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: The invention has been developed to solve the drawbacks of the conventional chuck construction, and it is an object of the invention to provide a compact chuck construction, by omitting the axial movement parts, which are inevitable in the conventional chuck construction. A chuck body 10 comprising an axially movable plunger 30 and a jaw 20, in which said jaw 20 having master jaw body 24 obliquely arranged with respect to the axis, said plunger 30 having a bush 41 which act as a wedge, and a driving means 50 at the rear end of the master jaw body 24, said wedge means 40 having a structure of canceling a moment applied to the jaw 20 as a result of clamping and the driving means 50 providing a reactant force to the master jaw body 24 for canceling drawing force applied to the plunger 30.