Abstract: A suspension unit comprises a cylinder, a diaphragm within the cylinder forming an end wall a pressure space in the cylinder filled with a mixture of fixed masses of gas and liquid and a damping piston working in the pressure space with a piston rod extending sealingly through one end of the cylinder. The position of the diaphragm is variable to adjust the pressure in the pressure space.

Abstract: In an hydraulically operated disc brake a stop is incorporated for determining the retracted position of the piston, the stop being movable towards the disc to compensate for wear of the friction pads and also acting as an anti knock-back device. The stop comprises a plate having an aperture through which a pin projects, the pin being fixed to the cylinder or to a second piston in the cylinder. An abutment member provides an abutment for the plate, and a first spring acts between the abutment member and the plate so as to urge the plate into a locked tilting position inclined with respect to the pin. A second spring acts on the abutment member to urge it in a direction away from the pad assembly.

Abstract: In a control valve assembly for a vehicle hydraulic braking system a differential piston works in a stepped bore in the housing of the valve and is exposed at its end of greater area to an inlet port and at its end of smaller area to a chamber in the valve, the inlet port communicating at all times with the chamber through a restricted passage in the piston, and the chamber communicating with a further chamber in which a valve is located at least when the valve is in a first position in which the inlet port is in communication through the chambers with an outlet port for connection to the wheel brake.

Abstract: In a pressure reducer valve assembly for a vehicle braking system a valve member co-operates with a valve seat of which opposite sides communicate with an inlet connected to a master cylinder and an outlet for connection to a brake, a pressure responsive member controls the position of the valve member in opposition to a spring urging the valve member away from its seat and the position of an abutment member for the spring is controlled in response to a difference in the pressures in two pressure spaces of a master cylinder which supply independent braking circuits.

Abstract: A pressure control assembly comprises a control valve set for controlling communication between an inlet and an outlet, a control spring acting in a sense to resist closure of the valve set and a device for varying the control force of the control spring acting on the valve set. The device for varying the control force may comprise a differential pressure responsive member which moves in response to a differential pressure to move an abutment engaging the spring between normal and actuated positions to compress or expand the spring and thus vary its force.

Abstract: In an hydraulically operated disc brake one of a pair of guide pegs for a caliper works in an inner elongated bore in a resilient bush with same play in a transverse direction the bush being located in a bore of one of a pair of guide members, the play between said peg and bush accommodating changes in the circumferential spacing of the guide members or guide pegs due to distortion of a stationary, drag-taking part of the brake.

Abstract: The present specification describes and claims a friction pad assembly for use in a sliding caliper disc brake and a sliding caliper disc brake incorporating such an assembly. The friction pad assembly comprises a backing plate, a pad of friction material secured to the backing plate, and a leaf spring, a central clip portion and two oppositely directed arms forming said leaf spring, the leaf spring being attached to the backing plate by means of said central clip portion. When the assembly is incorporated in a sliding caliper disc brake which comprises a torque member and a caliper member, the leaf spring engages the caliper member both pressing the friction pad assembly down onto guides in the torque member and biassing the torque member and caliper member apart to take up any clearance. Thus the possibility of the assembly rattling in the brake and the torque member and caliper member rattling together, is reduced.

Abstract: A sliding caliper disc brake has a caliper member slidably mounted on a fixed torque-taking member and carrying an actuator which urges a friction pad onto one side of a rotating disc whereupon the caliper member slides on the torque member and applies an opposite pad to the other side of the disc. Both pads are carried by the torque member so that circumferential drag forces experienced by the pads when they are clamped against the rotating disc are transferred directly to the torque member. The sliding connection is provided by a pin secured to one of the members and slidable in a bore in the other of the members.

Abstract: A disc brake comprises a fluid pressure-operated actuator for urging two pressure plates carrying friction pads to opposite faces of a disc. In the actuator a piston movable in a housing is detachably engaged with a draw-bar which acts on one of the pressure plates, the housing acting directly on the second pressure plate. A seal between the housing and the draw-bar contacts an enlarged portion of the draw-bar. Apparatus is provided to prevent the draw-bar from rotating.

Abstract: In a disc brake of the sliding yoke reaction type a friction pad assembly adapted to be applied directly to a rotatable disc by actuating means is provided at opposite ends with lugs which engage over spaced arms in a stationary member so that, when the brake is applied, the drag on the pad assembly is taken by the arm at the end of the brake with which any point on the disc first comes into alignment for a given direction of disc rotation.

