Lubrication Systems

If you were asked, “What is the most important job in caring for a car? ” you would probably say lubrication [53]. If any one job can be considered more important than another, you would be right. The different lubricants used in the tractor perform these essential functions:

Conduct away excessive heat.

Reduce friction and wear between moving parts.

Seal compression between pistons and cylinder walls.

Cushion [54] the loads on bearings of the power-transmitting system.

Because car work is so severe - long hours, heavy loads, dusty roads, rough ground, steep hills, and all kinds of weather – we have to be very careful about lubrication. Fortunately, however, the actual job of properly lubricating a tractor has been made quite easy. The petroleum industry has developed excellent oils and greases. Manuals tell what kinds and grades to use, and where and how often to apply them. The lubrication system holds and circulates an ample [55] supply.

Your job in properly lubricating a tractor can be summarized as follows:

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 car.

4. Changing lubricants as required.

5. Keeping these lubricants clean and free from contamination [56] and dilution [57].

Engine Lubrication System. You should understand the construction of the engine lubrication system and know how it circulates oil to all parts of the engine. In most tractors, oil is circulated and distributed, within the engine by a gear-type oil pump [58]. This maintains sufficient pressure to supply oil in proper quantities to all the working parts. This is a full-pressure-type lubrication system.

The oil intake of the pump and is of the floating type, composed of afloat with a metal screen, which prevents the entrance of large foreign particles that would damage the pump gears [59]. The intake is hinged in a way that permits the float to remain near the surface of the oil in the oil pan in order to draw in the cleanest oil. The pump forces the oil, under pressure, to the principal distribution passages drilled into the cylinder block. This pump also has a pressure regulating valve which maintains the specified pressure to protect the lubricating system and the pump mechanism when the lubricants are thickened by cold temperature.

The valve which regulates the pump pressure opens to permit oil to escape into the oil pan through a bypass. An oil pressure gage, which can be seen by the operator, is connected to the main oil passage. From the main oil passage the oil is forced through smaller passages drilled in the block to main crankshaft bearings and other parts of the engine. The excess oil is by-passed from the main oil passage through a smaller passage, is forced through the filter, and is then returned through a metering hole located in the central bolt of the filter, to the oil pan.

In the center bearing of the camshaft there is a small oil slot [60]. As the camshaft revolves, contacting the main oil passage, the oil flows through passage or intermittently lubricating the rocker arms and valves, and the exhaust valve stems and guides; the overflow returns to the oil pan. The intake valve stem guides are lubricated by oil vapors. The oil is forced under pressure from the three main crankshaft bearings through passages drilled in the crankshaft to the four con­necting rod bearings. On the larger engines the connecting rods [61] are drilled and the oil from the bearing is forced through this drilled oil passage to lubricate the piston pin [62] and cylinder walls. On the smaller engines the oil lubricates the connecting rod bearings, escapes at the ends, and splash lubricates the cylinder walls, piston pins, etc. The front camshaft bearing contains oil holes and passages which index with other passages at each revolution. As this occurs, the oil is forced intermittently through the drilled oil passages to the timing gears and through the oil passage to the governor assembly (on engines using a carburetor).

The purpose of the oil filter is to remove foreign matter from the oil and other substances which might damage the engine.