dry out and prevents water 
 getting into the fuel, if the water valve should 
 be left or leaks. 
 
 The hot air jacket around the bowl of the 
 carburetor must be kept clean, as the successful 
 operation of the carburetor depends upon this. 
 
 ALCOHOL. 
 
 The use of alcohol as a fuel for the internal 
 combustion engines is very clean and no carbon 
 whatever is caused from it. If a carbon deposit 
 forms in the combustion chamber, it is from 
 using too much lubricating oil and not from the 
 alcohol. 
 
 All that is necessary to equip Twin City motors 
 to burn alcohol, is to raise the compression of 
 the motor by putting in longer pistons, and to 
 replace the carburetor float with another which 
 has a specially prepared coating instead of the 
 shellac. 
 
 Gasoline is used to start the motor, but after 
 the bowl of the carburetor is warmed up, alcohol 
 can be used. 
 
 From eight to nine per cent more power can 
 be obtained with alcohol than with gasoline, al- 
 though about eleven per cent more alcohol will 
 be used than kerosene, and thirty-eight per cent 
 more than gasoline, for the same load. That is, 
 it will take 4.8 gallons of gasoline, 6 gallons 
 of kerosene or 6.7 gallons of alcohol for the 
 same time and load. 
 
 The better the .grade of alcohol, the less it will 
 take and the economy in the use of one grade 
 over the other will be all the way up to ten per 
 cent. 
 
About the Fuel System. 141 
 
 The gravity of a good grade of denatured 
 alcohol is .809, which is 7^. pounds to the gallon, 
 about the same as kerosene. 
 
 NAPHTHA. 
 
 Naphtha is used in the same way as kerosene, 
 but the amount used will be a little more than 
 gasoline and a little less than kerosene for the 
 same load, that is, .4.8 gallons of gasoline, 5.18 
 gallons of naphtha or 6 gallons of kerosene for 
 the same full load for the same unit of time. 
 
 A COMPARISON OF FUELS. 
 A comparison of fuel consumption of various 
 fuels, when the engine is working under full 
 load, is given in the table below, taking gasoline 
 as 1. Specific 
 
 Gals. Gravity 
 
 Gasoline 1.00 .7449 
 
 Naphtha 1.07 .7639 
 
 Kerosene 1.24 .8098 
 
 Alcohol 1-.38 .809 
 
 INSTRUCTIONS FOR BURNING KEROSENE WITH 
 CLAPPER VAPORIZER, USED ON BULL TRAC- 
 TOR (FIGURE 98 A-B-C.) 
 
 Always start the motor on gasoline and adjust 
 the needle valve in carburetor to handle the full 
 load as though you intended to run on gasoline, 
 and as soon as the vaporizer chamber is warmed 
 from the exhaust, switch from gasoline to kero- 
 sene. There is no other adjustment necessary. 
 In working the motor to its maximum capacity, 
 it may be necessary to open the needle valve in 
 carburetor about one-quarter turn, which you 
 would necessarily have to do with easoline. 
 
 With the use of kerosene in extreme loads, 
 or when there is a "metallic click" in cylinder, 
 use a small amount of water, the amount vary- 
 
142 Tractor Engines. 
 
 CLAPPER KEROSENE VAPORIZER. 
 
 
 Plate No. 1. 
 
 No. 1 Water spray valve. 
 
 No. 2 3-way valve. 
 
 No. 3 Carburetor drain. 
 
 No. 4 Carburetor needle valve. 
 Single adjustment for kerosene the 
 same as gasoline. 
 
 Plate No. 2. 
 
 Side view of Clapper Kerosene 
 Vaporizer showing simplicity of con- 
 struction. Positively no moving parts. 
 Unquestionably the greatest improve- 
 ment of the age for the successful 
 burning of kerosene. 
 
 If motor stops when 
 burning kerosene and 
 stands for any length 
 of time, switch 3-way 
 valve on to gasoline 
 and open pet-cock (No. 
 3, Plate 1) to drain off 
 the kerosene. Prime 
 cylinders before again 
 trying to start. 
 
 Operate tractor under 
 load at least five min- 
 utes before attempting 
 to switch \o kerosene. 
 
 Plate No. 3. 
 
 Always keep glass jar 
 in place. Empty out as 
 often as necessary (No. 
 2, Plate 3). 
 
 To fill oil reservoir, 
 remove plug in filling 
 pipe (No. 1 in Plate 3). 
 Fill to within three 
 inches of top. Be sure 
 to screw plug in tight 
 to avoid sucking air. 
 
 Fig. 98. Showing in detail the adjustments necessary. 
 
About the Fuel System. 143 
 
 ing to the load. When running idle or you stop 
 the motor, always shut off the water. It is ad- 
 visable to shut off the kerosene line before you 
 stop the motor to allow the carburetor to fill up 
 with gasoline ready for starting again. 
 
 You will get more power and better results 
 with a retarding spark on kerosene than gasoline, 
 due to the perfect vapor and more heat units 
 simply pnll magneto spark control rod back until, 
 from the sound and power developed, you have 
 the proper range for igniting the charge. 
 
 Fig. 99. Adjusting leaky carburetor. 
 
 A leaky carburetor is the result of dirt in the 
 inlet valve, preventing the float needle from 
 seating properly. 
 
 To remove this, remove plug from over the float 
 needle (Fig. 99) and work the needle in the inlet 
 valve up and down several times, pressing it 
 to its seat each time and turning it. This will 
 remove any foreign matter that may have gath- 
 ered there and allow the float needle to seat itself. 
 
 If this does not stop the leak, float is too high 
 and should be set lower. 
 
144 Tractor Engines. 
 
 Once a season, the float should have a coat 
 of shellac. It will take but a moment, as it dries 
 very rapidly. (Have float dry before putting 
 on shellac.) 
 
 There may be sediment in the bottom of the 
 bowl of the carburetor. Remove the bowl and 
 clean it out. 
 
 One of the most important points in connec- 
 tion with the operation of the tractor ^engine is 
 to keep grit and dust from reaching the bear- 
 ing surfaces, such, for instance, as the cylinder 
 walls, main and connecting rod bearings, etc. It 
 is obvious that any dirt carried in through the 
 air inlet on the carburetor will be brought into 
 direct contact with the cylinder walls, which 
 are, of course, covered with a layer of oil suffi- 
 ciently "tacky" to catch the grit and hold it. 
 Rapid wear of the wall surfaces can, therefore, 
 be expected. 
 
 But more than this the oil from the cylinder 
 walls is carried down, in part, by the downward 
 movement of the piston and a generous measure 
 of the grit reaches the crankcase chamber where, 
 in the case of the engine equipped with a circu- 
 lating lubricating system, it will enter the oil 
 supply to be circulated, and recirculated, to the 
 engine bearing surfaces. 
 
 It is only to be expected, therefore, that an 
 engine not protected in the best possible manner 
 from the entrance of grit, as above pointed out, 
 will wear out more quickly and give far greater 
 trouble, calling for frequent repairs, than one 
 adequately protected from such dust. There are 
 very few tractors now on the market, therefore, 
 on which the engines .are not equipped with some 
 device for freeing the air entering the carbu- 
 retor from contamination so that nothing but 
 pure, clear air is taken into the cylinders. 
 
 oat 
 
 '1PC 
 
About the Fuel System. 145 
 
 These air filters or air washers, as they are 
 variously called, are built to operate .on three 
 distinct principles. The simplest is nothing more 
 nor less than a filter, all the air entering the cyl- 
 inder being caused to pass first through a filter- 
 ing medium such as a piece of felt cloth by 
 means of which the dust is eliminated. Perhaps 
 the best-known device of this sort is the Orem 
 motor protector, in which the filtering felt is 
 stretched over the surface of a wire netting cyl- 
 inder from the interior of which air for the 
 carburetor supply is drawn; all the air reaching 
 the interior must pass through the cloth. 
 
 It is evident that strangulation of the air, or 
 any impediment to its free entry into the carbu- 
 retor, will result in a falling off in power ; as 
 the filter cloth does offer some resistance, its 
 area must be made sufficient to cut this resist- 
 ance to a minimum. In the Orem device, this 
 area has been figured with relation to the amount 
 of air a given engine will handle in a minute, 
 under full load operation. 
 
 Furthermore, unless some means were taken 
 to prevent such action, after a few moments of 
 operation under extreme dust conditions, the 
 filter cloth would become so clogged as to par- 
 tially strangle the air passage. In the Orem 
 device this is prevented by the simple expedient 
 of setting the cylinder upright, or in a vertical 
 position, whereby the vibration of the engine 
 itself is employed to cause the dust to drop off 
 the outside surface of the filter cloth into a col- 
 lecting funnel, from which it can be emptied 
 from time to time as occasion demands. The 
 device also serves as a regulator for the tem- 
 perature of the incoming air. This is effected 
 by connecting the outer cylinder to the air stove 
 on the exhaust pipe whereby heated air is brought 
 
146 
 
 Tractor Engines. 
 
 
 to the device. A regulating shutter is provided, 
 however, so that cold air can be introduced to 
 bring down the temperature of this air during 
 the hot summer months when particularly high 
 heat is not required. 
 
 The second type separates the dust from the 
 air on the centrifugal principle. The entering 
 air is caused to take up a very rapid swirling 
 or rotary motion by the form of the passageway 
 into the cleaner; due to their great weight in 
 comparison with the weight of the air itself, the 
 dust particles are thrown to the outer wall of 
 
 the case, where they 
 are caused to settle 
 out by gravity. The 
 well - clean-sed air is 
 drawn from the cen- 
 ter of the device, a 
 point which the heavy 
 dust particles cannot 
 reach because of the 
 effect of the centri- 
 fugal force acting on 
 them due to their 
 rapid circular motion. 
 By far the most 
 popular type of 
 cleaner, however, is 
 the air washer, one of 
 which is shown in the 
 
 accompanying illustration (Fig. 100). In this 
 type all the entering air is caused to bubble up 
 through a quantity of water, which collects the 
 dust and dirt and leaves the air absolutely clean. 
 Perhaps the effectiveness of the device as an air 
 cleaner is only partially responsible for the popu- 
 larity of the air washer; the other big point in 
 its favor is the fact that it humidifies the enter- 
 
 Fig. 100. A typical tractor 
 air washer. 
 
About the Fuel System. 147 
 
 ing air and acts, to a certain extent, to smooth 
 out the action of the engine and eliminate the 
 formation of carbon deposit. 
 
 A sectional view of a typical air washer such 
 as is fitted to the popular Case tractor is given 
 in Figure 100. It comprises a cylindrical vessel 
 partially filled with water, the level being indi- 
 cated by a glass sight on one side of the casing. 
 The air enters through a central pipe running 
 about half way up into the chamber; but the air 
 finds itself, not in the housing, but in a smaller 
 inverted cylinder placed over the air intake pipe. 
 This second or inner chamber is attached to a 
 metal float which rises and falls with the water 
 level in the air washer, and the only passage 
 for the air out of the chamber is past the bottom 
 of the inverted cup, over the lower surface of 
 the float and up along the sides. The top of the 
 air washej housing is attached to ,the carburetor 
 air intake, so that immediately the engine is 
 turned over, some of the air is exhausted, and 
 we have a partial vacuum formed sufficient to 
 cause the air to bubble through the water, finding 
 its way from the inner to the outer compartment ; 
 and in passing through the water it is freed of 
 its dust and dirt. 
 
 The arrangement of the inner chamber on a 
 float is a very simple means of insuring that the 
 air must pass through a given depth of water, 
 regardless of the quantity of water in the air 
 washer. In 6ther words, provided that the water 
 level is maintained so that it can be seen through 
 the sight gauge, the suction necessary to draw 
 the air through the air washer will always be 
 the same. The level of the water cannot be 
 brought too high, for if it should be brought 
 above the air intake pipe, it simply will overflow 
 and run off; it should never be allowed to evap- 
 
148 Tractor Engines. 
 
 orate to a point where the level cannot be seen 
 in the sight gauge, however, as then the desirable 
 features of the device are impaired and dirt will 
 be carried into the engine cylinders. 
 
 It is well to remove the drain plug from the 
 bottom of the device frequently and wash out 
 the sediment that has collected. The best plan 
 is to fill the washer to capacity with clean water 
 every day, making sure that the water filler plug 
 on top of the device is replaced tightly. If the 
 plug is not replaced, the washer might just as 
 well be off the engine for all the good it will do. 
 
 In the case of the dry types of air cleaners, 
 it is well to bear in min4 that cleaning the sedi- 
 ment trap should never be attempted with the 
 engine running. To do so means that the dirt 
 stirred up in the process will be drawn in large 
 quantities into the cylinders to the detriment of 
 the engine. 
 
CHAPTER VI. 
 
 Lubrication of the Engine. 
 
 Why One Oil Will Not Do for All Types. Factors 
 Affecting the Oil Used. 
 
 BETWEEN tractor success and tractor fail- 
 ure ; between a farm power machine which 
 runs well and delivers its power smoothly, eco- 
 nomically and reliably and one which is spas- 
 modic in its performance, unable to stand up to 
 its' work, unreliable and troublesome, there lies 
 a very narrow chasm a film of oil perhaps .003 
 of an inch in thickness, sometimes more and 
 oftentimes considerably less. 
 
 This oil film, quite regardless of the amount of 
 work or kind of work the tractor is called upon 
 to do, regardless also of temperature conditions 
 both inside and outside the engine ; and notwith- 
 standing other operative conditions which may 
 tend, at times, to destroy it, must be maintained 
 religiously. Even momentary failure of the oil 
 film at any one of a score of vital points in the 
 power plant will mean: first, k/ss of power out- 
 put and irregular operation ; second, and even 
 more annoying, excessive wear; eventual break- 
 down and stoppage ; troublesome and costly 
 repairs. 
 
 Broadly speaking, the oil film serves the same 
 purpose in a plain bearing as do the steel balls 
 in the ball-type anti-friction bearing. It separ- 
 ates the rubbing surfaces, keeping them out of 
 actual metallic contact and replaces the rubbing 
 friction, which otherwise would be set up be- 
 tween the metal surfaces in contact, with greatly 
 lessened friction between the liquid particles 
 
 (149) 
 
150 
 
 Tractor Engines. 
 
 themselves and between the liquid particles and 
 the metallic surfaces of the bearings, just as in 
 the ball or roller bearing the greatly lessened 
 rolling friction between the balls or rollers and 
 the raceways is substituted for the rubbing fric- 
 tion of the plain bearing surfaces. 
 
 Points in the engine (Figure 101) at which it 
 
 Fig. 101. Section through typical tractor engine, showing 
 points where oil is necessary. 
 
 is essential that this oil film be maintained for 
 the purpose of reducing friction, and the power 
 loss and wear which it entails, are the mainshaft, 
 crankpin, piston pin and camshaft bearings ; the 
 cylinder walls for lubrication of the cylinders 
 themselves, the pistons and piston rings ; the 
 cams, cam followers and cam follower guides; 
 the timing gear mesh and, where used, the tim- 
 ing gear idler wheel bearing. 
 
Lubrication of the Engine. 151 
 
 Wholly aside from its function of reducing 
 sliding friction between the piston and the cylin- 
 der wall, the oil film on the latter performs an- 
 other and a highly important service. Expand- 
 ing packing rings, called piston rings, are fitted 
 to the pistons as a means of filling the clearance 
 space which must be left between the piston and 
 cylinder walls in order to provide room for ex- 
 cess expansion of the piston over and above the 
 increase in diameter of the cylinder bore due to 
 the fact that the piston operates normally at 
 considerably higher temperature than the cylin- 
 der walls. 
 
 This will readily be appreciated when it is 
 considered that the cylinder walls themselves 
 are directly cooled by the water circulating sys- 
 tem, whereas the head of the piston is cooled 
 only by means of heat being conducted to the 
 piston skirt and transferred from that point 
 through the oil film to the cylinder walls for ab- 
 sorption by the cooling medium. These rings, 
 which are applied to the piston, must be so fitted 
 as to leave a working clearance in the ring slot; 
 were this not the case they would be likely to 
 stick in the ring slot, preventing their expansion 
 against the cylinder walls and thereby defeating 
 their own purpose. 
 
 Rings, for the most part, are eccentric in 
 form; that is, the outer or bearing surface is not 
 struck from the same center as the inner circle. 
 The slot or joint is formed at the thinnest portion 
 of this eccentric ring, this for the purpose of 
 providing approximately uniform tension against 
 the cylinder walls at every point on the ring 
 circle. A moment's thought will make it evident 
 that since the ring slot provided in the piston for 
 the reception of the ring is of uniform depth, 
 while the ring itself is of tapering form, there is 
 
152 Tractor Engines. 
 
 going to be a cavity or pocket between the bottom 
 of the ring slot and the ring itself at its narrower 
 portions. 
 
