CHAPTER XIII

TRACTORS AND FARM POWER

Because of our increased population, which results in a greater planted acreage, and the scarcity and increased cost of farm labor, farming has rapidly developed into an industrial science. Where formerly the farmer was content to perform certain parts of his work by hand, he today employs machinery for the same task, and is far more particular as to the working of his soil and the cost of production per acre. By the use of machinery his crop is marketed at less expense, in a shorter time, and he has more time in which to enjoy life than ever before.

The modern gasoline and oil engine has been the greatest factor contributing to the farmer’s ease and prosperity for it has eliminated the terrors and drudgery of plowing, churning, watering stock, sawing wood, threshing, and has besides given him many of the conveniences of city life, such as running water and electric light. The benefits of power are not only conferred on the farmer but his wife as well for the small domestic engines have saved the back of the house wife during the strenuous period of harvest time.

One of the difficulties of farming is the necessity of doing certain work in a limited time or else suffering a heavy loss. The breaking, the plowing, the harvesting, and the threshing each must be done at a certain time, often within a few days of each other in order to obtain the benefits of the best weather conditions. Threshing starts as soon as the grain is ready, and if rain interferes with the threshing, the farmer can start plowing immediately if provided with a tractor and thereby gain the undoubted benefits of fall plowing. Plowing at harvest time has much to do with eliminating weed seeds for the weeds are turned under while green, the seeds sprout and commence their growth and are winter killed before they reach maturity. In this way the field is practically freed from weeds in the spring. When the weather again becomes suitable, the threshing may be resumed and when completed he can again turn to his plowing.

Gas power is not to be considered merely as a substitute for animal power for the engine not only performs the work of the horses but also performs work that no horse can do, and does it with far less expense. In the hottest weather when horses are dropping in the broiling sun, the tractor moves tirelessly through the fields. Every farmer knows the expense attached to keeping a horse in the idle winter period for it must be fed, watered, and cared for, work or no work. When the engine is idle it costs nothing except for the interest on the investment, while animals grow old and are subject to disease whether they work or not.

The time of plowing and harvest is short and requires quick work, and continuous work. Horses cannot be driven at plow faster than one mile per hour, and cannot be worked more than 10 hours per day, while the tractor under suitable conditions can travel 2 to 3 miles per hour, and keep at it twenty-four hours per day. An ordinary tractor can break from 20 to 40 acres of ordinary loam per day and will plow in cultivated land from 40 to 50 acres per day.

The same factors govern the fuel consumption of a tractor that govern the rate of plowing, that is, the character of the soil and the depth of plowing. On an average, 1½ to 2½ gallons of gasoline will be used in breaking an acre of sod, and 1 to 1½ gallons of gasoline in plowing stubble. As kerosene contains about 18 per cent more heat per gallon than gasoline, the quantity of fuel used by an oil tractor is correspondingly less. When used for pulling wagons on the road at about 3 miles per hour the fuel consumption will approximate 4 gallons per hour, this consumption varying of course with grades, etc.

Thirty horse-power, at the speed given above represents a draw bar pull of about 9,000 pounds, which is equivalent to the tractive effort of from 30 to 40 horses, were it possible to concentrate the pull of so many horses at a single point, at one time. It would of course be impossible for the horses to maintain this effort for as long a time as the tractor. On a level road it will take about 100 pounds tractive effort for each 2,000 pounds of weight in the form of road wagons (including the weight of the wagon). The number of wagons that can be drawn with a given draw bar pull can be easily figured. When pulling on a grade, the effective draw bar pull will be reduced in proportion to the extent of the grade. While no fixed rule can be given regarding the number of plows that can be handled by a tractor, the average machine can pull six to eight breaking plows and from eight to twelve stubble plows, depending on the character of the soil and the depth of plowing. When the conditions permit the use of a greater number of plows, than specified above the amount of work done will of course be greater.

A tractor can haul four ten foot seeders and two twenty foot harrows and cover 7 or 8 acres per hour at a cost of from 12 to 15 cents per acre. At harvest time the tractor will also effect a great saving in time and expense for the average machine will handle five or six eight foot binders, making a cut of nearly 50 feet wide, and this can be kept up for 24 hours at a stretch.

