Regulated hydro-pneumatic strut

Claim 1

A level-regulated hydropneumatic strut including a cylinder having a housing, a piston and piston rod within the housing dividing the interior thereof into a piston space and an annular space, respectively, a hydroreservoir connected to the interior of the housing, and means for providing communication between the piston space, the annular space and the hydroreservoir being increasingly throttled, viewed from the level position of the piston upon elastic deflection of the piston dependent upon the path of the piston, the improvement being said piston rod having an axially extending bore, a tube attached to the cylinder housing extending through the piston into the bore of the piston rod in a seaLing manner, said tube having its outer periphery tapering over part of its length at both ends toward the center thereof, said tube, at its area of smallest diameter being provided with a transverse bore, said piston rod having a transverse bore for connecting the annular space with the axial bore of the piston rod, the transverse bore of said tube lying, in the level position of the piston in the area between the surface of the piston facing the piston space and the transverse bore in the piston rod, first spring means biased between the cylinder housing at one end of the tube, second spring means biased between the other end of the tube and the piston rod, said cylinder housing having two axially spaced abutments between which said tube is movable, a pressure connection, a drain connection, said cylinder housing in the area of said abutments having a plurality of communication means adapted to communicate with the pressure connection, the drain connection, and the piston space respectively, and said tube having communication means for coacting with the communication means of the cylinder housing whereby providing a three 3-way level control valve which is centered by said first and second spring means at the level position of the piston, the communication means providing communication between the pressure and drain connections respectively being separated from the communication means connected with the piston space.