Abstract: A brake actuator has a force applying device actuated by a rotary actuator shaft and arranged to separate opposed tappets to actuate braking elements. Each tappet includes a pair of threadedly engaged members which are relatively rotatable to enable the length of each tappet to be adjusted. An adjuster control device is operable to vary the length of one of the tappets and a transmission device interconnects the tappets to effect a corresponding variation in length of the other tappet. The transmission device, a ring gear, lies within the actuator housing at a location adjacent the axially inner end of the force applying device and cooperates with both tappets to transmit adjusting movement of one tappet to the other.

Abstract: The present specification discloses a disc brake for use on a commercial vehicle. The disc brake has a brake actuation mechanism which is movable axially by brake operator mounted in a part of the disc brake. The brake operator has an axis of actuation which extends in the same general direction as the axis along which the brake actuator moves to apply the brake. This construction leads to a compact overall design wherein the brake operator is part of the brake itself.

Abstract: An automatic brake adjuster has a strut composed of two parts between which there is a non-reversible threaded connection, relative rotation between the parts to vary the strut length being controlled by a clutch ring urged by a spring into clutching engagement with the housing. In order to prevent unwanted de-adjustment, the clutch ring forms a uni-directional locking connection with a housing by means of ratchet teeth on the external periphery of the ring and a pawl mounted in the housing.

Abstract: The present invention relates to disc brakes suitable for use on commercial vehicles, the disc brake incorporating a parking brake facility in addition to a service brake facility. The disc brake of the present invention comprises a housing within which a brake actuator is arranged, the parking brake facility being operable by a lever connected to a cam member which is eccentrically supported on a pivot pin carried by the housing. The cam member is arranged to act on the brake actuator arrangement as the lever is moved, the lever projecting laterally of the cam member, near to the axial mid region of the cam member.

Abstract: A wedge and roller actuator, primarily for a vehicle drum brake, has a wedge disposed between opposed tappets with interposed thrust-transmitting rollers. Inwardly directed thrust arising on one of the tappets is transmitted to a fixed surface of the actuator housing either by additional rollers or by one of the rollers. In the latter case, the surface of the housing reacting the inwardly directed force is inclined to the longitudinal axis of the wedge in the opposite direction to the opposed wedge surface.

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: An automatic adjuster includes a two part strut interconnected by a non-reversible thread so that extension of the strut under the influence of an adjuster device is effected by relative rotation between the two parts. The adjuster device includes a spigot, rotation of which is controlled by a clutch member as a result of a cooperation between helical teeth respectively on the strut part and spigot and also uni-directionally couples the spigot to a fixed member so that in the event of temporary clutch disengagement due to vibration, rotation of the spigot in the de-adjusting direction is prevented by rotation thereof is the adjusting direction is permitted when required.

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 and servo booster assembly for a vehicle braking system a mounting plate is connected to the rear end of a vacuum operated servo booster. A tubular extension integral with the mounting plate extends sealably through the movable wall of the booster substantially to relieve the booster housing of braking reaction forces. Circumferentially spaced axially extending slots divide the extension into axially extending arms which are secured to the master cylinder housing at their free ends by the engagement of a radially extending projection on the end of each arm with an annular recess in the outer surface of the rear end of the master cylinder housing. A sleeve integral with the front shell of the booster housing encircles the ends of the arms and holds the arm ends in interlocking engagement with the master cylinder housing. Alternatively, projections on the master cylinder housing and recesses on the ends of the arms may be provided to secure the arms to the master cylinder housing.

Abstract: A mechanical brake actuator has rotatable and non-rotatable cam components provided with confronting helical grooves between which ball bearings are arranged to form a helical thrust bearing. A push rod, connecting rod or the like acts generally tangentially on a lever arm on the rotatable cam component for turning the latter. The lateral reaction arising from the lateral force due to the push rod is transferred from the rotatable cam component to the non-rotatable cam component by the helical thrust bearing, thereby avoiding the need to provide a separate journal bearing for the rotatable cam component. The rotatable cam component acts on a tappet member via an axial thrust bearing and an automatic adjuster mechanism.

