CORE AS-OIL COOLER 3736537 - Caterpillar

Illustration 1 g00714447
Fan driveThe fan clutch is mechanically driven. The fan clutch is lubricated and cooled with oil. Engine lubricating oil that is filtered and cooled is piped to the fan clutch. Internal ports and orifices distribute lubrication and cooling oil. The fan clutch contains multiple clutch plates. Oil pressure activates the fan clutch. Oil pressure controls the fan speed by modulating the engagement and disengagement of the fan clutch.The fan operates at minimum speed of 100 to 300 rpm when there is no control pressure. With constant control oil pressure, the fan operates at 800 to 1150 rpm. The maximum fan speed is dependent on the application.The required amount of cooling oil to the fan clutch is based on the inputs that follow:
Coolant temperature
Brake oil temperature
Aftercooler temperature
Air conditioner pressure (if equipped)The fan drive valve adjusts the control oil pressure to the fan clutch. The adjustments are based on the inputs from the coolant temperature sensor and brake oil temperature sensors. The aftercooler temperature switch will override the signal to the fan drive valve when the actuation temperature has been reached. The air conditioner pressure switch overrides the signal to the fan drive valve when the actuation pressure has been reached. The override provides maximum fan speed when the following conditions are present:
High exhaust temperature
Heavy use of the air conditioner (if equipped)
Heavy retardingThe fan drive valve modulates the control pressure to the fan clutch. Modulating the control pressure changes the fan speed without shock loads. Modulating the control pressure allows the oil cooled clutch plates to slip. The slippage results in variable fan speed.