Simulation of power parameters of track mover of a tractor

Abstract

The expediency of use of analogy of wheel and track movers interaction with the supporting surface is established. The research aim is to implement the possibility of simulation of power parameters of a track mover with rubber-covered caterpillars using the positions designed for movers of wheeled vehicles. It is suggested to determine an axial force in plane of contact area of track mover through the sum of products of normal responses and adhesion coefficients on slipping and idling sections of elements of contact area. The normal response in each section should be determined taking into account the variable diagram of specific normal responses. Without slipping of elements, a rectangular diagram is assumed; with full slipping, a triangle one with right angle on the rear part of contact area is assumed. A diagram is a trapezoidal in case of the intermediate slipping. It is recommended to calculate the adhesion coefficient of elements of contact area in the sliding section through the descending elliptical dependence as a function of the relative normal response on slipping section of contact area. The low value is equal to the static friction coefficient of elements without slipping, the high value is equal to the coefficient of sliding friction with full slipping. It is recommended to calculate adhesion coefficient of the idling section through the ascending elliptical dependence as a function of the relative normal response on slipping section of contact area. The low value is equal to zero without slipping, the high value is equal to the static friction coefficient in the transition to full slipping of extreme rear element. The calculated values of the axial force coefficient for track mover of John Deere 8300RT tractor with 1.91 radians of central angle of contact area are well coherent with the actual data of drawbar tests of John Deere 8310RT, 8335RT and 8360RT tractors carried out in the University of Nebraska-Lincoln. The proposed simulation algorithm of power parameters of track mover could be useful when choosing the rational traction modes of tractors operation in different operating conditions.