The Oil Pump is used to force pressurized oil to the various parts of the engine. The inner rotor is shaped like a cross with rounded points that fit into the star shape of the outer rotor. The inner rotor is driven by a shaft turned by the camshaft. When it turns, its rounded points "walk" around the star shaped outer rotor and force the oil out to the delivery pipe.
Most Pumps Consist of Four Parts:
- Main Body
- Cover Assembly
- Sintered Gears
- An oil pressure relief valve (usually in the pump, but sometimes in the engine block).