when the articulated train is moving fast on a straight stretch no sharp curves are possible so that the distance x between tractor vehicle 2 and trailer 3 and thus the gap 1 can be shortened this results in better air flow across the gap 1 and less turbulence so that the fuel consumption and pollution emissions of the articulated train are reduced the detecting of the current speed of travel is done internally to the system by means of a speed pickup 9 located on the trailer 3 the speed pickup 9 in the embodiment of fig1 is arranged as a speed sensor 11 on one of the axles 10 of the trailer 3 the actual speed of the trailer 3 is determined from the number of revolutions of the axle 10 per unit of time and processed in an electronic controller 8 see fig2 and 3 into a signal for adjusting the distance x reducing of the distance x occurs by a telescoping of the hitch 4 the tension tube 5 permanently engaging the trailer 3 forms a first pipe segment 15 in which a second pipe segment 16 that can be adjusted in the lengthwise direction of the vehicle is movably held the tension lug 6 is an integral part of the second pipe segment 16 the particular distance x that is set is detected by a distance sensor 19 arranged on the back side of the tractor vehicle 2 and used in adjusting the intended.