Abstract: In a magnetic-tape apparatus having two winding mandrels journalled in a frame, and a drive system whose direction of rotation is reversible for the transport of the magnetic tape in two opposite directions, switching means for the drive system can be actuated by a detection system which detects a stoppage of both or one of the winding mandrels while the apparatus is in operation. The detection system comprises two plates which are pivotally mounted coaxial with one mandrel, a respective one of the plates being frictionally coupled to each mandrel.