SUMMARY
The objective of this study was to find out the effects of torque rise on lugging ability of tractors. In British terminology, torque rise refers to torque back-up or torque reserve. Torque rise is the amount of torque that the engine can produce above the manufacturers rated amount of torque. It is the percent increase in torque, from rated torque to peak torque. In order to meet the above objective, two tractor reports issued by Nebraska Tractor Test Laboratory were used. Powertrain schemas obtained from three different tractor manufacturers were used and the total transmission ratios from these schemas were calculated. The effect of torque rise on lugging ability of the two tractors with four different gear boxes was studied. From the study, it was concluded that higher torque rise enables the tractor to run in a wide range of torque and the gear box to be chosen should be such that it can match with the engine.