Patent ID: 8113323

Claim:
A self-pumping hydropneumatic spring strut with internal level control, the strut comprising: an oil-filled working cylinder divided into first and second working spaces by a working piston carried by a hollow piston rod, said first working space being connected to a high pressure chamber under the pressure of a gas cushion; and a piston pump which conveys oil from a low pressure chamber to the high pressure chamber, the piston pump comprising a pump rod received in a pump cylinder formed by the hollow piston rod, the pump rod being fixed in the working cylinder and having a bore connected to the low pressure chamber via a discharge valve, the pump rod having a distal end provided with a suction valve, and a down regulating opening between the discharge valve and the suction valve, the opening connecting the bore to the first working space as a function of the position of the working piston in the working cylinder, the pump cylinder being connected to the first working space by an outlet valve; wherein at least one of the discharge valve, the suction valve, and the outlet valve is a check valve comprising a housing having a bore with a circumferential wall formed with a plurality of guide ribs, a ball reciprocably guided in the bore by the guide ribs, and a resilient retaining element fixed in the housing over the bore, the retaining element capturing the ball in the bore and spring-loading the ball, the retaining element including at least one radially inward directed projection having a first end fixed to the retaining element and a second free end, the projection being axially resilient and limiting movement of the ball, the retaining element further including a closed circular outer area, a center, and a spiral-shaped spring tongue extending spirally from the outer area to the center, wherein the spiral-shaped spring tongue has a first radially outer fixed end connected to the outer area and a second radially inner free end; and wherein the at least one projection has an arcuate portion configured to mate with an outer surface of the ball.