Abstract: An internal shoe drum brake comprises a pair of brake shoes, an adjustable length strut extending between the shoes and having a ratchet movement of which adjusts the length of the strut, an actuating lever pivotally connected to one end of the strut and engaging one shoe, the lever being so arranged that a force acting on one end in a direction generally parallel to the drum axis rotates the lever to exert a force on one shoe and a reaction force through the intermediary of the strut on the other shoe to urge said shoes apart, and a pawl engageable with the ratchet. To reduce the number of parts the pawl is pivotally mounted on the other shoe and is rotatable about its pivot to move the ratchet and thereby adjust the length of the strut when there is excess wear of the shoes. Furthermore, the strut preferably has a portion which is engageable with a surface portion of the brake back plate, or a member secured to the back plate, to react forces to the back plate.

Abstract: In order to reduce the distortion of a servo booster housing in use the booster is provided with one or more force transmitting means which extend through the movable wall for transmitting reaction forces directly from the master cylinder housing to the vehicle bulkhead between which the booster is mounted. This enables a housing of lighter weight to be employed, and an overall saving in weight may be achieved.

Abstract: An anti-skid brake conrol system includes a sensor which produces a signal proportional to the acceleration of a braked wheel and a comparator that responds to the acceleration signal by producing a signal which undergoes a step change at set acceleration levels so as to divide successive deceleration/acceleration cycles into successive acceleration periods separated by intermediate periods. The output of the comparator is integrated to produce an output signal which changes in a progressive manner in one sense during each acceleration period and in the opposite sense during each intermediate period so as to vary in accordance with surface friction conditions. The output signal is used to vary a control parameter or function within the system in accordance with the surface friction conditions.

Abstract: In a vehicle disc brake of the single sided sliding reaction caliper type the drag on the friction pad assemblies is taken by a drag-taking member. The caliper is slidably mounted for movement relative to the disc on a guide in the form of a single pin which is located on the same side of the disc as that on which an actuator for the brake is located.

Abstract: An hydraulic pressure converter comprises a differential piston which works in a stepped bore in a housing. A pressure space is defined in the housing at the end of a portion of the piston which is of smaller area so that reciprocation of the piston in the bore causes hydraulic fluid to be drawn into the pressure space through a first one-way valve and then pumped to an outlet through a second one-way valve. Reciprocation of the piston is accomplished by subjecting the piston to pressure from a pump to move the piston in a first direction away from a stop face and against the force in a compression spring so that hydraulic fluid is drawn into the pressure space. A valve assembly is operative to reduce the force urging the piston in the first direction when the displacement attains a predetermined value whereafter the spring is operative to urge the piston in a second opposite direction to force fluid to the outlet from the pressure space.

Abstract: In an hydraulic anti-skid braking system a pump having a liquid throughput which is adapted to increase with the rotational speed of the wheel is arranged to control operation of a modulator valve assembly for relieving the pressure supplied to the brake when the deceleration of a wheel exceeds a predetermined value. A sensing device for sensing the deceleration of wheel operates a control valve assembly which is provided to control the supply of operating fluid from the pump output to the modulator valve assembly.

Abstract: An anti-lock brake control system for a vehicle with braked wheels comprises a sensor to produce a signal proportional to the deceleration/acceleration of the braked wheel, a deceleration sensing switch to respond to the deceleration/acceleration signal by producing a brake pressure release pulse when deceleration of the wheel exceeds a predetermined threshold level, a charge storage device which is adapted so that it charges in a predetermined progressive manner while the brake pressure release pulse is produced and discharges at a predetermined decay rate, a comparator that compares the potential on the charge storage device with a reference potential and produces an extension brake pressure release pulse according to their relative values, and apparatus to vary one of said potentials in a manner dependent on acceleration of the wheel above a preset acceleration threshold so that the extension brake pressure release pulse is terminated by increasing wheel acceleration.

Abstract: In a tandem servo booster provided with a pair of ties extending through the housing and diaphragm assemblies for transmitting braking reaction forces from the master cylinder housing directly to the vehicle bulkhead, the ties are tubular and are provided with axially spaced ports to provide fluid communication between pairs of alternate booster chambers. In another construction both ties provide fluid communication between the same two booster chambers, and the other two chambers are connected together by a tubular member which is secured to the diaphragm support plate of the front diaphragm assembly and extends rearwardly through a partition wall of the housing positioned axially between the two diaphragm assemblies.

Abstract: A fixture for use in bonding friction linings to platforms of brake shoes comprises an arcuate support against which the lining and the platform are compressed together by a spring assembly acting on the web of the shoe. The fixture preferably accommodates two opposed shoes simultaneously, with the shoes being urged apart by a single spring assembly to urge the linings into engagement with a single loop of this flexible metal band constituting the support.

Abstract: The present invention is concerned with a sliding caliper disc brake having a torque member and a caliper incorporating at least one hydraulic actuator. The caliper is attached to the torque member for sliding movement relative thereto and is arranged to act on a pair of friction pad assemblies. Mutually abutting surfaces of the caliper and a friction pad assembly are such that one of the surfaces is roughened while the other of the surfaces is formed of a material which is relatively soft in relation to one of the surfaces. Thus, under braking, the roughened surface is caused to impress itself into the softer surface so as to restrain rotation of the friction pad assembly relative to the caliper.

