Position sensing cylinder

A position-sensing hydraulic cylinder comprising:

• a hollow cylindrical housing;
• a piston and rod assembly reciprocal in the housing;
• a walled bore extending longitudinally into the piston and rod assembly;
• a support rigidly fixed with respect to the housing and reciprocally received by the bore, the support including a cross piece having one side defining a planar support surface and a stiffening ridge extending perpendicularly away from another side of the cross piece, the support having a generally T-shaped cross section;
• a potentiometer assembly having a potentiometer element disposed on the planar support surface, and wiper means slidably and resiliently engaging the potentiometer element for maintaining electrical continuity therewith;
• and
• a wiper carrier fixed for movement with the piston and rod assembly for carrying the wiper means, the wiper carrier including means cooperating with the support for permitting fluid flow through the wiper carrier and for substantially preventing fluid flow in the vicinity of the wiper means.

A position-sensing hydraulic cylinder comprising:

• a hollow cylindrical housing;
• a piston and rod assembly reciprocal in the housing;
• a walled bore extending longitudinally into the piston and rod assembly;
• a support fixed with respect to the housing and received by the bore, the wall of the bore slidably engaging the support to maintain alignment of the support within the bore, the support comprising a cross piece having one side defining the planar support surface and a stiffening ridge to the cross piece and extending perpendicularly away therefrom, the cross piece and ridge together forming the support with a generally T-shaped cross sectional shape, the cross piece and stiffening ridge having curved peripheral edges slidably engaging the wall of the rod bore;
• a potentiometer assembly including an elongated potentiometer element carried on a surface of the support and wiper means slidably and resiliently engaging the potentiometer element for maintaining electrical continuity therewith;
• and
• a wiper carrier fixed for movement with the piston and rod assembly for moving the wiper means relative to the potentiometer element, the potentiometer assembly generating signals representing relative positions of the wiper means and the potentiometer element, the wiper carrier having a hollow cylindrical body received by the piston and rod assembly and a wiper flange extending inwardly from the body, an end of the wiper means being embedded in the flange, the hollow body and the support cooperating to define spaces on either side of the stiffening ridge through which fluid flow is freely permitted, the flange having a surface which closely registers with surfaces of the potentiometer element and of the support to substantially prevent fluid flow through the wiper carrier in the vicinity of the wiper means.