<p>The coupling has a first shaft, a looped spring (2") wound around the first shaft and with two looped spring ends and a second hollow shaft concentric to the first shaft and arranged around the looped spring. It has an actuator for applying a controlled tangential force to at least one of the looped spring ends (7'', 8'') against the winding direction of the looped spring and a balancing gear mechanism (11') arranged between the actuator and the looped spring ends of the looped spring.</p>
