Abstract: A chuck is provided with a cylindrical workpiece gripping element having a jacket and an article gripping member and a resilient rubber-like sleeve sandwiched between. The jacket and gripping member are partially segmented into longitudinal strips so that the element as a whole can be diametrically expanded and contracted and when used to grip a workpiece having an eccentric surface the element will automatically adjust to apply equal pressure at all points on the workpiece surface and thus not distort the workpiece. The element is expanded and contracted by movable jaws.

Abstract: A collet chuck includes a body having a spindle adapter secured to one end and a collet retaining ring at the opposite end for holding a collet in place in the chuck. Stationary slip ring and piston assemblies are mounted to the rotatable body by bearings and include a hydraulically operated piston movable axially to engage an actuator having a camming surface engaging the collet. A plurality of springs extend between the body and the axially movable actuator for providing clamping pressure to the collet. The hydraulic piston operates in opposition to the springs for releasing the clamping pressure on the collet.