Influence of Layout and Mass Parameters of a Vehicle and Trailer on The Stability of a Light-Duty Road Train

The use of trailers with passenger cars, pickups, SUVs, and vans is commonly driven by the need to transport cargo, particularly oversized or specialized items (such as boats, watercraft, snowmobiles, etc.). However, the stability of such vehicle-trailer combinations depends on multiple factors and cannot always be guaranteed, even when the design is considered optimal. This study analyzes the influence of layout and mass parameters of the towing vehicle and trailer on the critical speed of a light-duty road train. It is shown that increasing the wheelbase and mass of the towing vehicle, as well as shifting the center of gravity of both the tractor and trailer forward in the direction of motion, and reducing the distance between the center of gravity of the tractor and the hitch point of the road train, lead to an increase in the critical speed. In contrast, increasing the trailer wheelbase slightly decreases this speed. The conducted analysis revealed that the critical speed for the studied road train configuration is only 29.4 m/s, which is significantly lower than the maximum possible speed of the towing vehicle alone. This highlights the necessity of a detailed study on how the mass and layout parameters of the vehicles affect the stability of the road train. The results demonstrate that increasing the towing vehicle’s wheelbase and mass, shifting its center of gravity forward, and reducing the distance to the hitch point improve the system’s stability and increase the critical speed. Conversely, the trailer’s base length and drawbar have minimal effect. The relationships obtained were described using simple regression equations, which can be applied in the design of control systems aimed at improving the stability of light-duty road trains.