Abstract: A parking brake mechanism for an air actuated disc brake includes an air chamber separated into a non-pressurised section and a pressurised section. A resilient device is located in the non-pressurized section and is movable along an axis to adopt a retracted parking brake-off position and a deployed parking brake-on position. The resilient device is biased into the deployed parking brake-on position. A latching device is arranged to selectively retain the resilient device in the retracted parking brake-off position. An actuator is arranged to selectively disengage the latching device to permit the parking brake mechanism to be applied. The mechanism is configured to introduce pressurized air into the pressurized section to return the resilient device to the retracted parking brake-off position.