Abstract: A power assisted pedal assembly comprises a brake pedal pivotally connected at one end to a lever which is pivotal about a fixed point, the brake pedal having a connection intermediate its ends with an actuating member of a master cylinder to apply an operating force to the actuating member, and a power assistor operable in response to movement of the brake pedal to apply an assisting force to the brake pedal. The power assistor has a force-transmitting member which is separate from the actuating member and which is in force-transmitting engagement with the lever on or close to the line of action of the force applied to the actuating member by the brake pedal. The brake pedal and the lever pivot about the fixed point when the power assistor is operative and the pedal pivots about a point intermediate the fixed point and the connection between the lever and the actuating member upon failure of the power assistor.

Abstract: In a control valve assembly of the kind set forth for vehicle braking systesm a valve-operating member for operating first and second valves is guided to slide in a bore in a piston. The valve-operating member is adapted to permit the second valve to close and the first valve subsequently to open when the first piston is returned to an inoperative retracted position in response to the pressure of fluid remaining the pressure space when the applying force is relieved, the pressure space being defined between the first piston and a second piston.

Abstract: In an internal shoe-drum brake of the duo-servo type for vehicles adjacent shoe ends are separated by an angularly movable cam. The cam is moved angularly by a separate cam lever to which it is coupled, and the cam is permitted a circumferential movement both with the shoe ends and relative to the lever in the application of the brake.

Abstract: In a master cylinder assembly a booster valve assembly is adapted to control two separate supplies of booster fluid, and each supply is capable of advancing a modulator piston independently to operate a master cylinder.

Abstract: In a disc for a disc brake a clamping assembly having a certain amount of resilience holds two identical braking portions in engagement with a central plate, and a coupling device is provided for transmitting torque from the braking portions to the central plate and for maintaining the braking portions concentric with the plate.

Abstract: A welding apparatus for welding together arcuate components, for example a platform and web of a brake shoe comprises a pair of opposed clamping members which are relatively movable to engage the web, one on each side thereof, over a substantial portion of the web surface area. The clamping members are continuously rotated by suitable drive arrangement. Preferably, two such pairs of clamping members are provided for clamping respective webs.

Abstract: In a wedge type actuator assembly in which the cage assembly in which the rollers are captive is not captive to the wedge member, an aperture in the housing through which the cage assembly is inserted during assembly of the actuator is shaped to allow insertion of the cage assembly only when it is correctly orientated with respect to the housing. A washer provided with a shaped aperture to receive the wedge member is keyed against rotation in a circular aperture in the housing and the washer ensures that the wedge member cannot be inserted into the housing when it is misorientated by 90.degree. about its axis of movement.

Abstract: In a railway disc brake, a plurality of arcuate elements or segments of a braking ring are attached to the rotor so that each element or segment can thermally expand and contract relative to the rotor, and pairs of circumferentially spaced locating abutments are provided for preventing radial inward and outward movement of the element or segment relative to the rotor at predetermined locations which are selected so that when the element undergoes thermal expansion or contraction with respect to the rotor there is no movement of the element into or out of engagement with the abutments. The abutments may take the form of radial projections on the element or segment or rotor, which projections are urged into engagement with a groove in the rotor or disc element, respectively by further abutments, such as in the form of camming wedges or springs. Alternatively the abutments may be lateral projections on the rotor which are a sliding fit in elongated grooves in the element or segment.

Abstract: In an actuator assembly for a vehicle brake a follower member normally operated by a wedge to apply a brake comprises a pair of hydraulic pistons working in a common bore in a housing, and the housing is provided with a supply port communicating with a pressure space defined between the adjacent ends of the pistons which abut when the wedge is displaced, and with an abutment face with which the innermost piston is engageable when the wedge is in its retracted position and the pressure space is pressurized.

Abstract: In a vehicle brake applying assembly a compression spring acts between reatively movable parts normally to urge the parts into an advanced position to maintain a desired braking clearance. After the braking clearance has been taken up the parts are relatively movable into a retracted position against the force in the spring to permit abutment surfaces to engage whereafter a positive brake applying force can be transmitted through the parts.

