MATHEMATICAL MODEL OF THE TRACK DEPTH FORMATION OF A FORESTRY TRACKED VEHICLE
The paper considers the effect of external forces acting on the tracked vehicle chassis and participating in the redistribution of normal reactions on the bearing surface of the continuous track. In the systematic operation of logging and forestry tracked vehicles, conditions may arise when only a part of the bearing surface of the continuous track transmits normal and tangential reactions. In combination with the focus transmission of normal loads, characterized by local maximum loads in the area of supporting rollers, the effect under consideration leads to an increase in overloads, as well as normal and tangential deformations of the soil. The fundamental works on the theory of motion of tracked vehicles practically do not consider this effect, but the results of observations on them and examples of its mathematical description in the related field, the theory of motion of transport vehicles, are known. The research purpose is to propose a mathematical model to estimate the track depth of a tracked vehicle, to predict the energy consumption in case of its motion on deformed forest soils, taking into account the effect of underutilization of the track support surface length in contact with the ground. The objects of research are the chassis of skidders, forwarders and harvesters based on tracked tractors, as well as the chassis of transporters-swamp buggies and other transport and transport technology machines used in logging and timber transportation industry. Conditions under which the epure of normal reactions under the track takes the form of a triangle and does not capture the bearing surface as a whole are formulated. Dependencies have been proposed to quantify the track depth to be formed, the value of work at the vertical deformation of the forest floor and the relative increase in the power of resistance to the motion of the chassis, depending on the relative effective length of the bearing surface. The results of calculations for cohesive and weakly cohesive soils are used as an illustration. The developed model is used independently; however, its integration into the method of the calculated estimation of the operating parameters of machine chassis is also possible.