The dispersal of the weight of the road train along several running axles makes it possible to reduce the specific axial weight and, with a significant increase in load capacity compared to single vehicles, use road trains on public roads. At the same time, the use of trailers as independent transport links in the composition of the road train leads to an increase in overall dimensions, mainly along the length of the road train. The increase in overall length and the presence of articulated joints between the links of the road train negatively affects such operational properties of the vehicle as maneuverability. For trailers, the length of the drawbar is chosen constant and maximum, ensuring unhindered folding of the links of the transport train at any turning radii that take place in operational conditions. At the same time, the maximum length of the drawbar is necessary only for small turning radii; in straight-line motion, such a length dimension of the drawbar is not required. Adjustment of the drawbar length is possible by modernizing and using traction-coupling devices that ensure the maintenance of the optimal length of the drawbar depending on the turning radius of the road train. The article proposes a method for determining the minimum required drawbar length in case of unsteady movement on a turn for a road train in composition with a single-axle trailer. An analysis of the interdependencies of the folding angles of the road train, the angle of rotation of the steered wheels in the process of turning the road train by 90° with a stationary and adjustable drawbar length is carried out. According to the results of research, a number of patented technical solutions for traction-coupling devices with adjustable length of the trailer drawbar are presented, which have a positive effect on the safety of the road train under operating conditions.