 This fact taken into consideration with the 
 clearance left for free movement of the ring in 
 its slot, makes it possible for the highly com- 
 pressed gases above the piston to work through 
 this clearance, in behind the ring, and then out 
 again at the bottom, escaping to the crankcase 
 chamber. 
 
 The second purpose of the lubricant on the 
 cylinder walls, then, is quite obvious. It must 
 serve to set up an oil seal adapted to fill this 
 clearance and prevent the gases from working 
 in behind the piston ring and making good their 
 escape. And by the way it performs this second 
 function, taking into consideration also its effi- 
 ciency as a lubricant, so is an oil judged proper 
 or improper for tractor engine use. 
 
 Any oil, to be of service either as a lubricant or 
 to maintain this desired piston ring seal, must be 
 capable of thorough and even distribution to 
 every point in the engine where a lubricant is re- 
 quired through the system of distribution pro- 
 vided by the engine designer. In determining 
 the proper lubricant for the engine, therefore, 
 our first consideration 'will be an analysis of the 
 system of lubrication employed. 
 
 Speaking generally, all tractor engine lubricat- 
 ing systems can be classified under five separate 
 distinct headings. Perhaps the simplest is the 
 plain splash system illustrated in Figure 102. In 
 this system the fresh oil is contained in a reser- 
 voir absolutely distinct and separate from the 
 crankcase and is fed to the crankcase in exactly 
 the proper amount to maintain a constant level 
 in the crankcase itself. The oil feed is accom- 
 plished by means of a plunger pump which is ad- 
 
Lubrication of the Engine. 153 
 
 justable, as to plunger stroke, so that the oil feed 
 can be adjusted to meet the operating conditions. 
 Oil dippers or splashers on the lower ends of 
 the connecting rods dip into the oil and splash 
 the lubricant up in the form of a fine spray, 
 projecting it to the cylinder walls for the lubri- 
 cation of the cylinders, pistons and piston rings 
 and to wells provided over the mainshaf t, cam- 
 shaft and piston pin bearings, and in most in- 
 stances to a well under the mainshaft timing 
 gear. Some of the spray is projected to the 
 cams themselves, the cam followers, and in some 
 cases to the valve stems for their lubrication. 
 
 Two methods are employed for conducting the 
 oil into the crankpin bearings ; the more usual 
 
 is to drill through the 
 connecting rod bear- 
 ing cap just in front 
 of the splasher, so 
 that the impact of the 
 ^^ rod with the oil drives 
 
 F/6.J02 ^F the oil into the bear- 
 
 Fig. 102. Splash system. * n g J the . leSS USUal 
 
 method is to drill 
 and counterbore two small holes in the connect- 
 ing rod bearing upper half at each side of the 
 rod proper by means of which a quantity of oil 
 is enabled to reach the crankpin bearing. 
 
 This system is known as the "all loss sys- 
 tem," for the reason that none of the oil, after 
 use, is returned to the reservoir ; all the oil 
 pumped into the crankcase is either used or 
 thrown off by the/ action of the engine. 
 
 In order to provide efficient and even distri- 
 bution of the oil throughout the crankcase 
 chamber, insuring a copious supply to every bear- 
 ing and rubbing surface, it is essential that the 
 oil splashed by the connecting rod dip be 
 
154 Tractor Engines. 
 
 thoroughly atomized or broken up into a form 
 where it is readily carried or floated on the 
 trapped air to the parts requiring lubrication. An 
 oil of proper body to lend itself readily to such 
 thorough atomization, therefore, is a prime 
 requisite with any system where the connecting 
 rod dip or splash is relied upon for the oil dis- 
 tribution within the engine itself. Such an oil 
 must be of medium or light body. An oil too 
 heavy in body will not be so finely divided under 
 the connecting rod impact and this condition is 
 particularly emphasized under winter conditions 
 when any oil shows a tendency to thicken up or 
 
 to increase in vis- 
 cosity. 
 
 Another point in 
 connection with the 
 "all loss" system is 
 fact that the oil in the 
 crankcase is constant- 
 l y being built up, as 
 sys F te g m. 103 ' Splash circulating to body and quality, 
 
 by the addition of the 
 
 fresh oil supplied by the pump or mechanical 
 oiler, as the case may be. Obviously, therefore, 
 an oil of lighter body can be used more effect- 
 ively than is the case where the whole oil reserve 
 is circulated and contaminated by the admixture 
 of fuel and carbon sediment. 
 
 The second lubricating system is the splash 
 circulating system illustrated in Figure 103. In 
 this system the bottom of the crankcase forms an 
 oil reservoir from which the oil is pumped, usu- 
 ally by a gear pump and less frequently by a 
 plunger pump or the centrifugal action of the 
 engine flywheel, either to dipper troughs, located 
 one under each connecting rod, or to open wells 
 over the mainshaft bearings from which the 
 
 ic 
 :d 
 
 ' 
 
Lubrication of the Engine. 155 
 
 overflowing oil supplies the dipper troughs. 
 Suitably placed orifices in the dipper troughs 
 serve to maintain - the oil level constant so that 
 the connecting rod dip is always the same. 
 
 It will be seen that in this instance it is not 
 essential that the quantity of oil supplied by the 
 pump be regulated to coincide with that used in 
 the lubrication of the engine. As a matter of 
 fact, the flow is always considerably in excess of 
 what the engine is using, and this excess over- 
 flows from the dipper troughs back to the reser- 
 voir for re-circulation by the pump. The cylin- 
 der walls, pistons and piston rings and all the 
 
 various bearing sur- 
 faces are lubricated 
 by the connecting rod 
 splash exactly as with 
 the plain splash sys- 
 tem. 
 
 Obviously, in order 
 to provide for thor- 
 gh atomization of 
 the oil and consequent 
 thorough and even distribution, an oil of light or 
 medium body should be used. On the other hand, 
 due to the fact that the oil is constantly being cir- 
 culated at^I subjected to wear and tear in the en- 
 gine itself, as a result of its usage and re-usage, 
 in order to provide maximum lubrication an oil 
 of heavier body is required than with the splash, 
 "all loss" system. The splash circulating sys- 
 tem by its nature is best adapted for handling a 
 medium bodied oil. 
 
 Third in line comes the force feed and splash 
 system illustrated in Figure 104. Here we have 
 the oil contained in a crankcase reservoir exactly 
 as with the splash circulating system, and forced 
 by a gear or plunger pump to each of the main- 
 
156 
 
 Tractor Engines. 
 
 shaft bearings under pressure, and in some in- 
 stances also to the camshaft bearings. . As a rule, 
 in order to maintain the pressure approximately 
 constant regardless of variations in engine speed, 
 a safety valve or by-pass is placed in the oil 
 header and set to permit any excess oil delivered 
 by the pump to be projected onto the timing- 
 gear train for lubrication of these gears. 
 
 The oil bleed from the mainshaft bearings 
 serves to maintain a constant level in the dipper 
 troughs which, as with the splash circulating sys- 
 tem, are equipped with properly placed overflow 
 orifices so that too high a level cannot be reached. 
 With .the exception of the mainshaft bearings- 
 rarely the camshaft bearings and the timing- 
 gear train, the dis- 
 tribution of the lubri- 
 cant to the various 
 surfaces is exactly 
 the same as with the 
 splash circulating sys- 
 tem. The conditions 
 encountered in this 
 system being so near- 
 ly identical with those on the splash circulating 
 system, it is evident that this system also will 
 operate at its best when a medium bodied lubri- 
 cant is employed. 
 
 In the fourth system of lubrication the con- 
 necting rod splash is done away with. It is called 
 the force feed system and is illustrated in 
 Figure 105. As with the force fee'd and splash 
 system, the oil is fed by pump pressure to each of 
 the mainshaft bearings and sometimes to the 
 camshaft bearings. An oil by-pass is incor- 
 porated in the system to maintain the pressure 
 approximately constant. From the mainshaft 
 bearings the oil is conducted either through drill- 
 
 . 105 
 
 Fig. 105. Force feed system. 
 
Lubrication of the Engine. 157 
 
 ings in the crank-webs or through the hollow 
 crankshaft to the crankpin bearings under pump 
 pressure. 
 
 The oil bleed from the crankpin bearings is 
 projected in the form of a very fine spray to the 
 cylinder walls for the lubrication of the cylin- 
 ders, piston and piston rings ; and to the piston 
 pin bearings, the cams, the cam followers and, in 
 some cases, to the camshaft bearings, where 
 these are not taken care of under pressure. The 
 excess oil, draining back from the crankcase 
 chamber walls, reaches the reservoir and is re- 
 circulated by the pump. 
 
 Here we have a condition where the more im- 
 portant bearings are 
 fed directly under 
 pressure from the 
 pump; it is also ap- 
 parent that since the 
 oil spray results from 
 the oil being pro- 
 jected through the 
 for very small annular 
 
 passage on either side 
 
 of the crankpin bearing under pump pressure, 
 augmented by centrifugal force, we have a posi- 
 tive means of finely dividing or atomizing the oil 
 so that the use of a heavier lubricant than that 
 best adapted for splash distribution, is made pos- 
 sible. The force feed system, where the oil pump 
 is submerged in the reservoir so that there will be 
 no. question as to the pump drawing a full supply 
 when the engine is started and the oil is chilled, 
 is preeminently adapted to handle medium 
 heavy-bodied and heavy-bodied oils. 
 
 There is not a great deal of difference between 
 the force feed lubrication system and the full 
 force feed system (Figure 106.) The pressure 
 
158 
 
 Tractor Engines. 
 
 line is carried one step further and the oil is led 
 up from the crankpin bearings to the piston pin 
 bearings by means of an oil pipe attached to the 
 side of the connecting rod, so that the piston pin 
 bearing is also fed under pressure. The oil bleed 
 from the crankpin bearings, however, is relied on 
 for the lubrication of the cylinder walls, pistons 
 and piston rings, cams ; generally also the cam- 
 shaft bearings and the cam followers. A by-pass 
 and oil pressure regulator, as a rule, takes care 
 
 of the timing- 
 gear lubrication. 
 Obviously, the 
 full force feed 
 system is like- 
 wise adapted to 
 the distribution 
 of a heavy- 
 bodied lubricant. 
 It was pointed 
 out before that 
 there are many 
 little points of 
 
 FK 107. Splash circulating system diversion in lllb- 
 as applied to the All-Work tractor en- * , . 
 
 gine. jicating systems 
 
 which would 
 
 seem, at first sight, to make them fall without 
 bounds, so to speak, with regard to these five 
 classifications. Take, for instance, the type 
 wherein a mechanical oiler is used, the oil being 
 forced to each of the bearings and to the cylin- 
 der walls under pressure. This can be classified 
 as a force feed system in which a series of 
 pumps one for each oil lead, in fact is sub- 
 stituted for the single pump used on the ortho- 
 dox system. It is not a circulating system, how- 
 ever, since the oil is not returned to the reservoir. 
 Such a system can be used for the distribution 
 
Lubrication of the Engine. 159 
 
 of either heavy, medium-bodied and light-bodied 
 lubricants, but the necessity of using exposed oil 
 leads demands a lubricant of sufficient fluidity 
 for efficient distribution under winter temper- 
 atures. 
 
 It must be considered that the details in the 
 arrangement of these systems will greatly affect 
 the choice of the lubricant as to body. For in- 
 stance, as was pointed out before, an oil pump 
 submerged in the lubricant is better adapted to 
 
 Fig. 108. Arrows show course oil takes from oil reservoir 
 through the motor on All-Work tractor. 
 
 handle a heavier oil than an elevated pump; and 
 this condition is greatly emphasized under winter 
 temperatures. Likewise a submerged gear pump 
 is better adapted to handle a congealed or thick- 
 ened oil than a plunger pump, which depends on 
 suction for its initial charge. On the other hand, 
 an elevated plunger pump is better adapted to 
 function properly, except at low temperatures, 
 than an elevated gear pump, since the latter can- 
 
160 
 
 Tractor Engines. 
 
Lubrication of the Engine. 161 
 
 not be packed tight enough to insure its being 
 primed sufficiently after a stop of considerable 
 duration, to circulate the oil immediately the 
 engine is started. 
 
 Where conditions tending toward irregular 
 pump action are encountered in the lubricating 
 system, in order to insure that degree of positive 
 action which is essential to correct motor per- 
 formance and power production, we naturally 
 are going to use a lighter grade of oil, which is 
 easier to move, than the general analysis of the 
 lubricating system as applied, would seem to 
 call for. 
 
 Having analyzed the system of lubrication and 
 determined from its general type, and from the 
 details of its construction, which is the proper 
 grade of oil for use with it, our next step will be 
 to analyze the engine construction with the view 
 of determining whether the oil, as recommended, 
 will properly perform its functions. For in- 
 stance, not all tractor engine designers are of the 
 same opinion as to piston material and piston 
 clearance ; nor are all of them sold on the eccen- 
 tric piston ring as against the concentric type 
 which eliminates, to a greater or less extent, the 
 oil cavity or pocket behind the ring. 
 
 We will find, therefore, that one engine when 
 cool will have a greater piston clearance than 
 another, and while it is the object of every 
 tractor engine designer to bring this clearance as 
 close as is consistent with free piston movement 
 and a high factor of safety against piston seizure, 
 still even at normal operative temperatures we 
 are going to find a great divergence in the 
 amount of piston clearance between engines of 
 different design and different manufacture. 
 
 Nor are all production methods identical. 
 One manufacturer will produce his cylinders by 
 
162 
 
 Tractor Engines. 
 
 a double-rough-cut-and-ream finished method, 
 whereas another will produce a fine cylinder 
 wall finish by the grinding method. 
 
 The oil, as determined, must be of a grade 
 which not only will lend itself to perfect distri- 
 bution through the oiling system, but will also 
 maintain the proper piston ring seal at normal 
 operative temperatures with mechanical clear- 
 ances as encountered in the particular engine 
 under consideration. 
 
 FIG. IIO 
 
 Fig. 110. The Big Bull force feed circulating oiling system 
 forces the oil through a hollow crank shaft and delivers it to the 
 inside of the connecting rod bearings. Reduces the amount of 
 oil used and is a positive feed, so long as there is oil in the 
 reservoir. The operator can see the oil flow all the time from 
 his seat. 
 
 Considering the bad effects of non-main- 
 tenance of this piston ring seal, let us assume 
 that we have the engine with one of the pistons 
 up nearly at the top of its compression stroke. 
 Above the piston we have, then, a more or less 
 wet mixture of gasoline and kerosene vapor and 
 air compressed to> approximately 60 pounds per 
 
Lubrication of the Engine. 163 
 
 square inch, depending on the compression ratio 
 of the engine and the position of the crankpin. 
 Since the piston ring seal is not being properly 
 maintained, some of this wet mixture will work 
 down past the pistons, "blow by" the rings and 
 the gasoline or kerosene, either of which is a 
 first-class solvent of the mineral lubricating oil, 
 will wash the lubricant from the cylinder walls, 
 further aggravating the situation, and paving the 
 way for increased "blow-by" on the next com- 
 pression stroke. 
 
 Fig. 111. Splash circulating system as modified by Avery. 
 
 In the meantime we have lost to the crankcase 
 chamber from the combustion chamber a quan- 
 tity of fuel a certain portion of the heat units 
 which we were counting on to develop full 
 p>ower from the engine. More than that, we have 
 reduced the compression, due to this loss, and 
 since the power that the internal combustion en- 
 gine is capable of developing is dependent almost 
 directly upon the compression pressure, within 
 limits, we have in this another source of reduced 
 power output or loss in efficiency. Still a third 
 
164 Tractor Engines. 
 
 source is the lack of effective lubricant on the 
 cylinder walls, which increases the piston fric- 
 tion, causing a power loss and a tendency to 
 overheat, as well as a tendency for rapid wear of 
 the pistons, piston rings and the cylinder walls. 
 
 Let us neglect for a moment the amount of 
 mixture which has escaped down into the crank- 
 case chamber, and let us consider that we have 
 turned the engine over past its top dead center 
 and that it is now on its power stroke. We now 
 have above the piston a quantity of intensely hot 
 gases at very high pressure. The temperature 
 
 range will be between 
 2000 to 3000 F., 
 while the pressure 
 will be, roughly, four 
 times the compression 
 pressure, or some- 
 wheres in the neigh- 
 borhood of 250 
 pounds per square 
 
 Fig. 112. Force-feed lubricator. inch. These gaSCS 
 
 are made up largely 
 
 of that inert constituent of the atmosphere 
 nitrogen and of the products of combustion of 
 the hydro-carbon fuel, which are carbon-dioxide, 
 carbon-monoxide and water vapor. There will 
 be traces of other gases, which we need 'not take 
 into consideration. 
 