A tractor of the average output can handle any separator, and with a 44″ cylinder machine can turn out from 2,000 to 3,000 bushels of wheat and 5,000 bushels of oats in a ten hour run. It will also handle any of the largest shredders. For irrigation work, silo filling, and wood cutting it is equally efficient.

(142) The Gas Tractor.

The tractor of the internal combustion type using gasoline or oil as a fuel is much more successful than the steam machine, both from the standpoints of convenience and cost of operation. There is absolutely no danger of fire whatever around a gas tractor for this reason the engine can be placed in any position regardless of the direction of the wind, which would be impracticable with a steam engine. This is a great advantage for if the wind is allowed to blow directly from the engine to the separator, it will be of great assistance to the pitchers who feed the separator.

When threshing or plowing in a remote field considerable difficulty is always experienced in supplying the steam tractor with the enormous amount of water that it consumes. To supply the water requires a team, tank wagon and drivers which is a considerable item in the running expense. The small amount of water used for cooling the gas engine is renewed once, or at the most, twice a day. Steam coal is bulky and requires the continuous service of a man and team to keep things moving, and this expense is greatly increased by the expense of the coal.

A gas tractor can be started in a very few moments while the engineer of a steam rig has to start in an hour or more before the crew to get steam up, etc. In addition to this there is the usual tedious routine of “oiling up,” cleaning the flues, etc. There is absolutely no danger of explosions with the gas engine which have proved so disastrous in the past with steam threshing engines.

With the gasoline, the operator is left free to work on the separator as he has no firing to do and does not have to concentrate his attention on keeping the water level at the correct point in the gauge glass. The engine is automatically lubricated in all cases so no attention is demanded on this score for it will run smoothly hour after hour without the least attention. This feature eliminates one high priced man from the job. On heavy loads the problem of keeping up the steam pressure is often a vexatious one, especially if a poor grade of coal is used. With a lower priced man as operator tending both the separator and the gas engine the crew need only consist of two pitchers to feed the machine, with a man and team for each pitcher. This small crew is easily accommodated at the farmers house, and does not require the services of a separate cook and camp equipment.

With a gasoline rig the expenses will be approximately as follows:

Engineer, wages and expenses $ 5.00 Two pitchers, at $3.00 6.00 Four men and teams 20.00 60 gallons of gasoline at 15c 9.00 Lubricating oil 1.00 —————— Cost per day $41.00

Taking 1,500 bushels (wheat) as a day’s work, the cost of threshing figures out at 2¾ cents per bushel.

According to data furnished by the M. Rumely Company, which is based on an actual test, the total cost of plowing, seeding, cutting and threshing, including ground rental and depreciation, amounted to $8.65 with horses and $6.55 with their oil tractor. These figures will of course vary in individual cases, but are principally of interest in showing the comparative cost of horse and tractor operation.

With a gasoline or oil tractor equipped with engine plows one man can tend to both the plows and the engine, although some operators prefer to have two men, one relieving the other consequently plowing more acres per day and reducing the cost per acre. In some cases one man is placed on the plows and the other on the engine. By running the tractor twenty-four hours per day, with two shifts of men, a much better showing is made by the tractor when compared with horse plowing, for with the latter method it would be necessary to supply twice the number of horses.

To show the relative merits of various grades of fuel we will print the data kindly furnished by Fairbanks Morse for a ten hour day.

═════════════════════╤════════╤════════╤════════ ITEM │Fuel Oil│Kerosene│Gasoline │ 3c │ 6½c │ 15c ─────────────────────┼────────┼────────┼──────── 60 Gallons Fuel │ $1.80│ $3.90│ $ 9.00 Lubricants │ .40│ .40│ .40 Engineer │ 3.50│ 3.50│ 3.50 Plowman │ 2.00│ 2.00│ 2.00 Repairs │ .12│ .12│ .12 Cost to Plow 24 Acres│ 7.82│ 9.92│ 15.02 Cost per Acre │ .32│ .41│ .63 ─────────────────────┴────────┴────────┴────────

Plowing at the rate of 20 acres per day, and kerosene at 6⅔ cents per gallon, the Rumely Company obtain the cost of plowing one acre as $0.66. In the latter figure the interest and depreciation are included which will increase the figures over those given by Fairbanks Morse. It should be understood that these costs are approximate and will vary considerably in different localities and under various conditions.

