Patent ID: 8490763

Claim:
A delay return gas spring, comprising: a cylinder; a piston at least partially received in the cylinder for reciprocation between extended and compressed positions over a cycle including a compression stroke and a return stroke, wherein the piston comprises: a piston rod having an end extending out of the cylinder, and a radially outwardly extending shoulder at an other end within the cylinder; a collar positioned directly against the radially outwardly extending shoulder of the piston rod at the other end of the piston rod; a collar retainer carried by the piston rod to retain the collar on the piston rod; and a retaining ring carried by the collar retainer to radially retain the collar retainer to the collar and thereby retain the collar to the piston rod; a seal disposed between the cylinder and the piston and, during a portion of the cycle, separating a primary chamber defined by the cylinder and the piston on one side of the seal from a secondary chamber defined by the cylinder and the piston on another side of the seal; and at least one passage communicating at one end with the secondary chamber and at an other end with the primary chamber; wherein the seal is relatively movable between an open position permitting free flow of gas through the at least one passage to a closed position at least partially restricting gas flow through the at least one passage so as to permit gas in the secondary chamber to be compressed in response to movement of the piston toward its extended position, thereby reducing a net return force on the piston and decreasing a velocity of the piston.