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| Illustration 1 | g00923168 |
This module discusses the features and operation of the all wheel drive system. In addition, the major electrical components and hydraulic components are discussed. The following Motor Graders are covered in this module:
- 143H
- 163H
The 143H and 163H are equipped with an electronically controlled AWD hydraulic system. The AWD hydraulic system controls the front wheels in the following three modes of operation: OFF, MANUAL and AUTOMATIC.
The AWD system has the following main components:
- Piston Pump
- Gear Pump
- Control Valve
- Flushing Valve
- Right and Left Motors
- Electronic Controls
Piston Pump
The piston pump is a variable displacement axial piston pump. The piston pump provides oil flow to the drive motors on the front wheels for the forward and reverse directions. The pump displacement is electronically controlled by the AWD Electronic Control Module (ECM) in order to regulate pressure up to 35000 kPa (5080 psi) in the system.
Gear Pump
The AWD gear pump is driven by the pump shaft from the hydraulic and steering pump. The AWD gear pump provides pressure in the charge circuit of the AWD system. The pressure in the charge circuit is controlled by two sequence valves in the flushing and cooling control valve. The AWD gear pump provides makeup oil for the closed loop. Also, the AWD gear pump provides oil for the AWD control system.
AWD Control Valve
The AWD control valve controls both the engaging and disengaging of the AWD closed loop hydrostatic circuit.
Flushing Valve
The flushing valve provides a passage for free flow between the AWD piston pump and the AWD piston motors. When the AWD system is engaged, the shuttle spool shifts in order to direct charge oil to the low pressure side of the drive loop for makeup oil and cooling oil.
AWD Motors
The motors are a dual displacement with a radial piston design. The small displacement is used for high speed and low torque. The large displacement is used for low speed and high torque.
Electronic Controls
Reference: Refer to Systems Operation/Testing and Adjusting, "Features".