MOTOR G-HYD 5W4189 - Caterpillar

Illustration 1 g00458938
Idler gear and components of the oil pump
(1) Snap ring
(2) Collar
(3) Spring
(4) Shim
(5) Oil pump cover
(6) Inner rotor
(7) Spring
(8) Outer rotor
(9) Bushing
(10) Idler gear
(11) Thrust washer Pressure for the lubrication system is supplied by an engine oil pump which uses rotors. The oil pump is part of idler gear (10). The idler gear is driven by the crankshaft gear.The oil pump has an inner rotor (6) and an outer rotor (8). The axes of rotation of the rotors are off-center relative to each other. There is a pin that is inserted through a hole in oil pump cover (5) into the outer rotor. The pin functions as a key in order to keep the outer rotor in a fixed position with the idler gear.The outer rotor is pressed in bushing (9). The bushing is pressed in idler gear (10). The inner rotor has four lobes which mesh with the five lobes of the outer rotor. When the outer lobe rotates, the distance increases between the lobes of the outer rotor and the lobes of the inner rotor in order to create suction. Then, the space between the lobes is filled with oil. When the distance decreases between the lobes, pressure is created. This pressure forces the oil into the chamber for the engine oil relief valve. Lubricating oil from the oil pan flows through a strainer and a line to the suction side of the engine oil pump. The suction side is in the timing gear case. The lubricating oil flows from the outlet side of the pump to a relief valve. The relief valve is installed on the right side of the cylinder block. The lubricating oil, which flows around the relief valve, flows to the oil filter.When the engine rpm increases, the flow rate of the oil pump increases. The increase in the flow rate from the oil pump causes the pressure to increase. The relief valve opens if the oil pressure is too high. When the oil pressure on the plunger of the relief valve is greater than the force of the spring in the relief valve, the relief valve opens. The lubricating oil which flows through the relief valve is returned to the oil pan.The oil filter is installed on the right side of the cylinder block. Turbocharged engines have an engine oil cooler that is installed between the oil filter and the cylinder block. The oil flows through the oil filter into the main oil gallery. The main oil gallery is drilled through the total length of the right side of the cylinder block. Oil flows from the main oil gallery through an externally mounted oil supply line to the cylinder head. An oil pressure switch measures the oil pressure at this location. This oil lubricates the rocker arm assembly. The oil passes through the rocker shaft to the bore of each rocker lever. Then, the oil flows from the rocker levers through holes that are located in the top of the