Patent ID: 7311312

Claim:
A chuck body comprising an axially movable plunger and jaw, said jaw having a master jaw body obliquely arranged with respect to an axis of the chuck body, said plunger receiving a bushing which acts as a wedge means cooperating with the master jaw body, a driving means disposed at a rear end of the master jaw body for forcing the master jaw body in a forward direction, said jaw having 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 and is restricted in rearward movement within a range of a gap δ, said jaw having a movement guided to an inside direction of the chuck body of the jaw by the front face of the master jaw body and a front end plate of the chuck body, said wedge means having a structure for canceling a moment applied to the jaw as a result of clamping and the driving means providing a reactant force to the master jaw body for canceling a drawing force applied to the plunger, wherein said jaw is constrained to be drawn radially inward in a direction perpendicular to the axis of the chuck body in a first movement in response to an axial movement of the plunger and a wedging action of the master jaw body and in a rearward direction parallel to the axis of the chuck body in a second movement.