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| Illustration 1 | g03796552 |
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(1) Input shaft
(2) Swashplate (3) Piston (4) Servo valve (5) Barrel (6) Actuator piston (7) Spring (8) Port plate (9) Port for drive loop (10) Charge pump (11) Port for drive loop | |
The pump for the winch hydrostatic system is a variable displacement piston pump. The winch pump is mounted to the back of the hystat drive pump. The input shaft of the winch pump engages a coupling from the hystat drive pump in order to drive the winch pump.
When the engine is running, input shaft (1) and the barrel (5) are rotating. There are nine pistons (3) in the barrel (5). Port plate (8) and swashplate (2) are stationary within the pump housing. Port plate (8) and swashplate (2) do not rotate. Spring (7) maintains a force against the barrel (5) and port plate (8). When the barrel is rotating, each piston (3) follows the angle of swashplate (2).
If the angle of swashplate (2) is zero, pistons (6) do not move in and out of the barrel (5) and there is no oil flow. Charge oil from charge pump (10) maintains oil pressure in the pump in order to perform the following tasks:
- Keep the barrel full of oil.
- Lubricate the pump components.
- Provide makeup oil for internal loss of oil that is due to leakage.
- Provide pilot oil to servo valve (4) in order to shift actuator piston (6) and change the angle of swashplate (2).
For additional information, refer to "Charge Pump".
The position of swashplate (2) is determined by actuator piston (6). The winch control lever that is located on the right console sends signals to the electronic control module (ECM). The ECM interprets the signals and the ECM sends pulse width modulated signals to the solenoids on either side of servo valve (4). As servo valve (4) is shifted to either direction, signal oil from passage (17) is directed to the corresponding end of actuator piston (3).
As actuator piston (6) begins to move, the angle of swashplate (2) begins to increase. As pistons (3) follow swashplate (2), pistons (3) begin to move in and out of the barrel (5). As piston (3) moves out of the barrel (5), oil is drawn from the motor of the drive loop through port plate (8). As piston (3) follows swashplate (2) and the piston moves into the barrel (5), the oil is pushed through port plate (8) into the motor of the drive loop.
As the angle of swashplate (2) increases, the output flow of the pump also increases.
The charge pump is a gerotor pump that is located on the rear of the winch pump. The charge pump provides oil for the winch hydrostatic system when you start the machine. Charge oil is also used as makeup oil for the drive loop. Charge oil is also used for lubrication of pump components and of motor components and for cooling of pump components and of motor components.
As the two gears in the charge pump rotate, oil is drawn from supply. The oil is forced out to the hydraulic oil filter. For additional information regarding the oil filter, refer to Systems Operation , "Hydraulic Oil Filter".
The oil returns from the hydraulic oil filter to servo valve (4) of the piston pump.
The oil also flows to the following components:
- 2 pressure limiter valves
- 2 High-pressure relief valves