Abstract: In a pneumatic or hydropneumatic tension spring which consists of a container in which a cylinder is concentrically arranged and a liquid and/or gas filling under pressure has an inward force upon a piston rod, between a working chamber on the piston rod side and an annular chamber a damper device is arranged which generates a greater damping effect in the inward movement of the piston rod than in the outward movement of the piston rod. Due to this measure a damped inward movement of the piston rod is achieved while the extraction of the piston rod can be effected without appreciable damping.

Abstract: In the illustrative embodiments described, a pneumatic spring includes selectively releasable structure, located in part at the outer end of the piston rod and in part at the corresponding end of the cylinder, for retaining the piston rod at or near its innermost position within the cylinder. The retaining structure carried by the cylinder preferably constitutes a sleeve surrounding the piston rod, and the structure carried by the piston rod may include projections for coacting with shoulders on the sleeve. Alternatively, the sleeve and piston rod may be formed with cooperating recesses for receipt of an external pin-like securing bracket.