Car suspension system

In a car suspension system according to the present invention, a cylinder assembly comprises a cylinder housing and a rod fitted therein for axial reciprocation. An oil chamber and a gas chamber are defined inside the cylinder assembly, and the capacity of the gas chamber changes as the cylinder housing and rod reciprocate relative to each other. A damping force-generating mechanism is provided in the oil chamber. A metal bellows is contained in the cylinder assembly so as to be coaxial with the cylinder housing. The bellows can extend and contract in the axial direction of the cylinder housing. Having a sealed internal space, the bellows divides the oil and gas chambers completely. Thus, when the rod reciprocates in the axial direction, relative to the cylinder housing, the bellows extends and contracts axially.