Self-pumping hydropneumatic spring strut

A self-pumping hydropneumatic spring strut, comprising:

• an oil-filled working cylinder having a working piston dividing said cylinder into two working spaces and a hollow piston rod carrying said working piston and which is moveable back and forth within the cylinder;
• a first high-pressure chamber comprising a first gas cushion with a first gas volume, and a second high-pressure chamber comprising a second gas cushion with a second gas volume, said first and second high-pressure chambers being connectable to or separatable from one of the working spaces in the cylinder such that the piston rod is selectively supported in both directions of movement on one of the first gas cushion, the second gas cushion, or both the first and second gas cushions, wherein each of said first and second gas cushions is a gas spring;
• a piston pump comprising a pump cylinder and a hollow pump rod having a bore connected to a low-pressure chamber, the pump cylinder being defined by the hollow piston rod, the pump rod having a first end attached to the working cylinder and a second end inserted into the hollow piston rod, the pump rod having a suction valve arranged at the second end;
• and
• a control channel selectively connecting the one of the working spaces to the low-pressure chamber through a control opening as a function of the position of the working piston in the working cylinder, wherein the piston pump is driven by movements of the piston rod to convey oil from the low-pressure chamber to the one of the working spaces so that the spring strut is extended by the piston pump when said control opening is closed to a partial spring extension position at which the control opening opens.