An Improved Traction Model for Ballast Selection

Coefficients of traction prediction equations developed by Brixius (1987) were modified to fit traction data obtained from an instrumented tractor operating on a grass surface. The modified equations which resulted in improved predictions of the net traction of the rear wheels of the tractor were developed into a traction model for a four-wheel-drive tractor using a commercial equation solving package. The model was used to predict the optimum ballasting for the tractor operating on the grass surface. The predictions indicated ballasting was not particularly critical for the grass surface involved.