Oil Injection Engines.

Engines using low grade fuels such as kerosene, usually experience much trouble in obtaining a proper mixture when the fuel is vaporized in an external carbureter even when the carbureter is specially designed for the heavy oil. This leads to fuel waste, starting troubles and cylinder carbonization, to say nothing of the objections of an odorous, dirty exhaust. To overcome the objections of carbureting the heavy oils it has been common practice to inject or aspirate a small amount of water, the water vapor tending to prevent the fuel from cracking and to distribute the temperature more uniformly through the stroke. The injection of water is not a particularly desirable feature, since its use involves one more adjustment and possible source of trouble when running on variable loads.

In the semi-Diesel engine the fuel is sprayed directly into the combustion chamber by mechanical means, thus making the fuel supply to a certain extent independent of atmospheric and temperature conditions. After the injection the spray is vaporized both by the hot walls of the combustion chamber and the heat of compression, the latter being principally instrumental in causing the ignition of the gas. In this case no electrical ignition devices are required, thus at one stroke overcoming one of the principal objections to a gas engine.

Until recently the semi-Diesel engines were confined to units of rather large size, the smallest being much larger than the engines usually used on the farm. It is now possible, however, to obtain oil engines of the fuel injection type in very small sizes, built especially for portable or semi-portable service. Not only is it possible to use a cheaper grade of fuel with this type of engine, but the fuel consumption is also less than with the carbureting type. To this may be added the advantages of an engine free from the troubles incident to the ignition and carbureting systems.

Good results may be obtained with small injection engines on oils running from kerosene (48 gravity) down to 28 gravity, the combustion in all cases being complete and without excessive carbon deposits. Little trouble is caused by variable loads as long as the speed is kept constant. Compared with gasoline, the heavier fuels are much safer to store and handle, owing to their high flash points.

The compression of the injection engine is much higher than the old carbureting kerosene engine as the compression heat is used in a great part to ignite the oil vapor. Usually the pressure is in excess of 150 pounds per square inch, the exact value being determined by the form of the combustion chamber, whether a hot bulb is used, etc. The high compression assists in increasing the economy of the engine.

Usually the piston either draws in a complete volume of pure air or draws in pure air through the greater part of the induction stroke, the spray either starting near the end of the suction stroke or during the early part of the compression. When a hot bulb is used the oil spray strikes the bulb forming vapor, the increasing compression caused by the advancing piston furnishing the air for combustion and forces the mixture into contact with the hot walls. Another type has no hot bulb, the lighter constituents of the fuel being vaporized and ignited by the compression alone, their inflammation serving to kindle the main, heavy body of the oil. In some engines, the combustion of the light constituents serves to spray the heavy oil through the valve and into the combustion chamber. Details of several of the most prominent makes of oil engines are described in an early chapter of this book.

As a rule, this class of oil engine does not run well when the speed is varied through any great range, nor when governed by a throttling type governor, since both of these conditions affect the compression. They may be either of the two or four stroke cycle type, and when of the latter they are much more successful than a two stroke cycle engine using a carbureter.

On small engines the fuel consumption will run about 0.7 pint per brake horsepower hour, this consumption decreasing on large engines to about 0.6 pint per brake horsepower hour or even less.

The accompanying diagram shows a diagram of a typical oil engine of the injection type, a pump P supplying the oil from auxiliary tank to the hot, extended combustion chamber R, this chamber being an extension of the cylinder C-C. Oil is kept at a constant level in K by an overflow pipe, the oil entering from the supply pump through pipe J, and entering the pump through M at N. By gauge glass L, the operator can tell whether he has a sufficient supply of oil.

The injection pump P is driven from the eccentric E (mounted on the main shaft S) through the eccentric rod G and the rod H. The governor weights W-W alter the amount of fuel supplied by changing the stroke of the pump, thus keeping the speed constant under varying loads. The governor acts by shifting E in relation to the shaft S, a spring T controlling the throw of the governor. The entire governor mechanism is contained in the fly-wheel F.

To start, the combustion chamber R is heated by the torch U, and after thoroughly heated, the starting fuel is injected by means of the hand lever I. This engine is of the two cycle type with scavenging air furnished by crank-case compression.

