Abstract: In order to safely and conveniently assemble and service new design spring brake actuators having power springs located in the middle of the actuator, the actuator's rear chamber cover must be able to withstand high localized forces from tools such as power spring compression rods. A reinforcement and method for its installation is provided, in which a plurality of reinforcement plates is stacked on the rear chamber cover about a tool-insertion aperture, and the outermost plate is crimped about the aperture, thereby securing the plates to the rear chamber cover in a cost- and time-efficient manner. Preferably, the lip of the rear chamber cover aperture is stamped when the cover is formed such that the lip protrudes axially outward to help assure that the lip is captured between the crimped reinforcing plate on one side and the remaining reinforcing plates on the other side.

Abstract: A power spring arrangement of a spring-type brake actuator for a vehicle brake, in which the actuator's power spring is located between the service brake actuator and parking brake release actuator, and the power spring comprises a plurality of concentric springs. The power spring is captured between the actuator's intermediate flange and a spring retainer. The use of two or more concentric springs allows higher parking brake actuator force to be generated than with a standard single power spring, without the need to enlarge the actuator housing or to use more costly spring materials or spring configurations.

Abstract: A pressure-energized seal for a spring-type brake actuator for a vehicle brake, in which the actuator's power spring is located between the service brake actuator and parking brake release actuator. The power spring is captured between the actuator's intermediate flange and a spring retainer. In order to prevent pressure leakage past the spring retainer into a power spring cavity, a pressure-energized seal is located between the plate and the housing. The seal member, which is carried by the spring plate or the housing, has a pressure-receiving section with resilient outer portions, which are deflected by pressure in the service chamber into firm contact with the spring plate and the actuator housing interior wall, increasing the sealing force between the seal and both the plate and the housing. The pressure-energized seal provides improved seal performance with a seal which is easy to inspect and/or replace, highly reliable, and relatively inexpensive.