Improving the tractive performance of walking tractors using rubber tracks

The pneumatic wheels of a walking tractor were replaced with rubber track system to improve draught. Performance was evaluated in agricultural soils and compared with that when fitted with wheels. Tests were carried out in sandy clay loam soil with cone index (CI) varying from 250 to 1000 kPa for both the tractors. Data of motion resistance, pull and slip were acquired using different sensors and data acquisition system. For CI of 250, 500 and 1000 kPa, the observed motion resistance values for tracks were found to be 1012, 775 and 620 N, respectively, which represent 18.75%, 14.36% and 11.5% of the weight of the tested walking tractor and 935, 675 and 530 N for the wheeled walking tractor which represents 17.32%, 12.5% and 9.8% of its weight, respectively. Rubber tracked walking tractor developed greater drawbar pull than the wheeled one in all soil conditions. The drawbar pull developed with tracks is 115.2%, 75.9% and 62.4% more than that developed by comparable walking tractor fitted with standard wheels, respectively in soils with CI 250, 500 and 1000 kPa. Tractive efficiency (TE) of walking tractors fitted with rubber tracks was higher in all soil conditions. Also, tracks reached peak TE at higher net traction ratio (NTR) and maintained higher TE for a wider range of NTR. Wheels reached maximum TE at lower values of NTR, which drops off at higher NTR values. The results indicate a significant improvement in the tractive ability of walking tractor.