Abstract: This invention relates to improvement of a chuck unit for machine tools consisting of main body, plunger, and master jaw. In a chuck where the master jaw and plunger engagement part constitutes an inverted T shape in cross section, slide surfaces of engagement between the wedge part of the master jaw and the plunger are formed into circular arc shape.

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: This invention relates to a cooling mechanism of a rotary hydraulic cylinder for chucking operation of machine tools. In a rotary hydraulic cylinder which consist of a rotor member having a reciprocable piston inside and in which working oil is fed to the piston in said rotor member, many fins are mounted, parallel to the movements of said piston rod, on the outer periphery of said working oil supplying member, and a cylinder-like cover whose side facing to said rotor member is folded inside to make a flange, is mounted at the edge, of said fins, facing said rotor, so that it may partially enclose the outer peripheral surface of said rotor member. The side of the rotor member enclosed by said cylinder-like cover, of said oil supplying member is provided with a rotary fan which rotates together with said roller member, thereby causing an air inlet opening of a fixed clearance between said cover and the rotary fan to be formed.

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.