 The escape of these gases past the piston has 
 two effects. One is, of course, -to cause a reduc- 
 tion in working pressure on top of the piston * 
 our real source of power and consequently we 
 have still another cause of power loss as a result 
 of the breaking down of the piston ring seal. 
 The second effect will be greatly to augment the 
 temperature of the piston and cylinder walls, due 
 to the passage of these intensely hot gases 
 
Lubrication of the Engine. 165 
 
 through the clearance space. Here again we 
 have a condition which tends to increase friction 
 and reduce -power output. 
 
 Let us now look into the crankcase chamber 
 and see what has happened there. On the com- 
 pression stroke we brought down a quantity of 
 vaporized fuel, which quickly condensed in the 
 crankcase chamber and mixed with the oil, reduc- 
 ing its body and impairing, to a greater or less ex- 
 tent, its lubricating efficiency. In aggravated cases, 
 the body of the oil will fall off sufficiently to im- 
 pair seriously 
 
 /7<7. If 3 
 
 Fig. 113. Crank shaft, showing how 
 the oil is carried to the bearings on 
 Leader tractor engine. 
 
 the lubrica- 
 tion of the 
 engine bear- 
 ings and we 
 wilf have in- 
 creased fric- 
 tion between 
 all the mov- 
 ing surfaces 
 and a tend- 
 ency for the 
 bearing sto roughen up in service. 
 
 On the power stroke the escaping gases car- 
 ried down with them a quantity of water vapor 
 which has also condensed in the cooler crankcase 
 chamber; and being heavier than the oil it has 
 been deposited at the bottom of the oil reservoir 
 or else, due to favorable oil temperature condi- 
 tions, has formed an emulsion with the oil. In 
 the former case the water will naturally settle 
 in the oil pump usually the lowermost point in 
 the reservoir and in case of a cold snap will 
 freeze up, locking the pump, resulting in a condi- 
 tion which will cause breakage of the oil pump- 
 shaft if the engine is started without first being 
 warmed up. In the second case, the mixture of 
 
166 Tractor Engines. 
 
 oil and water is not conducive to proper 
 lurication. 
 
 There is still another effect which we have not 
 considered. Let us now turn the engine over 
 until the piston is on the intake stroke. We then 
 have reduced pressure in the combustion cham- 
 ber above the piston and atmospheric pressure 
 in the crankcase chamber, and since the oil is not 
 of the character needed to maintain proper pis- 
 ton ring seal, we are going to get a "blow-by" in 
 the other direction, and this upward "blow-by" is 
 going to, carry a quantity of the lubricant up into 
 the combustion chamber where, being slow 
 burning, it is going to tend to produce carbon 
 deposit. This is a condition which must not be 
 lost sight of. 
 
 It will be seen, therefore, that the condition as 
 to piston clearance, and the ability of the lubri- 
 cant to maintain an effective piston ring seal, is 
 going to be second in importance in the deter- 
 mination of the proper grade of lubricant only 
 to the system of lubrication itself. Other fac- 
 tors which must be taken into serious considera- 
 tion are the normal operative temperatures of 
 the engine; the cylinder arrangement, the valve 
 arrangement; the engine speed; climatic con- 
 ditions, etc. 
 
 It is a fact, however, that each of these fac- 
 tors is so interlinked and influenced by some or 
 all of the others, that it takes an experienced 
 automotive engineer, who is not only thoroughly 
 grounded" as to tractor engine design and prac- 
 tice, but who also has had broad practical expe- 
 rience with tractor operation in the field, to size 
 up the situation as regards any particular engine 
 and make an oil determination on a scientific 
 basis. And at that, such a man must also be 
 thoroughly equipped with a knowledge of the 
 
 
Lubrication of the Engine. 167 
 
 characteristics as well as the character of the 
 various grades of lubricating oils he has under 
 consideration. 
 
 For the average tractor owner or operator to 
 try and judge the quality and lubricating value 
 of one oil as against another by so-called oil 
 tests, which are, at best, mere guess-work as he 
 applies them, is foolhardy. With lubricants, as 
 with other commodities, quality counts, and 
 quality cannot be obtained without careful atten- 
 tion to detail in process and procedure at the oil 
 refinery; and this very carefulness, which is the 
 tractor owner's safeguard as to lubricating value, 
 means, of course, increased cost. It could not 
 be otherwise. 
 
 Every reputable oil manufacturer maintains a 
 corps of highly trained technicians, who make a 
 sufficient number of both physical and chemical 
 tests in a fully equipped laboratory and under 
 conditions which assure the utmost in accuracy 
 to determine uniformity of product and to elim- 
 inate even slight variations in the character of 
 their products from day to day. 
 
 These tests, however, are by no means a 
 measure of the lubricating value of an oil. The 
 value of an oil as a lubricant depends, first, upon 
 the stocks from which it is made and the pro- 
 cess or processes employed in the refining of 
 these stocks; and second, upon the process or 
 processes employed in combining these stocks. 
 Upon these two features alone depends the 
 character of the lubricant and no tests which it is 
 within the power of the average oil user to make 
 can determine them. 
 
 The safest and best course for the tractor 
 operator is to buy the best oil the market offers, 
 quite regardless of the cost, and to use the par- 
 ticular grade of that oil for his tractor engine 
 
168 Tractor Engines. 
 
 which the oil manufacturer has specified for this 
 purpose. If this plan is followed, the tractor 
 owner will find that the recommendation offered 
 him by the oil manufacturer has been determined 
 only after careful analysis of his engine con- 
 struction by a lubricating engineering staff, every 
 member of which not only knows tractor engines 
 from front to rear and also "crosswise," but also 
 is thoroughly versed in what the lubricants, as 
 recommended, will and will not do and the 
 reasons therefor. 
 
 DETAILED CARE OF LUBRICATING SYSTEMS. 
 
 There is not a great deal that need be said' 
 with regard to the care of the lubricating sys- 
 tems which fall under the circulating classifica- 
 tion. The principal point to bear in mind is to 
 keep the reservoir well filled, as indicated by the 
 level gauge, so as to be sure that the engine has 
 plenty of oil. 
 
 For the benefit of readers in doubt as to which 
 grade of oil to use, a chart is appended covering 
 most tractors on the market at present; This 
 chart has been carefully prepared by experienced 
 lubrication engineers and the user will do well 
 in following it to the letter. But in doing so, see 
 to it that you obtain the best lubricant that the 
 market affords ; it ,4s well worth the additional 
 cost. 
 
 With circulating systems, frequent draining of 
 the system and refilling with fresh oil is essen- 
 tial for the reason that there always will be a 
 certain amount of fuel admixture which will im- 
 pair the quality of the oil and its value as a lub- 
 ricant; also a certain amount of sedimentation, 
 particles of metal, carbon and grit drawn in 
 through the breather pipe. 
 
Lubrication of the Engine. 169 
 
 Where kerosene is used as fuel, the best plan 
 is to drain the reservoir after every 25 hours of 
 service, draining while the engine is still warm, 
 so as to carry out the last trace of sediment. 
 
 Where the fuel is gasoline, once in 50 hours 
 is generally sufficient for draining. 
 
 Do not flush out the crankcase with kerosene 
 after draining, as some of the kerosene will be 
 trapped in the dipper troughs or other basins in 
 
 
 12 Drtfc* pof MM 
 
 Fig. 114. Adjustment of mechanical oiler on the Aultman- 
 Taylor tractor. 
 
 the engine and will remain to impair the quality 
 of any fresh oil added. The best plan is to drain, 
 wash out with a quart of fresh oil, and then 
 refill the system with new oil. 
 
 When the oil pan can be removed from the 
 bottom of the engine so that all points can be 
 reached and mopped out, the system can safely 
 be washed out with kerosene not otherwise, 
 however. 
 
170 
 
 Tractor Engines. 
 
 The care and adjustment of systems employ- 
 ing the force feed mechanical lubricator can be 
 gathered from the following excerpts from 
 manufacturers instruction books dealing with the 
 subject : 
 
 DIRECTIONS FOR DETROIT FORCE-FEED OILER. 
 (Figure 115.) 
 
 Be sure the tank, or reservoir, is perfectly 
 clean before filling with oil the first time. ? Any 
 
 foreign substance 
 is apt to injure 
 your engine's 
 bearings. 
 
 Be sure to 
 strain your oil be- 
 fore filling the 
 tank always. 
 
 To fill, unscrew 
 the filler cap "A" 
 and pour in the 
 oil. 
 
 Amount of oil 
 in tank is shown 
 
 /V<3 
 
 i WJ 
 
 Fig. 115. 
 oiler. 
 
 A< by the position of 
 
 the pointer. If 
 
 it points to "EMP" the tank is empty; if it 
 points to "FULL" the tank is full. Different 
 levels are indicated by the different positions of 
 the pointer. 
 
 Regulation of each feed is accomplished by 
 adjusting the button "C" in front of that feed. 
 
 When the small stop or projection with the 
 zero mark (0) on the bottom of "C" is against 
 and on the right-hand side of the stop/ pin so 
 that the zero mark is in line with the mark "D" 
 no oil is being fed. 
 
 To feed, turn the button to the left, or in a 
 
Lubrication of the Engine. 171 
 
 counter clockwise direction. One complete turn 
 to the left opens the feed to full capacity. 
 
 To decrease the feed, turn to the right, or in 
 a clockwise direction. 
 
 The regulating buttons are slotted for a screw- 
 driver, coin or other flat piece of metal, as the 
 adjustment is purposely made stiff. 
 
 Once the feeds are adjusted, no further regu- 
 lation is necessary. 
 
 It is not necessary to turn off the feeds every 
 time the engine stops. The force feed oiler 
 starts and stops automatically with the engine. 
 
 To adjust the feed of oiler to your engine: 
 Every engine is different from every other en- 
 gine and no absolute rules can be laid down as 
 to the exact quantity of oil required for your 
 engine. 
 
 If your engine is new, pour about a quarter of 
 a teacup of oil through the spark plug hole on 
 each cylinder and turn the engine over by hand 
 several times to be sure the cylinder and ringf 
 are thoroughly lubricated before starting. Pour 
 oil in each crankcase, too. 
 
 The best way to do this is to feed plenty of 
 oil at first. Take one feed at a time and very 
 slowly and gradually cut down the amount of 
 oil fed to the one bearing until you have found 
 the least amount of oil that will give adequate 
 and perfect lubrication. After one feed is ad- 
 justed, the others can be regulated in the same 
 way. 
 
 Great eare will have to be taken in this pro- 
 cess not to feed so little oil that a bearing is 
 burned out or a crankshaft, piston or cylinder 
 scored. Overheating and squeaking are signs of 
 too little lubricating oil being fed. 
 
 Blue smoke at the exhaust indicates too much 
 
172 
 
 Tractor Engines. 
 
 lubricating oil to the cylinder. Black smoke in- 
 dicates too much gasoline. 
 
 ADJUSTING OILER ON BULL TRACTOR. 
 (Figure 116.) 
 
 
 Do not close off feed valves on lubricator 
 until the motor has run several days, and then 
 with caution. 
 
 All inside parts of motor are lubricated with a 
 six-way force-feed oiler. 
 
 Fig. 116. Adjusting mechanical oiler. 
 
 Before starting motor, be sure this oiler is 
 filled with good clean oil, and turn oiler by hand 
 to see that it pumps freely. 
 
 Always keep oil in the crankcase up to level 
 with drain cock on the flywheel side of crank- 
 case, but never above the level. 
 
 After motor starts be sure that every pipe is 
 feeding properly. You will find pipes running 
 to cylinders, main bearings and connecting rod 
 bearings. 
 
 After the engine has been run several days 
 
Lubrication of the Engine. 173 
 
 and the journals are well seated, adjust the feed 
 pipes, as follows : 
 
 Front cylinder, four to five drops ; rear cylin- 
 der, leave wide open. Main bearings, four to 
 five drops, leave connecting rod bearing feeds 
 wide open. 
 
 Each feed pipe has a separate adjustment. If 
 lead pipes overflow, the motor should be stopped 
 and the pipes cleaned out at once. 
 
 WHAT OIL TO USE IN YOUR TRACTOR. 
 
 SUMMER 
 
 WINTER 
 
 Acme 
 
 
 
 Albert Lea 
 
 Medium heavy 
 
 Medium 
 
 Allis-Chalmers . 
 
 
 Medium 
 
 Allis-Chalmers (General Purpose)... 
 All Work 
 
 Medium 
 Heavy 
 
 Medium 
 Medium 
 
 
 
 
 Appleton 
 
 Medium heavy 
 
 Medium 
 
 Atlas 
 
 
 Medium 
 
 Aultman-Taylor 
 
 Heavy 
 
 Medium 
 
 Aultman-Taylor (22-45) 
 
 Medium hea^y 
 
 Medium 
 
 Aultman-Taylor (15-30) (Waukesha) 
 Automotive 
 
 Medium heavy 
 Medium heavy 
 
 Medium 
 Medium 
 
 Auto-Tiller 
 
 
 Light medium; 
 
 
 
 
 Avery (5-10 H P ) 
 
 Medium 
 
 Medium 
 
 Bates Steel Mule 
 
 Heavy 
 
 Medium 
 
 Bean Track-Pull 
 
 Medium 
 
 Medium 
 
 Beaver (Brantford Canada) 
 
 
 Medium 
 
 Beeman Garden Tractor 
 
 Medium 
 
 Medium s 
 
 Belt Rail. . 
 
 Medium heavy 
 
 Medium 
 
 
 
 
 Best 
 
 Heavy 
 
 Medium 
 
 Big Bull 
 
 Heavy 
 
 Medium 
 
 Blue "J" 
 
 Medium heavy 
 
 Medium 
 
 Buckeye (Ohio) 
 
 Heavy 
 
 Medium 
 
 Cleveland 
 
 Medium heavy 
 
 Medium 
 
 Coleman ... 
 
 Heavy 
 
 Medium 
 
 
 Medium heavy 
 
 Medium 
 
 COD 
 
 
 Medium 
 
 Craig ... 
 
 Medium heavy 
 
 Medium 
 
 Creeping Grip 
 
 Medium heavy 
 
 Medium 
 
 Cultitractor 
 
 Medium heavy 
 
 Medium 
 
 Dakota 
 
 Medium heavy 
 
 Medium 
 
 Depue 
 
 Medium heavy 
 
 Medium 
 
 Eagle . 
 
 Medium heavy 
 
 Medium 
 
 
 Heavy 
 
 Medium 
 
 Fageol 
 
 Medium heavy 
 
 Medium 
 
 Farm Horse 
 
 Heavy 
 
 Medium 
 
 Fitch Four Drive 
 
 Medium heavy 
 
 Medium 
 
 Flour City 
 
 Heavy 
 
 Medium 
 
 
 Medium 
 
 Medium 
 
 Frick . 
 
 Heavv 
 
 Medium. 
 
174 
 
 Tractor Engines. 
 
 
 SUMMER 
 
 WINTER 
 
 Galloway . ..*... 
 
 Heavy 
 
 Medium 
 
 Gehl 
 
 Medium heavy 
 
 Medium 
 
 Gile 
 
 
 
 Gilson (12-25) 
 
 Heavy 
 
 Medium 
 
 Gilson (15-30) 
 
 Medium heavy 
 
 
 Graham 
 
 Medium heavy 
 
 Medium 
 
 Grain Belt 
 
 Medium heavy 
 
 Medium 
 
 Gray 
 
 Medium heavy 
 
 Medium 
 
 Hart Parr 
 
 Heavy 
 
 Medium 
 
 Heider 
 
 Medium heavy 
 
 
 Hession 
 
 Heavy 
 
 Medium 
 
 Hicks 
 
 Heavy 
 
 
 Hollis 
 
 Medium heavy 
 
 Medium 
 
 Holt Caterpillar . 
 
 Heavy 
 
 Medium 
 
 Holt Caterpillar (Model 45) 
 
 Medium heavy 
 
 Medium 
 
 Huber 
 
 Medium heavy 
 
 Medium 
 
 Ideal (Brantford, Canada) 
 Illinois 
 
 Medium heavy 
 Heavy 
 
 Medium 
 Medium 
 
 Indiana 
 
 Medium 
 
 
 International 8-16 
 International 15-30 
 
 Medium 
 Medium heavy 
 
 Medium 
 
 Junior Ideal (Brantford, Can.) 
 K. C Prairie Dog 
 
 Medium heavy 
 Medium heavy 
 
 Medium 
 Medium 
 
 
 Medium heavy 
 
 
 La Crosse 
 
 Heavy 
 
 Medium 
 
 Lang 
 
 Heavy 
 
 
 
 Medium heavy 
 
 
 Leader 
 
 Medium heavy 
 
 
 Liberty 
 
 Heavy 
 
 
 Lightf oot 
 
 Medium heavy 
 
 Medium 
 
 Little Giant 
 
 Medium heavy 
 
 
 Maxim 
 
 Heavy 
 
 Medium 
 
 Minneapolis ... 
 
