Abstract: An improved diaphragm-type pneumatic brake actuator wherein the diaphragm is releasably secured to the piston as the diaphragm is inverted during actuation of the braking system of a vehicle thereby reducing wear of the flexible diaphragm and improving the performance of the brake actuator. In the disclosed embodiment, a rib or lip is formed on the surface of the diaphragm which receives the periphery of the piston as the diaphragm is inverted forming a mechanical interlock between the diaphragm and the piston thereby preventing spacing of the contact surface of the piston and the central portion of the diaphragm and frictional wear between the peripheral edge of the piston and the diaphragm.

Abstract: The present invention provides a brake actuator assembly including a housing having a generally radial annular flange portion and a cover having a generally radial annular flange portion generally co-axially aligned with the generally radial annular flange portion of the housing. A cup-shaped flexible diaphragm having an outer radial annular rim portion is disposed between the generally radial annular flange portions of the housing and the cover. A retaining element generally surrounds and compresses the generally radial annular flange portions of the housing and the cover against the rim portion of the flexible diaphragm. The rim portion of the diaphragm includes a wedge-shaped edge portion and co-axially aligned flats on opposite sides of the rim portion adjacent to the wedge-shaped edge portion aligning the flange portions of the housing and the cover. In another embodiment, a flexible brake diaphragm includes a cup-shaped flexible diaphragm having an outer radial annular rim portion.

Abstract: Brake actuators are provided with self-centering diaphragms. In one embodiment, the diaphragm is provided with a centering bead radially outwardly of a sealing bead. The centering bead ensures the diaphragm is properly centered prior to the brake actuator housings being secured together. In a second embodiment, the self-centering structure includes structure fit into mating structure in one of the brake actuator housings to ensure the diaphragm is properly centered. The self-centering structure ensures the brake actuator diaphragms are properly centered before connection of the two brake actuator housings. This invention is particularly useful in the type of brake actuator housings having deformed housing portions.