Abstract: A chuck body is made up of axially movable plungers and jaws, in which the jaw has a master jaw body obliquely arranged with respect to an axis of the chuck body, the jaw also has a front face of the master jaw body and a rear end face of a master jaw head for restricting a position of the jaw with respect to the chuck body, a plunger receives a bushing which acts as a wedge means cooperating with the master jaw body, a driver at a rear end of the master jaw body being restricted in a backward movement within a range of a gap ?, and a wedge having a structure of canceling a moment applied to the jaw as a result of clamping, the driver providing a reactant force to the master jaw body for canceling a drawing force applied to a plunger.

Abstract: A chuck of the type having a body with a plunger that moves axially and is operably connected with wedges that move the jaws radially in response to movement of the plunger. The body is formed with guide surfaces, which maintain contact with the plunger at all times, and also with bearing surfaces which support peripheral surfaces of the wedges.

Abstract: A power cylinder for operating a chuck for a machine tool has a rotary cylinder casing, a pair of check valves for confining a pressure fluid in an operating chamber, accumulators for absorbing impacts of the pressure fluid, and detecting means for detecting the fluid pressure in the operating chamber. The power cylinder can be rotated in a state wherein the feeding and discharging of the pressure fluid is stopped.

Abstract: Three gripping jaws are slidably engaged in respective radial guide grooves in the front face of an annular jaw carrier for holding work to be machined. Each gripping jaw has a wedge integrally projecting rearwardly therefrom. The wedge is of T-shaped cross section, including a web extending radially of the jaw carrier and a flange at the inner end of the web. Slidably mounted in the jaw carrier for axial movement therein, a plunger has undercut wedge grooves for slidably receiving the flanges and parts of the webs of the respective wedges, causing the radial motion of the gripping jaws by a wedging action upon axial motion of the plunger. A pair of opposed overhanging portions formed by each undercut wedge groove in the plunger are caught between the jaw carrier and the flange of one of the wedges.