pressure in the auxiliary pressure chamber 26 and thus in the auxiliary pressure partial chamber 27 of the cylinder a counter force is exerted which corresponds to the piston area less the piston rod cross sectional area multiplied by the pressure in the auxiliary pressure chamber 26 the damping piston 17 provided with the damping valve 18 serves for the damping of the outward thrust movement in order to achieve a hydraulic end position damping it is readily possible for a certain quantity of liquid to be provided in the partial chamber surrounding the auxiliary piston rod 19 which quantity by reason of an appropriate position of installation of the temperature compensated gas spring effects a liquid damping when the piston rod 3 is in the nearly outermost position the form of embodiment according to fig2 differs from that according to fig1 essentially in that a partition 28 is provided in the interior of the damping cylinder 16 this partition 28 can be formed for example by a separator piston movable axially in the damping cylinder 16 or can consist of a fixed partition which is formed by a microporous sintered part acting as oil barrier but letting the gas through almost without hindrance in this way irrespective of the position of installation of the temperature compensated gas spring the quantity of liquid situated in the damping chamber can be held without danger of liquid flowing away into the main pressure chamber 22 through the passage opening 24 so that a constant or nearly constant outward thrust force of the piston rod is maintained.