Some issues of redistribution of axial loads between truck and semi-trailer

Among the most important trends in the development of forest transport in the country is a continuous increase in the share of automobile forest transportation and an increase in the distance of transportation of forest from harvesting sites to places of subsequent processing or delivery to the final consumer. All this aggravates the problem of the justified choice and rational operational parameters of timber-carrying road trains for transporting timber as tree-lengths and assortments, as well as the efficient organization of timber-carrying vehicles and calculation of production rates. Modern forestry trains are equipment of high operational parameters. The carrying capacity of the forestry road train increases, its engine power decreases, its own specific weight decreases, and structural stresses increase. Semi-trailers in the forestry industry of our country have been in operation for quite some time. During this period, the technology of harvesting and timber transportation has changed several times. The aim of the study is to examine the axial loads arising from the movement of an optimally loaded timber truck when moving along forest roads of various categories. This study is based on the provisions of the theory of traffic in off-road conditions. To determine quantitative indicators the methods of statistical equations and dependencies were used to specify the coefficients of comparison of factor and effective attributes, as well as methods for solving trigonometric equations and dependencies. The study describes the effect of the dynamic loads arising in the coupling devices during the operation of timber tractors equipped with a semitrailer pole carriage in difficult road climatic conditions. The article discusses the role of improving the design of coupling devices and forestry road trains to increase the volume of timber transportation and throughput by installing the drive on a semi-trailer. Thus, the coupling weight of the road train becomes equal to the full weight, which significantly increases the parameters of flotation on the forest roads of the lower category. The tangential traction on the driving wheels should be ensured by the adhesion of the wheels to the road, therefore, the redistribution of axial loads when the active semitrailer pole carriage is used is very relevant. The obtained theoretical dependences allowed the authors to determine the load redistribution coefficients from the timber truck to the wheels of the semitrailer pole carriage in the process of timber transportation along the forest roads of the lowest category to ensure the reliability of the timber truck and its trouble-free operation.