This work deals with issues related to increasing the stability of the movement of machine units. Manoeuvrability is also one of the most important aspects of machinery, especially trailers. The results of the research carried out in the article allow us to find one of the ways to increase the productivity of trailed machine units, reduce operating costs and improve the quality of agricultural work. In order to increase the productivity and efficiency of the use of machine units, it is necessary to increase the working speed, width of grip, rationally use the agricultural machines that are part of the machine units. The result of improving these indicators can be: lower operating costs for performing mechanized work, reducing the metal consumption of the process of creating machines, shortening the time of work. The current state of the problem is briefly considered, the relevance of the research is substantiated, the purpose of the work is formulated, and the main theoretical principles of the operation of machine-tractor units are presented. A review of scientific works on the outlined issues was carried out, the advantages and disadvantages of the use of combined trailed tillage machines were analysed, the problems that arise when using trailed machine-tractor units were identified, tasks and ways to improve the stability of straight-line movement and manoeuvrability of trailed machine-tractor units were outlined, and also considered different criteria for evaluating their straight-line movement stability and manoeuvrability. The main parameters affecting the stability and manoeuvrability of machine units, and especially combined ones, are considered. The design of the traction coupling device, which increases the indicators of stability of movement and manoeuvrability of trailed machine-tractor units, is described, and a kinematic analysis of the operation of the proposed traction coupling device is performed. The theoretical justification of the problem of the stability of tillage machine units, which consists in the occurrence of external disturbances from the reaction of the soil environment on the working bodies, and as a result, the deviation of trailed machines from straight-line movement, is considered. This deviation is eventually stabilized by the traction force and reappears with the opposite sign, resulting in oscillatory processes described by the laws of vibration. It is to compensate for such deviations that a special construction of the traction-coupling device is designed, which ensures the stability of the unit and ultimately increases its efficiency. Keywords: machine unit, towing links, experiment, operation, turning, manoeuvrability, tractor, tillage unit, traction and coupling device.