The different lubricants used in the tractor perform the following essential functions:
Conduct away excessive heat.
Reduce friction and wear between moving parts.
Seal compression between pistons and cylinder walls. Cushion the loads on bearings of the power-transmitting system.
Because tractor work is so severe - long hours, heavy loads, dusty fields, rough ground, steep hills, all kinds of weather - one must be very careful about lubrication.
The job in a properly lubricating tractor can be summarized as follow s:
1. Selecting the kinds of lubricants recommended by the manufacturer.
2. Applying these in correct amounts at recommended intervals.
3. Maintaining proper quantities within the tractor.
4. Changing lubricants as required.
5. Keeping these lubricants clean and free from contamination and dilution.
Proper lubrication is essential to the successful economic operation and expected life of the tractor.
The three most common lubrication systems employed in tractor engines are: I) circulating splash; 2) pressure circulation; 3) full-pressure lubrication. The circulating-splash system depends on cups or splashers on the lower end of the connecting-rod bearing which splash oil from troughs onto the cylinder walls, pistons, connecting rods, gears, shafts and bearing housings. This is, in reality, an oil mist that covers all surfaces. Oil enters the wrist-pin bearings as it is wiped off the cylinder walls by an oil ring. The main and connecting-rod-bearings are lubricated by a pump and drilled passages in the crankshaft.
The principal parts of an internal-combustion engine requiring lubrication are pistons, piston rings and cylinder walls, main bearings, connecting- rod bearings and piston pins, valve mechanism, camshaft and timing gears, valve stems and guides and the governor. The oil is supplied to these parts from the crankcase oil reservoir.
In the pressure-lubrication system the lubricating oil is directed under pressure through rifle-drilled passages in the crankcase to the main bearings, camshaft bearings, timing gears, governor, valve mechanism and oil filter. The cylinder walls and wrist pins are lubricated in a manner similar to the circulating-splash system. In full-pressure lubrication drilled passages in the crankcase deliver oil to all members including timing gears and rocker-arm shaft. The wrist pins and cylinders are lubricated through drilled connecting rods receiving oil from the crankshaft bearings.