Abstract: A gas spring assembly includes a cylindrical tube, a piston slidable within the tube and defining a gas pressure chamber, a rod extending from the piston through one end of the tube, and a seal assembly including an axially compressible, consumable seal for preventing escape of gas between the rod and the tube. A stop formed in the inner wall of the tube is adapted to engage the piston to limit the extension of the rod to a constant, maximum value, regardless of axial compression and consumption of the seal. The seal assembly is disposed between the stop and one end of the tube, opposite the piston, and includes gas passageway allowing pressurized gas to act on one end of the seal assembly to thereby bias the seal assembly toward one end of the tube.