Conceptual Energy Model of the Dynamics of a Transport-Technological Unit for the Appearance of Two Drive Axles

With an increase in the number of driving bridges of the transport-technological unit, its passability increases. However, at the same time, undesirable phenomena of power circulation in closed power circuits of the chassis and transmission of the transport-technological unit may occur. In the transport-technological unit, a closed circuit forms a power flow that passes through the driving bridges, connected to each other on the one hand by the transmission shafts, on the other - through the wheels and the road. In this power flow, kinematic inconsistency, and therefore circulation, occurs due to the fact that the radii of the wheels are not equal to each other, or due to the fact that individual wheels take different paths when moving on an uneven road. The role of compensating the kinematic mismatch of the friction clutch in the closed power flow of the transport and technological unit is played by wheels with elastic tires, which are frictionally connected to the road. Therefore, the issue of power circulation should be considered in the paper, it should be started by considering the rolling of an elastic wheel on the road. Energy losses occur in the tire when an elastic wheel rolls on an undistorted road. They consist of elastic hysteresis losses due to tire radial deformation and tire elastic sliding losses due to tangential deformation. It is proved that the power lost due to hysteresis is equal to the product of the angular velocity of the wheel and the moment of rolling resistance, which is equal to the product of the normal load on the shoulder of the rolling resistance. It was also found that in order to evaluate the conditions for the appearance of power circulation in a multi-drive tractor-transport unit, it is not necessary to consider all closed circuits that the tractor-transport unit may have; it is enough to consider one of the contours, or, in other words, a transport unit with two driving bridges. From the obtained dependencies, it follows that the circulation depends on the difference in the free radii of the wheels, the coefficient of tangential elasticity of the tires and the movement resistance of the transport-technological unit. If the difference in wheel radii is zero, there is no circulation. Thus, the reason that causes the circulation of the power of the transport-technological unit moving in a straight line lies in the unevenness of the free radii of its wheels.