Bearing floatation of forest machines (theoretical calculation)

Abstract

The purpose of the article is to summarize the calculation procedure and calculate the forest machines floatation depending on the type of mover and soil conditions. Research methods are analysis of literary sources, numerical methods of applied mathematics during calculations and calculated data approximation. Formulas and the procedure for calculating the track depth, the coefficients of resistance to movement, adhesion and traction of the forest machines movers are given. In the compiled mathematical model, slipping is not an input parameter; its value is determined by calculation comparing the resistance forces to movement and the mover adhesion to the bearing surface. According to the calculations results, it was found that forestry machines with a caterpillar mover have greater cross-country ability compared to wheeled vehicles. On weak and moderate soils, the bearing floatation loss of tracked vehicles due to insufficient mover adhesion to the bearing surface does not occur. A factor limiting the pressure of the caterpillar mover on the bearing surface should be recognized as the track depth, since at a pressure of more than 0.04 MPa, the track depth exceeds the machine clearance. To ensure the bearing floatation of wheeled vehicles on weak soils, the pressure of the wheeled mover should be limited to 0.6 MPa. To ensure the bearing floatation of wheeled vehicles on moderate soils, the pressure of the wheeled mover should be limited to 0.95 MPa.