A maneuvering element consisting of a crank provided at one end with a protruding handle and at the other end with a hollow bush which actuates a rotation transmission shaft and furthermore providedwith a safety system, consisting of a button housed within a cavity obtained in the crank for the actuation of a locking pin, and with the buton there is associated a retaining feature of the locking pin axially controlled by the button and apt to rotate between a fastening position and an unlocking position.