Group 13, Wiring, Switches, and Instruments
13-4-4 • Switches and Sensors SM 765, Sep ’06
Parking Brake Switch Description
The parking brake switch is mounted to the hood under of
parking brake assembly. The brake handle center pin
depresses the switch when the hand lever is not applied.
This depressing of the switch closes the contacts.
When the parking brake is applied, it releases the switch,
allowing the contacts to return their normally open posi-
tion. This open circuit signals the controller to disable the
drive motors.
IMP
RTANT
The switch must cut electrical current to the
drive motor before the brakes apply. Other-
wise, excessive lining wear will result and the
drive motor will overheat.
Parking Brake Switch Adjustment
1. Turn key switch OFF.
2. Loosen parking brake switch mounting screws.
3. Adjust position of switch so that there is contact with
the center pin and the switch actuates (clicks) just as
the parking brake lever is fully released.
4. Tighten mounting screws.
5. Check operation of switch before truck is returned to
service.
Parking Brake Operation
The operator applies the parking brake by pull up on a
parking brake, which is then held by a ratchet. The pull-
ing up the brake lever tensions cables connected to a brake
shoe at each brake assembly, thereby applying the brakes.
The operator releases the parking brake by push down on
a Parking lever. Return spring returns the lever and
cable to the off position. The lever also operates the park-
ing brake interlock switch and the parking brake indicator
light switch.
Parking Brake Switch
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