Tire traction models - Comparative analysis and validation

The paper presents a comparative analysis of different tire traction models. The model developed by the authors, starting from a Bekker type pressure-sinkage relationship, was compared with the Wismer&Luth, the MacLaurin and the Gee-Clough models, in terms of specific net traction coefficient. Traction force and traction efficiency were also calculated. In order to validate the theoretical results, field tests were developed, using the U-650 tractor, equipped with the P2V plow. Variation of plow width and depth allowed different traction forces and drive wheel slips to be obtained. During the experiments, drive wheel slip and net traction force were measured directly, for wheel slip up to 30%. The results predicted by the proposed model fit well the experimental results; the average differences between calculated and measured data did not exceed 0.25...0.4 kN for the traction force and 4...5% for the traction efficiency. Applying the original Gee-Clough and Wismer&Luth equations leads to significant differences compared to experimental data over the entire range of wheel slip values (0 to 100%). When the MacLaurin wheel numeric is used in the Gee-Clough and Wismer&Luth equations, the specific net traction coefficient given by the Wismer&Luth model matches the experimental data and the values given by the proposed model when drive wheel slip does not exceed 28...29%.