ABSTRACT
Off-road vehicle performance differs from normal performance on paved roads mainly due to soil deformability. Vertical deformation of the soil surface (compression) under a running device increases motion resistance. The cause is a loss of driving energy due to greater rolling drag. Similarly, longitudinal deformation (shearing) weakens driving action as a result of wheel slip and a loss of friction between tyre and soil surface. These effects depend on surface type and condition, and off-road performance results for a given vehicle may vary over a wide range.
