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| Illustration 1 | g06360474 |
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(1) Input shaft
(2) Piston pump front section (3) Solenoids (4) Ports for oil flow (5) Solenoids (6) Piston pump rear section (7) Ports for oil flow | |
The All Wheel Drive piston pump (AWD pump) is a variable displacement axial piston pump. The pump contains two rotating piston and barrel assemblies. The front section (2) contains a pump rotating assembly. The rear section (6) contains a pump rotating assembly. The AWD piston pump is fastened to the engine PTO drive. The flywheel in the engine drives the input shaft for the piston pump. Input shaft (1) turns the barrel assemblies.
The AWD piston pump is controlled by the All Wheel Drive Electronic Control Module (AWD ECM). The AWD ECM receives inputs from the following:
- The transmission speed sensor
- The speed sensors for the AWD motors
- The AWD control switch
- The AWD aggression control dial
The AWD ECM will interpret the inputs. The AWD ECM will send a signal to solenoid valves (3) and (5). If the AWD ECM determines that more speed is required of the front wheels, the solenoid valves will upstroke the pump. If the AWD ECM determines that less speed is required of the front wheels, the solenoids will destroke the pump.
The AWD ECM will control the amount of oil flow and the direction of oil flow from the piston pump. The pump control valve will control the direction of the swashplate and the angle of the swashplate. When charge oil is sent to two of four actuator pistons, the swashplate will change angles. The tilted swashplate causes the pistons to move in and out of the barrel assembly. As the barrel assembly turns, the movement of the pistons causes oil flow from either port (4) or port (7). The main relief valves limit the output pressure of the pump.