Patent ID: 7131518

Claim:
Motion control apparatus for use with a rod, with the rod having an axis defining an axial direction, with the rod shiftable in the axial direction, with the apparatus comprising, in combination: a housing having an inside housing surface forming a hole to receive the rod there through along the axial direction; a piston mounted in the inside housing surface of the housing that is moveable between a rod motion controller engaged position and a rod motion controller unengaged position; an end cap slideably mounted on the inside housing surface of the housing to allow motion of the end cap in the axial direction; a friction collar mounted between and contacting with the housing and the end cap, with an engaging force being generated by the friction collar with the rod when the piston is moved to the rod motion controller engaged position, and when the piston is in the rod motion controller unengaged position, the rod moves in the axial direction; and a backlash reducer reducing relative motion in the axial direction between the friction collar and the housing and between the friction collar and the end cap when the piston is in the rod motion controller engaged position and when the piston is in the rod motion controller unengaged position to reduce backlash in the axial direction when the piston is in the rod motion controller engaged position, with the backlash reducer comprising a holder mounted on the inside housing surface in an adjustable position in the axial direction and abutable with the end cap to reduce backlash by reducing relative motion in the axial direction between the friction collar and the housing and between the friction collar and the end cap, with the holder comprising: an internal retaining ring mounted on the inside surface of the housing, with the end cap having a first end in contact with the friction collar and a second end held by the internal retaining ring in a backlash reducing position to reduce backlash by reducing relative motion in the axial direction between the friction collar and the housing and between the friction collar and the end cap.