Abstract: A self-energizing disc brake of the spreading type is disclosed. In the disc brake rotatable friction discs provided on opposite sides with linings are adapted to be brought into engagement with radial braking surfaces in a housing by an actuator assembly. The actuator assembly comprises pressure plates located between the discs and centered by pilot lugs, and balls located in oppositely inclined recesses in the adjacent faces of the pressure plates. At least the linings which engage with the pressure plates are separated into annular rings by an annular groove, and the groove is substantially coincident with a pitch circle of constant diameter upon which the recesses lie in an angularly spaced relationship. The groove increases the degree of cooling in the regions of the base of the recesses, thereby reducing the likelihood of hot spotting occurring in such regions.

Abstract: An hydraulic actuator comprising a pair of oppositely acting hydraulic pistons working in a bore incorporates an automatic slack adjuster assembly which is housed in aligned bores in the pistons and acts as a strut to determine the relative retracted positions of the pistons. The adjuster assembly comprises a clamp member movable with the piston, and an adjuster member, the members including interengaging parts which co-operate with each other to form a releasable detent, in combination with a spring ring for biassing the interengaging parts into engagement, and the piston and the clamp member are provided with interengaging inclined faces to provide a wedge action and enhance the engagement of the interengaging parts when the bore is pressurized, and a stop loaded by a spring is provided in the bore with which the adjuster member is adapted to co-operate when movement of that member in a brake-applying direction exceeds a distance sufficient to take up the braking clearances.

Abstract: In a master cylinder assembly comprising two pedal-operated master cylinders, each master cylinder comprises a pedal-operated piston of stepped outline working in a complementary stepped bore in a housing and having an inner end of smaller area carrying a first seal and an outer end of greater area carrying a second seal, a pressure space in the bore in advance of the inner end of the piston, a quick-fill chamber defined in the bore between the inner and outer ends of the piston, a normally-open recuperation valve providing communication between a reservoir for fluid and the pressure space at least when the piston is in a retracted position, and a normally-closed pressure-limiting valve assembly between the quick-fill chamber and the same or a second reservoir.

Abstract: In a disc brake the application of the brake is initiated by angular movement of at least one pressure plate with respect to a reaction member to cause the pressure plate to move axially into engagement with a friction disc which, in turn, is urged into engagement with a surface in a stationary housing. The angular movement is effected hydraulically by an actuator comprising a piston working in a bore of a cylinder, the axis of which is substantially at right angles to that of the brake. The piston acts through a part-spherical rocking thrust coupling associated with a pull-rod passing through the actuator with a substantial clearance, the inner end of the pull-rod being pivotally coupled to a lug on the pressure plate, and the outer end being adapted for connection to a hand lever by which the pull-rod can be moved in a brake-applying direction.