Abstract: The fifth wheel of an articulated vehicle comprising the coupling between a semi-trailer and a tractor is provided with measuring apparatus for measuring forces imparted from the semi-trailer. The apparatus comprises a sensing device for measuring horizontal loads, and a sensing device for measuring vertical loads. The signals from the sensing devices and are fed into an electronic controller, in turn to cause the brakes on the trailer to be applied to achieve balanced braking, anti-lock control, and traction control of the wheels. A tractor fitted with a braking system of the brake-by-wire type with a conventional semi-trailer, without modifications to semi-trailer or to the braking components of the semi-trailer can therefore be used.

Abstract: A vehicle brake has a fixed backplate carrying a pair of friction elements and an actuator operable to urge the elements into braking engagement with a rotary braking surface. An abutment for the elements has a portion which is deflectable by load on the elements arising from braking torque. A radiation input device directs radiation at a surface of the deflectable portion and a device is provided to sense radiation after its impingement on the portion and to transmit the sensed radiation to a device producing a responsive electrical output representing deflections of the portion.

Abstract: A brake actuator has a body containing a pair of brake-applying members which may be actuated hydraulically to separate the friction elements of a brake into engagement with a rotatable braking surface. The members are interconnected by a mechanism in the form of a shaft of which respective end portions are provided with reversible threaded portions of opposite hand which engage corresponding threads within the members, the shaft being constrained against axial movement between bearings. Any excess movement of one of the members relative to the other is transmitted to that other member such as to cause an opposite and proportional force on the other member to substantially equalize the wear rates on the friction elements.

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 modulator assembly for a vehicle braking system includes a valve means for isolating a master cylinder from a brake actuator when a wheel slip condition arises at a braked wheel. Pressure modifying means is provided in the form of a piston which is moved axially by rotation of a motor armature 11 via a screw threaded connection to modify the braking pressure to correct the slip condition. Axial movement of the armature 11 moves a valve stem axially to close the valve means.

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 pneumatically operated servo-booster has a housing divided by a movable diaphragm assembly into chambers (A, B), and a hub connected to the diaphragm and forming a vacuum valve seat for co-operation with a spring-loaded valve member. A valve element movable relative to the hub forms an atmospheric valve seat for co-operation with the valve member. A sleeve co-axial with but separate from the hub carries an abutment member which forms a fixed abutment for the valve seat when the sleeve is in abutment with the shoulder of the housing. When the seat abuts the member, co-operation of the vacuum valve seat with the valve member under the action of pressure in one of the chambers maintains the atmospheric valve in a position of readiness for activation of the booster. This arrangement contributes to increased sensitivity of operation.

Abstract: A fluid-tight connection between a pair of pipes containing hydraulic fluid is formed by a pair of connectors of the invention. Each connector has a body part engaged respectively with the pipes, the body parts being coupled together by a coupling sleeve which engages a shoulder 20 of one of the body parts and is locked to the body parts by a circlip 23 engaged within grooves 22 and 25 respectively in the other body part and the sleeve. Each body part has a respective seal member each incorporating a diaphragm sealing over an end of its associated body part and a bead engaging the internal wall of the sleeve. Air trapped between the diaphragms is expelled past the seal members during insertion of the connector parts into the sleeve. Application of system pressure subsequently ruptures the diaphragms to establish communication between the pipes and urges the seals outwardly to seal against leakage of system fluid.

Abstract: A power valve for a vehicle braking system includes a main pressure chamber (4) defined between the body (1) and spool (2) and connected to the outlet (5), the spool being displaceable under an input effort to close communication between the chamber (4) and a reservoir port (8) and open communication of the chamber (4) with an inlet (7), and an auxiliary chamber (10) to which fluid pressure may be supplied through a port (11) to exert a force on the spool for reducing the pressure supplied to the outlet (5) for a given input effort applied to the spool (2).

Abstract: A selector valve for a vehicle braking system in which brakes mounted on opposite sides of the vehicle can be operated selectively either together or independently, comprises an operating lever (9) for displacing a valve spool (2) to control communication between inlet ports (3,4) and outlet ports (5,6), the lever being guided by a slot (8) which includes latching notches (20) in which the lever is engageable to preselect a particular steering mode of brake operation. The lever is automatically disengaged from the notches after each brake operation by a piston (15) which is actuated by the fluid pressure in a chamber (16) connected to an inlet port (4).

Abstract: An hydro-pneumatic suspension assembly for vehicles comprises a pressure chamber in a combination with an hydraulic suspension unit of the self-levelling type. The unit incorporates a spool valve for maintaining the length of the unit at a predetermined value irrespective of the load. The spool valve is responsive to the position of a piston rod which carries the piston of the unit, and a damper, comprising a restricted passage, is incorporated to delay the response of the spool valve to movement of an assembly comprising the piston and the piston rod.