Evaluations comparing 6×2 and 6×4 trucks by FPInnovations’ Performance Innovation Transport (PIT) group showed that 6×2 tractors consume less fuel than similar 6×4 tractors. PIT traction performance evaluations showed that 6×2 tractors’ traction was reduced compared to 6×4 models. The not‐for‐profit engineering and research center for the North American trucking industry conducted the tests of five North American truck models at the Transport Canada Motor Vehicle Test Centre in Blainville, Quebec.
“The objective of our Energotest trials is to conduct controlled test‐track studies for the trucking industry of technologies that increase fuel efficiency and lower emissions of greenhouse gas,” said Yves Provencher, director of PIT. “These results scientifically demonstrate that for the vehicles tested, 6X2 tractors have better fuel performance than similar 6×4 tractors, which can lead to significant savings for fleets.”
In the evaluations of fuel consumption and traction performance of 6×2 and 6×4 tractors, PIT compared the following vehicles:
• 2013 Volvo VNL 64T 6×4—Meritor MT40‐14XC rear axle, 2.64 ratio;
• 2014 Volvo VNL 62T 6×2—Meritor RS23‐160/161 rear axle, 2.67 ratio; Volvo non drive axle;
• 2012 Kenworth T660 6×4—Dana Spicer D40‐170P rear axle, 3.21 ratio;
• 2012 Kenworth T660 6×2—Dana Spicer D40‐170P rear axle, 3.21 ratio; modified (emptied rear housing, removed the drive shaft between front and rear housing, change gears in the front housing, same ratio); and
• 2012 Kenworth T660 6×2—Dana Spicer D40‐170P rear axle, 3.21 ratio; modified (switched front and rear housing, emptied rear housing; gears not changed)
In tests using the SAE J1321 Fuel Consumption Test Procedure ‐Type II (SAE International 2012) for Kenworth models, 6×2 tractors consumed from 2.6% to 3.5% less fuel than similar 6×4 models. Using the TMC‐SAE Type III Test Procedure (SAE J1526), the Volvo 6×2 tractor used 3.3% less fuel than the OEM’s 6×4 model.
PIT traction performance evaluations of the 6×2 and 6×4 tractors used a pull sled test to compare pulling distance, maximum speed and acceleration. When pulling the same sled on a similar surface, the 6×2 tractors traveled from 5.4% to 13.5% shorter distances, reached maximum speeds that were about 17% lower, and exhibited from 10.5% to 35% slower acceleration rates compared to the 6×4 tractors.