A first input member (6) and a second input member (7) are arranged along a first axis (4) and coupled in such a manner that a movement of the first input member along the first axis is converted into a rotational movement of the second input member with respect to the body (1). A first output member (8) and a second output member (9) are arranged along a second axis (5) and coupled in such a manner that a rotational movement of the first output member is converted into a movement of the second output member along the second axis with respect to the body. The second input member and the first output member are releasably rotationally coupled.