Patent ID: 6491143
Filing Date: 2002-12-10
Classification: F16F

Abstract:
A gas spring comprising:a casing defining in part a main gas chamber adapted to receive a gas under pressure; a piston rod assembly received at least in part in the casing for reciprocation between extended and retracted positions; a first sealing surface within the gas spring; a second sealing surface constructed to provide a substantially gas-tight seal with the first sealing surface during a portion of the stroke of the piston rod assembly to define in part a secondary gas chamber separate from the main gas chamber and adapted to contain a gas under pressure providing a force on the piston rod assembly opposed to the force on the piston rod assembly of the gas in the main gas chamber to reduce the net force on the piston rod assembly during said portion of the piston rod assembly stroke and configured so that when the piston rod assembly is in its extended position, the gas pressure in the secondary gas chamber is greater than gas pressure in the main gas chamber.