Prediction the Specific Fuel Consumption and Determination the Draft Force range of a Tractor to operate at the Maximum and Optimum Traction Efficiencies

摘要

Prediction equations were derived to estimate the specific fuel consumption of a tractor at maximum and optimum efficiencies for ballasted and none ballasted traction wheels. The equations can also be used to predict the specific fuel consumption for different tractor forward speeds and powers at traction wheels. A draft force range at which the tractor works at the maximum traction efficiency was determined from the field experiments results and it is 10 to 15kN for none ballast traction wheels. The maximum traction efficiency (71%) of the tractor occurred at draft forces 10 and 15kN (i.e at the boarders of the draft force range), while the optimum traction efficiency (74%) occurred at draft force of 12.5kN, which represents the middle of the draft force range. Outside this range the traction efficiency declines gradually as the draft force decreases less than 10kN or increases more than 15kN. The lower value of the specific fuel consumption (0.22kg/kWh) within the draft force range was recorded at the maximum traction efficiency and draft force values 10 and 15kN respectively, while the lowest value of the specific fuel consumption (0.18kg/kWh) was recorded at the optimum traction efficiency and draft force value 12.5kN (at the middle of the draft force range). Thus the specific fuel consumption range, which corresponding to the draft force range is 0.22-0.18-0.22kg/kWh. When the traction wheels of the tractor were ballasted with 300kg, the maximum and optimum traction efficiencies increased to 74% and 77% respectively, the draft force range widened to 9-16kN and the specific fuel consumption range decreased further and became 0.20-0.14-0.20kg/kWh.