Principles of Operation

Principles of Operation

Parking Brake System
When the parking brake control is pressed, tension is applied to the front parking brake cable. This tension pulls on the LH rear parking brake cable, which is attached to the LH rear parking brake shoe actuator and applies the LH rear brake shoes. At the same time, the tension in the LH rear cable causes the LH rear cable conduit to attempt to straighten out. This straightening effect causes the LH rear cable conduit to pull on the RH rear parking brake cable, which is attached to the RH rear parking brake shoe actuator and applies the RH rear brake shoes.

Automatic Parking Brake Release
The parking brake control is equipped with an automatic release mechanism that consists of the following components:
^ a vacuum actuator (mounted on the parking brake control)
^ a vacuum switch (mounted on the steering column for column shift vehicles and on the selector lever assembly for floor shift vehicles)
^ vacuum tubes
^ an actuation lever (connecting the actuator to the parking brake release)

Vacuum is supplied to the vacuum switch at all times (a vacuum reservoir supplies the vacuum when the engine is not running). When the transmission selector lever is placed in DRIVE, a tab on the selector lever actuates the vacuum switch which supplies vacuum to the vacuum actuator. When vacuum is supplied to the actuator, it moves a lever that is connected to the parking brake control and releases the parking brake.