Biological Systems Engineering


Date of this Version



Published in Applied Engineering in Agriculture Vol. 21(6): 949−954. Copyright © 2005 American Society of Agricultural Engineers. Used by permission.


Improvement of agricultural tractor performance was analyzed using the data from 926 diesel tractors tested at the Nebraska Tractor Test Laboratory from 1959 through 2002. The performance analysis included the specific volumetric fuel consumption, power per unit weight, traction coefficient, maximum torque rise, and sound level. They were evaluated based on the PTO power level and chassis type of tractor. Some of the results are: (1) The average specific volumetric fuel consumptions for the maximum PTO and drawbar powers increased by 20.5% and 23.4% to 3.47 kW•h/L and 3.01 kW•h/L, respectively, from 1959 through 2002. (2) The average maximum PTO and drawbar powers per unit weight of ballasted tractors increased 72.1% and 66.2% to 1.48 and 1.28 kW/kN from 1959 through 2002. (3) The traction coefficient increased 24.4% for 4WD tractors and 27.4% for standard tractors from 1959 through 2002, resulting in 1.02 and 0.94 for 2001-2002 respectively. In the 2001-2002 period, the average torque rise of the tractors in a PTO power range of 37-75 kW was 27.7%, which was 18.4% increase from 1992 through 2002. The tractors with greater PTO power than 187 kW had an average torque rise of 50.8%, which was 30.9% increase over the same period. The maximum sound level within the cab in the early 1970’s ranged from 83.0 to 93.6 dBA and reduced to 73.5 to 88.5 dBA in the 2001-2002 period, which was about 9.3% to 21.5% reduction from 1972 through 2002.