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 39 of 1015
TM 9-2320-272-24-l
l-20. CONTROL SYSTEM OPERATION (Contd)
c. Parking Brake System Operation.
A
mechanical and air-actuated brake system performs the following for all vehicles covered in this
manual:
(1)
Keeps vehicle from rolling once it has stopped.
(2)
Slows down or stops vehicle movement.
(3)
Provides emergency stopping if there is a complete air system failure.
The mechanical brake system is covered below. The compressed air function of the brake system will be
covered in a following paragraph. Major components of the parking brake system are:
Key Item and Function
7
PARKING BRAKE WARNING LIGHT
- Illuminates when parking brake is engaged.
8
PARKING BRAKE CONTROL LEVER
- Is positioned up to engage parking brake; down to
disengage parking brake.
9
PARKING BRAKE CONTROL LEVER ADJUSTING KNOB
- Permits operator to make minor
tension adjustment of parking brake.
10
PARKING BRAKE CABLE
- Links parking brake control lever to brakeshoe lever.
11
BRAKESHOE LEVER
- Lever turns cam which pushes brakeshoes against drum.
12
PARKING BRAKE ADJUSTING NUT
- Permits major tension adjustment between parking brake
lever and brakeshoes.
1-29
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