Abstract: A fluid pressure braking system for a vehicle equipped with a drive line retarder automatically reduces the braking pressure level communicated to the brakes controlling the driven wheels of the vehicle to adjust for the retardation effected by the retarder. The retarder is actuated automatically each time the brake is applied by calculating the appropriate retardation level as a function of the brake pressure being demanded by the vehicle operator and by the load carried by the vehicle.

Abstract: An air dryer of the type fitted with a purge valve 92 is fitted with an input cut-off valve (81) which closes when the purge valve is opened in order that the compressor output line 2 is not vented thereby maintaining compressor and/or turbo charger pressure during off-load conditions.

Abstract: A spring force actuator comprising a housing, an output member axially moveable in the housing, a spring captive between the member and the end wall of the housing. The actuator further comprises an axially located screw-threaded wind-off element operable to apply an opposing force to the spring between the output member and the end wall. The wind-off element is threadedly cooperable with a nut which is non-rotationally captive in an externally accessible recess of the end wall.

Abstract: In an adaptation of an air dryer assembly for removing moisture from a stream of compressed air a container comprising a first part 15 and a second part 7 with a separable annular seal 17 and the adaptation including passageways for directing flow of compressed air from one part 2 of the main body via the inner container to another part 3 of the main body.

Abstract: An anti-skid brake control system for a vehicle having a first and a second set of wheels with each wheel being provided with a brake and a brake actuator. The first set of wheels tend to lock at a lower braking pressure than the second set of wheels. Wheel speed sensors are fitted to the first set of wheels. The system includes a first and a second regulator for separately regulating the braking pressure acting on the brake actuators of the first and second set of wheels respectively. The first and second regulator co-operate to control the braking pressure acting on the first and second sets of wheels by equalizing the braking pressure.

Abstract: A pipe fitting comprising a first part (1) with a rotatable insert (15) axially located therein by an annular abutment face (19) and having resiliently radically deflectable abutment faces (12a) which are engageable with ends (7a) of notches (7) of a second tubular part (2), rotation of the insert relative to the tubular part (2) enabling the abutment faces (12) to ride out of the notches (7) to permit release of the tubular part (2) from the first part (1).

Abstract: A dual circuit foot valve for a compressed air braking system has a plunger (38) which acts through a spring (39) on a first piston (6) which carries an exhaust seat for a first double valve controlling the supply of pressure from an input port (27) to a first circuit delivery port (28), the delivered pressure at (28) acting beneath the piston (6) in a sense to cause lapping of the valve and also acting above a second piston (16) which similarly acts as a control piston for a further double valve controlling the supply of pressure from an input port (29) to a second circuit delivery port (30), a further spring 43 being carried within the piston 6 to be engageable with a projection (55) of the second piston (16) following operation of the plunger to act on the second piston to beneficially influence the differential between the two delivered pressures.

Abstract: In an air pressure proportioning variable load valve for a vehicle compressed air braking system the operating mechanism for a self-lapping valve assembly includes a fluid pressure responsive piston arrangement which is operable above a given fluid pressure (PI) to adjust the position of the self-lapping valve arrangement relative to a variable area pressure responsive assembly whereby the rising output pressure corresponds initially to rising input port pressure up to the given pressure (P1) followed by progressive adjustment before proportioning by virtue of relative areas of the variable area assembly.

Abstract: A variable load valve for a vehicle braking system has a variable area ratio assembly the effective area ratio of which changes to tend to counteract unbalance of pressures between an input port and an output port and a double valve assembly which is moveable by a load dependent mechanism relative to the variable area ratio assembly, the double valve being arranged in the manner of a relay valve between the output port and a supply port or a vent port to relay pressure from the supply port to the output port in accordance with the magnitude pressure at the input port and the position setting of the double valve relative to the variable area ratio assembly. By provision of a further pressure responsive device a check valve and a further port the valve is adapted also to perform the function of a relay emergency valve.

Abstract: A quick release valve comprising a main casting (1) and a closure member (5, 27, 45) crimped on after insertion of a rubber valve member (9, 30, 48) and an `O` ring seal (13, 39, 49).

Abstract: A pressure reducing valve is constricted with a stepped piston affording a pressure responsive area on one side responsive to the pressure at an output port and a smaller pressure responsive area on the other side, contained between the seals of the two piston diameters and responsive to the pressure at an input port, the piston carrying a self lapping valve assembly connected via a passage to the smaller area for controlling the pressure at the output port in relation to that at the input port.