Hydropneumatic vehicle suspension system

The control system for a hydropneumatic vehicle suspension has cylinders (1, 2) mounted between the sprung and unsprung masses. The piston chambers (3, 4) are fed from a first hydraulic tank (15) and the chambers around the piston rods (7, 8) from a second tank (12). A pressure control valve (20) is mounted in the line (19) feeding the chambers around the piston rods. A servo valve (6) is operated by the fluid flowing to the piston chambers and opens the control valve when this exceeds a predetermined threshold. An Independent claim is included for a method for controlling a hydropneumatic vehicle suspension