Suspension means for vehicles

Claim 1

Hydro-pneumatic suspension means for a vehicle comprising in combination a housing assembly and a piston member, said housing assembly and said piston member being adapted for connection between sprung and unsprung parts of a vehicle and being relatively movable in response to relative movement between the sprung and unsprung parts, wherein the housing assembly incorporates a pressure chamber containing a trapped volume of gas under pressure which defines a gas spring for supporting the load on a wheel or axle of the vehicle, a working chamber containing a trapped constant volume of liquid, a height adjusting chamber to which liquid is supplied to compensate for changes in the pressure in the pressure chamber due to changes in the loading on the vehicle, a first flexible diaphragm for separating said gas in said pressure chamber from said liquid in said working chamber, a second flexible diaphragm for separating said trapped volume of liquid in said working chamber from any liquid in said height adjusting chamber so that no transfer of liquid between said working chamber and said adjusting chamber can take place, a third diaphragm disposed between said piston member and said housing assembly and through which oscillations between said piston member and said housing assembly are transmitted to said gas spring by displacement of said liquid in said working chamber, and damping valve means separate from said piston member and disposed within said working chamber, said liquid in said working chamber being forced through said valve means to damp out oscillations of said gas spring in response to relative movement between the sprung and unsprung parts, and wherein a supply of liquid of which the pressure can be altered to compensate for changes in the pressure in said pressure chamber due to changes in the loading on the vehicle is provided for supply to said height adjusting chamber, whereby a ride height for the vehicle can be maintained substantially at a constant value.