Abstract: In a servo booster the movable wall is sealed to the rear housing wall by a rolling diaphragm supported on a sleeve which projects forwardly from the rear housing wall, and fluid communication between the rear housing chamber of the booster and a valve chamber in the valve body is provided by inter-communicating passages in the valve body and diaphragm support plate. The passage in the diaphragm support plate terminates in a port opening to the rear booster chamber. In one construction the sleeve is elliptical in transverse cross-section and a pair of tie rods extend right through the booster, through the bore of the sleeve, for relieving the booster housing of braking reaction forces. In another construction, instead of tie rods, the sleeve is extended to provide a tube, arms extend through slots in the tube to connect integrally the diaphragm support plate and the valve body, and one arm contains the passage.

Abstract: A vehicle drum brake has a shoe mounted on a back plate, one end of the shoe engaging an actuator and the other end engaging an abutment. To avoid the use of a fluid pressure control valve to vary the braking effort of the brake in dependence upon vehicle loading, the abutment is in the form of a roller which engages an arcuate member on the shoe, the roller being movable laterally of the shoe to vary the braking effort for a given actuating force. The roller may be connected to a pivoted lever which is rotatably mounted in the back plate and which is connected to a sprung part of the vehicle by a linkage. Movement of the sprung part due to changes in vehicle loading rotates the lever and moves the roller.

Abstract: In a vehicle disc brake a pair of friction pad assemblies are adapted to be applied simultaneously to the respective inboard and outboard faces of each of a pair of relatively fixed, axially spaced, rotatable discs by an actuator assembly. The actuator assembly comprises a pair of first and second rigid clamp assemblies which are relatively movable axially, and an actuator acting between the two clamp assemblies. The clamp assembly is arranged to apply the friction pad assemblies to the inboard faces of the discs and the clamp assembly is arranged to apply the friction pad assemblies to the outboard faces of the discs.

Abstract: In a control valve assembly for vehicle hydraulic braking systems pressurization of a distributor chamber in a housing is controlled by a valve operating mechanism. The valve operating mechanism comprises a piston working in the distributor chamber, a recuperation port in the wall of the housing for connection to a reservoir for fluid and communicating with the chamber on one side of the piston, an axial bore through the piston providing communication between the recuperation port and an inlet passage for connection to a source of high pressure fluid, an axially movable valve member for alternate engagement with first and second axially spaced seatings, the first seating comprising a seating surrounding the opening in the piston and the second seating leading to the inlet passage, and a spring for urging the valve member normally into engagement with the second seating with the valve member spaced from the first seating.

Abstract: In a control valve assembly for a vehicle dual hydraulic braking system separate brake-applying valves in a common body are operable independently or simultaneously to cause hydraulic fluid from a distributor chamber to be supplied to one or both of a pair of outlets for connection to brakes on wheels on opposite sides of the vehicle. Each brake-applying valve comprises a valve member which is urged into engagement with a seating surrounding a respective outlet by means of a spring. An operating member for moving the valve member away from the seating in a brake applying direction is coupled to a respective brake pedal, and the operating member is also coupled to the valve member through a lost-motion connection.

Abstract: A control valve assembly for a vehicle dual hydraulic braking system in which hydraulic fluid from a distributor chamber can be supplied to one or both of a pair of outlets for connection to brakes on opposite sides of a vehicle. The assembly incorporates a pressure control valve operable to supply fluid under pressure to the chamber from an outlet for connection to a pressure source, irrespective of whether one or both of two separate brake-applying valves are to be operated, and a one-way valve is located on the upstream side of the pressure control valve to prevent flow in a reverse direction. A back-up piston works in a bore in communication with the chamber, and is provided to pressurize fluid in the chamber after an exhaust valve has closed and a pressure control valve has opened.

Abstract: A control valve assembly for vehicle dual hydraulic braking systems is operated by a lever mechanism. The lever mechanism comprises first and second levers which are pivotally connected to each other by a first pivot. One lever acts on a valve mechanism for controlling pressurization of a distributor chamber, and the other lever is pivotally connected to a housing through a second pivot. Each lever acts on a respective one of a pair of brake-applying valves for controlling the supply of pressure fluid in the chamber to an outlet in the housing for connection to a wheel brake.

Abstract: In a rotor for vehicle brakes, for example, discs for disc brakes and drums for shoe-drum brakes, the braking member is carried from one side of a driving component for connection to a wheel or shaft. The outer face of the member remote from the driving component comprises a braking surface which can be engaged by at least one friction member. The braking member comprises an annulus, and the driving component a cast mounting which is formed with a discontinuous abutment face with which the braking member is in direct intimate contact over a substantial area. Clamping members additional to and separate from the annulus and the mounting are provided for clamping the annulus against the abutment face to maintain the intimate contact between them.