Abstract: A tool clamping and releasing device comprises an axially movable tie rod and a shifting apparatus for the tie rod actuated by cup springs. The shifting apparatus comprises a sliding collar subject at one end to the action of the cup springs and which is provided with cams on the opposite end. A rotary collar has pins engaging the cams so that axial movement of the sliding collar rotates the rotary collar, which has a ramp; the tie rod has a cooperating ramp, so that axial movement of the sliding collar causes rotation of the rotary collar and axial movement of the tie rod.