Abstract: A suspension unit for mounting an axle to the body of an automobile or a handle-bar to the fork of a bicycle or motorcycle. A pair of pistons (15, 29) operate in tandem in separate chambers (17, 31) having a compressible gas in spaces (21, 35) on one side of the piston and an uncompressible hydraulic fluid in spaces (19, 31) on the other side of the piston. One of the pistons (15) responds to external disturbances (caused by e.g. road bumps) to drive the other piston (29) against the compressible gas which responds resiliently to return the pistons to normal intermediate placements, thereby maintaining or recovering proper height of the automobile or′cycle parts. The hydraulic fluid spaces are communicated via constrictor passage to provide suitable dynamic dampening.