Air operated spring brake

Claim 1

A spring operated brake actuator in combination with an air operated service brake actuator having a diaphragm movable in the presence of air pressure to actuate brakes on a vehicle, said spring operated actuator having a housing, an auxiliary diaphragm in said housing dividing the latter into a spring chamber and a fluid pressure chamber, a spring in said spring chamber acting on said auxiliary diaphragm to move the latter generally longitudinally of said housing in a brake applying direction upon a decrease in pressure in said fluid pressure chamber, said auxiliary diaphragm being movable generally longitudinally in the other direction to compress said spring in the presence of pressure in said fluid pressure chamber to allow operation of said service brake actuator independently of said spring operated actuator, a push plate in said fluid pressure chamber connected to said auxiliary diaphragm for movement with the latter, a push member extending generally longitudinally in said housing and having an end portion projecting through a wall of the latter, means connecting the other end of said push member to said plate for longitudinal movement of said push member with said plate and for universal angular displacement of said push member relative to said plate during longitudinal movement, a bearing slidably supported on said push member, and mounting means for supporting said bearing relative to said wall for universal angular displacement of said push member relative to said wall during longitudinal movement of said push member, said one end of said push member engaging the diaphragm of said service brake actuator to operate the latter in the absence of pressure in said fluid pressure chamber.