Abstract: A fluid-pressure operated servo-motor assembly transmits an effort from a pedal to a master cylinder for wheel brakes. The assembly includes in a housing, a pedal-operated input member, an output member acting on the master cylinder and a movable wall for transmitting the effort between them. The effort is augmented by fluid pressure in a boost chamber acting on the movable wall. The boost pressure is controlled by a valve in a stationary part of the housing. An operating assembly controls operation of the valve, and comprises a non-rotatable operating member, and a rotatable actuating member co-operating with the valve.To ensure positive operation of the valve, a helical engagement provided between the operating and actuating members, and the co-operation of the valve with the actuating member are arranged so that relative axial movement between the members causes rotation of the actuating member to operate the valve.

Abstract: A control valve assembly for a vehicle braking system comprises an inlet, an outlet, a proportioning valve having a control valve member movable to open and close the valve to control communication between the inlet and the outlet, and an inertia-responsive device, preferably a pendulum, responsive to deceleration of the vehicle and operable to reduce the pressure at the outlet after the valve has closed. The inertia-responsive device supplies a signal in dependence upon deceleration, and a servo system applies a force to the control valve member in response to the signal to move the control valve member in a direction to reduce the outlet pressure.

Abstract: In a servo-motor assembly for a vehicle braking system a valve controlling the servo pressure is operated by an operating assembly including a rotary valve actuator positioned between a pedal-operated input member and an abutment member. The valve actuator is axially movable through a limited distance and a camming mechanism translates axial movement of the actuator into angular movement which operates the valve.

Abstract: Servo boosters for vehicle hydraulic braking systems are described which incorporate a novel arrangement for providing an increasing reaction force on the input member in response to an increasing output force. In the novel arrangement a first thrust assembly is interposed between the input member and the output member, and a second thrust assembly is interposed between the movable wall of the booster, which may be a diaphragm or a piston, and the output member. The thrust assemblies each generally consist of rotatable parallel plates having inclined ramp surfaces on opposed faces co-operating with balls or rollers located between the plates. Some of the plates of the two thrust assemblies are keyed together. Axial forces between the members generate torques in the thrust assemblies and since the torques must balance each other as a result of the connections between the plates a fixed relationship is maintained between the input and output forces and the force exerted by the movable wall.

Abstract: A control valve assembly for a vehicle braking system, comprises a valve controlling communication between an inlet and an outlet, the valve having a valve seat carried by a control piston and an inertia-responsive member, preferably a ball, movable into engagement with the valve seat to close the valve at a predetermined deceleration of the vehicle. A disabling device is provided which is operable in response to the pressure at the outlet to hold the valve open. The disabling device comprises an auxiliary piston which is biased to an inoperative position and is movable, in response to a predetermined outlet pressure, against the biasing force to hold the ball off its valve seat.

Abstract: A friction pad assembly for a rail vehicle brake comprises a pad of friction material carried by a rigid backing plate, and the backing plate is detachably mounted on a shoe. A part-circular notch at one end of the shoe receives the stem of a headed stud which acts as an abutment for that end of the backing plate, and the backing plate is urged into engagement with the stud by means of a keeper which acts on the opposite end of the backing plate. The keeper comprises a stop member in combination with a relatively movable resilient abutment comprising a strip of metal which is bent into a loop and of which a forward terminal projection of part-circular outline is received in a notch of complementary outline in the other end of the backing plate.

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: A power operated actuator assembly incorporates a stop mechanism for opposing movement of an actuating member if a booster fluid supply is operative. The stop mechanism comprises a chamber which is supplied with a metered proportion of pressurized fluid when the actuating member is moved such that the greater the force on the actuating member, the greater will be the magnitude of the force due to the pressurized fluid opposing movement of the actuating member.

Abstract: A system is disclosed for monitoring operation of a speed sensor which produces a pulse signal with a repetition frequency related to the speed being sensed.An analogue speed signal is derived from a pulse signal having a repetition frequency related to the sensed speed and is fed to an integrator which, under the control of the pulse signal, performs successive separate integrating operations on the analogue speed signal in the periods between successive pulses, and a comparator compares the integrated sum thus produced with a reference value corresponding to a limit for normal generation of pulses, to produce a warning signal if the integrated sum exceeds the reference value. The system may include a timer to respond to successive warning signals and produce a malfunction signal if they occur with less than a predetermined time interval between them.

Abstract: A vehicle load-sensing assembly for use with a vehicle fluid-pressure braking system comprises an input member subjected to a force in a road spring and a valve which has a movable valve member for controlling the flow of fluid through the valve. A thrust transmitting mechanism is located between the input member and the valve member. The thrust transmitting mechanism comprises relatively movable parts, and a camming device is disposed between the parts to transmit movement between the parts to control operation of the valve member.