Abstract: A chuck for clamping workpieces or tools is provided. The chuck has a chuck body and at least two clamping jaws are radially displaceably guided in the chuck body and are operable, via wedge surfaces, by a driven chuck piston that is axially displaceable. The chuck piston is in the form of a closed, first annular piston having an outer surface that is guided all the way around in a bore of the chuck body, with a forward region of the outer piston surface being provided with tangentially extending wedge surface, the number of which corresponds to the number of clamping jaws, with these wedge surfaces cooperating with correspondingly shaped counter-surfaces of the clamping jaws. A second annular piston, which operates in an opposite direction, is disposed in the chuck body concentric to the first annular piston. The second annular piston is also provided with tangentially extending wedge surfaces that cooperate with corresponding counter-surfaces of the clamping jaws.

Abstract: An arrangement for mounting a power-operated clamping device for workpieces or tools on a hollow machine-tool spindle in which is disposed a securing rod that is adapted to be coupled with a drive member of the respectively mounted clamping device, and that is adapted to be actuated by a hydraulic or pressurized cylinder secured to the rear end of the spindle. Secured to a flange on the front end of the spindle is an intermediate ring to which the body of the clamping device is adapted to be secured via at least two securing pins. To provide a structurally straightforward design that requires no additional pressure medium cylinder, the securing pins are secured to the clamping device body and are axially oriented, with each securing pin being provided with a notch that has a tightening surface. Key rods are displaceably guided in the intermediate ring, with each key rod having a key that is introducible into a respective notch of the securing pins.