Abstract: In a power assistance system for a vehicle steering mechanism fluid pressure providing the assistance is supplied from a pump driven intermittently by an infinitely-variable electric motor. For a rack and pinion mechanism fluid pressure chambers are formed by sealing boots at each end of the rack, and are connected through the pump, which is operative to create a pressure differential between the chambers, and thus across the rack to provide power assistance. The electric motor is energized as required to drive the pump in the appropriate direction, and when the motor and pump are inoperative fluid is allowed to flow freely between the chambers to accommodate fluid displacement as a result of unassisted operation of the steering. The pump is preferably a turbine pump, which allows fluid flow when inoperative. The system provides power assistance efficiently, and relatively cheaply.

Abstract: An hydraulic braking system includes a primary pressure source connected to a brake actuator and operable by a force input device, a fluid displacer actuated by an electrical stepper motor operated by a controller in response to action of the force input device, as sensed by a sensor, whereby fluid displaced from the displacer is added to that displaced from the primary pressure source for application to the brake actuator. By suitable programming of the controller, servo-assistance and/or quick-fill modes can be produced by the displacer and wheel-slip correction and anti-skid facility can be provided.

Abstract: A braking system for a vehicle has a stepper motor which controls the application of friction elements to a rotating part such as a brake drum. A control circuit controls the motor so that an output member is positioned by the motor in accordance with a variable demand signal. In one application, the control circuit receives a brake pressure signal from a transducer and controls the motor so as to compensate automatically for brake wear. In another application, the motor controls a debooster of an antilock brake system. The system also may include means for operating a parking brake.

Abstract: An internal shoe drum brake has a body (1) carrying a plurality of circumferentially spaced friction elements (2) movable into engagement with a rotatable drum (3) by a hydraulic system including an actuator (5) having a pressure-applying cylinder (2) in which a pressure-generating piston (21) is driven by an electrical stepper motor (28), slave cylinders (4) which actuate the friction elements, and internal ducts (7, 8) for transmitting pressure from piston (21) to slave cylinders (4).

Abstract: A rotary electric drive device for use in a vehicle anti-skid braking system has a rotary armature supported by a thrust race in relation to a housing. One part of the thrust race has external teeth for co-action with a pawl which is disengaged from the teeth for one direction of rotation of the armature but engages the teeth during rotation in the other direction to lock the race part to the housing. When this happens, slipping occurs between opposed contiguous faces of the armature and part respectively in order to dissipate some of the rotational energy of the armature when the drive device is de-energized.

Abstract: A combined brake release solenoid valve and motor driven debooster has a plunger forming part of the debooster, which, on brake re-application is moved to a flow-restricting position in which there is only a restricted connection between the brake master cylinder and the slave cylinder, so as to avoid over-rapid brake re-application. In one embodiment, the plunger is positioned to provide a stop for the solenoid valve. In another embodiment, the plunger coacts with a separate valve seat.

Abstract: A caliper is mounted on an axle casing of a rail vehicle by a first bracket and by a second bracket positioned between the disc and the first bracket. One of the brackets is detachably mounted on the casing and is removable to permit the caliper to be removed by movement in a generally axial direction. To permit this to happen the caliper and the other detachable bracket both lie outside the projected peripheral edge of a flange on the axle on which a wheel is mounted.

Abstract: An electrical solenoid valve has a coil and a movable armature. A first valve element is subject to pressure from an inlet and a second valve element is operated by the armature, when the coil is energized, to close a port in the valve element and so isolate the inlet from a pressure fluid outlet to a brake. The valve element is displaceable under the effect of a pressure differential across it as a result of closing the port, the force derived from the then predominant inlet pressure being transmitted by the second valve element to load a spring device connected to the armature. Such spring loading increases the force tending to release the armature and leads to rapid opening of the port (18), when required.

Abstract: A brake adjuster wherein a thrust block is axially slidable in a cylinder bore and rotatably connected to one of two screw threaded adjuster members which are themselves interconnected by a self-sustaining thread. In use a power spring acts on the thrust block to move it axially within the cylinder bore to apply pressure to a friction pad via the adjuster members. The brake may be released by applying hydraulic pressure to the thrust block, at which time one adjuster member is rotated via a clutch, when a predetermined clearance has been taken up, relative to the other to adjust for pad wear. No relative adjustment occurs during application of the brake under the action of the power spring.

Abstract: The present specification discloses an actuator for use in a vehicle brake. The actuator incorporates an adjuster which automatically provides an adjustment to take account of pad lining wear, to thus maintain a substantially constant brake clearance. The brake actuator of the present invention comprises a hollow piston which is axially slidably located in a cylinder with an elongate shaft extending axially through said cylinder and said hollow piston. Said shaft is fixed in a position within the cylinder and carries a spiral thread and axially extending splines. An adjuster nut is rotatably mounted on said spiral thread and is engaged by detent means mounted on said axial splines. Said detent means are spring biassed against the adjuster nut by a spring which engages said piston.

Abstract: The present specification discloses a brake actuation system for a vehicle, which is applicable to both hydraulically or pneumatically operated/spring released brakes and spring operated/hydraulically or pneumatically released brakes. With such brakes it is often necessary to have secondary means for brake operation or release. Such braking systems thus have primary and secondary means for brake operation or release. The present invention provides a fail-safe system which can provide at least an indication of impending failure. The brake actuation system of the present invention comprises a cylinder within which two axially aligned pistons are axially slidable, the space between one end of the cylinder and one piston being connected to a primary power system and the space between said pistons being connected to a secondary power system.

