TUBE 4542155 - Caterpillar

Illustration 1 g01185582
When the engine is operating, the fan pump generates flow. Pump supply oil flows to the cooling fan solenoid, and flows to the fan motor. Inside the fan motor, supply oil closes the anticavitation check valve. Supply oil is also available at the inlet port of the rotating group of the fan motor.The machine ECM energizes the cooling fan solenoid when the engine is operating. This solenoid directs some oil to the oil cooler bypass manifold. The remaining supply oil is sent through the fan motor. The amount of flow which is directed through the fan motor is dependent upon the operating temperature of the machine.When the engine is stopped, the inertia of the fan blades and of the rotating components in the fan motor cause the fan motor to continue to turn for a brief period. Since the engine is not operating during this time, the fan pump does not provide the flow that is needed to prevent motor cavitation. In this case, the anticavitation check valve opens. The anticavitation check valve prevents motor cavitation by allowing the fan motor to draw oil from the return line.