(143) Construction of Gas Tractors.

A gas tractor may be considered as being simply a special application of the gasoline or oil engine in which the engine drives the road wheels through a train of gearing instead of driving its load by a belt from the pulley. Four intermediate mechanisms must be provided between the engine and the road wheels in order that the tractor may properly perform its work. These devices are known as the “clutch,” the driving gears, reverse gear and the “differential” gear. It should be understood that these mechanisms do not change the construction or operation of the engine in the slightest, and that the principles that apply to the engines described in the previous chapters apply also to the engine of the tractor. The following will briefly describe the functions of the intermediate trains in their proper order, starting at the engine.

The Clutch.

A tractor is arranged to pull its load in two different ways, first by the draw bar, as when pulling plows, and secondly by a belt from the engine pulley as in driving a threshing machine or circular saw. In the first case it is necessary to drive the road wheels through the gear train, and in the second case it is necessary to disconnect the road wheels while driving the thresher or saw. As the engine cannot be started while under load it is also necessary to disconnect the road wheels to free the engine while turning it over to get the first explosion.

The device that connects and disconnects the engine from the road wheels is known as the =CLUTCH=. This usually consists of two or more friction surfaces that form a part of the driving gear, which may be brought into frictional contact with the engine pulley, when it is necessary to drive the road wheels. When the two members of the clutch are brought into contact they revolve together, thus connecting the engine with the driving gear.

Reverse Gears.

As it is not practicable to reverse the direction of rotation of the gas engine, the rotation of the road wheels is reversed by means of gears contained in the driving train. In some tractors the reverse gears are similar to those in an automobile, being located in the transmission. In other tractors two bevel pinions are provided that fit loosely on the engine shaft and engage with a large bevel wheel that forms part of the driving gear. A sliding jaw clutch that revolves on the engine shaft is arranged so that it can connect with either of the bevel pinions causing them to rotate with the engine shaft and drive the main wheel. As the two pinions are on opposite sides of the large bevel wheel, they run in opposite directions in regard to it, so that it is possible to reverse the large wheel by engaging the clutch with either one or the other of the bevel pinions.

The Differential Gear.

The differential gear makes it possible to apply the same amount of power to each of the road wheels, and also allows one wheel to rotate faster than the other when turning around a corner. If both road wheels were rigidly fastened to a single rotating axle it would be practically impossible to turn a corner for it would be necessary for the engine to slip one or the other of the wheels because of their difference in speed, as the outer wheels turn faster than the inner.

The Driving Gear.

The driving gear consists of a series of spur gears arranged for the purpose of reducing the high speed and small “pull” of the motor into the low speed and heavy pull of the road wheels. This reduction in speed is generally brought about by a double system of shafts, the second shaft from the motor carrying the differential gear and meshes directly with the master gear on the bull wheel. The first shaft is an idler.

(144) Fairbanks-Morse Oil Tractor.

The Fairbanks-Morse 30–60 Horse-power Oil Tractor gives an effective draw bar pull of 9,000 pounds and develops over 60 horse-power at the belt pulley which is more than sufficient to drive any farm machinery. It will operate equally well on kerosene, distillate oils, and gasoline, any of which will develop the rated horse-power. Two forward speeds and one reverse are obtained by a gear transmission of the automobile type, the forward speeds being 1¾ and 2½ miles per hour and the reverse 1¾ miles. Combined with the governor variation, it is possible to get the proper speed for any kind of work.

The fuel is sprayed directly into the cylinder with a spray of water, the proportion of water to oil being nearly equal at full load. As explained in Chapter VII, the water spray aids in the combustion of the heavier oils, eliminates soot and tarry deposits, and makes the engine run more smoothly because of the reduction of the explosion pressure. The spray also reduces the temperature of the cylinder and minimizes the dangers of preignition. The engine is of the slow speed type running at a normal speed of 375 revolutions per minute, and the two cylinders have a bore and stroke of 10½ × 12 inches. The speed regulator supplied with the engine gives an extreme variation of 300 to 375 R.P.M.

The cylinders are cast two in a block which arrangement permits of the bores being brought close together and gives an easy circulation of cooling water. The value of this practice has been proved in automobile work where a simple and rigid structure is absolutely necessary.

