Abstract: An operating unit for a transfer tool machine comprises a turret head having a rotary plate, a plurality of tool holding devices arranged on the rotary plate, a supporting arm supporting the turret head on the tool machine framework and a mandrel which is driven by a reducing driving device also mounted on the machine tool framework.

Abstract: A device for controlling the locking and unlocking operations of a gear wheel-rotary disc assembly comprises a ball for circulating screw having one end thereof coupled to a rotating coupling member. The screw is in turn rotatably engaged in a fixed ring-nut, which is housed in the bed of the device, to allow the screw to be axially driven, under the control of a driving motor.With respect to prior like devices, the inventive device allows the rotary disc to be driven quicker and more accurately from a locking position to an unlocking position thereof.