Abstract: A device for subjecting a shaft to a combined simple rotation and alternating rotation of limited extent about its own axis, the device including two supporting plates which rotate with the shaft coupled to a vibration generator and, between the plates, a part of a gear system which rotates freely with respect to the shaft and is associated with rotation actuation motor. Two first slotted holes are formed in each one of the plates so that they are diametrically opposite with respect to the shaft, the first slotted holes being arranged, upon assembly, at second slotted holes formed in the gear system, elastic compression springs being rigidly coupled between the first and the second slotted holes.