Manoeuvrability and directional stability of three-link road trains type “B-triple”
Abstract
Improving the efficiency of freight road transport, in particular container transport, requires changes to the length and full mass of trailer and semitrailer road trains. Accordingly, for three-link layout schemes, the overall dimensions and weight parameters increase, while it is necessary to comply with the requirements for axle loads. Since the regulatory frameworks of many countries require compliance with the axle load, this makes it necessary to increase the number of axles and to extend the road train, which adversely affects its turning performance. Conversely, improving turning performance through the use of steered axles (wheels) on trailers and semitrailers reduces straight-line directional stability. Therefore, to enhance the applicability of such road trains, the option of employing a dual steering drive system for the steered bogie axles of semitrailers is considered. The research methodology involves taking into account folding angles of the road train links, steering drive transmission ratios and accordingly the turning angles of the semitrailers steered axles, which determine the links trajectories displacement and the road train swept path width for different locations of the semitrailer with extended-base and for circular movement of the road train. For a three-link “B-triple” road train with non-steered semitrailers, the swept path width was 11.3 m, which significantly exceeds the permissible value of 7.2 m. Equipping the semitrailers with dual steering drive systems for the rear bogie axles substantially improved manoeuvrability, reducing the swept path width to 9.13 m, however, this value still does not meet regulatory requirements. At the same time, road trains with rear-steered axles (wheels) of the trailer links demonstrate inferior directional stability compared to road trains with front-steered axles (wheels) of the trailer links. To reach a final conclusion regarding the feasibility of a particular road train configuration, further studies on such road trains' directional stability are required.