HOSE AS 3979707 - Caterpillar

Illustration 1 g00975752
Fan motor (1) is a fixed displacement gear motor. The fan motor drives the radiator fan. The fan motor serves to draw cooling air through the cooling package. Hydraulic oil for the fan motor is provided by the gear pump.
Illustration 2 g00975753
Hydraulic Schematic (1) Gear motor (fan) (2) Check valve (3) Relief valve (4) Motor (5) Line to the propel charge filter or to the valve for the leveling blade (if equipped) (6) Line from steering pumpThe gear motor (fan) includes the following major components:
Check valve (2)
Relief valve (3)
Motor (4) When the machine is started, the priority valve for the gear pump (steering) shifts and the fan motor receives a continuous supply of oil. This supply from the gear pump (steering) will vary. The oil that is delivered to the gear motor (fan) is less during extreme steering input.The oil from the gear pump (steering) enters the inlet port and flows into the cavity that is formed by the gears in motor (4). The pressure of the hydraulic oil forces the gears to turn. As a result, the motor shaft will rotate causing the fan to rotate. As the gears rotate, the hydraulic oil passes through the outlet port of the motor. If the machine is equipped with a leveling blade control valve, this oil will go to this valve. If the machine is not equipped with a leveling blade control valve, the oil will go to the propel charge filter.The speed of the fan is controlled by the flow of oil from the priority valve that is part of the gear pump (steering) and relief valve (3). Adjustment of the relief valve is required in order to change the speed of the fan.Check valve (2) prevents fan motor (4) from cavitating when the engine is shut down and the fan rotates to a stop. As the fan rotates to a stop, the check valve will open allowing fan motor (4) to draw oil downstream in the hydraulic circuit.Reference: See Specifications, System Operation, Testing and Adjusting, "Fan Motor (Radiator Cooling)" in order to adjust the speed of the fan.