Patent ID: 8714318

Claim:
A spring brake actuator, comprising: a spring housing connected with an intermediate flange to form a parking brake actuator chamber; a service brake housing connected with the intermediate flange on a side opposite the spring housing; a parking brake release actuator located within the parking brake actuator chamber, the parking brake release actuator including a parking brake release piston and a diaphragm which divide the parking brake actuator chamber into a parking brake release chamber on an intermediate flange side of the parking brake release actuator and a power spring chamber on an opposite side of the parking brake release actuator; a parking brake actuating power spring located in the power spring chamber biasing the parking brake release piston away from the rear of the spring housing; and an internal breather valve arranged to control air flow between the parking brake release chamber and the power spring chamber, wherein the internal breather valve is co-axial with a parking brake application rod connected to the parking brake release piston and is in fluid communication with a passage of the parking brake application rod extending between the parking brake release chamber and the power spring chamber.