Drawbar tests for the farm wheeled tractors (Tab. 1) were carried out on the farm road and the cultivated field (Tab. 2)
The results are as follows:
1) Coefficient of rolling resistance (C₁) is 0.0388 on the farm road and 0.153 on the cultivated field. Coefficient of impact resistance (C₂) is 0.00971 on the farm road and 0.0198 on the cultivated field (Tab. 3).
2) Coefficient of rolling resistance shows a tendency to decrease with increasing total weight of tractor (Fig. 1).
3) On the farm road, the tiresize has little effect on tractive coefficient of driving wheel (Fig. 4) but on the cultivated field tractive coefficient of driving wheel increases with in creasing the tiresize (Fig. 5). Tractive coefficient of driving wheel for 7-24 tire and 8-24 tire at 20% slip is 58% on the farm road and 39% on the cultivated field.