All of the valves are in the heads of the cylinder which eliminates heat radiating pockets in the combustion chamber. Both the inlet and exhaust valve are mechanically operated through substantial push rods and valve rockers, and are completely surrounded by water. Large clean out holes are provided in the separately cast cylinder head making it accessible for the removal of scale and sediment. A single cylinder head serves for both cylinders which contributes to easy cooling passages and a single arrangement of exhaust and inlet piping. The valves are in cages bolted to the cylinder head in such a way that they are easily removed for inspection without disturbing the piping or connections.

The pistons are easily removed without taking the heads out of the cylinder or taking down any shafting. The valve rocker arms are provided with easily renewed bushings and grease cups. As the engine is of the four stroke cycle type with both cylinders on the same side of the crank-shaft, only a single throw crank shaft is used, which is without intermediate bearings.

Dual ignition is used, the high tension magneto and the two unit spark coils shown in Fig. 126 being independent of one another so that either the magneto or battery can be used for starting or for continuous operation. The magneto is mounted directly on the engine bed and is gear driven from the crank shaft. The ignition advance and retard lever and ignition switch are mounted on the engine in an accessible position. As the coil is mounted on the engine the leads are short and the vibrators are directly under the supervision of the operator.

Close speed regulation is maintained by a throttling type governor. The voluntary speed variation used to slow the engine down to meet certain conditions encountered in plowing is accomplished by a small lever located at the end of the cylinders. The cooling water is circulated through the cylinders by a gear driven centrifugal pump. From the cylinders the water enters a closed radiator of the automobile type located at the front of the traction where it is cooled without loss. A nine feed, forced type oiler is used which supplies oil to the cylinders and bearings, and also to the transmission gears. External bearings which are subjected to dust are equipped with grease cups. The fuel pump which takes its supply from an 80 gallon tank is in an accessible position near the operator and is provided with a handle by which it is operated when starting the engine.

The clutch which is located in the flywheel at the right of the engine is operated by a lever on the footboard. All of the friction faces and levers are arranged inside of the pulley so that they are not only protected from injury but are prevented from tearing the belt should it slip from the pulley face.

A powerful foot with a drum on the differential gear will hold the outfit on a grade independent of the engine.

The transmission is of the shifting gear type with hardened steel gears. The transmission gears are enclosed in a practically dust proof case, this being connected with enclosed crank case and better providing for air displacement of the pistons. Power is transmitted to the truck through the clutch on the left hand side of the engine, which is operated by combined clutch and shifting lever on the footboard. This lever has an interlocking device, arranged so that it is impossible for the operator to shift the gears before the clutch is disengaged, or to engage the clutch until the gears are completely in mesh. It is also impossible to get two sets of gearing in mesh at one time and prevents any possibility of stripping gears by applying the load on the corners of the teeth.

The drive wheels are 78″ diameter, 30″ face. These give a very large bearing on the ground which is particularly desirable when using the engine for cultivating or seeding on plowed ground. The front wheels are 48″ in diameter, 14″ face. The wheel base is long and engine is easy to guide. The drive wheels are covered by a metal housing which protects the operator and the working parts of the engine from dust and mud.

This engine gives a drawbar pull on low gear of 9,000 lbs., which will haul from 8 to 12–14″ plows, according to the character of the plowing. The hitch is placed about 18″ above the ground and consists of a heavy bar extending approximately to the middle of the bull wheels on each side, thus providing for hitching the load most satisfactorily.

(145) The Rumely “Oil Pull” Tractor.

The Rumely oil-pull tractor is driven by a two cylinder, four stroke cycle oil engine, having a bore and stroke of 10 × 12 inches giving 30 tractive horse-power and 60 horse-power at the pulley. The cylinders are cast single and are provided with independent heads. The pistons are easily removed by unbolting the cylinder heads and the crank end of the connecting rod, after which operation they may be pulled out upon the platform. The exhaust and inlet valves are in easily removable cages placed on either side of the cylinder. The stems of the valves are at right angles to the bore of the cylinder and open directly into the combustion chamber without pockets or extensions to the chamber.

