Abstract: A wheel cylinder comprises a bore closed by two pistons which define a pressure chamber therebetween. The pressure chamber is divided into two compartments by a partition member placed in the bore and which comprises a passage communicating the two compartments. One of the compartments is connected to a source of pressurized fluid and a control valve is mounted in the passage for controlling the pressure in the other compartment as a function of the pressure in the one compartment, whereby the wheel cylinder acts as a proportioning valve.

Abstract: A wear indicator for the friction material of a drum brake shoe includes a spring-loaded captive plunger carried in an elongated sleeve attached to the brake shoe. The plunger includes an enlarged head which abuts the sleeve and which is recessed below the surface of the unworn friction material at a depth which corresponds to a worn-out shoe. When the shoe wears to a sufficient degree, the plunger head is worn off by the rotating brake drum and the plunger is released. When freed, the plunger is moved by the spring bias and slides within the sleeve to press against an electrical contact carried by the backing plate of the brake to close an alarm circuit.

Abstract: A hydraulic amplifier comprising a housing wherein is defined a pressure chamber. A servo piston is slidable in a bore opening onto the pressure chamber. The amplifier also comprises a set of control valve connectible to a high pressure fluid source and a low pressure reservoir. An operator operated control rod has one end projecting into the chamber. In the pressure chamber is mounted a lever mechanism comprising a lever having one end pivoted on a pin associated with the housing, and the other end is moved by the control rod. The lever mechanism also comprises a rocker member which is pivoted on the lever and whose respective ends can bear on the servo piston and are adapted to move at least one valve in the control valve set. The pin is slidable relative to the housing and is urged by resilient means into an idle position. The control valve set comprises an exhaust valve operated by a rocker member, and a high pressure valve operated in response to the movement of the pin from its idle position.

Abstract: A braking correction device of the type having a housing in which is defined a bore with a stepped piston slidably mounted therein so as to divide the bore into an inlet and an outlet chambers respectively communicating with the master cylinder and the brake actuators. The stepped piston has a head with a peripheral groove in which an annular ring is mounted with axial and radial clearance. The ring cooperates with the bore surface to control communication between the inlet and outlet chambers as a function of the position of the stepped piston. The bore surface has a first part forming a fluid tight side wall and a second part forming a side wall of porous material. The second part is adjacent the outlet chamber. A radial clearance is provided between the piston head and the bore surface of porous material for by-passing the sleeve of porous material to ensure the unihibited hydraulic flow between the inlet and outlet chamber is obtained during the non proportioning phase.

Abstract: A servomotor for power actuation of a mechanical or hydraulic control, for example brake master cylinders for motor vehicles, is disclosed. The servomotor includes a housing in which a power piston separates a low pressure chamber from a high pressure chamber. The power piston being movable from an idle position in response to a pressure difference between the chambers. The pressure difference being controlled by a valve associated with an inlet control member. An auxiliary power member is located in the high pressure chamber. The auxiliary power member has a pressure compartment connectible to an external pressure source. The auxiliary power member is adapted to move the power piston from its idle position irrespective of the establishment of the pressure difference, to permit the servomotor to be used in an automatic or emergency service brake system.

Abstract: A disc brake of the type comprising a caliper or frame member slidably and floatingly mounted on a fixed member by way of two guide keys is disclosed. According to the invention, the guide keys slidably cooperate with one of the members by way of guide surfaces and floatingly cooperate with the other member by way of a cylindrical surface cooperating with a substantially plane surface. Preferably, the lines of contact defined between the cylindrical surfaces and the plane surfaces are comprised in a plane substantially parallel to the disc faces and which lies between the faces or offset relative to the latter towards an actuator.

Abstract: A braking correction device comprises two correcting valves of which the inlets are separately connectible to two independent braking pressure sources and the outlets to two independent sets of vehicle brake actuators, each valve having a piston and being capable of controlling the pressures at its inlet and outlet in accordance with a predetermined relationship.

Abstract: The invention relates to a servomotor for assisting the operation of a power brake system. The servomotor includes in a housing a power-assisting part and a part forming a hydraulic master-cylinder. The power-assisting part is adapted in use to be connected to an external power source such as a vacuum source. A valve assembly operated by an operator-operated intake member controls the generation of a pressure differential across a driving piston by allowing air to replace the vacuum on one side of the piston. The master-cylinder part includes an assembly having two coaxial pistons. The first piston is attached to the driving piston of the power assist part whereas the second piston is actuated by the intake member. Both coaxial pistons project into a chamber which is divided by a sealing ring. The central piston is adapted to pass through the sealing ring in response to an input force from the input member to further pressurize the fluid in the outlet portion of the chamber.

Abstract: The braking correcting device of the hydraulic type comprises a housing in which is defined a cavity. A stepped piston is disposed movable in the cavity and has one end which projects outwards from the housing, the piston having a head slidable in a bore formed in the cavity of the housing for separating the cavity into an inlet chamber which adjoins the piston end face having the smaller effective cross sectional area, and an outlet chamber which adjoins the piston end face having the larger effective cross sectional area. The piston head contains a peripheral groove which receives with axial and radial clearance a ring of elastomeric material capable of disconnecting the two chambers when the piston moves a predetermined distance from its idle position which is fixed relative to the housing, overcoming a return force. The bore comprises a first portion having a fluid tight side wall adjoining the inlet chamber, and a second portion contiguous to the first portion and adjoining the outlet chamber.

Abstract: A braking correction device comprising two correcting valves of which the inlets are separately connectible to two independent braking pressure sources and the outlets to two independent sets of brake actuators, each valve being capable of controlling the pressures at its inlet and outlet in accordance with a predetermined relationship and comprising a piston subject to resilient return spring. The correction device comprises force distributing member situated between the resilient return spring and the pistons of the correcting valves, the distributing member comprising a block of elastomeric material enclosed in a rigid shell comprising a cylindrical cavity in whose bottom the force distributing block is fitted, the cavity comprising a cylindrical edge slidable receiving an assembly comprising two projections contacting the block and co-operating with the pistons of the valves. The braking correction device is intended for a dual vehicle hydraulic brake system.

Abstract: The invention relates to a hydraulic servomotor comprising a housing provided with a bore slidably receiving two pistons separating an actuating chamber from an utilization chamber, said pistons including an annular outer piston and an inner piston received within the annular piston. Releasable coupling means are provided between both pistons to permit said pistons to move in unison when high pressure fluid is available in the actuating chamber and to permit the inner piston to be moved alone by the push rod in the event of a high pressure failure in the actuating chamber. The motion of the outer piston towards the interior of the actuating chamber is limited by an abutment fixed to the housing.