TM-9-2320-272-24-1
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 1 OF 4
JUNE 1998
TM-9-2320-272-24-1 - Page 40 of 1015
TM 9-2320-272-24-1
l-20. CONTROL SYSTEM OPERATION (Contd)
d. Steering System Operation.
The steering system is identical for all models covered in this manual. It is a hydraulically-assisted system
that provides ease of turning and control for the operator. Major components of the steering system are:
Key
1
2
3
4
5
6
7
8
9
10
11
l-30
Item and Function
OIL RESERVOIR AND STEERING PUMP -
Combined in one unit, the reservoir serves as an oil
fill point and the pump creates pressure.
ACCESSORY DRIVEBELTS
- Transmit mechanical power from accessory drive pulley to steering
pump pulley to drive the steering pump.
STEERING WHEEL
- Serves as manual steering control for operator.
STEERING COLUMN UNIVERSAL JOINT
- Connects, at an angle, the steering wheel column
and input shaft of power steering gear.
POWER STEERING ASSIST CYLINDER
- Receives hydraulic pressure from steering gear to
assist in turning front wheels.
STEERING KNUCKLE
- Serves as pivot point and link for front wheels from tie rod assembly.
TIE ROD ASSEMBLY
- Connects steering knuckles so both wheels turn at the same time.
STEERING ARM
- Connects drag link to steering knuckle.
DRAG LINK
- Transmits movement from steering arm to pitman arm.
PITMAN ARM
- Transfers torque from power steering gear to drag link.
STEERING GEAR
- Converts hydraulic pressure from steering pump to mechanical power at
pitman arm.
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