Development of a tractor dynamic stability index calculator utilizing some tractor specifications

To examine the effects of different geometries and mass specifications of a tractor operating across irregular sloping grounds on the lateral stability of this machine, a dynamic model was developed. In the proposed model, overturn and skid instabilities were studied and the tractor stability indexes were formulated (i.e. TSI overturn and TSI skid). Using a modified Excel spreadsheet package employing the parameters of the model, the TSIs were then determined. Finally, the effects of variation in the parameters of the model on TSIs were evaluated. The results of the analyses indicate that changing the tractor mass moment of inertias about the x- and y-axes had no influence on TSIskid, whereas increasing the tractor mass moment of inertias about the x-axis by 71% led to a 2.5% reduction of TSI overturn and increasing the tractor mass moment of inertias about the y-axis by 71% led to a 1.8% reduction of TSI overturn. However, increasing the wheel–ground coefficient of friction from 0.34 to 0.84 improved TSI skid by up to 27%. Moreover, the effect of tractor wheel track width and the height of its center of gravity on TSI overturn was greater than the effect of the tractor wheel base on this stability index. Therefore, the best strategy for stabilizing a tractor against overturn is to lower the tractor’s center of gravity and increase the tractor’s wheel track width simultaneously.