Abstract: An outer cylinder (18) is coaxially disposed around an inner cylinder (12). The lower ends of the cylinders (12), (18) are closed but communicate with each other and are mechanically connected to an axle of a wheeled vehicle. A piston (13) is sealingly slidable in the inner cylinder (12) and is connected via a piston rod (14) to a frame of the vehicle. The rod (14) extends upwardly through a rod guide (17) which closes the upper end of the inner cylinder (12). A seal (24) disposed above the rod guide (17) closes the upper end of the outer cylinder (18). The inner cylinder (12) and lower portion of the outer cylinder (18) are filled with liquid which damps movement of the piston (13) caused by irregularities in the road surface. The upper portion of the outer cylinder (18) is filled with compressed air. An annular check valve (63) is disposed in a passageway (56) leading from a space ( 26) between the rod guide (17) and seal (24) to the upper portion of the outer cylinder (18).