Abstract: In a dual hydraulic master cylinder assembly both pressure spaces are connected by a transfer passage incorporating a transfer valve which is open when both master cylinders are operated simultaneously, and the transfer valve comprises an unsprung valve member for engagement with one of a pair of spaced valve seatings to cut-off communication between the pressure spaces when one master cylinder is operated on its own.

Abstract: In a spreading disc brake relative angular movement of the pressure plates to initiate the application of the brake is effected by a fluid pressure actuator acting on a pull-rod through a pivotal thrust coupling so arranged as to confine rocking movement of the pull-rod to a single plane normal to the brake axis.

Abstract: In a tandem master cylinder main and secondary pistons are interconnected by a rigid sleeve. One end of the sleeve is secured to one of the pistons, and an inwardly projecting lip or flange on the other end of the sleeve provides an abutment for a head on an axial stem extending from the other piston towards the said one piston. The head is axially slidable in the sleeve and is introduced into it through an opening in the wall of the sleeve, which opening is connected by a longitudinal slot to the end of the sleeve which is provided with the lip or flange.

Abstract: In a disc brake of slidable-caliper reaction type of the caliper is located in a gap between spaced arms in a stationary member, and a resilient blade spring acts between one end of the caliper and one of the arms. The blade spring is interposed between the caliper and a key engaging with the stationary member, and the blade spring is provided with spaced tags which engage with opposite ends of the one arm to prevent the key from moving with respect to the stationary member.

Abstract: A vehicle disc brake of the sliding caliper reaction type including a caliper slidably mounted on a carrier wherein the carrier incorporates spaced arms extending axially in a direction away from the plane of the disc and providing spaced parallel guides with which complementary axially extending guides on the caliper co-operate slidably, and a slipper is located between the guides of at least one co-operating pair.

Abstract: An automatic slack adjuster for a vehicle brake is disposed between a piston and another component, such as a counter piston, of a hydraulic actuator. The adjuster mechanism is housed in an encapsulating container which is positively attached to the piston. A strut, on which an auxiliary mechanical actuator fitted to said other component acts, is in screw-threaded connection with a nut of the adjuster mechanism. The adjuster mechanism is of the incremental type and is adapted to turn the nut responsively to excess axial travel between the container and the strut upon hydraulic brake application, the strut being sealed to said other actuator component. Grossly excessive travel between the piston and the other actuator component beyond the maximum possible travel between the strut and the container is permitted by displacement of the strut relative to said other component.

Abstract: In a pneumatically-operable actuator assembly for a vehicle hydraulic braking system a control valve assembly comprises a first valve responsive to a signal of deceleration for controlling communication between an inlet passage for connection to a supply of air under pressure and a modulator chamber through a supply chamber, and a second valve downstream of the first valve for controlling communication between the modulator chamber and an exhaust passage and responsive to pressure in the supply chamber, the first valve being substantially smaller than the second valve whereby the pressure in the modulator chamber can be reduced rapidly in response to a relatively small reduction in the pressure in the supply chamber.

Abstract: In a wedge actuator the inner end face of one tappet which co-operates with the wedge member is made normal to the axis of movement of that tappet, and the line of action of the wedge member is inclined to the plane of that end face.

Abstract: In a vehicle hydraulic braking system the supply of fluid from an hydraulic master cylinder to the slave cylinder of a wheel brake is controlled by an actuator assembly which includes a modulator assembly for controlling the supply to the slave cylinder in accordance with the deceleration of a wheel operated by the slave cylinder, and both the master cylinder and the actuator assembly are actuated in response to separate supplies of the same fluid pressure medium.

Abstract: In an hydraulically-operated braking system for vehicles a supply of hydraulic fluid under pressure from a pump is utilized for applying a wheel brake, and the pump is responsive to rotation of the braked wheel so that the brake applying force is dependent upon the speed of rotation of the wheel and the wheel is automatically prevented from locking, and the system incorporates an hydraulic accumulator adapted to define a reservoir of high pressure for providing an instantaneous supply of high pressure fluid to apply the brake.This invention relates to improvements in hydraulically-operated braking systems for vehicles of the kind in which at least one brake is adapted to be applied in response to a supply of hydraulic fluid under pressure from a pump, and the pump is responsive to rotation of a wheel so that a brake applying force is dependent upon the speed of rotation of the wheel and the wheel is automatically prevented from locking.