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| Illustration 1 | g03665690 |
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Rear of Vehicle (1) WDS motor | |
WDS motor (1) is located on the water pump at the rear of the vehicle.
WDS motor (1) is an axial piston motor with variable displacement. The maximum displacement is
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| Illustration 2 | g03665708 |
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Motor (water Pump) (2) Port "A" (3) Port "B" (4) Port "X" (5) Port "U" (6) Port "E" (7) Motor inlet pressure sensor | |
Hydraulic ports are located on the housing of WDS motor (1). Each of these ports is identified by a lettered designation which is cast into the housing next to the port. The function of each port used in the motor is as follows:
Port "A" (2) is the high-pressure port when the system is in operation.
Port "B" (3) is the low-pressure port when the system is in operation.
Port "X" (4) is the control pressure port inlet. Pressure arrives to this port when the system calls for the motor to be destroked. The control pressure actuates the servo control spool.
Port "U" (5) is a case drain port. In motor (1) for the water pump, case drain oil flows from port "U" to the hydraulic cooler and hydraulic oil tank.
Port "E" (6) is the charge pressure port inlet for swashplate servo operation. Charge pressure is present at this port when the engine is running. The servo control spool regulates the charge pressure from port "E" in order to actuate the swashplate servo. The swashplate servo positions the swashplate in order to govern the motor displacement.
WDS motor (1) is connected to the water pump by a coupler and turns in. The WDS motor is controlled by hydraulic control signal from the pump (water delivery) to motor port "X" (4). Control pressure at port "X"operates a proportional control spool. The spool allows charge pressure at port "E" (6) to flow to the internal swashplate servo. The servo varies the swashplate angle in order to set motor displacement.
When there is no control pressure at port "X" (4) the variable displacement of WDS motor (1) defaults to maximum. As control pressure increases the motor destrokes, reducing displacement. With constant supply flow volume, the motor will increase speed with the destroke.
The internal leakage in the system is inherently low. Oil flow is primarily closed-loop from the pump (water delivery) to WDS motor (1) and back to the pump. The motor has an internal case-flushing shuttle valve feeding oil flow to a flushing relief valve. The flushing relief valve flushes oil from the low- pressure side of the loop into the motor case. This purged flushing flow is circulated from case port"U" (5) to the hydraulic oil cooler and tank.