Evaluation of Tractor-Trailer Rolling Resistance Reducing Measures 2010-01-1917
This study aimed to evaluate several rolling resistance reduction measures applicable to class 8 tractor-trailer combinations. Two methods have been employed: fuel consumption tests according to the SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure - Type II, and long-term operational observations using control and test vehicles monitored throughout baseline and test periods.
One way to reduce the rolling resistance is to use wide-base tires: two different Type II fuel consumption tests revealed a more than 9 % improvement in fuel economy for a tractor-trailer combination equipped with wide-base tires. Long-term operational observation assessed the use of single wide-base tires on two 8-axle B-train tractor-trailer combinations. The results showed an average 5.11% fuel improvement and an average 4.37% energy intensity improvement. Other tests compared single-wide base tires with different tread patterns and tire compounds.
Another possibility to reduce fuel consumption is to use tires with low rolling resistance: track-test fuel consumption tests resulted in up to 2.4% improvement in fuel economy for tractor-trailers equipped with these tires on their drive axles, compared to normal tires. Long-term operational observation demonstrated 6.27% fuel improvement and 4.13% energy intensity improvement for the vehicle equipped with a technology package that included low rolling resistance tires on drive and trailer axle. Energy intensity represents the quantity of energy required per unit of production.
Other approaches to reduce rolling resistance and their impact on fuel consumption have been assessed. The influence of lift axles on fuel consumption for unloaded B-trains was evaluated, and the tests resulted in 4.7% improvement in fuel efficiency with three out of five axles raised. Other tests confirmed that maintaining the correct tire pressure can be as important as selecting the right tires. Tests conducted with two different self-adjusting wheel balancers showed no statistically significant influence on fuel consumption.
Conservative estimations demonstrate that rolling resistance reduction measures could bring annual greenhouse gas emissions reductions of up to six tonnes per vehicle with very short payback periods, and they represent viable measures for reducing fuel consumption and greenhouse gas emissions.