Abstract: In a disc brake of the spreading type, angular movement of the pressure plates to apply the brake is effected by a brake-applying member which co-operates with at least one of the balls comprising a rolling actuator body and located in complementary opposed recess in the two plates. The member may comprise a wedge disposed between a pair of balls and radially displaceable to separate the balls. Alternatively the balls may be received in openings in the inner ends of a pair of toggle links, or in a fitting or other member which can be withdrawn from the brake in a radial direction. In another construction a ball is received in an opening in a bell-crank lever of which one arm reacts against one of the pressure plates.

Abstract: A housing for a disc brake incorporates an expander mechanism formed by two pressure plates and, a stack of friction discs between one plate and a braking surface, and a single friction disc between the other plate and another braking surface. The one plate is formed by separate inner and outer concentric rings, and the inner ring and the other plate are slidably coupled against relative angular movement. In normal braking an annular piston works in an annular hydraulic cylinder in the other plate to urge the inner ring and the plate axially apart so that the single friction disc engages with the braking surface and the inner ring engages with a corresponding inner ring of friction lining material on the adjacent disc of the stack, thus urging the stack into engagement with the braking surface.

Abstract: In a disc brake of the sliding yoke reaction type the noise due to "squeal" or "twitter" is substantially eliminated by resiliently biassing the yoke in grooves in a stationary member so that it engages an upper face of a groove on one side of the brake and a lower face of a groove on the other side. A dampening assembly may be provided between the yoke and a complementary face of one of the grooves. Alternatively the noise may be reduced by providing an abutment of stepped outline on the yoke which engages a friction pad assembly to apply it to the disc when the brake is applied.