Fluid-actuated hollow power chuck

A fluid actuated type hollow power chuck comprising:

• a chuck body having a central through bore therethrough of uniform diameter and adapted to be mounted on a hollow spindle of a machine tool, said chuck body having a large outer diameter front part facing away from the spindle and a small outer diameter rear part facing toward the hollow spindle, and having means extending through said front and rear parts for mounting the chuck body directly on the spindle;
• chuck jaws mounted on a radial face of the large outer diameter front part of said chuck body for radial movement thereon;
• a generally hollow cylinder body having a forward part secured to said large outer diameter front part of said chuck body and a rearward part spaced radially from said small outer diameter rear part of said chuck body, said chuck body and said cylinder body defining an annular cylinder chamber therebetween around the outer surface of said rear part of said chuck body;
• an annular piston in said annular cylinder chamber and having an axial piston sleeve integral with and extending from the rear thereof and slidably and sealingly fitted between the rearward part of said chuck body and said cylinder body and projecting rearwardly of said cylinder body;
• power transmitting means operatively connecting said piston to said jaws for operating said jaws in response to axial movement of said piston;
• and
• detection means provided at a position rearward of said cylinder body for detecting axial displacement of the end of said piston sleeve which is outside of said cylinder body which is indirectly indicative of radial displacement of said jaws.