PIT Compares 6x2 and 6x4 Tractors
August 15, 2013
FPInnovations’ Performance Innovation Transport group, a not‐for‐profit engineering and research center for the North American trucking industry, announced results of performance evaluations comparing 6x2 and 6x4 trucks that took place during the PIT Energotest trials at the Transport Canada Motor Vehicle Test Centre in Blainville, Quebec in June 2013.
The test results show that 6x2 tractors consume less fuel than similar 6x4 tractors. PIT traction performance evaluations show that 6x2 tractors’ traction was also reduced compared to 6x4 models.
“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. “The results being released scientifically demonstrate that for the vehicles tested, 6X2 tractors have better fuel performance than similar 6x4 tractors, which can lead to significant savings for fleets.”
In the evaluations of fuel consumption and traction performance of 6x2 and 6x4 tractors, PIT compared the following vehicles:
• 2013 Volvo VNL 64T 6x4‐Meritor MT40‐14XC rear axle, 2.64 ratio
• 2014 Volvo VNL 62T 6x2‐Meritor RS23‐160/161 rear axle, 2.67 ratio; Volvo non drive axle
• 2012 Kenworth T660 6x4‐Dana Spicer D40‐170P rear axle, 3.21 ratio
• 2012 Kenworth T660 6x2‐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)
• 2012 Kenworth T660 6x2‐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, 6x2 tractors consumed from 2.6% to 3.5% less fuel than similar 6x4 models. Using the TMC‐SAE Type III Test Procedure (SAE J1526), the Volvo 6x2 tractor used 3.3% less fuel than the 6x4 model.
PIT traction performance evaluations of the 6x2 and 6x4 tractors used a pull sled test to compare pulling distance, maximum speed and acceleration. When pulling the same sled on a similar surface, the 6x2 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 6x4 tractors. This test was a first field cooperation with the NACFE and PIT wishes to thank the group for its participation.