Patent ID: 8172052

Claim:
A shock absorber system including a stem and a body, in which slides a piston mounted on a first end of a tube and defining at the least an upper chamber and a lower chamber in the body, the stem of the shock absorber including a stem body, joined to the second end of the tube and supporting a cup on which a spring transmits the weight of the vehicle, characterized in that the stem body includes an approximately cylindrical housing, in which slides a piston, an end of the piston being joined to a first end of a rod sliding in the tube and another end of the piston being joined to an attachment fastener of the shock absorber on the vehicle, and in that a prestressing means exert a force that tends to displace the piston sliding in the stem body, driving the rod in its displacement, depending on a balance between a force applied on the fastener joined to the stem piston and the force exerted by the prestressing means, the displacement of the rod towards the bottom resulting in the opening, at the second end of the rod, of a larger section for passage of oil from the lower chamber towards the upper chamber and, consequently, a rapid recovery of the shock absorber system, characterized in that the piston is constituted by an end stop piston and an annular piece coupled between themselves by a hollow extension, and defining an upper chamber, an intermediate chamber and a lower chamber, the end stop piston including a recess in which is lodged an anti-return valve sealed by a foil washer overbridged by a spring, and in that the oil passage from the lower chamber towards the upper chamber includes a recess of an annular piece in which the second end of the rod, having a rectangular section, forms vertical channels, that communicate with a cavity situated between the rod and the tube, in communication with the lower chamber, via radial channels bored in the tube and with the interior of the hollow extension, in communication with the upper chamber, via the anti-return valve, the recess and passage sections of the end stop piston, the opening of a larger section of the oil passage allowing a rapid recovery of the shock absorber system.