RETAINER 8J8862 - Caterpillar

Illustration 1 g03688459
Illustration 2 g03693672
(1) Pump #1 (Displacement 165 cc)
(2) Inlet port
(3) Pump #2 (Displacement 45 cc)
(4) Electrohydraulic pump actuator solenoid
(6) Discharge port
(5) Pump #2 control valve
(7) Pump #1 control valve
(8) Electrohydraulic pump actuator solenoid
(9) Pump displacement position sensorImplement Pump Operation
The implement pump is made of a two variable displacement piston pumps that supplies oil to the implement system.The left implement pump (1) is a 165 cc variable displacement pump equipped with a displacement position sensor. The left implement pump (1) is electronically commanded by the implement ECM. The displacement sensor (9) sends a PWM signal to the implement ECM. The PWM signal communicates the swashplate positioning in the implement pump. The right implement pump (3) is a 45 cc variable displacement pump electronically commanded by the implement ECM. The right implement pump (3) has no displacement position sensor.The implement pump is electronically controlled. The pump is connected to the accessory drive and input shaft.Oil from the hydraulic tank is drawn into the pump through the suction port (3). The oil is sent to the two implement pumps through the discharge pump port (4).Pump and Pump Control Valve - Low Pressure Stand By
When the implement pump is at low-pressure standby, the implement ECM sends a proportional amount of current to the solenoid valve. The implement ECM determines the amount of current required to produce low-pressure standby. The implement ECM gathers this information using the input signals from the pump pressure sensor, implement pump position sensor, and the implement pump calibration data.In the minimum displacement position, the ECM sends a minimum current to the pump solenoid. The solenoid valve directs pump oil flow to the end large actuator.The spring force and the pressure on the end of the large actuator work against the pump output oil and spring force on the end of the small actuator.The actuator moves to the left and the large actuator moves to the right. This action will rotate the swashplate to the required angle that is needed to produce low-pressure standby. Minimum oil flow is directed to the implement control valve.Pump and Pump Control Valve - Constant Flow
When the flow demands of the implement system have been met, the implement pump moves to a constant displacement position. The implement ECM determines the amount of current required to maintain the pump swashplate. The implement ECM uses the input signals from the pump pressure sensor, lift and tilt linkage sensors, lift and tilt lever position sensor, and pump calibration data.In a constant displacement position, the implement ECM sends current to the pump solenoid valve. The solenoid valve meters the pilot oil to the large actuator to maintain the swash plate.The pump output oil and spring force on the small actuator work against the spring force and the pilot pressure on the large actuator. The actuator shifts to the right and the swashplate moves to the desired angle. The oil flow is directed to the implement control valve.Pump and Pump Control Valve - Maximum Displacement
When the implement system requires