Internal check valve

Abstract

An internal check valve for use in a linear hydraulic motor in the form of a piston-cylinder unit including a cylinder body (38) reciprocally slidable on a piston component (40). The piston component (40) includes a tubular piston rod (52) and a piston head (60) defining first and second working chambers (136, 140) within the cylinder body (38). The tubular piston rod (52) includes a center tube (102) located within the piston rod (52). The center tube (102) provides a fluid passageway (134) through its center which communicates with a first working chamber (136). An annular second passageway (142) is formed by and radially between the piston rod (52) and the center tube (102). A spring biased check valve (116) is positioned within the piston rod (52, 54) and is operatively connected with one of the passageways (134, 126, 130). The check valve (116) has a valve member displaceable from a valve seat (120) by hydraulic pressure to overcome the spring bias (122, 124) and allow flow in one direction. The center tube (102) is axially displaceable relative to the piston rod (52). Displacement is effected by end of stroke movement of the cylinder body (38) and displacement of the center tube (102) causes displacement of the valve member (116) to mechanically open the check valve.

Dependencies are inferred from the claim text.