Dynamics of single and double tractor wheel systems in the vertical direction

Abstract

The paper presents the results of studies of the dynamics of single- and double-wheel systems of a tractor in the vertical direction, depending on the profile of the supporting surface. The study was carried out for single and twin wheel systems of tractors of the KhTZ-240 series.
It is noted in the work that an increase in the productivity and efficiency of the use of machine and tractor units is achieved by increasing the working speeds, working width and rational use of agricultural machines that are part of the units. In this case, both the unevenness of the field surface and the speed of movement are sources of additional vibrations and vibrations of the unit. Additional vibrations of the constituent elements of the tractor lead to an increase in soil compaction. For a better understanding of this process, it is necessary to take into account the physics of the reaction of tires to irregularities in the surface of the field, in particular the effect of the elastic part of the wheel.
The wheel mathematical model includes a rolling resistance coefficient that depends on the tire pressure and speed. An equivalent dynamic model of single- and double-wheel systems has been compiled, it moves along the support surface in MatLab \ Simulink.
It is determined that the minimum radius of a single wheel is 0.7599 m, and the maximum is 0.8605 m.
Accordingly, the swing of the radius of a single wheel is 0.1006 m. The radius of a double wheel has a minimum value of 0.75 m, a maximum of 0.820 m, and swing - 0.07 m. The swing of the radius of the double wheels is lower by 0.03 m than for single wheels. A double wheel has a lower amplitude and swing of the velocity of the center of mass in the vertical direction than a single wheel. The twin wheel has less deformation in the vertical direction, that is, the dynamic radius remains more stable.
The transfer functions of the dependence of the speed of the center of mass of the wheel in the vertical direction on the rate of change in the height of the profile of the bearing surface for single- and double-wheel systems are formed. The logarithmic amplitude-phase frequency characteristics of single and double wheels in the vertical direction are calculated.