Abstract: A rotatable braking member, for example a disc or a drum, for a vehicle brake is provided with a separate plurality of spaced cooling fins having a co-efficient of thermal conductivity higher than that of the braking member to dissipate heat to a flowable working medium within passages between adjacent fins, and at least some of the passages are substantially uninterrupted circumferentially with respect to the direction of rotation of the braking member.

Abstract: A sliding caliper disc brake has a caliper member which applies friction elements to opposite sides of a rotatable disc and which is slidably mounted on a fixed torque-taking member by a single pin disposed at one side of the caliper. The other side of the caliper is urged into sliding engagement with the torque member by a spring arranged between the caliper and a projection on the torque member. The caliper carries a lug which is normally spaced from the projection but is engageable with the projection to limit outward pivoting of the caliper about the pin in the event of failure of the spring. The caliper lug may engage the spring so as to slide the spring on the projection upon sliding of the caliper so as to maintain spring orientation as the friction elements wear.

Abstract: In a brake actuator an electric motor is operable when energized to hold a resilient brake applying assembly in a retracted energy-storing position and to retain the assembly in the retracted position.

Abstract: In an anti-skid hydraulic braking system for a vehicle a master cylinder supplying fluid under pressure to apply a brake includes an operating piston and a boost piston both working in a common bore with a boost chamber defined in the bore between adjacent ends of the piston. A boost control valve is provided between the pistons and is movable between a normally open inoperative position in which the boost chamber is in communication with return and outlet ports in the cylinder and an operative closed position when the master cylinder is operated in which the boost chamber is isolated from the return and outlet ports so that pressure in the boost chamber is increased to advance the boost piston in the bore to pressurize liquid in a pressure space.

Abstract: A brake comprises a friction pad carried by a support and engageable with a braking surface of a rotor. An adjusting device moves the friction pad relative to the support to compensate for wear of the friction material. The adjusting device comprises a screw extending parallel with the direction of movement of the friction pad and a thrust member in screw threaded engagement with the screw member and engaging the friction pad. The thrust member transmits braking forces from the screw member to the friction pad and can rock into force-transmitting engagement with the support under the action of the braking and reaction forces.

Abstract: In a disc brake a thrust transmitting device is interposed between a friction pad assembly and a piston for applying the friction pad assembly to a rotatable disc. The device comprises a shim of which a part is cut-out over a portion of what would otherwise be the area of contact between the piston and the friction pad assembly so that thrust is applied to the friction pad assembly only over the remainder of that area, and the device includes a projection defining a stop to prevent insertion of the shim into the brake with the pad assembly in position, the axial length of the thrust transmitting device being less than the thickness of the pad assembly minus the wear thickness thereof.

Abstract: A valve assembly for use in a vehicle braking system comprises two valves having respective inlets for connection to separate wheel brakes. Each valve has a plunger carrying one part of a valve set which co-operates with a stationary part of the valve set to control communication between the inlet and outlet, and a spring urging the plunger in a direction to maintain the valve set open. Each plunger has opposed piston portions of different dimensions subjected to the pressure at the inlet of the associated valve to produce a net force tending to close the valve, and a further portion subjected to the inlet pressure of the other valve to produce an additional force which is removed upon failure of that inlet pressure of the other valve.

Abstract: An hydraulic reservoir for a dual circuit braking system of the kind comprising a container divided into two chambers by a partition provided with a hole at an intermediate height, and a fluid level sensor located in one chamber, in which the chambers are sealed from each other in use apart from the hole in the partition, and one of the chambers is sealed against atmosphere by sealing means which can be released to allow leveling of the fluid during filling.

Abstract: In an internal shoe-drum brake of the duo-servo type a strut assembly with which non-actuated shoe ends engage is slidably guided in an open-ended through bore in a fixed housing and the length of the strut assembly is substantially greater than the maximum transverse dimension thereof.

Abstract: A brake pressure failure warning circuit for a multi-line brake system includes a plurality of pressure switches sensitive to the fluid pressure in the respective lines and each actuable when the pressure in the associated line reaches a predetermined value, a detecting circuit connected to the switches and arranged to produce an output signal when any of the switches are actuated, a muting circuit arranged to prevent the detecting circuit's producing an output signal when all of the switches are actuated and warning means operable by said output signal.