CONNECTOR 6K2088 - Caterpillar

Illustration 1 g01269420
Oil DistributionWhen the engine is operating, the fan pump generates flow. Pump supply oil is directed to the fan motor. Supply oil is also directed to the fan control valve. 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.Inside the fan control valve, supply oil acts on the bypass spool and flows through an orifice. Downstream from the orifice, supply oil acts against the opposite side of the bypass spool in conjunction with a spring. Supply oil also flows to the fan control valve.The fan control valve contains the cooling fan solenoid. The machine ECM evaluates the operating temperature of the machine in order to determine parameters that are needed to control the fan solenoid. When the operating temperature is low, the machine ECM sends the maximum signal to the fan control solenoid. In this case, the fan control valve opens a passage for supply oil to flow into the pump case drain.As supply oil flows across the fan control valve, the bypass spool shifts against the force of the spring. This shift directs oil into the displacement piston cavity. Pressure in the displacement piston cavity works against the bias spring. As the pressure in the displacement cavity increases, the displacement piston moves the swashplate to the minimum angle. In this case, the fan motor operates at minimum speed.
Illustration 2 g01269422
Temperature IncreaseAs the operating temperature of the machine increases, the machine ECM decreases the strength of the signal which is sent to the cooling fan solenoid. This action causes the fan control valve to close. As the fan control valve closes, the pressure which acts against the bypass spool and in conjunction with the spring increases. The bypass spools shift. As a result, the pressure in the displacement piston cavity decreases. As the pressure in the piston cavity decreases, the bias spring forces the displacement piston to move the swashplate in the pump to a greater angle. The pump produces more flow, and the speed of the fan motor increases.Note: Under normal operating conditions, the machine ECM always sends a signal to the cooling fan solenoid. The signal is never completely discontinued. The minimum signal determines the maximum fan speed.When the engine is stopped, the inertia of the fan blades and the inertia of the rotating components in the fan motor cause the fan motor to continue to turn, for a brief period of time. Since the engine is not operating during this time, the fan pump does not provide flow in order 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.