Methods to Calculate Slip Coefficient of Soil as a Factor of Tractive Performance

Abstract

Two methods to calculate slip coefficient which are more accurate and simpler than Janossi's and Reece's were found.
(1) The 0.63 times method: The j value when τ is 0.63 times τ^max on τ—j curve corresponds to K value by Janossi's tangential method.
(2) The maximum method: If j₀, the j value when the shearing strength becomes maximum value, is kown, K is given by the following equation.
K=j₀/4.6
(3) The 0.63 times method is suitable to predict the tractor performance in usual field work, and maximum method is suitable to know the maximum tractive force of tractor on the soil.