 Heavy 
 
 
 Mogul (I H Co ) 
 
 Medium heavy 
 
 
 National 
 
 Medium heavy 
 
 Medium 
 
 Neverslip (20-12) 
 
 Heavy 
 
 
 Neverslip (30-18, 10-6) 
 
 Medium heavy 
 
 Medium 
 
 New Age . . . 
 
 Medium heavy 
 
 Medium 
 
 Nilson 
 
 Medium heavy 
 
 Medium 
 
 Oil Pull (20-40) (Rumely Co.) 
 Oil Pull (12-20, 16-30) (Rumely Co.) 
 Oil Pull (Rumely Co.) 
 
 Medium heavy 
 Medium heavy 
 Heavy 
 
 Medium 
 Medium 
 Medium 
 
 Parrett 
 
 Medium heavy 
 
 
 Pioneer 
 
 Heavy 
 
 Medium 
 
 Plow Man 
 
 Medium heavy 
 
 Medium 
 
 Porter 
 
 Medium heavy 
 
 Medium 
 
 Port Huron ... 
 
 Heavy 
 
 Medium 
 
 Reed 
 
 Medium heavy 
 
 Medium 
 
 Royer 
 
 Heavy 
 
 Medium 
 
 Russell 
 
 Medium heavy 
 
 Medium 
 
 Russell (Giant) 
 
 Heavy 
 
 Medium 
 
 Sandusky . . .... . . 
 
 Medium heavy 
 
 Medium 
 
 
 Heavy 
 
 Medium 
 
 Square Turn 18-35 
 
 Heavy 
 
 Medium 
 
 Standard 
 
 Medium heavy 
 
 Medium 
 
 Stinson 
 
 Medium heavy 
 
 Medium 
 
 Stone . . . . . 
 
 Medium heavy 
 
 Medium 
 
 Strite 
 
 Heavy 
 
 Medium 
 
 Titan (I. H. Co.) 
 
 Medium heavy 
 
 Medium 
 
 Topp-Stewart . . . . . . . . 
 
 Medium heavy 
 
 Medium 
 
 Townsend 
 
 Heavy 
 
 Medium 
 
Lubrication of the Engine. 175 
 
 SUMMER 
 
 WINTER 
 
 
 
 
 
 Medium heavy 
 
 
 Trundaar 
 
 
 
 Twin City 
 
 Heavy 
 
 Medium 
 
 Twin City (Model 16) 
 
 Medium heavy 
 
 
 Twin City (Model 12-20) 
 Uncle Sam 
 
 Medium heavy 
 Medium heavy 
 
 Medium 
 Medium 
 
 Velie 
 
 
 
 Victory 
 
 Medium heavy 
 
 Medium 
 
 Wallis Cub (Junior) 
 Ward 
 
 Medium heavy 
 Medium heavy 
 
 Medium 
 Medium 
 
 Waterloo Boy 
 
 Medium 
 
 Medium 
 
 Whitney 
 
 Medium heavy 
 
 Medium 
 
 Wichita 
 
 Medium heavy 
 
 Medium 
 
 Wisconsin 
 
 Heavy 
 
 Medium 
 
 Yankee 
 
 Heavy 
 
 Medium 
 
 Yuba 
 
 Medium heavy 
 
 Medium 
 
 Yuba (Model 12) . . 
 
 Medium 
 
 Medium 
 
 
 
 
CHAPTER VII. 
 
 Cooling. 
 
 Why It Is Necessary and Various Ways 
 Which It Is Carried Out. 
 
 IT is necessary to waste some of the heat gen- 
 erated by the combustion of the gases in the 
 engine cylinders in order to bring the working 
 temperature of these cylinders down to a point 
 where we can maintain a film of oil between the 
 piston and cylinder walls and also in order to 
 prevent the temperature from mounting so high 
 as to cause warping and weakening of the metal 
 or even melting. 
 
 There is another reason, and a highly impor- 
 tant one, for cooling the cylinders. Let us con- 
 sider that the piston is on the intake stroke and 
 that the various parts of the engine are intensely 
 hot. Immediately the cool incoming gas strikes 
 the hot walls it is heated and, naturally, rapid 
 expansion takes place in accordance with the 
 degree to which the gas is heated. This expan- 
 sion, of course, tends to fill up the space and to 
 prevent more gas from entering the cylinder so 
 that we do not get a, full cylinder charge, and 
 naturally the power of the engine falls off. The 
 engineer describes this condition by saying that 
 the "volumetric efficiency" of the engine is im- 
 paired. 
 
 If, however, we keep tKe engine cylinder stone 
 cold, which would permit us to crowd in the 
 largest fuel charge, we have an equally bad effect 
 and we lose power from three causes :' First, 
 
 (176) 
 
Cooling. 177 
 
 that to keep the cylinder cold we must take away 
 a very large portion of the heat generated by the 
 combustion of the gases, and every unit of heat 
 taken means a loss of power ; second,, the chilled 
 cylinder does not further the complete vaporiza- 
 tion of the fuel, and it was pointed out before 
 that vaporization is necessary for any body to 
 take fire and burn; thirdly, all those parts that 
 are not vaporized before the fuel is ignited must 
 be vaporized by the heat liberated when the 
 vaporized parts take fire, which means that the 
 rate of combustion will be slow and the power 
 developed will be impaired as a result. 
 
 Besides, it being necessary for a substance to 
 be vaporized for combustion to take place, it is 
 also necessary to raise it to its critical temper- 
 ature that is, the point at which it will take fire 
 whether a flame is present or not. A match 
 applied to a sheet of newspaper, first converts a 
 small portion of the paper into a gas and raises 
 the temperature of this gas above its critical 
 temperature. The combustion of this gas gives 
 heat enough to gasify the adjacent paper and 
 heat up the new gas, and so the flame travels 
 slowly along until the whole paper is consumed. 
 If, however, we were to place the sheet of paper 
 in a very hot oven, where there was plenty of air 
 and elevate the temperature to a point sufficient 
 to gasify the paper and ignite its gas the whole 
 sheet would burst into flame simultaneously we 
 would have very rapid combustion. 
 
 In the cylinder of the gas engine we simply 
 substitute the gasoline mixture for the news- 
 paper. When the cylinder is cold, the igniting 
 spark must raise a small quantity of the mixture 
 to a point beyond the critical temperature, so that 
 it ignites and the flame so started travels through 
 the mixture. But its spread or travel is com- 
 
178 Tractor Engines. 
 
 
 paratively slow and the power developed is les- 
 sened as a result. 
 
 If now, we heat the gases up to a point more 
 nearly approaching their critical temperature, we 
 not only insure thorough vaporization, but we 
 also make it easier for the flame to travel once 
 it is started by the electric spark, and we get 
 very rapid combustion and greater power from 
 the same amount of fuel. 
 
 , Fig. 117. Thermo-syphon cooling system solid arrows show 
 water circulation; broken arrows, exhaust and air circulation. 
 No water pump or fan is used on the Avery tractor. 
 
 Here, then, we have two contradictory condi- 
 tions, one calling for cooling of the cylinder in 
 order to give a power increase, and the other 
 calling for heating of the cylinder in order to 
 effect the same result. In order to strike the 
 best possible balance and obtain best results, it 
 is apparent that a compromise is necessary. In- 
 deed, the present internal combustion engine is a 
 compromise in many respects besides this. 
 
 All considered, best results from the engine 
 
Cooling. 179 
 
 are obtained when the cylinder walls are main- 
 tained at a temperature in the neighborhood of 
 200 to 225 degrees F. In other words, where 
 water cooling is adhered to, as in the case of 
 practically all tractor engines, the temperature of 
 the cooling water emerging from the cylinder 
 jackets should be in the neighborhood of 200 
 degrees F. to obtain best results from the engine. 
 The cooling system of a typical engine is de- 
 tailed in Figure 117. The cylinders are sur- 
 rounded with a jacket which is cast integral with 
 the cylinder block, and passages at the top of 
 the cylinder block casting lead to the head cast- 
 ing to conduct the water to a 
 similar jacket provided in the 
 latter (Figure 118-A). 
 
 Water, like other substances, 
 expands when heated, except 
 between the very narrow lim- 
 its explained in the first chap- 
 ter, which obviously does not 
 enter into our present consid- 
 eration. If we had a cubic 
 
 .Fig. 118-A. Section | nch f Water and ^^ *> 
 
 showing cylinder it would occupy a space larger 
 than one cubic inch at the 
 higher temperature; but its weight would 
 would be the same, so that its weight for a unit 
 of volume in the second case must be less than in 
 the. first. In other words, the density or specific 
 gravity of water decreases when the water is 
 heated, and since an object of less density than 
 water will float on water, it stands to reason that 
 there will be a tendency for heated water to rise 
 in and float on the top of a body .of water at 
 lower temperature. 
 
 If, then, we have the cylinder jacket of the 
 engine filled with water and the water adjacent 
 
180 Tractor Engines. 
 
 
 the cylinder walls becomes heated, the tendency 
 will be for this warmer water to work to the top 
 of the jacket. An outlet pipe is arranged at the 
 topmost front portion of the cylinder head casting 
 and this outlet is attached by means of a section 
 of rubber hose to a tank formed on top of the 
 radiator. The radiator is composed of an upper 
 and a lower tank connected together by a series 
 of vertical copper tubes arranged in rows from 
 front to rear of the radiator ; the tubes are passed 
 through a large number of copper plates arranged 
 one on top of another and spaced a short distance 
 apart. The purpose of these plates is not so much 
 to support the tubes as it is to increase the radiat- 
 ing surface providing a greaft area for contact with 
 the air, just as with a house- wafming radiator, 
 the radiating surface is increased by increasing 
 the number of coils of pipe or by providing cast- 
 ings with large surface. It is evident, then, that 
 as the water discharged from the engine into 
 the top header passes downward through these 
 tubes, it will be cooled, giving up some of its 
 heat to the tubes from which it is transferred 
 to the flanges and the air, and in order to insure 
 this transfer of heat, a fan is generally mounted 
 behind the radiator and belted to a pulley wheel 
 attached to the front end of the crankshaft or 
 to some other convenient shaft. This fan creates 
 a suction which draws the air through the pas- 
 sages of the radiator "between the flanges and 
 the vertical tubes. In the case of the Avery 
 tractor, pictured herewith, the draught is created 
 by the engine exhaust, no fan being used. 
 
 From the lower header of the radiator, another 
 pipe is arranged which conducts the water to a 
 point on the right side of the engine near the 
 middle, where the water enters at the lowest 
 point in the engine water jacket, becomes heated 
 again, rises and .continues the circulation. 
 
Cooling. 181 
 
 We call such a system which circulates the 
 water by virtue of the natural tendency for the 
 water to rise when heated and sink when cooled, 
 the natural circulation system or "thermo-syphon 
 system." It has a couple of points of advantage 
 over the system in which the water is circulated 
 by an engine pump ; the biggest point in its favor 
 is the fact that it eliminates the pump and the 
 complication which attends its installation and 
 use. Another point in its favor is that the water 
 does not begin to move until it becomes heated, 
 so that the cylinders reach their working temper- 
 ature more quickly when the engine is started 
 from cold. Larger inlet and outlet water piping 
 is required than with the pump system, due to 
 the fact that the force causing circulation is 
 limited. 
 
 It will be noticed that the connections between 
 the engine and the radiator are made .with rub- 
 ber hose of the proper size clamped in place with 
 suitable hose clamps to insure against the hose 
 slipping off and against leakage at the joints. 
 The use of the rubber hose is not so much for 
 the purpose of simplifying attachment and de- 
 tachment as it is to protect the radiator from the 
 vibration when the engine is in operation which, 
 were metal pipe used, would be transmitted 'to 
 the radiator and soon cause rupture of the joints. 
 
 It is necessary to keep the radiator full of 
 water at all times. Filling is accomplished by 
 taking off the radiator cap 'and pouring in clean 
 water, preferably rain water or soft water; use 
 hard well water only when none other can be 
 obtained and replace with soft water at first 
 opportunity. Screw the radiator cap back firmly 
 in place when the radiator is filled, to guard 
 against its working off. There is a small over- 
 
% 
 
 182 Tractor Engines. 
 
 flow pipe or tube leading from inside the filler 
 neck on the radiator down the rear right side of 
 the device to a point beneath the pan. 'This is 
 to provide for expansion of the water which al- 
 ways takes place when the water is heated and 
 which would burst the radiator if means were not 
 taken to get rid of the excess. It also serves to 
 permit the escape of any steam generated in the 
 engine jackets with the engine in operation. 
 The amount of cooling surface of the radiator 
 
 Fig. 118-B. Hopper cooling on Mogul 10-20. 
 
 and the water capacity of the system have been 
 so proportioned to the amount of heat it is nec,es- 
 sary to get rid of as to maintain the engine cylin- 
 ders at or near their proper working temperature 
 at all times. 
 
 In Figure 118-B is pictured a Mogul 10-20 
 engine equipped also with a thermo-syphon sys- 
 tem, but of very much simpler design. As a 
 matter of fact, it consists simply of a large box 
 or hopper surrounding the single-cylinder of this 
 engine and which takes the place of the water 
 jacket. This box is filled with water and serves 
 
Cooling. 183 
 
 at once as water jacket, water tank and radiator. 
 The heated water simply rises to the top of the 
 hopper and is cooled on contact with the air. 
 The capacity of the hopper is comparatively large 
 so that fairly good cooling is obtained; no fan 
 or forced draught is used. 
 
 While the simple hopper system is well adapted 
 to function perfectly on such low-powered en- 
 gines as the one described above, when we come 
 
 Fig. 119. Pump system on Aultman-Taylor. 
 
 to engines of high power more adequate means 
 of cooling must be provided. As a matter of 
 fact, at the present time the manufacturers who 
 are relying on thermo-syphon circulation of the 
 cooling water are greatly in the minority. Most 
 tractor engineers feel that an engine running 
 constantly , at nearly full load like the tractor 
 engine, and where temperatures are bound to be 
 high, needs forced water circulation quite as well 
 
184 Tractor Engines. 
 
 as forced oil circulation, and the result is that 
 pump cooling is coming more and more to the 
 fore. 
 
 The pump system differs from the simpler 
 thermo-syphon system in one particular only. 
 That is in the employment of a pump generally 
 of the centrifugal or impeller type to draw the 
 water from the bottom of the radiator and force 
 it through the cylinder jackets. The centrifugal 
 pump is employed because of its simplicity it 
 being devoid of valves and checks and the fact 
 that in case of pump failure the pump offers no 
 impediment to the circulation of the water by the 
 thermo-syphon system, so that the engine will 
 be reasonably well cooled. Figure 119 shows 
 the pump system applied to a typical tractor, the 
 Aultman-Taylor. 
 
 There are two other details in connection with 
 tractor engine cooling that it is well to note. 
 The first is the employment of oil in the cooling 
 system instead of water, which- is carried out 
 in the case of some of the larger Rumely jobs; 
 and the second is the employment of a water 
 temperature regulator for maintaining the water 
 jackets always at uniform temperature at which 
 the fuel is best handled, a practice which is being 
 introduced by the Case people and which closely 
 follows what has been found best in automobile 
 practice. 
 
 The use of oil in the Rumelys determines 
 slightly higher cylinder jacket temperatures than 
 can be maintained with water because of its com- 
 paratively low boiling point, bringing the cylin- 
 der temperature up to a point which is practically 
 the ideal. At the same time, the oil being non- 
 freezing at any climatic temperatures encoun- 
 tered in this country at least, there is not the 
 slightest need of draining the engine cooling 
 
Cooling. 
 
 185 
 
 system during the cold weather and no danger 
 of freezing and damaging the mechanism. 
 
 The device used on the Case for temperature 
 control is a simple little thermostat which regu- 
 lates a by-pass valve, as shown in Figure 120. 
 The thermostat itself comprises a little metal 
 cylinder, corrugated to make it flexible and ex- 
 tensible as to length, to one end of which is at- 
 tached the rod which actuates the by-pass valve. 
 This cylinder is half filled with a very volatile 
 liquid which when heated expands, creating suf- 
 ficient pressure within 
 the cylinder to cause 
 it to elongate, moving 
 the rod and actuating 
 the valve. 
 
 It will be seen, by 
 reference to the fig- 
 'ure, that the circulat- 
 ing system between 
 the engine jackets and 
 the radiator is "short- 
 circuited" by a by-pass 
 pipe and the thermo- 
 stat cylinder is placed 
 in this pipe. The ar- 
 rangement is such 
 that when the water 
 
 FIG. 1 2O 
 
 Fig. 120. Syphon regulator 
 showing path of circulation. 
 
 is cold, the thermostat closes the passage from 
 the radiator to the engine pump and opens 
 the by-pass pipe into the pump intake so that 
 the water does not circulate through the 
 radiator at all, but simply passes through the 
 by-pass. 
 
