Patent ID: 7559542

Claim:
A gas spring, comprising: a casing defining in part a gas chamber; a piston rod assembly having a piston rod received at least partially in the casing for reciprocation between extended and retracted positions, and a piston head carried by the piston rod; a housing at least partially received in the casing and having a through bore sized to receive said piston rod for relative movement therein as said piston rod assembly reciprocates between its extended and retracted positions; and an annular ring carried by the housing, encircling the piston rod, having a generally U-shaped cross section with a pair of axially spaced apart legs and an interconnecting bight portion with the legs extending circumferentially and generally radially and inclined relative to one another so that at least one of the radial legs flexes between an axially compressed position when said piston head is in its fully extended position and engaged with one of the legs of the annular ring to apply a force to the piston head and an uncompressed position as said piston rod moves toward its retracted position and the piston head is out of engagement with the annular ring and it does not apply force to the piston head, and the maximum axial distance between the radial legs is less in the compressed position than in the uncompressed position.