Abstract: An improved diaphragm-type pneumatic brake actuator includes a flange case, a cover cooperable with the flange case, a flexible diaphragm extending between the flange case and the cover forming a lower pneumatic chamber and an upper pneumatic chamber on opposed sides of the diaphragm. A piston assembly is disposed in the cover for moving a spring between compressed and decompressed positions. A spring guide is disposed between the cover and the piston assembly in the upper chamber. The spring guide prevents direct contact of the spring with the cover to prevent formation of a corrosion cell.

Abstract: An improved diaphragm-type pneumatic brake actuator includes a flange case, a cover cooperable with the flange case, a flexible diaphragm extending between the flange case and the cover forming a lower pneumatic chamber and an upper pneumatic chamber on opposed sides of the diaphragm. A piston assembly is disposed in the cover for moving a spring between compressed and decompressed positions. A spring guide is disposed between the cover and the piston assembly in the upper chamber. The spring guide prevents direct contact of the spring with the cover to prevent formation of a corrosion cell.

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.