Abstract: The invention relates to a vehicle air supply system (10) adaptable to occasionally supply large volumes of air at relatively low pressure for purposes such as tyre inflation. The system has a compressor (12), an air dryer (14), a reservoir (18) adapted to receive air from the compressor via the air dryer, and control means (20) operable to cause a standard regeneration of the air dryer when a predetermined system condition is met. The control means is also operable to cause an intermediate regeneration of the air dryer in advance of said predetermined system condition being met, wherein the control means are further operable to inhibit said intermediate regeneration. The control means is operable so as to prevent saturation of an air dryer desiccant in circumstances where the compressor is on load for an extended period of time, and thus likely to be pumping a large volume.

Abstract: A vehicle air supply system having a compressor, an air dryer, a reservoir adapted to receive air from the compressor via the air dryer, and control means operable to cause a standard regeneration of the air dryer when a predetermined system condition is met, the control means being further operable to cause an intermediate regeneration of the air dryer in advance of said predetermined system condition being met.

Abstract: A vent valve for an air braking system of a vehicle comprises an elastomeric valve member (11) held in relation to a vent (17) and having a restricted vent passageway. A continuous depending rib (23) is engageable with a valve seat (28) to close the vent passageway as increasing pressure acts on the head (21) of the valve member (11). The valve member (11) permits a fluid chamber to be connected to exhaust until pressure in the chamber reaches a predetermined level.

Abstract: An air braking system of a vehicle has a compressor, non-return valve, manifold, electrically actuable demand valve, an air consumer circuit. An auxiliary circuit connects the manifold to the consumer circuit via an electrically actuable valve and non-return valve. In the event of electrical failure air under pressure can be supplied to the consumer circuit via the auxiliary circuit. In another aspect a plurality of consumer circuits are provided. These circuits may be charged from the compressor via the manifold, or interconnected via the manifold independently of the compressor. This arrangement permits more flexible compressor operation and/or a greater reserve in the event of failure of the pressure source.

Abstract: A drain valve of an air braking system for vehicles has a drainage piston, a main sump and auxiliary sump. Moisture passes from the main sump to the auxiliary sump in response to pressure at a signal port which closes off air supply through ports. A reduction in pressure at the signal port causes the ports to be reconnected and allows moisture to be expelled through the drainage outlet.

Abstract: Air braking system of vehicles usually have a piston compressor (C) and a desiccant (D) for drying the compressor output air. The desiccant is periodically regenerated by downstream air from e.g. a reservoir (R). When a compressor is brought on load, the initial charge of air may be oil laden. The invention provides a delay mechanism to permit such initial charge of air to pass directly to exhaust.

Abstract: A device (10), and a method for forming such a device (10), for a fluid system for a vehicle, comprises first and second members (12, 13). The first member (12) is adapted for direct mounting on the chassis or engine of a vehicle (11); the second member (13) defines at least part of a leak tight fluid chamber (15) of the device (10). The first member (12) is of a thermoset material suitable for withstanding operating conditions and loads associated with direct mounting of the device (10) on the chassis or engine (11), and the second member (13) is of a thermoplastic material suitable for welding to ensure leaktightness of a fluid chamber (15). The second member (13) is interlocked with the first member (12) during moulding thereof.

Abstract: An apparatus and method for controlling an electrically driven vacuum pump (16) for a motor vehicle provides that below a predetermined level of vacuum (approaching atmospheric pressure) the pump (16) runs at a first speed, and above that level of vacuum the pump (16) runs at a lower speed or is stopped. Pump control is by switching of a single pressure switch (21) between two states, switching from the first state to the second state being accompanied by a time delay to ensure a minimum running period at the first speed.

Abstract: An exhaust gas pressure modulation valve for a diesel engine vehicle combines the functions of an exhaust brake and a warm-up valve and has a single butterfly valve (12) to close the exhaust passage. The butterfly is reactive and opens automatically at a predetermined back pressure to prevent engine damage. The butterfly includes a small bypass passage or aperture (29) to permit a low throughput of exhaust gas when closed.

Abstract: An exhaust modulator in or to be fitted in the exhaust system of an engine, having a body defining a flowpath therethrough for engine exhaust gases, a gate in the exhaust flowpath movable between an open and a closed position, one or more bleed flowpaths communicating between opposite sides of the gate, and a flow control mechanism. The mechanism is responsive to one or more operating parameters to control the flow of exhaust gases along the one or more bleed flowpaths so as to limit the back pressure applied to the engine to different predetermined levels as required for operation of the modulator in selected modes.

Abstract: A reciprocating vacuum pump has a disc shaped piston (22, 122) having a peripheral elastomeric seal (52, 152) with oppositely directed, radially outwardly extending skirt portions (54,56); the piston is driven axially by a rod (34, 134) reciprocal in a lubricated bearing (42, 142) and a lubrication flowpath (50,48; 150,148) is defined between the bearing (42, 142) and the side of the piston (22, 122) opposite thereto.