Practical Hand Book of Gas, Oil and Steam Engines / Stationary, Marine, Traction; Gas Burners, Oil Burners, Etc.; Farm, Traction, Automobile, Locomotive; A simple, practical and comprehensive book on the construction, operation and repair of all kinds of engines. Dealing with the various parts in detail and the various types of engines and also the use of different kinds of fuel.

by John B. Rathbun

(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.

Fig. 127. Fairbanks-Morse Tractor Transmission with Two Forward Speeds and One Reverse.

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.