Clamping chuck with six arms mounted on ball joints compensated two by two

Jaw type clamping chuck having a body and comprising a plurality of jaw carriers sliding in the body of the chuck through the action of a traction rod moving axially, said traction rod having a mechanism converting this axial movement into a radial movement of members for clamping a workpiece effected by pivoting arms and a connection by truncated sphere and inclined plane, the clamping chuck comprising at least six jaw carrier arms which are actuated two by two by a compensator, each compensator being articulated on a pulling member centered on the axis of the chuck and sliding axially in its main body through the action of the traction rod, the compensator having two rectangular openings oriented along the radius of the chuck, the edges of the inner side of which form a ramp on which bears a plane face of the truncated sphere connected to the corresponding jaw carrier arm, wherein the compensator hinges with the pulling member via a pin passing through a central hole in said compensator.