 Naturally, there being only a slight amount 
 of water in circulation, it heats up very quickly 
 and the engine attains its normal operating tem- 
 perature in no time. As the water heats up, the 
 
186 Tractor Engines. 
 
 
 thermostat expands and allows more and more 
 cool water to be drawn into the system from 
 the radiator; and it is so set that it will propor- 
 tion the feed between the two in such' a manner 
 as to feed water at a constant temperature to 
 the engine throughout the day and quite regard- 
 less of operating conditions and loads carried. 
 
CHAPTER VIII. 
 
 Care of the Cooling System. 
 
 Any Leaks That Develop in the Water System 
 Should be Stopped Immediately. 
 
 IF leaks are at the hose joints, tightening the 
 clamps or replacing the rubber hose with new 
 hose will effect a cure. The hose should be re- 
 placed every season with new hose anyway, 
 because the action of the hot water tends to rot 
 it, causing the inner lining to peel off, and the 
 circulation of the peelings will carry them, in 
 time, to the top header of the radiator, where 
 they are likely to block one or more of the tubes, 
 causing partial stoppage of the circulation. 
 
 From time to time the drain cock provided at 
 the lowermost point in the radiator, where the 
 water passes out to the cylinder jackets, should 
 be opened and the water drained from the sys- 
 tem ; the system should be flushed out with fresh 
 water, which will have the effect of cleaning out 
 the rust and any sediment due to the use of 
 hard water. It is well, once in every month, to 
 put. a pound of washing soda into the radiator 
 and leave it there for a day .or so, permitting the 
 free circulation of the hot soda solution. This 
 will free any scale formed on the inside walls of 
 the cylinder jackets and in the radiator itself as 
 a result of the use of hard water, and will also 
 help loosen any accumulation of rust ; the system 
 should then be thoroughly flushed out, preferably 
 by removing the hose connections and turning a 
 hose first through the radiator and then through 
 
 (187) 
 
188 Tractor Engines. 
 
 the engine jackets. This will carry off any sedi- 
 ment and leave the system perfectly clean. 
 
 The fan belt should be kept perfectly tight by 
 means of the adjusting screw provided in the fan 
 bracket. Take up the slack in the fan belt until 
 the fan begins to drag when turned by hand. 
 
 There are two gaskets, one on the inlet nipple 
 flange and the other on the outlet nipple flange, 
 to which the connections to the radiator are 
 attached, which will leak occasionally unless the 
 stud screws holding them to the cylinder castings 
 are drawn up tightly. Leakage of water from 
 the cylinder head gasket should be corrected im- 
 mediately by drawing up on the hold-down bolts 
 by means of which the head casting is fastened 
 to the cylinder block, which will have the effect 
 of compressing the gasket and stopping the leak. 
 
 Never put any solid or any liquid containing 
 a solid substance in the radiator to stop leakage. 
 There are several radiator compounds on the 
 market intended for this purpose, which are 
 liquids of a special nature, which solidify or get 
 gummy when they are mixed with warm water 
 and brought into contact with the air. These 
 substances are perfectly safe for use in the cool- 
 ing system to correct small leaks, and they will 
 actually act to prevent the formation of scale at 
 the same time, when used in accordance with 
 the manufacturer's directions. 
 
 Overheating of the engine as evidenced by 
 boiling of the water and poor operation of the 
 motor as a whole may be caused by a variety of 
 troubles. The presence of excessive carbon de- 
 posit in the combustion chamber and on top of 
 the pistons will cause it, the cure being to remove 
 the carbon as directed in a previous chapter. 
 
 Racing the engine is a frequent cause; run- 
 ning with the spark retarded; poor spark; in- 
 
 . 
 
Care of the Cooling System. 189 
 
 sufficient oil, use of poor oil or the use of oil 
 of a grade unsuited to the engine will cause over- 
 heating; improper carburetor adjustment, giving 
 either too lean or too rich a mixture and thereby 
 causing slow burning, which exposes a greater 
 area of the cylinder walls to the heat ; fan blades 
 bent, belt broken or slipping; improper circula- 
 tion due to clogged or jammed radiator tubes, 
 leaky connections or too little water in system. 
 
 The correction for most of these is apparent 
 or has already been explained. Those having 
 to do with the ignition system will be explained 
 fully in a later chapter dealing with this impor- 
 tant system. 
 
 The repair of a leaky radiator, provided it is 
 not badly broken by a smashup or some similar 
 mishap, is a job that is best left to a mechanic 
 who has specialized in work of this sort unless 
 the man undertaking the job has had quite some 
 experience in the manipulation of soldering tools. 
 The first thing to do is to remove the radiator 
 from the tractor, which is done by disconnecting 
 the hose connections to the engine and undoing 
 the bolts which fasten the radiator brackets to 
 the frame. 
 
 With the radiator off, the next step is to locate 
 the leak or leaks. This is done by plugging up 
 the inlet and outlet passages of the radiator, 
 using large cork stoppers if they can be had of 
 ample size, or potatoes in case stoppers are not 
 handy. Then with a tire pump, force air into 
 the radiator through the overflow pipe, at the 
 same time submerging the radiator in a tub of 
 water. The bubbles caused by the escaping air 
 will indicate the place where the radiator is leak- 
 ing; it should be marked for identification when 
 the radiator is removed from the water. Next 
 place the radiator on a work bench and heat the 
 
190 
 
 Tractor Engines. 
 
 
 tubes around the leak with a blow-torch. When 
 they are just a little hotter than the boiling point 
 of water, ordinary acid soldering solution, made 
 by treating muriatic (hydrochloric) acid with 
 pure zinc, is poured through the fins all over 
 the leaky tubes to thoroughly clean their surfaces. 
 Then melt a ladleful of 
 solder, which should be 
 ordinary half in half 
 plumbers' sol- 
 der, and after 
 blocking the 
 radiator up 
 from the bench 
 sufficiently to 
 be able to hold 
 another ladle 
 beneath it, pour 
 the solder 
 through the 
 fins and over 
 the tubes, catch- 
 ing it in the 
 empty ladle, as 
 shown by the 
 sketch (Figure 
 121). Then 
 turn the radia- 
 tor over and 
 repeat the op- 
 eration, pour- 
 ing through in 
 the opposite direction. Apply more of the sol- 
 dering solution and heat once again with the 
 torch until the solder melts and runs into the 
 leaks, sealing them against further leakage. Be- 
 fore putting the radiator back on the tractor, it 
 is best to test it once again to make sure that 
 
 Fig. 121. Method of repairing vertical 
 tube radiator. 
 
Care of the Cooling System. 191 
 
 all the leaks have been soldered up. In case a 
 tube is jammed, the best plan is to cut it off 
 an inch above and below the clotiire and sweat 
 a new piece of tube of the correct length and 
 diameter in place of the piece that has been 
 removed. 
 
 During winter weather some precautions must 
 be taken to protect the radiator from freezing, 
 especially when the tractor is left standing with 
 the engine shut off. Freezing of the water in 
 the radiator is bound to cause the tubes to burst 
 and leak, and if the water freezes in the engine 
 jackets, the jacket itself will burst in nine cases 
 out of ten and it will be necessary to have it 
 welded to effect a repair. In some cases of 
 radiator freezing the rupture will be so bad that 
 it will be necessary to replace the radiator with 
 a new one. It is well, therefore, to take the 
 simple precautions necessary to guard against 
 such a contingency. 
 
 If the tractor is used only occasionally during 
 the winter months, the best plan is to pour hot 
 water into the cooling system when starting out. 
 This will facilitate starting of the engine. Cover 
 the lower portion of the radiator with a piece of 
 cardboard, so that the cooler water at the bottom 
 of the radiator will not freeze. At the end of 
 the day, drain the cooling system thoroughly by 
 opening the drain cock, letting the engine idle 
 while the water is running out, in order to pro- 
 vide sufficient heat to dry the jackets thoroughly. 
 
 If the tractor is used a great deal throughout 
 the winter, the best plan is" to use a non-freezing 
 solution in the cooling system. There are several 
 substances which can be mixed with the cooling 
 water and which will have the desired effect of 
 lowering its freezing point. Quite the most com- 
 monly used is wood or denatured alcohol. A 20 
 
192 Tractor Engines. 
 
 
 per cent solution of alcohol and water does not 
 freeze until a temperature of 15 degrees F. is 
 reached; a 30 per cent solution freezes at 8 de- 
 grees below zero, and a 50 per cent solution at 15 
 degrees below. Glycerine and calcium chloride 
 are sometimes used instead of the alcohol. 
 
 The trouble with alcohol is that its boiling 
 point is quite a bit lower than that of water, so 
 that it evaporates quickly, and it is therefore 
 necessary to replenish the supply from time to 
 time in order to guard against freezing. The 
 glycerine, on the other hand, attacks the rubber 
 hose connections, causing swelling and peeling, 
 while the calcium chloride forms an alkali solu- 
 tion which sets up electrolytic action between 
 the copper radiator tubes and the solder, causing 
 them to corrode, which, of course, is not at all ' 
 desirable. There are several compounds on the 
 market intended to prevent freezing of the cool- 
 ing water and which are said to be free from 
 any of these defects. 
 
 During the last year or so it has become quite 
 common practice to drain the water from the 
 cooling system and fill it up with kerosene during 
 the winter months. This practice will work out 
 to advantage in cases where the tractor is used 
 often but not driven very hard and is stopped 
 frequently. For very hard plugging the use of 
 kerosene is not to be recommended, for the simple 
 reason that its specific heat its capacity to ab- 
 sorb heat is only about one-half that of water 
 while its conductivity of heat is only about one- 
 third that of water. It is evident that it has not 
 the capacity for carrying away enough of the 
 heat from the cylinders to provide for proper 
 cooling if the engine is run all out for long in- 
 tervals. 
 
CHAPTER IX. 
 
 Ignition System. 
 
 How the Spark Is Produced and Controlled to 
 Obtain the Desired Results. 
 
 IN order to ignite the mixture in the cylinder 
 of the engine, a spark which is hot enough to 
 raise the gas adjacent to its critical temperature 
 and thereby set fire to it is essential. The 
 simplest way of producing a spark in the cylin- 
 der of an engine at exactly the time required to 
 ignite the mixture is to make use of the electric 
 current, which in its action is practically in- 
 stantaneous. 
 
 To thoroughly comprehend the operation of 
 the ignition system we must start right at the 
 beginning and learn something of the nature of 
 the electric current and its generation. We all 
 know what a magnet is a common horseshoe 
 magnet such as the schoolboy uses for a play- 
 thing. Let us consider its properties for a 
 minute. It is nothing more than a simple bar of 
 steel, bent in the shape of a horseshoe and mag- 
 netized, and it has the property of attracting 
 things made of iron and steel, and to a lesser 
 degree, manganese and nickel. More careful 
 examination of the properties of the magnet re- 
 veal that the action of the two ends is not the 
 same and we have come to know one end as the 
 North or Positive end of the magnet and the 
 other one the South or Negative pole. We have 
 .discovered that issuing from the North pole 
 there are certain lines of magnetic force which 
 
 (193) 
 
194 
 
 Tractor Engines. 
 
 spread apart somewhat in the air and then con- 
 verge again and enter the South pole of the mag- 
 net. It is these lines of magnetic force their 
 exact nature is quite unknown to us which give 
 the magnet the property of attracting substances 
 susceptible to magnetic influence. 
 
 Let us consider that we have such a magnet 
 (Figure 122) and that it is a very strong one, 
 which means that there are a whole lot of mag- 
 netic lines of force crowded into a very small 
 space between the two poles. Let us suppose, 
 also, that we have a loop of wire like a hoople 
 
 !/ 
 
 N 
 
 ^l*N 
 
 t I *\ 
 
 'NO N 
 
 \v 
 
 OAR 
 
 MAGNET 
 AND 
 
 or F-ORCE: 
 
 Fig. 122. Typical magnets illus- 
 trating lines of magnetic force or the 
 magnetic field set up between the 
 poles. 
 
 OF" FOKCf. 
 
 a complete circle, in other words. We hold 
 the hoople in one hand and the magnet in the 
 other and we move the loop in so that the wire 
 on one side of the loop enters between the poles 
 of the magnet and crosses or cuts every one of 
 the lines of magnetic force traveling between 
 these poles. While we are actually moving the 
 wire through the field of magnetic force and 
 actually cutting lines of force, there is a current 
 of electricity generated in the wire and flowing- 
 through it. And furthermore, the faster we cut 
 
Ignition System. 195 
 
 the lines of force that is, the greater number of 
 lines cut in a given interval of time the greater 
 will be the strength of the current. 
 
 Now let us suppose that we have carried the 
 loop all the way in and have reversed the motion 
 and are bringing it out again; it is then cutting 
 the lines of force in the opposite direction, and 
 while it is actually moving, there is a current 
 generated in the wire. But this time, due to the 
 reversal of the direction in which the lines of 
 force are cut, the current flows in the opposite 
 direction to which it was flowing in the first 
 instance. If now we keep the coil of wire mov- 
 ing in and out, we will have a current flowing 
 as long as there is movement, and it will reverse 
 itself each time the direction of motion is re- 
 versed and we have what we term an "alter- 
 nating" current. If it were always flowing in 
 the same direction we would call it a direct 
 current. 
 
 The important thing to bear in mind is that 
 there must be a complete circuit for the current 
 to flow through if we open the loop of wire 
 the current stops immediately, regardless of the 
 movement of -the coil and that the current flows 
 only while the lines of magnetic force are actu- 
 ally being cut. It makes no difference whether 
 we move the magnet or move the coil; provided 
 the motion is such that lines of force are cut 
 by the wire, we set up a current of electricity in 
 the loop. It is a fact, also, that both can be held 
 still and by decreasing and increasing the- 
 strength of the magnet, we cause the lines of 
 force themselves to move, and in so moving to 
 cut the coil -of wire and get the same effect 
 but always to get a current lines of force must 
 be cut by the wire loop. This latter principle 
 should be borne distinctly in mind, as it is all- 
 
196 Tractor Engines. 
 
 important to a thorough understanding of the 
 ignition system. 
 
 The current generated by the simple apparatus 
 we have described would be so slight as to be 
 imperceptible and incapable of measurement 
 except by the finest of instruments. Since the 
 current strength depends upon the number of 
 lines of force which we cut in a given interval 
 of time, it is obvious that there are three ways 
 of increasing its strength: 
 
 1. Increase the speed of the moving part, 
 whether it is the magnet, the coil or the field 
 itself. 
 
 2. Increase the number of lines of force, or 
 in other words, the strength of the magnet. 
 
 3. Increase the number of turns of wire on 
 the coil, for it is obvious that two loops will cut 
 twice as many lines of force in a given interval 
 of time as one loop. 
 
 Here we have concretely stated the elements 
 of a practical dynamo. If we employ field mag- 
 nets of great strength, and if we employ a large 
 number of turns of wire on the revolving arma- 
 ture, and if, furthermore, we rotate the armature 
 at high speed, we produce a current at fairly 
 high pressure or voltage. 
 
 But even so, it takes very high electrical pres- 
 sure to force a current to jump over even the 
 smallest air gap. If the wire in a circui't be 
 broken and the ends separated by even the slight- 
 est distance, for instance, the current is imme- 
 diately interrupted and does not jump the gap 
 and produce a spark except at the very instant 
 when the break occurs. And we can bring the 
 two ends together just as close as we care to, 
 without rhaking them actually touch, and the cur- 
 rent flow will not be re-established. 
 
 In order to get the current to jump a gap of 
 
Ignition System. 197 
 
 i 
 
 sufficient length to ignite the mixture in our 
 cylinders, therefore, we have to resort to special 
 means to increase the pressure far and above 
 the voltage that can be created directly by a 
 dynamo such as we have described above of a 
 size to be applicable to the tractor engine. There 
 are two methods of accomplishing this. The first 
 is to make use of an induction coil or a trans- 
 former coil, and its operation will not be hard 
 to comprehend, provided we have grasped the 
 fundamental principles of the dynamo just 
 described. 
 
 Let us go back once again to our loop of wire 
 and consider that we have current flowing 
 through it. It is a peculiar fact that whenever 
 current flows through a conductor such as a wire, 
 all around that wire we create a field of mag- 
 netic lines of force exactly as we have lines of 
 magnetic force issuing from the magnet. Any 
 wire with electric current flowing through it, 
 therefore, is in reality a magnet, and the strength 
 of the magnet will depend upon the strength 
 of the current flowing through it, and the num- 
 ber of turns of wire on the coil. Now, if we coil 
 the wire up into a helix, which is a coil like an 
 exhaust valve spring, having all the layers in- 
 sulated from each other, and inside that coil we 
 place a core made of soft iron wire, the lines of 
 magnetic force engendered by the passage of the 
 current will flow through that core and one end 
 will become a North pole and the other a South 
 pole and the lines of force from the North pole 
 will bulge out around the coil on all sides and 
 bend in again to meet the South pole while cur- 
 rent is flowing through that coil. 
 
