Hydraulic cylinder with drift stop

摘要

A hydraulic fluid power cylinder assembly 10 includes a cylinder chamber 14, a piston 15, a piston rod 19 and an end cap 21. End cap 21 includes a drift stop chamber 24 and a drift stop blocking surface 25. Chamber 24 is in open fluid pressure communication with chamber 14 under all conditions. Piston 15 includes a piston body portion 16 and a drift stop body portion 29. Drift stop body portion 29 includes a drift stop blocking member 31 and a positioning surface 34 for preventing the blocking member 31 from contacting the walls of cavity 24 and cylinder chamber 14 when disengaged from blocking surface 25. In one position drift stop body portion 29 is received within drift stop cavity 24, and blocking member 31 engages blocking surface 25 to prevent unintended movement of piston 15.

主权项

1. A fluid power cylinder assembly comprising a cylinder body and a piston,
the cylinder body having a generally cylindrical interior surface defining a longitudinally extending cylinder chamber, the piston having a generally cylindrical longitudinally extending piston body portion with a generally cylindrical exterior surface slidably disposed within the cylinder interior surface, a drift stop body portion fixed to the piston body portion and spaced laterally inwardly from the interior surface of the cylinder body, a longitudinally extending drift stop cavity defined by a longitudinally extending drift stop cavity wall, the drift stop cavity having an open end opening into the cylinder chamber, the drift stop cavity being in open fluid pressure communication with the cylinder chamber under all conditions, the drift stop body portion extending longitudinally into the drift stop cavity when the piston body portion and the drift stop body portion are each in one position, the drift stop body portion being longitudinally spaced from the drift stop cavity when the piston body portion and the drift stop body portion are each in another position, a drift stop blocking surface carried by the drift stop cavity wall, a laterally movable drift stop blocking member carried by the drift stop body portion, the drift stop blocking member having one position engaging the drift stop blocking surface to limit longitudinal movement of the piston when the piston body portion and the drift stop body portion are each in their one position, and the drift stop blocking member having another position spaced from the drift stop blocking surface when the piston body portion and the drift stop body portion are each in their other position, wherein the drift stop body portion extends longitudinally from the piston body portion, a combined lateral cross sectional area of the drift stop body portion within the drift stop cavity and piston body portion within the cylinder chamber is substantially equal to a lateral cross sectional area of the cylinder chamber, and the combined lateral cross sectional area is exposed to fluid pressure of the drift stop cavity and cylinder chamber under all conditions, and wherein the force of fluid pressure acting on the combined lateral cross sectional area provides the sole means for disengaging the drift stop blocking member from the drift stop blocking surface.