THE EFFECT OF THE TIRE INFLATION PRESSURE AND THE ADDED WEIGHT TO THE TRACTION WHEELS ON SOME OF THE TRACTOR FIELD PERFORMANCE PARAMETERS OF 2WD (MF285S)

This research was conduct to investigate the effect of the tire inflation pressure and the added weight to the traction wheels on the power available at the traction wheels, the draft power and the rolling resistance. Four tire inflation pressure values (0.5, 1.0, 1.5 and 2.0bar) and four weights (0, 150, 350 and 450kg) were used. The experiments were conducted on MF285S tractor of two wheels drive (2WD). The results showed that the tire inflation pressure of 1.0bar surpassed the other tire inflation pressures, it gave the highest PF (16kW) which occurred at F of 18kN while tire inflation pressure of 1.5bar came second, it gave PF of 14.5kW which occurred at F of 17kN, while tire inflation pressure of 0.5bar came third (12kW, at F of 15kN) and the tire inflation pressure of 2.0 was last (10.5kW at F of 14kN). The power at the traction wheels was not used completely due to the limit soil strength. The power losses in wheels slip and the rolling resistance (Pd-PF) increased as the draft force increased. It was higher for inflation pressure of 2.0bar it approached 18kW (66% of Pd) at F of 20kN, while it was the lowest for tire inflation pressure of 1.0bar (8kW) and it composed 33% of Pd while it was medium for tire inflation pressures of 0.5 and 2.0bar. The addition of weight to the traction wheels increased PF when F is constant, At F value of 15kN, PF increased from 12 to 13, 16 and 18kW, 450 kg increased PF by 50%, when zero weight (dynamic weight of the traction weight is 17.37kN), 250kg (19.82kN), 350kg (20.8kN) and 450 (21.78kN) were added to the traction weigh respectively. The power losses decreased from 18kW to 9kW (50%) when zero and 450kg were added to the traction wheels at F value of 20kn respectively. For 250 and 350kg weights the power losses were medium. The lowest rolling resistance was recorded for inflation pressure of 1.25bar. The rolling resistance increased with added weight but the tire inflation pressure of 1.5bar gave the lowest value while 1.5 became second.