System for automatic adjusting of a gap between a motorcar and a trailer coupled to it

The system comprises a length adjustable drawbar (4) with a draw tube (5) and a tow eye (6) arranged at the end side of the draw tube. The tow eye is displaceable over a predetermined travel path corresponding to the draw tube by an actuator (7) in the vehicle longitudinal axis. A control unit is provided, which is an electronic control unit (8) for processing a speed signal to a speed probe and is connected with the actuator. The speed probe is formed from Controller area networkbus.