Abstract: Valve system for a vehicle gas suspension system having a central chamber (41) to which pressurized gas is admitted via valve 50 or from which pressurized gas is exhausted via valve 51. Interposed in gas communication paths between the central chamber and each gas suspension unit (46-49) is a respective on-off valve unit (42-45). The valve system includes a regenerative drier (56) and a cushion valve (70) for protecting a compressor from overload during start-up.

Abstract: A vehicle suspension system incorporating suspension units (46-48) associated with respective vehicle wheels and selectively controllable to vary the ride height of the vehicle. Vehicle speed sensors and height sensors are responsive to departure of the ride height from a predetermined height datum which is a function of the vehicle speed and to provide a signal related thereto to control movement of at least one suspension unit thereby to tend to move at least a part of the vehicle to said predetermined height datum. Timer means are provided so that the movement of a suspension unit in response to a signal from a height sensor is inhibited until a signal of at least a predetermined magnitude has persisted for at least a prescribed part of a prescribed period of time.