A bell crank rocker arm acts on the valve stems which in turn is actuated through a push rod that extends from the cam-shaft in the crank chamber. The cam-shaft, rocker arms, valves, and half time gears are clearly shown by Fig. 128. The housings of the inlet valves connect directly with the special kerosene carburetor made by the Rumely Company. The Higgins carburetor used on these engines is very simple and effective in vaporizing the heavier fuels and has no springs nor internal mechanism to get out of order. The carburetor is controlled directly from the governor which regulates the air, water and kerosene required for the combustion, and has no manual adjustments that need attention from the operator. A constant flow of kerosene and water is maintained through the carburetor by means of force pumps, the level in the device being kept constant by overflow pipes through which the excess returns to the supply tanks.

As in nearly all types of low compression, or carbureting oil engines, the Rumely engine receives an injection of water in the cylinder to aid the combustion and cooling, and to reduce the initial pressure of the explosion. While the initial pressure is reduced by the water vapor, and with it the strain on the engine, the mean effective pressure is increased because of the absorption of heat from the walls and the more perfect combustion. The only moving part in the carburetor is a single plate controlled by the governor which is produced with one or more air passages. The governor that operates this valve is driven by gears and regulates the speed by throttling the charge. The speed of the engine can be varied from 300 to 400 revolutions per minute while the engine is running.

In this engine it is a very simple matter to remove the crank-case cover and the cylinder heads and expose the whole of the working mechanism of the engine.

After removing the cylinder heads and without changing his position, the operator can examine, clean, and, if necessary, regrind the valves. Also without changing position the operator can control his reverse transmission gears, friction clutch for starting the tractor. He is also in reach of the ignition apparatus, governor carburetor and oiler.

The crank case is cast in one piece. The bearings are cast integral with the crank case, and are fitted with interchangeable, adjustable, babbitted shells. Binder caps hold the bearings together and keep the babbitted shells securely in position. The design permits removal of binder caps for examination of crank shaft bearings without distributing the adjustment. The crank case is secured to tractor frame by well fitted bolts, thereby avoiding annoyance from loose bolts and nuts.

The crank case is covered with a sheet steel lid that shuts out all dust and dirt. This cover can easily be removed at any time by simply unscrewing the bolts that hold it in place. It is constructed with this cover on top instead of on the side or end, which permits of easy access to any working parts in the crank case.

To further facilitate the accessibility to working parts in the crank case, a secondary cover is provided which can be removed in a couple of minutes. This opening is large enough to allow the operator to reach any point within the crank case.

All cams are key-seated upon the cam shaft with double key-seats, which absolutely prevent any possibility of slipping or alteration in the timing of the engine. The exhaust and intake valves are mechanically operated. The valves are constructed with steel stem, nickel-steel heads, the whole being highly finished.

Valve cages are oil cooled, thereby eliminating all possibility of the valves overheating or warping. The valves themselves can be removed by simply unscrewing the connection. The engine is provided with a set of relief cams by which the compression can be relieved—this greatly facilitates the starting of the engine.

The piston is equipped with five self-expanding rings. Connecting rod is of drop-forged steel construction. Crank-pin bearings are made in halves and lined with shells of special metal.

A combination of mechanical force feed and splash lubrication is employed. Six force feed tubes enter the crank case, on to each bearing, and two tubes force oil into the cylinder. The crank case contains two gallons of oil and is arranged so that any surplus may be drawn off immediately. The lubricator has a gauge glass that shows the quantity of oil supplied at all times, and which is always in view of the operator.

A make and break system (low tension) furnishes the ignition spark, which is supplied with current by a Bosch low tension magneto under normal running conditions, and a battery for starting and for use when the magneto fails. The magneto is of course gear driven so that its armature has a fixed relation with the piston position. The igniters of either cylinder may be easily removed for examination by simply unscrewing two nuts.

Oil is used as a medium for carrying heat from the cylinder walls to the radiator. In the construction of the cooler the company have followed new principles, thus accomplishing the desired result with a minimum amount of metal and liquid. There is no surplus of liquid, just enough oil being used to fill the cylinder jackets, radiator and circulation pipes. The oil is kept in a constant flow from the cylinders to the radiator and back to the cylinders by a large pump which is driven by a chain direct from the crank shaft. The radiator is self-contained and will hold the oil for an indefinite period.

