In order that a signal can be transmitted without contact from a stationary vehicle part to a rotationally mounted vehicle part, in the case of axial displacement between the parts, provision is made for a rotary transformer having pot-type cores for primary and secondary windings which have L-shaped profiles. These pot-type cores are mounted coaxially inside each other such that one or a plurality of air gaps existing between them run parallel to the rotational axis and are intersected by the magnetic flux radially with respect to the rotational axis. One of the surfaces of the two pot-type cores bordering on the air gaps is provided with a bevel, which tends to decrease the width of the air gap when an axial displacement lengthens the path of the magnetic flux. One of the pot-type cores may include a plurality of ring segments.