<p>A piston rod having a variable volume auxiliary chamber extends into a primary chamber in a casing. Normally open valve means are arranged between the primary and auxiliary chambers which are filled with a compressible medium and which are in communication when the shock absorber is at rest. The variable volume auxiliary chamber accommodates changes in volume of the compressible medium resulting from changes in temperature of the medium. When impact forces are imposed on the piston rod, initial movement of the piston rod closes the valve means and subsequent movement of the piston rod into the primary chamber reduces the volume of the compressible medium therein thereby effecting energy absorption.</p>
