Abstract: A fluid-operated brake actuator having a check valve in the spring chamber to equalize the pressure on opposite sides of an operating movable diaphragm. The brake actuator comprises a service brake housing divided into first and second service chambers by a diaphragm or piston, and a spring brake housing arranged in tandem with and attached to the service brake housing, also divided into a first and second spring chambers by a diaphragm or piston. The check valve connecting the first and second spring chambers blocks flow between the first and second chambers when the second spring brake chamber is pressurized and opens up flow between the two chambers when the second spring chamber is depressurized.

Abstract: A vehicle suspension adjustment mechanism comprises pairs of plates having mutually complementary annular ribs and grooves for mutual interengagement to facilitate rotation of the pairs of plates with respect to each other. One of the pair has an enlarged semicircular aperture and the other of the pair has a smaller circular aperture of the same diameter as the trailing arm pivot bolt. The alignment position of the trailing arm relative to the vehicle frame is adjusted by rotating one of the plates relative to another of the plates.