Abstract: An automatic adjuster for a vehicle brake actuator has a non-rotatable brake shoe-engaging tappet, an adjuster member having a threaded shank threadedly engaged with a nut, the adjuster member co-acting with the tappet so that said rotation of the adjuster member causes axial movement of the tappet. The adjuster member is drivingly coupled by a coupling member to a shaft having an external reversible thread and a spring acting between the tappet and shaft urges the tappet against the shoe. A clutch ring has an internal reversible thread whereby it engages the corresponding thread on the shaft and is resiliently urged towards a fixed clutch face. The clutch ring controls rotation of the adjuster member during brake actuation and release to adjust the retracted position of the tappet to compensate for wear of the brake shoe.

Abstract: A hydraulic actuator for a vehicle brake incorporates an automatic adjuster which includes a strut of variable length formed by members which are threadedly interengaged by way of non-reversible screw thread connection. The member is an adjuster shaft which forms a reversible screw thread connection with a drive ring arranged to control rotation of the adjuster shaft during brake application and release. The non-reversible thread is subject, during brake application, to an axial force which is the resultant of forces derived from the braking pressure applied to different areas defined respectively by a seal on the piston and a further seal on the adjuster shaft. This ensures that random rotation of the adjuster shaft during brake application is resisted without the necessity for the application of axial spring load.

Abstract: In a master cylinder assembly of the kind in which transfer chambers in pedal-operated master cylinders are connected by a transfer passage, each master cylinder has a transfer valve which is normally open and which is movable into a closed position to isolate the transfer chamber of that master cylinder from a reservoir in response to an increase in pressure in the transfer chamber when the other master cylinder is operated on its own.

Abstract: A disc brake assembly includes one or more rotatable friction discs which are slidably keyed to a second portion of a two part shaft assembly and the second portion surrounds and is rotatable relative to the first portion which transmits drive directly to a wheel and drives the second portion through a reduction gear train so that the second portion can rotate at a greater speed than the first.