The radiator is composed of a number of sections of pressed galvanized steel. Oil circulates freely within the sections and the air is drawn round the outside. There is a constant flow of oil inside and a constant current of air outside.

The engine is provided with a smooth-working, efficient friction clutch, which is easily handled by a platform lever and with little exertion on the part of the operator. The toggle bolts are adjustable so that any wear in the blocks can be taken up.

The clutch and brake are so connected that when the clutch is thrown out the brake is immediately applied and when thrown in the brake is released.

The various movements of the valves and the ignition mechanism on the face of the flywheel, are marked so that one can check up the timing of the engine. By bringing any one of these marks to coincide with the stationary pointer attached to the side of the crank case, one can easily ascertain whether the adjustments and the timing are exact.

The crank shaft is supported by two end, and one intermediate bearing, the latter bearing being placed between the two throws of the crank shaft. As the two cylinders are placed on the same side of the crank shaft, the two throws are also on the same side of the shaft and to balance these throws cast iron counter weights are bolted on the bottom of the crank arms. The bearings are exceptionally long, the total length of the three bearings amounting to more than half the length between the outer ends of the bearings.

The frame of the tractor consists of four twelve inch “I” beams securely riveted together with intermediate channel stiffeners. The cast steel bearings are riveted to the frame so that the whole construction is one unyielding mass. The bearings are in halves which makes the removal of the shafts an easy task.

With the exception of the differential and master gears all of the gears are cut out of semi steel blanks. The fly wheel has a face of 11 inches, and a diameter of 36 inches.

(146) The “Big Four” Tractor.

The Big Four tractor differs from the majority of tractors in having a four cylinder vertical type motor of 30 tractive and 60 brake horse-power capacity. The cylinders have a bore of 6½ inches and a stroke of 8 inches. The engine runs at the comparatively high speed of 450 revolutions per minute. Gasoline is used for fuel, and is vaporized in a conventional type of jet carburetor.

Both the inlet and the exhaust valves are placed in a pocket at one side of the cylinder making what is known as an “L” engine. The cylinders and the heads are cast in one piece, doing away with points between the cylinders and heads. The pistons and connecting rods may be removed without disturbing the cylinders or their connections by pulling them out through hand holes in the base of the crank case.

The four throw crank shaft is provided with five bearings, these intermediate bearings between the throws and two end bearings in the case. The interior working parts of the motor are lubricated by the splash system with a positive forced feed oiler. The splash pools can be adjusted at a minute’s notice so that any desired oil level can be obtained. Grease cups provide the lubrication for all bearings outside of the motor.

Water is circulated by a direct driven centrifugal pump, and as the cooling water is in a closed system the same water is used over and over again without much loss, a bucketful or so a day being an ample supply. The tubular radiator situated in the front of the tractor is provided with a cooling fan that is driven from the engine in a manner similar to automobile practice. A high tension magneto is gear driven from the cam shaft, and is mounted on a rocking bracket so that the armature is advanced and retarded as well as the circuit breaker.

An internal expanding clutch connects the motor with the driving gear by operating on the inner run of the fly-wheel. The motion of the engine is transmitted to an intermediate reversing device through bevel gears, this being necessary for the reason that the crank-shaft runs “fore and aft,” or parallel to the length of the tractor. A double acting jaw clutch engages with either one or the other of a pair of bevel pinions that run in opposite directions. Motion from the reverse gear is transmitted directly to the different shaft, and from there it is transmitted to the master gears on the bull wheels. The differential shaft is in one piece.

The main driving wheels are very large when compared with the wheels of an ordinary tractor, for they are eight feet in diameter and are proportionately broad. This no doubt gives splendid tractive effect in soft and uneven fields and must save the machine from “stalling” under adverse conditions. Another unusual feature is the automatic steering device used in plowing. This device consists of a long tubular boom that is fastened to the swiveled front axle of the tractor and a small wheel fastened to the outer end of the boom. The small wheel rolls in the next furrow and compels the tractor to plow in a line parallel to it. This steers the tractor more accurately than would be possible by hand and at the same time enables one man to operate both the engine and the plows.

Cost of Gas Engine Operation (American).