 If we pass more current through the coil the 
 lines of force will bulge out further, like a barrel, 
 and if we suddenly stop the flow by breaking 
 
198 Tractor Engines. 
 
 the circuit, they will very quickly collapse in 
 ward the coil and then stop flowing. But the 
 big point to bear in mind is that varying the 
 strength of the field by making and breaking the 
 circuit will cause that magnetic field to move 
 quickly away from and toward the coil. 
 
 Now let us say that we have such a coil with 
 one end attached to the dynamo terminal or to 
 one pole of a battery of dry cells and the other end 
 grounded so that the circuit is complete. And 
 supposing on top of that coil, but fully insulated 
 from it, we wind another coil consisting of a 
 very large number of turns of very fine wire 
 and we fasten one end of this second coil to the 
 spark plug terminal and the other end we ground. 
 Then we have substantially a complete circuit, 
 the only break in it, provided / the plug is screwed 
 into place in the cylinder, is the spark gap in 
 the plug. By "grounding," we mean attaching 
 the wire to the metal part of the machinery so 
 that the machine itself, such as the engine frame, 
 becomes part of the circuit. All ignition circuits 
 are grounded in this way. 
 
 Supposing now that we have the dynamo run- 
 ning so that current is flowing through the first 
 coil, which we will call our primary coil ; then 
 the magnetic field set up around this primary coil 
 will completely envelop the second coil, which 
 we will call our secondary coil. If now we sud- 
 denly break the dynamo or primary circuit, caus- 
 ing a sudden stoppage of the current flow, the 
 magnetic field issuing from the primary circuit 
 will suddenly collapse, cutting all of the very 
 many turns of wire on the secondary coil so that 
 we have an abundance of lines of force moving 
 at very rapid rate and cutting a great number 
 of wires every condition favorable for the pro- 
 duction of high electrical pressure, and conse- 
 
Ignition System. 
 
 199 
 
 quently we can take from the coil, just at the 
 instant the primary circuit is broken, current at 
 sufficiently high pressure to jump the spark plug 
 gap and return to the grounded end of the 
 secondary circuit through the metal parts of the 
 engine. 
 
 This arrangement of the primary and second- 
 ary circuits is shown in detail in Figure 123, ex- 
 cept that a battery of dry cells is substituted for 
 the dynamo in order to make the operation clear. 
 
 Fig. 123. Construction of conventional induction coil used for 
 ignition purposes. 
 
 The primary circuit is represented by the 
 heavy line and the arrows indicate the direction 
 of flow. Considering the switch at E and F 
 closed, the current starts and flows through the 
 timer, which is also considered to be making con- 
 tact and completing the circuit, to the binding 
 post M. Thence through the contact C to spring 
 contact B and through the heavy coil around the 
 soft iron core and out to the grounded terminal 
 
200 Tractor Engines. 
 
 U. Thence through the metal parts back to the 
 grounded terminal of the battery at I. It was 
 said that when the current is flowing through the 
 primary, the core really becomes a magnet. Such 
 being the case, it attracts the little piece of soft 
 iron D mounted on the contact spring A and in 
 pulling it it separates the contacts B and C and 
 breaks the circuit. The magnetic field immedi- 
 ately disappears and the spring draws the arma- 
 ture back and the contacts again meet and re- 
 establish the circuit and the same thing occurs all 
 over again. The spring keeps on vibrating, 
 alternately making and breaking the circuit, first 
 building up and then destroying the magnetic 
 field around the primary coil, keeping it in con- 
 stant agitation so that it is continually causing 
 lines of magnetic force to be cut at a very rapid 
 rate and consequently, in the secondary coil 
 shown in lighter line on top of the primary, 
 there is generated a current at very high pressure 
 or voltage. 
 
 From one of the secondary terminals, the plug 
 cable leads to the spark gap X, which in the case 
 of the ignition coil is the terminal on the spark 
 plug, while the other secondary terminal is 
 grounded so that the current jumps the gap to 
 the grounded terminal on the spark plug and 
 makes its way back through the metal parts of 
 the engine to the grounded secondary spark coil 
 terminal. It will be understood from what we 
 have said of the nature of the secondary current, 
 that extra precautions must be taken to prevent 
 its escape, since its pressure is so high that un- 
 less well insulated it will pass to the metal parts 
 of the tractor and complete the secondary circuit 
 without bothering to cross the spark plug gap, 
 and in such a case the cylinder will miss fire, 
 since there is no spark occurring in it to set fire 
 
Ignition System. 201 
 
 to the mixture. For this reason, the secondary 
 wiring leading from the high-tension terminals 
 of spark coils to the spark plug terminals are 
 made of very heavily insulated ignition wiring 
 and care should be taken in case replacement is 
 necessary to use secondary wiring for the plug 
 cables. The primary wiring, on the other hand, 
 which carries the current at low pressure, need 
 not be so ^leavily insulated, since the voltage is 
 not sufficient to cause it to jump an air gap or 
 break down the insulation. 
 
 When we start the flow of electric current, it 
 acquires a certain amount of momentum in a 
 manner somewhat similar to bodies which are in 
 movement. When we come to stop it suddenly 
 it offers some resistance and tends to persist in 
 its forward movement. If, then, we open the 
 contact points B and C, the primary current flow- 
 ing through the circuit, due to this momentum, 
 tends to keep on flowing and this continued flow 
 is evidenced as a blue spark across the air gap 
 which is formed between the points. The spark 
 is undesirable from two' standpoints. In the first 
 place, it causes burning and pitting of the c6n- 
 tact points, and in order to resist the heat of 
 the spark it is necessary that these points be 
 made of heat-resisting metal. In days before the 
 war, platinum was the metal invariably used, but 
 owing to its scarcity at present, tungsten and 
 tungsten alloys are being used with very good 
 results. 
 
 The second bad effect of this spark across the 
 points is that just so long as a spark is present, 
 current must be flowing, as it is the current 
 which is the cause of the spark. It will be re- 
 membered that to set up an intense current in the 
 secondary we said it was necessary to cut the 
 greatest number of lines of force possible with 
 
202 Tractor Engines. 
 
 the coil in the shortest interval of time in other 
 words, it is necessary to destroy the primary 
 magnetic field as quickly as possible. It is de- 
 sirable, therefore, to eliminate this spark so that 
 the current in the primary circuit will stop short 
 and the field will be instantly destroyed. 
 
 To do this, and eliminate the spark, we make 
 use of a special little device called a condenser, 
 which is connected up to both of the contact 
 points on the circuit breaker, so that when the 
 points open it in reality bridges the gap left 
 between them. It is indicated by the letter L in 
 Figure 123. The condenser is composed of alter- 
 nate layers of tinfoil and paraffin paper which 
 serves to insulate one tinfoil layer from the next. 
 Every second lay^er of tinfoil is brought out on 
 one side of the condenser, all being fastened to- 
 gether and connected to a terminal, and every 
 second layer is treated in the same manner on the 
 other side of the instrument, so that one terminal 
 is completely insulated from the other. The de- 
 vice, therefore, offers no path for the current. 
 
 It has, however, the singular property of being 
 able to absorb electrical current and the amount 
 it will absorb depends upon the area of the tin- 
 foil used in its construction. When the contact 
 points are opened, the onrush of the current, due 
 to its inertia, causes it to flow into the condenser, 
 charging it, and checking the tendency of the 
 current to flow across the points and cause a 
 spark. When the contact points come together 
 again, the condenser is discharged through the 
 primary circuit, helping to establish the circuit 
 again. 
 
 To use a crude analogy, it acts in a manner 
 similar to the air dome or chamber used on a 
 fire engine. If the fireman suddenly turns off 
 the hose nozzle with the pump in operation, the 
 
 
Ignition System. 203 
 
 water, due to its inertia and the action of the 
 pump, is forced into this air chamber compress- 
 ing the air above it. If this chamber were nbt 
 provided, the water would burst the hose just as 
 in the electric system the inertia of the current 
 will cause it to jump the gap between the open- 
 ing contacts when no condenser is provided to 
 absorb the current. When the fireman opens the 
 nozzle again, the air pressure forces the water 
 out of the dome through the hose, helping to' 
 re-establish the flow of water and give a good, 
 strong stream. 
 
 We find that with a plain coil without a con- 
 denser, the spark is very weak altogether too 
 weak to jump the plug gap in the engine cylin- 
 der and that sparking at the circuit breaker soon 
 causes the points to burn and wear away. With 
 the condenser in the circuit, 'we get a fine hot 
 spark with none of this trouble. 
 
 There generally is a separate spark coil used 
 for each cylinder. They are. very compact, the 
 condenser being embodied right in the coil, which 
 is protected with a wax composition insulation 
 and which has the little electromagnetic circuit 
 breaker mounted right on top of the coil unit. 
 There are only three terminals on the coil, be- 
 cause, since one end of the primary coil and one 
 end of the secondary are grounded as described 
 above, to simplify the construction, the grounded 
 ends of the coils are connected together inside 
 the insulation and only one ground wire serving 
 for both primary and secondary coils is brought 
 out to the metal contact. , 
 
 It is necessary, of course, to' pass the mag- 
 netic current through the proper coil at exactly 
 the instant the spark is required in the particular 
 cylinder which is at the top of its compression 
 stroke and ready to fire. For this purpose we 
 
204 
 
 Tractor Engines. 
 
 use a little rotary switch called a timer, which 
 is mounted on the front end of the camshaft so 
 that the rotary contact member revolves at half 
 the speed of the crankshaft. The timer (Figure 
 124) consists of a ring of fiber insulating material 
 in which are embedded four short segments of 
 brass mounted diametrically opposite one an- 
 other. Contact is established between these seg- 
 ments and four screw terminals or binding posts 
 mounted on the 
 outside of the 
 timer. 
 
 The rotary 
 contact m e m- 
 b e r comprises 
 a lever fitted 
 with a compar- 
 atively large 
 roller at one 
 end, the lever 
 being pivoted 
 to a fulcrum 
 attached to the 
 end of the cam- 
 shaft by means 
 of a screw 
 thread and lock 
 nut. At the 
 other end of the lever is a helical spring anchored 
 to a projection on the fulcrum arm, the arrange- 
 ment being such that the spring keeps the roller 
 constantly in contact with the inner side of the 
 fiber ring on which are placed the brass contact 
 segments. The ring is held stationary, although 
 it is adapted to turn through a short arc, so that 
 when the engine is in operation the roller makes 
 one complete circuit of the ring for every two 
 revolutions of the crankshaft and makes contact 
 
 Fig. 124. Construction of typical timer 
 or commutator. 
 
Ignition System. 205 
 
 with each of four segments once. A metal cover 
 provided with an oiler is fitted to the commuta- 
 tor to keep out the dirt and keep in the light 
 machine oil which is used for lubrication. 
 
 It will be seen that the rotary contact maker is 
 not insulated from the camshaft in other words, 
 it is "grounded" to the engine. Each time it 
 makes contact with one of the segments, there- 
 fore, the coil to which this segment is attached is 
 also grounded, so that the primary circuit is 
 completed, current flows through that particular 
 coil, but not through any of the others, since they 
 are not grounded and the circuit is not complete, 
 and the circuit breaker vibrates and we get cur- 
 rent from the secondary coil which is conducted 
 from the proper terminal in the middle row of 
 terminals on the back of the coil box to the spark 
 plug in the cylinder ready to fire. It jumps the 
 gap, ignites the mixture, returns through the 
 metal of the engine and through the timer to 
 the ground wire which, it will be remembered, 
 is attached to the grounded terminals of both 
 primary and secondary circuits. 
 
 Figure 125 gives a cross-sectional view of a 
 typical spark plug screwed into the cylinder and 
 also indicates the path of the secondary current. 
 N represents the high tension terminal on the 
 coil from which the current passes immediately 
 the timer establishes contact to the terminal on 
 top of the plug. It then flows down through 
 the central electrode, as indicated by the arrows, 
 jumps the spark gap two gaps are indicated in 
 the plug illustrated to the grounded electrode 
 which is attached to the spark plug shell. As the 
 shell is screwed into the metal cylinder, the cur- 
 rent is grounded and travels back to the grounded 
 secondary coil winding through the metal parts 
 of the engine. 
 
206 
 
 Tractor Engines. 
 
 
 The plug consists of an outer shell of steel or 
 brass adapted to screw -into the plug hole in the 
 cylinder, an inner insulator generally made of 
 porcelain, special stone composition or mica and 
 through which runs the central or insulated elec- 
 trode, and a compression nut and packing or 
 gasket by means of which the various parts are 
 
 Fig. 125. Construction of a typical spark plug. 
 
 held together so as to correctly insulate the cen- 
 tral electrode and at the same time make the 
 construction perfectly gas-tight and prevent loss 
 of compression. The illustration shows a special 
 type of plug provided also with an outer insu- 
 lating shell, adapted to keep moisture from the 
 main insulator and thus prevent short-circuiting 
 of the plug, for it is a fact that with the high- 
 
Ignition System. 207 
 
 tension secondary current, moisture either on the 
 plugs, the coil or the wiring will result in the 
 current taking the easiest way back to ground 
 and it will become short-circuited and will fail 
 to pass through the plug and across the spark 
 gap and missing will be the result. 
 
 To go back to the case of the burning news- 
 paper which was used as an illustration in one of 
 the previous chapters : if we light one corner of 
 it with a match, it takes some little time for the 
 flame to spread and set the whole paper in flames. 
 In the mixture in the cylinder we are igniting the 
 gas at just one corner in the little cylinder 
 pocket in which the valves are mounted, to be 
 exact and it takes an appreciable interval of 
 time for the entire body of gas to become ignited 
 and develop its greatest heat and consequently 
 the greatest pressure on top of the cylinder. In 
 order to obtain maximum power from the engine, 
 it is necessary that we should apply this maxi- 
 mum pressure or push on the top of the piston 
 just as, or very shortly after, it starts on its down 
 stroke. If we have a slow-speed engine, the 
 travel of the piston is comparatively slow, and if 
 we ignite the gas just as the piston reaches the 
 top of its stroke, the very rapid travel of the 
 flame results in our obtaining the maximum 
 pressure very nearly at the top of the stroke and 
 we obtain full power. 
 
 With a high-speed engine, however, the piston 
 travel is exceedingly fast, and if we wait to ignite 
 our gas at the very top of the piston travel the 
 piston will be quite some distance down before 
 the flame has spread all through the mixture and 
 developed the maximum pressure. We will have 
 only a portion of the working stroke to travel 
 and cannot, therefore, take full advantage of 
 the pressure we have developed; moreover, a 
 
208 Tractor Engines. 
 
 large portion of the cylinder wall will be ex- 
 posed to the intensely hot gases at the moment 
 of maximum pressure, and as a result we will 
 have a tendency for the engine to overheat. 
 
 We overcome this condition on a high-speed 
 engine by a little dodge which we call advancing 
 the spark. That is, we cause the spark to occur 
 in the cylinder while the piston is still coming up 
 on the compression stroke, and the amount we 
 advance it gives just sufficient time for the full 
 expansion of the gases to take place while the 
 piston is still coming up, so that when it reaches 
 the top we have developed the full pressure, and 
 consequently we get greater power, greater speed 
 and a cooler running engine. 
 
 It stands to reason that a tractor engine is 
 neither a high-speed engine nor a low-speed one, 
 but is a variable speed engine, partaking of the 
 characteristics of both. As a consequence, we 
 must so arrange things that we can cause the 
 spark to occur early when running at high speed 
 and late at low speed to get the best results 
 from our engine, regardless of conditions. And 
 so we have, on the modern tractor engine, a vari- 
 able spark controlled by a spark control lever 
 near the operator, by means of which the oper- 
 ator can cause the spark in the 'cylinders to occur 
 at the proper time to meet the conditions called 
 for by the speed of the engine. 
 
 This variation is brought about by rotating the 
 body of the timer through a slight arc, this being 
 accomplished by means of rods and levers at- 
 tached to the spark control lever. If, for in- 
 stance, we rotate the timer body in a clockwise 
 direction or in the direction opposite to the rota- 
 tion of the camshaft, we are bringing the con- 
 tacts up to meet the rotating contact maker and 
 the contact will be established earlier in the 
 
Ignition System. 209 
 
 stroke this we call advancing the spark; when 
 we rotate the timer body in the same direction 
 as the camshaft rotates, the spark will occur later 
 and we call this retarding the spark. The arc 
 through whiclrthe timer can be rotated is slight, 
 only about 10 to 12 degrees, which corresponds 
 to 20 to 24 degrees of crankshaft movement; 
 this is because that much advance is sufficient 
 to accomplish the purpose at the highest speeds 
 and further advance is harmful to the engine; it 
 
 DISTRIBUTOR GEAR MAGNETS HIGH TENSION COIL 
 
 - ^^^^^^^^^^ CONDENSER 
 
 HIGH TENSION BRUSH 
 
 OIL RESERVOIR 
 
 COLLECTOR RINC 
 
 BREAKER POINTS 
 LOCK NUT 
 
 GROUND BRUSH 
 CAM 
 
 UPULSE STARTER 
 
 ADVANCE LEVER ' ' *HB " CATCH' 
 
 ARMATURE GEAR / <7, COLLECTOR BRUSH 
 
 PRIMARY WINDING ARMATURE 
 
 Fig. 126. Magneto and impulse starter. 
 
 likewise is not advisable to retard the' spark 
 further than is allowed for by this limited arc. 
 
