Pull and lift forces acting on single cage wheel lugs

Abstract

The lug forces, normal and tangential, on a single model cage wheel lug were measured in a wet clay soil. These normal and tangential forces were converted into lug pull and lift forces. The effect of lug sinkage, slip and soil moisture content on lug forces was investigated. Lug normal and pull forces increased up to a certain degree of lug rotation and then after attaining a peak value decreased. The lug tangential and lift force also increased up to a certain angle of lug rotation, then dropped continuously, attained a negative peak value and finally rose again to become zero at lug exit. Increase in lug sinkage showed an almost proportionate increase in lug forces while increase in soil moisture content caused a decrease in lug forces. The effect of lug slip on lug forces at constant sinkage was found to be statistically nonsignificant as lug slip was always high. Using the passive pressure soil failure theory the lug forces were predicted and compared with the measured values. It was found that the theory did not predict the lug forces accurately.