NUT 5315837 - Caterpillar

Illustration 1 g06187614
Fan Hydraulic System
(1) From propel pump
(2) Oil cooler
(3) Fan motor
(4) Anticavitation check valve
(5) Speed adjustment valve
(6) Oil cooler bypass
(7) From vibratory valveWhen the engine is operating, the vibratory pump draws oil from the hydraulic tank through a suction strainer. Supply from vibratory valve (8) is sent to fan motor (3).Inside fan motor (3) supply oil is routed to four components. One route flows to the gears of the fan motor. The second route seats anticavitation check valve (4). The third route flows to speed adjustment valve (5).Speed adjustment valve (5) is an adjustable relief valve. This valve allows a controlled amount of hydraulic oil to bypass fan motor (3). This valve controls fan speed.When the engine is operating, supply oil flow is directed through fan motor (3). In this case, the fan operates at high speed.When the engine is stopped, the inertia of the fan blades causes fan motor (3) to continue to turn for a brief period. Since the engine is not operating during this time, the vibratory pump does not provide flow to prevent motor cavitation. In this case, anticavitation check valve (4) opens. The anticavitation check valve prevents motor cavitation by allowing the fan motor to draw oil from the return line.