 The second method of increasing the electrical 
 pressure to a point where it will jump the plug 
 gap is based upon exactly the - same principles 
 as outlined above; but the entire apparatus, in- 
 stead of being made up in the form of separate 
 units, is included in a single instrument which 
 is called a magneto (Figure 126). 
 
 The device comprises a set of strong electro- 
 
210 
 
 Tractor Engines. 
 
 Fig. 127. Testing magnets of a magneto. 
 
 magnets, the bars being horseshoe-shaped and 
 made of special steel, rich in magnetic proper- 
 ties, so as to obtain the maximum effect (Figure 
 127). Arranged to rotate in the magnetic field 
 
 set up by these 
 magnets in a 
 m a n n e r t o 
 take da van- 
 tage of the 
 greatest num- 
 ber of lines 
 of force, is an 
 armature 
 made of soft 
 iron. Wound on this armature is a coil compris- 
 ing a comparatively large number of turns of 
 fairly heavy wire. One end of this coil is 
 "grounded" to the armature itself and the other 
 end is brought out to a screw on the end of the 
 armature shaft by means of which it is carried 
 to a circuit breaker. The arrangement is such 
 that the contact of the circuit breaker touches 
 grounded contact located on the breaker disc, so 
 that ordinarily the circuit is complete, an$ 
 when the armature is rotated the current gen- 
 erated in the coil flows to ground through the 
 circuit break- 
 er and thence 
 back to the 
 grounded ter- 
 minal of the 
 coil. But twice 
 during each 
 revolution of, 
 the armature 
 shaft a. little 
 cam (Figure 
 
 128) On the Fig 128 . Magneto breaker points. 
 
Ignition System. 211 
 
 breaker housing is brought into contact with the 
 lever of the circuit breaker, lifting it from contact 
 with the grounded contact, and thereby inter- 
 rupting the circuit exactly as was done with the 
 electro-magnetic circuit breaker described in con- 
 junction with the induction coil. The only dif- 
 ference is that there is but a single break in the 
 case of the magneto. A condenser is shunted 
 across the breaker points exactly the same as 
 with the coil and it serves the same purpose ; 
 it checks the flow of current immediately and 
 stops arcing at the breaker points. 
 
 From what we know of the performance of 
 the current, it is not hard to see that all around 
 the coil on the armature, we are going to have set 
 up a second magnetic field during the interval 
 when the breaker points are closed and the cur- 
 rent is flowing through the coil, because the coil 
 itself is cutting lines of force. Nor is it hard to 
 see that interruption of the current flow by break- 
 ing the points apart with the cam action is going 
 to result in a sudden collapse of this second 
 magnetic field twice during each revolution of 
 the magneto armature. 
 
 This coil on the armature, therefore, correT 
 sponds exactly to our primary coil in the case 
 of the induction coil, and we call it the primary 
 coil of the magneto. Over it we wind a sec- 
 ondary coil comprising a very large number of 
 turns of very fine wire ; one end of the secondary 
 we ground to the armature, the connections cor- 
 responding exactly to the coil connections, and 
 the other we take to a rotary arm on a distrib- 
 utor (Figure 129) which is built right in with 
 the magneto. This rotary arm turns as the ar- 
 mature rotates, the gearing depending on the 
 number of cylinders on the engine, and the 
 arrangement is such that each time the breaker 
 
212 
 
 Tractor Engines. 
 
 points open, 
 the arm is in 
 contact with 
 a segment on 
 the distributor 
 plate so that 
 the high - ten- 
 sion current is 
 directed to the 
 cylinder plug 
 in the cylin- 
 der ready to 
 fire. Each 
 segment has a cable leading to a plug, and the 
 connections are made in accordance with the 
 firing order of the engine (Figure 130). 
 
 In order to advance and retard the spark, as 
 we did in the case of the coil ignition system, we 
 rotate the breaker box slightly; rotation in the 
 direction opposite to the rotation of the arma- 
 
 129. Distributor construction. 
 
 . /so 
 
 Fig. 130. How magneto is wired in accordance with engine 
 firing order. 
 
Ignition System. 213 
 
 ture results in earlier opening of the breaker 
 points and advance in the time of sparking; 
 rotation in the same direction as the armature 
 retards the spark. 
 
 In the case of slow-running engines, where 
 we cannot turn them over fast enough to assure 
 rapid movement of the armature and the pro- 
 duction of a good hot spark, the armature is 
 fitted with a special coupling through which it 
 is driven and which we call an impulse starter. 
 It is simply a little device which stops rotation 
 of the armature at some point in its revolution 
 and holds it until the piston is in proper position 
 for the spark to pass, the meantime winding up 
 a spring. Immediately the proper piston position 
 is attained, a trip releases the armature and the 
 spring gives it a very quick turn over the point 
 where the breaker opens, and we have a good, 
 hot spark for starting. 
 
 There is one other system of ignition used on 
 a few tractors which is interesting, although not 
 frequently met with at the present time. This 
 we call low tension or "make-and-break" igni- 
 tion, for the reason that the current is not 
 stepped up to a point where it will jump a gap 
 in the cylinder. In fact, in the cylinder, ,the 
 sparking points are brought together just before 
 the spark is desired and the current flow is estab- 
 lished, and then very quickly separated at the 
 instant the spark is required, with the result that 
 in separating, due to the inertia of the current 
 as described above, the current tends to jump 
 the widening gap and we obtain a spark. Natu- 
 rally, since a spark across these contacts is just 
 what we want, no condenser is used with this 
 system. 
 
 The mechanical arrangement of the system 
 as applied to the Rumely tractor is made per- 
 
214 
 
 Tractor Engines. 
 
 fectly plain in Figure 
 131. A cam actuates a 
 rod whereby the points 
 are first brought to- 
 gether in the cylinder 
 and then very rapidly 
 separated when the 
 rod tappet drops off 
 the hill of the cam at 
 the instant the spark 
 is wanted. The elec- 
 trical circuit is very 
 simple; either a low- 
 tension magneto is 
 used and connected 
 directly to the insu- 
 lated spark plug termi- 
 nal, the other side be- 
 ing grounded, or else a 
 set of dry cells is em- 
 ployed, in which case 
 the voltage is in- 
 creased slightly by 
 running the current 
 through an induct- 
 ance coil, which is a 
 single coil of very heavy wire wound over a 
 soft iron core. The inductive effect of the field 
 set up by this coil on the coils themselves gives 
 rise to 'self-induction/' whereby the higher volt- 
 age necessary to produce an effective spark is 
 obtained. 
 
 Fig. 131. Low tension 
 niter on Rumely tractor. 
 
CHAPTER X. 
 
 Care of Ignition System. 
 
 THE high-tension magneto is one which fur- 
 nishes a jump spark without the use of a 
 spark coil. In a magneto of this kind, the arma- 
 ture, in addition to serving the purpose of an 
 ordinary armature, also acts as a coil, or step- 
 up transformer, and with its interrupter and 
 distributor forms a complete ignition system, the 
 only outside parts being the spark plugs. 
 
 On account of the K. W. Magneto being of 
 this compact type, eliminating coils, batteries, 
 extra wiring and trouble of shortage, it was 
 chosen as part of the equipment of the "Twin 
 City" motors. 
 
 K. W. Magneto, Model HK. By oscillating 
 the breaker box, as shown in Figure 132, the 
 
 spark is advanced or 
 retarded. Full retard 
 is when the spring is 
 almost touching the 
 spider marked E. 
 When this spring 
 touches the spider, 
 the circuit is ground- 
 ed, and this stops the 
 motor. It is well for 
 the operator to re- 
 move the circuit 
 breaker once a week 
 or more and clean out 
 any surplus oil, then 
 oil the wick in the 
 
 Fig. 132. K-W magneto. 
 
 (215) 
 
216 
 
 Tractor Engines. 
 
 IOO 
 
 roller on the upper contact arm with two or three 
 drops of good sewing machine oil. Make sure 
 that the contact points are clean, and that no 
 
 oil has lodged 
 on them. 
 
 Oil on the 
 breaker paints 
 is an insula- 
 tion, and will 
 c a u s e Si ar d 
 starting a n d 
 probable miss- 
 in g at I o w 
 speed. In re- 
 placing the cir- 
 c u i t breaker 
 
 
 Fig. 133. Cross-section 
 magneto, model H-K. 
 
 K-W 
 
 box, be sure 
 that the contact 
 spring No. 189 has been properly replaced, and 
 that nut No. 79 is tight (Figure 133). 
 
 Once a week place a few drops of oil in each 
 of the three bearings. One oiler is located on 
 each side of the rotor shaft and one bearing on 
 the distributor shaft. 
 
 At least once a week look at the distributor 
 and see that it is free 
 from carbon dust. This 
 is accomplished by re- 
 moving the high-ten- 
 sion cable marked 100 
 and the spider marked 
 No. 1. 
 
 K. W . Magneto, 
 Model TK. To set 
 the Model TK is 
 much the same as the 
 HK. It is not neces- 
 sary to remove the 
 
 Fig. 
 K-W 
 
 134. Impulse starter on 
 magneto. 
 
Care of Ignition System. 217 
 
 Fig. 135. Testing magneto. 
 
 distributor cover, as a sight glass is provided 
 at "A" through which a small hole locates 
 the position of the distributor brush. 
 
 The motor 
 is stopped 
 when pro- 
 jector "D" 
 touches screw 
 "E." 
 
 The break- 
 er box is the 
 same. 
 
 To time 
 the magneto. 
 1. Have pis- 
 ton in cylin- 
 der No. 1 at highest point of compression, which 
 is firing position. Have rocker arm "A" (Figures 
 137-138) horizontal as shown. 2. Shift magneto 
 around until distributor brush- "B" touches seg- 
 ment "S," thus connecting with cylinder No. 1. 
 3. Shift magneto slowly by hand to the right 
 until contacts "P" are just beginning to separate. 
 This is the 
 firing point of 
 the magneto, 
 and must oc- 
 cur when the 
 piston is at 
 highest point 
 of firing 
 stroke. It 
 will be found 
 that the mag- 
 n e t o will 
 have to be 
 
 advanced slightly from this setting on account 
 of the impulse starter. Rotate the magneto to 
 
 Fig. 136. Filing breaker points. 
 
218 
 
 Tractor Engines. 
 
 the right several holes. The impulse starter 
 should trip just as the top center mark on fly- 
 wheel passes center point on engine for about 
 one inch. At this point secure magneto with the 
 two bolts through the coupling flange. 
 
 P'jrriHG/ ORDER J-3-4-2 
 FOUR CYLINDERS 
 
 MAGNETO 
 
 Fig. 137. Timing K-W magneto to a four-cylfnder engine. 
 
 Six CVLIMDERS 
 FIG. 139 
 
 Fig. 138. Timing K-W magneto to a six-cylinder engine. 
 
 4. When one cylinder is all right, proceed to 
 connect the others, as shown in the diagram. 
 The firing order is 1, 3, 4, 2 on the four-cylinder 
 motors, and 1, 4, 2, 6, 3, 5 on the six-cylinder 
 motors. 
 
Care of Ignition System. 219 
 
 5. Replace parts on the magneto and start the 
 engine to test the setting. See that all nuts and 
 connections are tight, especially nuts 55 and 56, 
 Figure 133. Also see that retainer spring No. 
 189 has been replaced. To advance shift coup- 
 ling against direction of rotation. To retard shift 
 coupling with direction of rotation. 
 
 Finding which cylinder misses. Open priming 
 cups one at a time. Watch for the flame shoot- 
 ing out, and listen for the sharp report. The 
 cylinder that only hisses and makes no report is 
 the one at fault. The missing might be from 
 the following causes : 
 
 1. Too much water when running on kerosene. 
 
 2. Too much fuel. 
 
 3. Crack in porcelain of spark plug. 
 
 4. Poor porcelain in spark plug. 
 
 5. Spark plug gap out of adjustment. 
 
 6. Valve or tappet sticking. 
 
 7. Wire leakage. 
 
 8. Magneto trouble. 
 
 (1) Usually when the cylinder stops firing 
 from the first cause, a white smoke emerges 
 from the priming cup, and by closing the water 
 valve and changing to gasoline the trouble can 
 be remedied. 
 
 (2) Adjustment of the fuel valve and allow- 
 ing more air will remedy this. 
 
 (3) and (4) Change spark plugs by placing 
 the supposedly defective one in a cylinder that 
 is firing. 
 
 (5) Gap should be about 1-32". 
 
 (6) Remove the valve or tappet and with a 
 fine emery cloth smooth the surface and oil 
 well before replacing. 
 
220 
 
 Tractor Engines. 
 
 
 (7) Remove the wire and hold about 
 from the cylinder (Figure 139). If there is 
 no spark, remove the wire from its fastenings, 
 but first test out the magneto by placing a wire 
 
 Fig. 139. Detailed method of testing spark plug. 
 
 in the defective wire connection on magneto and 
 hold close to some part of the motor. If this 
 shows a spark, then there must be a breakage 
 in the insulation around the wire. 
 
 (8) There are two places where the trouble 
 
Care of Ignition System. 221 
 
 may be remedied. One is the breaker box and 
 the other the distributor. If these two places 
 are well cleaned, and the trouble has not been 
 located, there might be dirt lodged in between 
 the magnets. Clean this out thoroughly, and if 
 this does not remedy the trouble, the magneto 
 should be removed and shipped back to the fac- 
 tory. It is well for the operator to have an extra 
 breaker box. In this way he would eliminate a 
 
 TO TEST SPARK. (See Fig. 139.) 
 
 Remove high tension wire from spark plug. Hold it one- 
 fourth of an inch away from the plug. When the engine is 
 turned over with the switch turned onto the batteries there 
 should be a spark. If not, test the batteries. 
 
 Do not under any circumstances when testing spark 
 allow the end of the clip on the high tension wires to be 
 more than % of an inch from some metal as when you do 
 and the motor is running there is a re-action sets in which 
 is extremely hard on the coil. 
 
 If there is a spark, remove the spark plug. Attach the 
 wire the same as though the plug was in place. Lay it on 
 the cylinder. (See cut.) If there was a spark when the 
 first test was made there should be one now. (Have spark 
 plug gap set as per instructions under spark plugs.) If no 
 spark appears at the gap, the chances are that there is a 
 broken porcelain. 
 
 CAUTION At no time should the wires touch the 
 cylinders nor be allowed to get water soaked, as this will 
 cause a short circuit. If a spark appears at the gap and 
 the cylinder does not fire it is reasonable to assume that the 
 cylinder has, (a) too much lubricating oil in the combustion 
 chamber, (b) is wet or (c) does not get the proper mixture 
 of gas, (d) engine has lost compression. 
 
 lot of lost time in testing this part of the mag- 
 neto out by simply removing the old one and 
 slipping the extra one on. 
 
 Spark Plugs. The spark plugs, perhaps, will 
 require more attention than any other part of 
 the ignition system. They will require cleaning 
 from time to time, because carbon is bound to 
 form in any engine burning a hydrocarbon as 
 fuel, and is bound to be troublesome in a case 
 where the engine is over-oiled or where the car- 
 
222 Tractor Engines. 
 
 buretor is adjusted to supply too rich a mixture. 
 This carbon will deposit on the inside of the 
 shell covering the insulator, and since carbon is 
 a good conductor of electrical current, will, in 
 time, present an easier path for the flow of the 
 current than the plug gap, and missing will be 
 the result. 
 
 To test for a short-circuited plug, have the 
 engine running at the speed at which the miss 
 is most noticeable. Take a wooden-handled 
 screwdriver and touch the blade to the 'terminal 
 of the first plug and to the metal of the engine 
 at the same time. This will short-circuit it and 
 there will be no spark. If this plug has been 
 missing, this will have no effect on the opera- 
 tion of the engine ; if, however, this happens to 
 be a good cylinder, the miss will be emphasized. 
 Do this with all the cylinders in turn until the 
 one is located where the short-circuiting has no 
 effect on the operation. Remove this plug and 
 replace it with another known to be in good con- 
 dition and the trouble will disappear. 
 
