Parking Brake Chamber Internal Breathing System

A parking brake release actuator, comprising:

• a flexible diaphragm configured to divide a parking brake actuator chamber of a spring brake actuator into two chambers;
• a piston member affixed to the flexible diaphragm;
• and
• an internal breather valve arranged to control air flow between opposite sides of the piston member.

A vehicle brake assembly, comprising:

• a brake, wherein the brake includes one of a disc brake and a drum brake;
• and
• a spring brake actuator coupled to the brake to apply a brake actuation force, the spring brake actuator including
• 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 actuator 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.

A vehicle axle assembly, comprising:

• a vehicle axle;
• a brake coupled to the vehicle axle, wherein the brake includes one of a disc brake and a drum brake;
• and
• a spring brake actuator coupled to the brake to apply a brake actuation force, the spring brake actuator including
• 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.

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 means located within the parking brake actuator chamber for releasing a parking brake function of the spring brake actuator;
• a parking brake actuating means located in the power spring chamber for biasing the parking brake release means in a parking brake application direction;
• and
• an internal breather means arranged to control air flow between the parking brake release chamber and the power spring chamber.

A method of operating an spring brake actuator, comprising the acts of:

• admitting pressurized fluid into a parking brake actuator chamber of the spring brake actuator to cause a parking brake release piston to compress a power spring;
• and
• releasing the pressurized fluid,
• wherein when a pressure of the pressurized fluid decreases to a predetermined level a flow control device permits a portion of the pressurized fluid to pass from the parking brake actuator chamber into a chamber containing the power spring.