═══════════════════════════╤═════════════════════╤═════════════════════ │ GAS PRODUCER PLANT. │ NATURAL-GAS ENGINE. │ │ │ Three- Half │ Three- Half │Load. quarter Load. │Load. quarter Load. │ Load. │ Load. ───────────────────────────┼─────────────────────┼───────────────────── 1 Fuel per hp-hour │ 1.25 1.5 1.8 │10 cu. 12 cu. 15 cu │ lb. lb. │ ft. ft. ft. 2 Fuel per hp-year (4,500 │ 2.5 3.6 │45,000 54,000 67,500 hours) │ tons 3 tons tons │ cu. cu. ft. cu. │ │ ft. ft. 3 Cost of fuel │ $4.00 per ton │ 30 cents per 1,000 │ │ cu. ft. 4 Cost of fuel per year │$10.00 $12.00 $14.40│$13.50 $16.26 $20.25 5 Cost of attendance per │ 0.40 cent │ 0.25 cent hp-hour │ │ 6 Cost of attendance per │ $18.00 │ $11.25 year │ │ 7 Lubricating oil per │ 0.006 pint │ 0.006 pint hp-hour │ │ 8 Cost of oil per year at │ $0.84 │ $0.84 25 cents per gal. │ │ 9 Scrubber and cooling │ 8 gals. │ 5 gals. water per hp-hour │ │ 10 Cost of water per year │ │ at 30 cents per 1,000 │ $1.44 │ 0.90 cubic feet │ │ 11 Operating expenses; │$30.28 $32.28 $34.68│$26.49 $29.19 $34.24 items, 4, 6, 8 and 10 │ │ 12 Saving by Diesel engine │ 5.43 6.47 7.90 │ 1.64 3.39 6.56 13 Interest, depreciation │ │ and maintenance │ 6 + 7 + 2 = 15% │ 6 + 7 + 2 = 15% respectively in per │ │ cent of investment │ │ 14 Assuming $80 initial │ │ cost per hp. the │ $12.00 │ $12.00 yearly fixed charges │ │ will be │ │ ───────────────────────────┴─────────────────────┴─────────────────────

═══════════════════════════╤═════════════════════╤═════════════════════ │ LOW-PRESSURE OIL │ DIESEL ENGINE. │ ENGINE. │ │ Three- Half │ Three- Half │Load. quarter Load. │Load. quarter Load. │ Load. │ Load. ───────────────────────────┼─────────────────────┼───────────────────── 1 Fuel per hp-hour │1 lb. 1.25 1.60 │ 0.50 0.55 0.60 │ lb. lb. │ lb. lb. lb. 2 Fuel per hp-year (4,500 │ 643 803.5 1028.5│321.5 353.5 386 hours) │gals. gals. gals. │gals. gals. gals. │ │ 3 Cost of fuel │ 3 cents per gallon │ 3 cents per gallon │ │ 4 Cost of fuel per year │$19.30 $24.10 $30.85│$9.65 $10.60 $11.58 5 Cost of attendance per │ 0.25 cent │ 0.30 cent hp-hour │ │ 6 Cost of attendance per │ $11.25 │ $13.50 year │ │ 7 Lubricating oil per │ 0.006 pint │ 0.007 pint hp-hour │ │ 8 Cost of oil per year at │ $0.84 │ $0.98 25 cents per gal. │ │ 9 Scrubber and cooling │ 5 gals. │ 4 gals. water per hp-hour │ │ 10 Cost of water per year │ │ at 30 cents per 1,000 │ 0.90 │ 0.72 cubic feet │ │ 11 Operating expenses; │$32.29 $37.09 $43.84│$24.85 $25.80 $26.78 items, 4, 6, 8 and 10 │ │ 12 Saving by Diesel engine │ 7.44 11.29 17.06 │ ... ... ... 13 Interest, depreciation │ │ and maintenance │ 6 + 7 + 2 = 15% │ 6 + 10 + 3 = 19% respectively in per │ │ cent of investment │ │ 14 Assuming $80 initial │ │ cost per hp. the │ $12.00 │ $15.00 yearly fixed charges │ │ will be │ │ ───────────────────────────┴─────────────────────┴─────────────────────

From a Paper Read Before the American Institute of Electrical Engineers.