Kinematic discrepancy and moving resistance dependence on tires air pressure in 4x4 tractors

Abstract

The article presents and analyzes the reasons of kinematic discrepancy in 4x4 tractors. The kinematic discrepancy between the driving wheels occurs in tractors and other self propelled machines. In field works, the slippage of the driving wheels is usually adjusted by changing the mass of ballasts and air pressure of tires, but, by adding weight and changing tire air pressure, the wheel rolling radius is changed, too. During transportation, tractors are equipped with trailers and semi trailers. Depending on the load weigh the vertical forces of the tractor and the wheel radius change in wide range. Kinematic discrepancy occurs, then the wheel rolling radius is changed disproportionately. Due to kinematic discrepancy, the front and rear wheels have to slip unequally, some of them can even slide. These factors have negative effect for the tractor performance parameters, the transmission is loaded heavily, power losses are increased, the tires wear faster, fuel consumption is increased. But it is hard to find scientific articles on the impact of kinematic discrepancy on tractor rolling resistance and braking performance. In this article kinematic discrepancy of 4x4 tractors depending on the tire air pressure is shown and analyzed.