PLATE 5S2864 - Caterpillar

Illustration 1 g00629571
Hydraulic Cooling SystemIn the hydraulic cooling system, the hydraulic cooling piston pump provides oil flow to the hydraulic cooling fan motor. The hydraulic cooling fan motor drives the cooling fan.The hydraulic cooling piston pump is the top right-hand pump on the pump drive. The regulator control valve for the hydraulic cooling piston pump is mounted on the top right rear corner of the pump.On machines (S/N: 7LL1-63), the cooling pump control solenoid valve for the hydraulic cooling piston pump is mounted to the pump room fire wall to the right of the radiator cooling pump control solenoid valve. On machines (S/N: 7LL64-UP) the cooling pump control solenoid valve for the hydraulic cooling piston pump is located in the control manifold valve to the right of the radiator cooling pump control solenoid valve.The hydraulic cooling fan motors and the cooling fans are mounted at the left rear corner of the left-hand module. Lines from the hydraulic cooling fan motors are connected to the fan motor makeup valve.The engine control module is located on the right front corner of the engine.Operation of the Hydraulic Cooling System
The temperature sensor provides a signal about the temperature of the hydraulic oil to the engine control module. The hydraulic oil temperature is monitored by the engine control module. The engine control module signals the machine control module about the state of the hydraulic oil. The machine control module sends a Pulse Width Modulated (PWM) signal to the control solenoid valve. The control solenoid valve modulates the signal pressure from the solenoid valve back to the regulator control valve for the hydraulic cooling piston pump in order to control the pump flow. The flow from the hydraulic cooling piston pump is directed to the hydraulic cooling fan motor, the fan motor makeup valve, and the control solenoid valve. The control solenoid valve regulates the signal pressure to the regulator control valve for the hydraulic cooling piston pump.If the hydraulic oil temperature rises above 90 °C (194 °F), the engine control module will derate the engine horsepower up to 15 percent until the problem with overheating is eliminated.The engine control module also sends a signal about the hydraulic oil temperature to the Vital Information Management System (VIMS) module. This action is performed over the Cat data link. The VIMS module makes the information about the temperature available to the operator in the cab. The VIMS module is located behind the cover of the large electrical panel that is located in the cab support.Operation of the Cooling Fan
Illustration 2 g03791927
Chart of Fan Speeds for the Hydraulic Cooling SystemWhen the temperature of the hydraulic oil is below 61 °C (141.8 °F), the fans will operate at minimum speed of 485 50 rpm.When the temperature of the hydraulic oil is above 72 °C (161.6 °F), the fans will operate at a speed of 950 10 rpm.Note: The fan speed is reduced during a combined operation of boom RAISE and swing to reduce the hydraulic system load and