Spring brake actuator with diaphragm retainer

A brake actuator assembly comprising:

• a pressure plate presenting an opening that extends through the pressure plate from a first end of the pressure plate to a second end of the pressure plate;
• a push rod that is coupled to the pressure plate, wherein the push rod extends through the opening in the pressure plate from the first end of the pressure plate to the second end of the pressure plate, wherein the push rod comprises an outer surface and at least one protrusion extending outward from the outer surface;
• a diaphragm that is coupled to the pressure plate;
• and
• a retainer that engages the protrusion, wherein at least a portion of the diaphragm is positioned between the pressure plate and the retainer.

A brake actuator assembly comprising:

• a housing;
• a pressure plate presenting an opening;
• a push rod that is coupled to the pressure plate, wherein the push rod comprises an outer surface and at least one protrusion extending outward from the outer surface, wherein the push rod comprises an interior surface surrounding a passageway;
• a diaphragm that is coupled to the pressure plate, the diaphragm and pressure plate dividing the housing into a spring chamber and a pressure chamber;
• a retainer that engages the protrusion, wherein at least a portion of the diaphragm is positioned between the pressure plate and the retainer;
• and
• a valve assembly that is coupled to the push rod, the valve assembly comprising a seal that is biased to a closed position with a biasing force, wherein the seal is operable to move to an open position when a force exerted on the seal due to a pressure in the spring chamber exceeds the biasing force, wherein the valve assembly is operable to exhaust air from the spring chamber and the passageway when the seal is in the open position, and wherein the valve assembly blocks air from entering the spring chamber through the passageway when the seal is in the closed position.