Abstract: A hydrapneumatic suspension unit for a vehicle has a first and and a second chamber separated by valve assembly in communication with both chambers for controlling the flow of liquid therebetween. The first said chamber is liquid filled and includes a slidably mounted piston connected by a linkage to the road wheel. The second chamber includes a first compartment containing the liquid and a second compartment containing a compressible medium, wherein the first and second compartments are separated by a floating piston or a diaphragm member to permit compression and restoration of the compressible medium. The valve assembly includes a damping valve, a low-restriction check valve for permitting one-way flow of liquid from the first to the second chamber, and a damping bypass valve for enabling quick return of liquid from the second chamber to the first chamber. Interconnection may be provided to establish equalization between two or more suspension units.