Illustration 1 | g00602095 |
(1) Spring (2) Air chamber (3) Rod assembly (4) Piston (5) Air inlet |
The parking brake is released and activated by air chamber (2). Rod assembly (3) is connected to the lever that moves the brake linings which contact the brake drum. When air pressure is blocked from the control valve (parking brake) to air inlet (5), there is an absence of air pressure in air chamber (2). Spring (1) forces piston (4) completely to the right. The parking brake remains engaged.
The parking brake chamber stays activated until the air system is at the normal operating pressure and the knob for the control valve (parking brake) is depressed. At this time, air pressure flows to air chamber (2). This pushes piston (4) to the left. Rod assembly (3) moves the lever that moves the brake linings away from the brake drum. This releases the parking brake.
When air pressure decreases the knob for the control valve (parking brake) moves upward. This automatically blocks the flow of air to air chamber (2). Spring (1) is no longer in compression and the rod assembly (3) is pulled into the parking brake chamber. This action moves the lever which moves the brake linings that make contact with the brake drum. The parking brake is now activated.
This operation takes place when the knob for the control valve (parking brake) is manually moved to the ON position. This activates the parking brake.