Disc brakes for vehicles

A disc brake comprising a housing incorporating rotatable friction discs, opposed radial surfaces, pressure plates located between said friction discs and balls located in co-operating oppositely inclined recesses in adjacent faces of said pressure plates, and an actuator assembly of which the axis is substantially at right angles to the axis of the brake, said actuator comprising a first component fixed relative to said housing, and a second movable component movable with respect to said component, said actuator assembly hydraulically initiating application of the brake by effecting angular movement of said pressure plates in opposite directions whereby said pressure plates move apart into engagement with said friction discs which are urged into engagement with said radial surfaces in said housing, one of said pressure plates being provided with a lug which engages with a stop abutment to arrest said one pressure plate, whereby continued angular movement of the other of said pressure plates provides a servo action, said actuator assembly incorporating a part-spherical rocking thrust coupling through which said movable component acts, and a pull-rod passing through said actuator assembly with a substantial clearance and with which said coupling co-operates, and a thrust member disposed between said movable component and said spherical rocking coupling, the inner end of said pull-rod being pivotally connected to the junction of a pair of toggle links connected between lugs on said pressure plates and the outer end of said pull-rod being extended for connection through a specifically defined point to a transmission member, and said thrust member being engageable with a thrust transmitting force on said movable component for sliding motion in a transverse direction with respect to the axis of said actuator assembly to accommodate angular movement of said pull-rod when the brake is applied.