Abstract: A self-pumping hydropneumatic spring strut that continuously regulates the pressure in the low- and high-pressure work cavities of the work cylinder to control the height of the vehicle body during all vehicle operation situations. According to the present invention, a valve is provided between the high-pressure work cavity and the pump cylinder. The valve is movable axially within the pump cylinder and advantageously blocks a first nonreturn valve between the pump cylinder and the low-pressure work cavity when spring strut is caused to elongate, and unblocks this first nonreturn valve when the spring strut is caused to compress.

Abstract: According to the present invention there is provided a vehicular height adjusting device capable of diminishing a shock caused by a sudden change in pressure of an accumulator oil chamber at the time of adjusting the vehicular height to adjust the vehicular height in a gentle manner and capable of diminishing a beat noise of an opening/closing valve generated by the vehicular height adjusting operation, thereby improving the comfortableness.

Abstract: A hydraulic shock absorber including a cylinder having a hydraulic fluid sealed therein, a reservoir connected to the cylinder so that a pressure is always transmitted between the cylinder and the reservoir and a self-pumping mechanism provided between the cylinder and an oil tank to effect feeding and discharge of the hydraulic fluid between the oil tank and the cylinder by extension and contraction of a piston rod, to thereby control a length of extension of the piston rod. The cylinder is connected to a pressure accumulating mechanism having a pressure accumulating tank and a switching valve mechanism. The switching valve mechanism is adapted to be switched to accumulate a pressure in the pressure accumulating tank or apply a pressure accumulated in the pressure accumulating tank to the cylinder.

Abstract: Self-pumping hydropneumatic shock absorbing strut with internal level control, in particular for motor vehicles, in which, to regulate the level, a pump which is driven by the movements of the spring transports damping medium from a low pressure chamber which is under a lower pressure into a high pressure chamber which is constantly pressurized by the respective spring force of the shock absorbing strut. During this process, when a specified level is exceeded, the damping medium can flow back into the reservoir via a regulating device, whereby the regulating device is a recess between the work chamber and the low pressure chamber, which regulating device can be controlled by a magnetically actuated closing element.

Abstract: In the self-pumping type shock absorber wherein the working fluid is pumped up from a reservoir to an accumulator by a pump operated in accordance with the expansion and contraction stroke of the shock absorber cylinder-piston assembly so that the pressurized working fluid is supplied to the cylinder chamber space of the cylinder-piston assembly so as to increase the overall length of the cylinder-piston assembly such as to increase the vehicle height supported thereby, the passage for conducting the pumped up working fluid into the accumulator and the passage for conducting the stored high pressure working fluid from the accumulator into the cylinder chamber space are separated and a variably controllable throttle is provided in the latter passage, so that a variably controlled additional damping force is uniformly available throughout the expansion and contraction strokes of the shock absorber.

Abstract: A hydraulic actuator including a pressure cylinder forming a working chamber having first and second portions operable to store damping fluid. The hydraulic actuator further includes a piston disposed within the pressure cylinder between the first and second portions of the working chamber, and a piston rod for supporting the piston in the pressure cylinder. In addition, the hydraulic actuator includes a reservoir for storing damping fluid as well as a pump at least partially disposed within the hydraulic actuator for pumping damping fluid from the reservoir to the working chamber.

Abstract: A self adjusting shock absorber comprising a cylinder and a shock absorbing piston movable in the cylinder and having a shaft extending externally of the cylinder. A reservoir is associated with one end of the cylinder. A flow passage is provided in the shock absorbing piston. A pump comprises a cylinder formed in the shock absorbing piston, and having a position sensing bleed orifice intermediate the ends thereof. A pump piston is fixed to the shock absorbing cylinder and is operable in the pump cylinder. The piston functions when in a position on one side of the position sensing bleed orifice to produce a pump "down" cylinder and when operating on the other side of the position sensing bleed orifice to provide a pump "up" cylinder. The pump piston has a first passage providing selective communication between the shock absorbing cylinder and one end of the pump cylinder, and a second passage providing communication between the shock absorbing cylinder and the other end of the pump cylinder.

Abstract: A self-leveling combined shock absorber and liquid spring assist unit comprising a pair of tubular structures of the piston and cylinder shock absorber type, one of which defines a load bearing spring chamber and the other of which includes an elongated displacement member for the spring chamber, the displacement member being tubular and cooperating with a pump rod to provide a pump-up function for the unit. An improved pump check valve arrangement between the end surface of the displacement member and the exterior annular surface of the pump rod is provided for controlling the flow of hydraulic fluid between the pump chamber and the load bearing spring chamber which comprises an annular body of elastomeric material having an annular anti-extrusion washer of rigid material embedded therein which is spring urged into sealing engagement by a coil spring and held in assembled relation by a rigid tubular element fixed to the exterior periphery of the displacement member.