 If a plug is badly short-circuited, it can be 
 tested by laying it on the cylinder with the plug 
 cable attached and seeing if a spark jumps the 
 gap. If it does, the plug is O. K. If not, it needs 
 attention. This test is not conclusive, however, 
 because it is a well-known fact that the spark 
 will jump the gap easier in the open air than 
 under the conditions encountered in the cylinder ; 
 it may show a spark on the outside and still fail 
 to function in the engine, which causes quite a 
 bit of annoyance to the inexperienced operator. 
 
 One of the larger spark plug makers has 
 brought out a little spark plug cleaner which 
 should be in every tool kit. It is a small glass 
 jar shaped like a chemist's test tube, flared at 
 
Care of Ignition System. 223 
 
 the open end, where a rubber collar is fitted 
 of a size adapted to fit the shell screw of the 
 plug. In the jar are a couple of dozen steel 
 needles. The plug is screwed into this jar, which 
 should be half filled with gasoline, and violently 
 agitated for a few mo- 
 ments. The combined 
 action of the gasoline 
 and the pricking action 
 of the needles which 
 come in contact with the 
 entire surface of the in- 
 
 Fig. 140. Spark plug gaps. su j atorj act tQ dean the 
 
 carbon off in a jiffy, leaving the plug perfectly 
 clean. 
 
 In the absence of such a device, unscrew 
 the compression nut and remove the porcelain or 
 mica insulator. Clean the carbon off with fine 
 sandpaper or emery cloth ; clean inside of the 
 shell. It is a good plan to examine the porcelain 
 insulator for cracks, discarding it if it shows any, 
 and replacing the old one with a new insulator, 
 which the maker is prepared to supply. It is well 
 also to put in new compression washers when 
 cleaning the plugs, as the old ones lose their 
 life. S e t up 
 the compres- 
 sion nut firm- 
 ly to prevent 
 leakage. Al- 
 w a y s adjust 
 the plug gap 
 (Figures 140 
 and 141) to 
 .025 or .030 
 of an inch and adjust all the plugs the same. It is 
 well to use one make of plug throughout the cylin- 
 ders; it makes replacement and handling easier. 
 
 141 
 
 Fig. 141. Method of ascertaining correct 
 adjustment of plug gap with a "feeler" 
 gauge. 
 
224 Tractor Engines. 
 
 Ignition Coils. The ignition coils as used are 
 perfectly adjusted at the factory, and this ad- 
 justment should not be disturbed except to install 
 new contact points or to reduce the gap between 
 the points, which naturally will increase with 
 wear. 
 
 If the contact points are found to be burned 
 or pitted, they should be filed flat with a mag- 
 neto file and then the adjusting thumbnut should 
 be turned down so that with the vibrator spring 
 held down, the gap between the points will be 
 a trifle less than 1/32 of an inch. Then set the 
 lock nut so that this adjustment cannot be dis- 
 turbed. Do not bend or hammer on the vibra- 
 tors, as this will most certainly affect the opera- 
 tion of the cushion spring of the vibrator bridge 
 and reduce the efficiency of the unit. 
 
 With the vibrators properly set, if any par- 
 ticular cylinder fails or seems to develop weak 
 action, change the position of the unit supplying 
 the spark to this cylinder, substituting one of 
 the other units for it. If the unit is really at 
 fault, the cylinder which operated badly before 
 will now function properly, but the one with the 
 bad unit will show poor operation. The first 
 symptom of a defective coil unit is the buzzing 
 of the vibrator with no spark at the plug 
 (Figure 142). 
 
 Remember that a loose wire connection, faulty 
 spark plug, damp ignition cable or a faulty timer 
 may cause irregularity in the running of the 
 engine. These are points that must be considered 
 before laying the blame on the coil. 
 
 When the vibrators on the coils are not prop- 
 erly adjusted, more current is required to make 
 and break the contact between the points, and as 
 a result, when the engine is turned slowly by 
 hand to start, there will not be sufficient current 
 
Care of Ignition System. 225 
 
 generated by the magneto to operate the vibrators 
 and hard starting will ensue. Do not allow the 
 contact points to become ragged. If they are in 
 poor shape they are very likely to stick and cause 
 
 TESTING COIL. 
 
 Attach wires to four good strong dry cells as shown 
 in cut. 
 
 Wind the red and yellow wires together, making one wire 
 out of the two. 
 
 Hold the two high tension cables J4 of an inch apart. 
 
 Throw switch on to batteries. 
 
 Strike the green wire smartly against the united red and 
 yellow wire. 
 
 If the coil is good, there will be a strong spark jump the 
 gap between the two high tension cables. 
 
 CAUTION Do not mistake a damp coil for a defective 
 one. Do not mistake a set of poorly insulated wires which 
 are shorting for a defective coil.- 
 
 NEVER USE MORE THAN SIX DRY CELLS. 
 
 NOTE In case your coil gets wet or if you are having 
 trouble and think it is in the coil, do not write the factory 
 or send for an expert, but take the coil off, put it in a 
 WARM oven and thoroughly dry it out. 
 
 Now, test your coil as instructed, connected to good dry 
 cells and if it then refuses to work, it is time to call for 
 help. 
 
 'Be sure that it is properly wired, as per the wiring in- 
 structions pertaining to this particular magneto. 
 
 Fig. 142. Detailed method of testing ignition coil. 
 
226 Tractor Engines. 
 
 unnecessary difficulty in starting and are apt to 
 cause an occasional miss when the engine is 
 running. 
 
 In order to determine which cylinder is miss- 
 ing without resorting to the use of a screwdriver 
 to short-circuit the plugs open the throttle until 
 the engine is running at a fairly lively clip and 
 then hold down the vibrators on the two outside 
 coils. Do this with the fingers just preventing 
 the vibrators from buzzing. This will stop two 
 cylinders from firing. If the remaining two fire 
 regularly it is evident that they are not at fault 
 and that the miss must have come from one or 
 the other of the cylinders you have put out of 
 commission. Now relieve No. 4 and hold down 
 the other three; if the engine continues to run, 
 the trouble will be with No. 1. In this manner, 
 all the cylinders can be tested in turn and the 
 missing one located. Do not forget that Coil 4 
 leads to Cylinder 3 and Coil 3 to Cylinder 4. 
 When the missing cylinder has been located, ex- 
 amine both spark plug and vibrator as well as 
 the wiring. 
 
 Commutator or Timer. The commutator 
 should be kept clean and well oiled with light 
 machine oil at all times. If ignition trouble is 
 experienced which cannot be traced to the plugs 
 or the coils, examine first the wiring leading to 
 the commutator. In case this is chafed and is 
 making contact with some metal part of the trac- 
 tor, the primary circuit will be short-circuited and 
 we will have a continual buzz of one or more of 
 the vibrators ; sometimes the contact will be made 
 intermittently, with the result that the cylinder 
 affected will fire at the wrong time. This is a 
 dangerous condition, and it is highly advisable 
 when this wiring shows wear, to discard it, and 
 put in all new wire, being careful to follow care- 
 
Care of Ignition System. 227 
 
 fully the wiring arrangement between the coils 
 and the commutator. If one cylinder persists in 
 missing, and there is no buzzing of the vibrator 
 on that particular cylinder, it is evident that the 
 commutator brush is not making contact on that 
 particular segment, or else the wire to that coil 
 from the commutator is broken inside the insu- 
 lation. Test for the latter by removing the wire 
 from the commutator terminal and touching to 
 any metal part of the car. If the vibrator buzzes, 
 the trouble is in the commutator; if there is no 
 buzz, the wire is probably broken and should be 
 replaced with a new one. 
 
 If misfiring occurs when running at high speed, 
 inspect the commutator. The surface of the ring 
 around which the roller travels should be clean 
 and smooth, so that the roller makes a perfect 
 contact at all points. If the roller fails to make 
 a good contact on any one of the four segments, 
 the corresponding cylinder will not fire. Clean 
 these surfaces if dirty. In case the fiber, seg- 
 ments and roller are badly worn, the most satis- 
 factory remedy is to replace them with new 
 parts. The spring should be strong enough to 
 ensure a good, firm contact between the roller 
 and the segments. 
 
CHAPTER XI. 
 
 Engine Troubles. 
 TKeir Causes and Remedies. 
 
 THE following suggestions may be of assist- 
 ance in^ locating and remedying engine 
 troubles. These suggestions are made to enable 
 the operator to effect emergency repairs in the 
 field. In all but the simplest cases we recom- 
 mend that the trouble .be submitted to a compe- 
 tent repairrrian for correction. 
 
 The points under the following subheadings 
 have been arranged, in so far as possible, in 
 related groups. 
 
 For example, under the subheading "Engine 
 Refuses to Start," points 2 to 4, inclusive, deal 
 with Ignition; points 7 and 8 with Compression, 
 and points 5 and 9 with Fuel. 
 
 It is recommended, in every case of trouble, 
 that the operator look for the simplest cases and 
 apply the simplest remedies first, working up 
 progressively through the more complex. 
 
 ENGINE REFUSES TO START. 
 
 CAUSES OF TROUBLE. 
 
 1. Ignition switch off. 
 
 2. Broken electrical 
 circuit. 
 
 3. Interrupted electri- 
 cal circuit. 
 
 4. Fouled or broken 
 spark plug. 
 
 5. Insufficient ga-soline 
 supply. t 
 
 6. Poor carburetion. 
 
 REMEDIES. 
 
 1. Turn switch to starting position. 
 
 2. Examine wiring for break. See 
 . that connections at mganeto and 
 
 spark plug terminals are clean and 
 tight. 
 
 3. Lack of insulation may cause 
 a ground connection or a short-cir- 
 cuit. Rewind defective wiring with 
 tape or renew wiring. 
 
 4. Clean foul plug; replace cracked 
 plug. 
 
 5. Test for gasoline sup'ply at 
 carburetor by flooding. Replenish 
 supply in gasoline tank. 
 
 6. Mixture too lean or too rich. 
 Adjust carburetor for correct mixture. 
 
 (228) 
 
Engine Troubles. 
 
 229 
 
 CAUSES OF TROUBLE. 
 
 r. Poor compression. 
 
 REMEDIES. 
 
 7. Test compression by hand- 
 cranking. 
 
 (a) The piston rings may be 
 gummed or stuck in their recesses. 
 After a run, while the engine is still 
 warm, introduce about two table- 
 spoonfuls of kerosene through the 
 priming cocks of each cylinder and 
 allow it to remain over night. This 
 will free the rings. 
 
 A Open the pet cock in the end of the cylinder and blow out 
 any oil by turning the engine over. 
 
 B Look for a leaky intake manifold gasket. 
 Fig. 143. Tracing troubles. 
 
232 
 
 Tractor Engines. 
 
 CAUSES OF TROUBLE. 
 
 13. Worn or 
 piston rings. 
 
 broken 
 
 REMEDIES. 
 
 line is indicated. Further, the jet 
 of carburetor may be clogged, in 
 which case remove and clean jet. 
 
 13. Renew worn or broken rings. 
 Use correct oil an oil which wi" 
 form a perfect piston ring seal. 
 
 
 ENGINE MISFIRING. 
 
 1. Carbon on spark 
 plugs. 
 
 2. Insufficient g a s o- 
 line supply. 
 
 3. Fuel mixture too 
 "lean." 
 
 4. Fuel mixture too 
 "rich." 
 
 5. Valve stuck. 
 
 6. Intake manifold 
 leaks. 
 
 1. Clean or replace plugs. Select 
 correct oil to meet requirements of 
 engine. Adjust carburetor for cor- 
 rect mixture. 
 
 2. Replenish supply. See that 
 "shut-off" cock in gasoline line is 
 wide open and that there are no 
 leaks. 
 
 3. Too much air; too little gaso- 
 line. 
 
 4. "Rich" mixture will be indi- 
 cated by misfiring in the cylinders. 
 
 5. Clean valve stem with kero- 
 sene. 
 
 6. Examine for air leaks and 
 repair. 
 
 ENGINE STOPS. 
 Ignition switch off. 1. Turn switch on. 
 
 1. 
 
 2. Broken 
 circuit. 
 
 electrical 
 
 3. Contact in jtimer 
 poor. 
 
 4. Insufficient spark. 
 
 5. No gasoline. 
 
 2. Examine terminals for loose 
 connections. Examine wiring for' 
 poor insulation or break. 
 
 3. Clean and make adjustments 
 for strong contact. 
 
 4. (a) Magneto demagnetized. 
 Have remagnetized. 
 
 (b) Spark plug points improperly 
 adjusted. Adjust gap between spark 
 plug points to a space of about the 
 thickness of a postcard. Too wide 
 or too small a gap will interfere 
 with proper ignition. 
 
 5. Replenish supply and note that 
 carburetor float chamber is full. 
 
 ENGINE OVERHEATING. 
 
 1. Over-retarded spark. 
 
 2. Incorrect timing of 
 valves. 
 
 3. Throttled exhaust. 
 
 Clogged muffler. 
 Clogged radiator. 
 
 1. After starting, spark should 
 be advanced as far as possible at all 
 times unless engine labors. 
 
 2. The correction of this trouble 
 should be left to 'a competent gar- 
 ageman. / 
 
 3. See that exhaust passages are 
 clean and that exhaust valves raise 
 sufficiently. 
 
 4. Disconnect and clean out soot 
 and products of incomplete combus- 
 tion. 
 
 5. Introduce cleaning compound 
 into radiator and allow it to circu- 
 late while car is running from 50 to 
 100 miles. Then wash out thoroughly 
 with clean water. I^rain and refill. 
 
Engine Troubles. 
 
 233 
 
 CAUSES OF TROUBLE. 
 
 6. Deficient water cir- 
 culation. 
 
 7. Fan not working. 
 
 8. Racing of engine 
 on low gear. 
 
 9. Continued use of 
 low gear. 
 
 10. Lack of oil, or in- 
 correct oil. 
 
 11. Incorrect carbure- 
 tion. 
 
 REMEDIES., 
 
 6. (a) Test for clogging of radi- 
 ator or water jackets. 
 
 (b) Test for clogging of water hose. 
 
 7. Lubricate bearings; tighten belt. 
 
 8. Partially close throttle, there- 
 by decreasing speed of engine. 
 
 9. Use low. gear only when nec- 
 essary. 
 
 10. Fill lubricating system with 
 correct grade of oil. 
 
 11. Adjust carburetor for -cor- 
 rect mixture. 
 
 ENGINE KNOCKS. 
 
 1. 
 
 far. 
 
 Spark advanced too 
 
 2. Carbon deposit. 
 
 3. 
 
 Fuel mixture 
 "rich." 
 
 4. Loose bearings. 
 
 . 
 
 8. 
 
 Worn bearings. 
 
 Loose flywheel. 
 Engine labors. 
 Carburetor float 
 
 leaking. 
 
 1. Retard spark advance lever 
 on quadrant of steering wheel to 
 prevent premature ignition. 
 
 2. Results in preignition. Re- 
 move accumulated carbon from com- 
 bustion chamber and make sure that 
 piston rings are free in their re- 
 cesses. Use correct oil. 
 
 3. Reduce gasoline feed by ad- 
 justing carburetor. 
 
 4. Have engine bearings fitted 
 properly and tightened. 
 
 5. Refit, or, if necessary, renew 
 bearings. 
 
 6. Make flywheel fast to shaft. 
 
 7. Change to lower gear. 
 
 8. Remove and repair float. 
 
 Over-retarded spark. 
 Insufficient spark. 
 
 3. Fuel 
 weak. 
 
 mixture too 
 
 EXPLOSIONS IN MUFFLER. 
 
 1. Advance spark for earlier ig- 
 nition. 
 
 2. (a) Magneto demagnetized. 
 Remove and have remagnetized. 
 
 (b) Spark plug defective. Re- 
 new plug. 
 
 (c) Spark plug points improperly 
 adjusted. Adjust gap between spark 
 plug points to a space about the 
 thickness of a post-card. 
 
 3. Too much air; too little gaso- 
 line. An unconsumed fuel charge 
 is forced into muffler and this charge 
 is fired by a subsequent charge. 
 Adjust or clean carburetor so that 
 proper fuel mixture for complete 
 combustion is admitted into combus- 
 tion chamtfer. 
 
 4. Remove valve cap and free valve 
 in guide. Regrind valve if necessary. 
 See that spring has proper strength. 
 
 OVERHEATED EXHAUST PIPE. 
 
 Over-retarded spark. 1. Advance spark for earlier ig- 
 
 nition. 
 
 Clogged muffler. 2. Disconnect muffler and remove 
 
 soot and products of incomplete 
 combustion. 
 
 4. Exhaust valve stuck. 
 
 2. 
 
APR 12- '84 - 
 
 
 ,,.* 
 
477 
 
 Hal lock, S 
 
 TL233 
 H28 
 
 Tractor 
 
 engines. 
 
 PHYSICAL' 
 SCIENCES 
 LIBRARY 
 
 T-L 1 33 
 
 14 
 
 UNIVERSITY OF CALIFORNIA LIBRARY