Abstract: A controller for controlling the increase in fluid brake pressure as a brake is applied irrespective of how rapidly the operator applies the brakes. The controller includes a valve between inlet and outlet ports in a valve body, the valve having opposing faces subjected respectively to pressure at the outlet and pressure in a volume chamber between the valve and a spring loaded piston and connected to the outlet through a restricted orifice. The valve seeks an equilibrium position wherein the rate of rise in pressure at the outlet is controlled and the deceleration of the vehicle is controlled even when the operator applies the brakes at an excessive rate.

Abstract: A clutch servo for a vehicle cable-operated clutch system has a housing, an input member to which an input force is applied by the cable which has an inner cable and an outer sheath, an output member connected to a clutch, and a movable wall for augmenting the output force which acts through the output member. The movable wall is operated by a fluid pressure chamber, pressurization of which is controlled by a valve in response to the input force. In one construction the inner cable is movable relative to the movable wall and a locking device is incorporated to lock the inner cable and the movable wall against relative movement when the movable wall is not in its retracted position. This ensures that the servo is not affected by adjustment of the cable to compensate for clutch lining wear when this adjustment is performed between the servo and the pedal.

Abstract: The friction pad assembly of the present invention has a generally rectangular back plate with two retaining tabs projecting from opposite side edge regions, at an angle to the general plane of the back plate. The support or shoe is also generally rectangular and has a recess formed in each of two opposing side edges, the retaining tabs on the back plate engaging snugly into these recesses. The support has a further H-shaped recess in its front face within which an elongate spring plate is secured so as to project beyond opposing ends of said support. Thus, in use, the friction pad assembly can be quickly and simply mounted on the support and when the brake is operated the end region of the spring plate through which pad drag is passed to pad guides, flexes to thus allow for unhindered axial movement of the friction pad assembly and support.

Abstract: The present specification discloses a brake actuator incorporating a mechanically operated adjuster, the adjuster compensating for friction pad wear. The brake actuator comprises two adjuster members interconnected by a self-sustaining thread and located between a friction pad and an actuation member, the actuation member being biassed by a main spring to a brakes-on position with at least one hollow piston being displaceable under hydraulic pressure to compress the main spring and move the actuation member to a brakes-off positon, a second piston being carried within the hollow piston and being carried within the hollow piston and being axially displaceable therein under the hydraulic pressure and against a further spring, to cause interengaging clutch elements to rotate one adjuster member relative to the other adjuster member, a stop being arranged to limit the available movement of the clutch elements.

Abstract: The present invention relates to a disc brake for use on a railway vehicle. The brake includes a service brake for normal brake applications and an auxiliary or parking brake which is spring applied and hydraulically or pneumatically released. The disc brake includes a caliper supporting a service brake actuator and an auxiliary brake actuator arranged to apply opposed friction pads to opposite sides of a braking disc. The auxiliary brake actuator consists of one or more spring elements which engage around outer peripheral regions of the caliper and grip the caliper to apply spring force to the pads from the exterior of the caliper, the spring elements being releasable by a hydraulic or pneumatic piston such that the spring force of the spring elements is then reacted through the caliper. By this arrangement of spring elements, the spring elements being preferably located in grooves on the outer surface of the caliper, a compact disc brake construction is achieved.

Abstract: The present invention provides a brake actuation and adjuster system comprising means for applying brake actuation pressure both to a brake actuator member and to a pump. The pump is arranged to pump pressure fluid to an adjuster control valve and an adjuster actuator, and the brake actuator member is arranged to be moved by said brake actuation pressure to then open the adjuster control valve against the pressure of the pressure fluid after the brake actuator has moved to a predetermined release position. Thus, in one embodiment, brake actuation pressure primes the pump causing the pump to force pressure fluid to the adjuster actuator. If adjustment is necessary, it is effected until the adjuster control valve is opened to release the pressure fluid. Thus a simple, independent adjuster arrangement is provided which does not affect available brake performance.

Abstract: An anti-skid hydraulic braking system incorporates a modulator assembly for modulating the supply of fluid from a master cylinder to a brake in accordance with skid signals. The modulator assembly comprises a de-boost piston located in a bore in a housing, an expander chamber connected to the brake, a first valve between the master cylinder and the chamber, and a second valve for controlling the application of the de-boost piston of a fluid sustained-support force. The modulator assembly incorporates a safety piston which prevents the first valve from closing unless a device, suitably an hydraulic accumulator or pump, and which provides the fluid sustained-support force, is operative.

Abstract: A vehicle suspension system for a pair of wheels has two torsionally stiff members each of which carries an axle for a respective wheel. The load on each wheel is supported by a gas spring to which relative movement of the wheel and vehicle body is transmitted. The springs are mounted in respective members which are connected to the body, and lever mechanisms are provided to transmit the relative movement of the wheel and body to the springs, the lever mechanisms also being connected to the body. The lever mechanisms are preferably bell-crank levers. The system may also accommodate a levelling system, and interconnections between fluid volumes of the springs, especially where the members are connected by a member which is rigid in bending but torsionally flexible. The system is particularly useful as a rear suspension for a passenger car.

Abstract: The regulator valve has a first restriction of fixed size in series with a second, variable restriction defined between a tilting wall and an annular valve seat provided on a fixed wall. The tilting wall is sealed around its periphery to the fixed wall by an elastomeric membrane to define between the walls a first chamber, and the walls are biassed apart by a compression spring. A second chamber is defined on the opposite side of the tilting wall to the first chamber such that the tilting wall is subject to the pressure differential between the first and second chambers, and the first restriction connects the two chambers. The size of the second restriction is thereby made dependent upon the pressure difference between the two chambers. The tilting wall tilts about a fulcrum line. The valve seat may be pressure-balanced by a balancing member.