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NACFE Updates 6×2 Confidence Report

A report by Heavy Duty Trucking’s Jim Park highlights the latest Confidence Report from the North American Council for Freight Efficiency, showing 6×2 drivetrains are still viable options for fleets looking for fuel and weight savings.

This latest report shows 6×2 technology is evolving as product refinements emerge and fleets continue to work around some of the configuration’s perceived challenge. Uptake on the technology, meanwhile is lower than what was predicted.

“While we found that the fuel savings benefits as well as the challenges from the original report are largely still true, new product refinements are coming to the market that are aimed at addressing some of the concerns fleets had about 6×2 axles,” said Yunsu Park, NACFE study team manager. “For instance, fleets dedicated to 6x2s are improving tire wear by changing the tire models they use and [electronically] limiting [engine] torque when launching the truck. Also, driver training has proven to be a significant part of a successful 6×2 implementation.”

The study team identified three generations of 6×2 products, but focused special attention on Generation III products, which contain liftable pusher axles, automatic axle-load biasing and traction control.

Among the lessons learned by early adopters of Gen I systems are that tire wear is higher when compared to equivalent 6×4 vehicles, with some fleets experiencing a 50–70% reduction in tire life on their drive tires. Fleets that have adopted best practices have cut this penalty significantly, decreasing the reduction in life to 20% on the driven axle.

Additionally, driver perception, particularly as it relates to safety and traction of 6×2-equipped vehicles, has not improved. Many drivers have not actually experienced or been trained on this configuration and often only hear feedback from a negative and sometimes vocal minority.

However, fleets that have implemented a complete Generation II system have found tire wear and traction issues can be managed at a much reduced level and are able to benefit from the fuel savings. Unfortunately for some fleets, the damage in driver perception was done before a full Generation II system could be implemented.

Despite those hurdles, fleets are seeing successes with 6×2.

“Fleets that are dedicated to 6×2 are making them work and have improved their tire wear and traction concerns pretty significantly,” explained Mike Roeth, executive director of NACFE and operation lead of Trucking Efficiency. “We have found that switching to 6×2 is not a simple implementation. It takes a systems approach and some effort from an engineering and spec’ing standpoint as well as a higher degree of driver training.

Additional Conclusions From the NACFE Report:

  • Drive tire wear on 6x2s will not achieve parity with 6x4s. However, measures can be taken to reduce the accelerated wear. Selecting a retread trailer tire for the free-rolling axle may result in the lowest cost option for fleets.
  • Fleets should take a system-wide approach and implement the full Generation II package including load-shifting technology, traction control, and engine parameters to limit torque in low gear, at clutch engagement, and under engine braking.
  • Good and consistent driver communication and training is critical with this technology. Drivers should understand the overall benefit of 6x2s, how the systems work, and when a manual intervention is beneficial.
  • Traditional 6×4 systems are improving, reducing the potential efficiency gains of a 6×2 system albeit at a greater cost.
  • Residual values for 6x2s remain a problem due to the reputation of Generation I systems. Fleets that have persisted and implemented Generation II 6x2s do not report a problem with residual values, although these are typically smaller fleets and would not turn over a large number of trucks at once.
  • Fleets should gain knowledge of 6×2 tag axle systems and test not only the technology but also their internal processes for managing engine parameters and driver communication and training.
  • Fleets that are below 60,000 lbs. GCWR at least 30% of the time should consider testing a liftable 6×2 axle system.

Meanwhile, as intelligence is being gathered south of the border,  Transport Canada’s government-industry working group continues to study 6×2’s from the Canadian perspective.  CTA, other industry associations along with representatives from all Canadian governments have been providing support for this work since Winter 2016.  The research being conducted by the National Research Council and the University of Waterloo is focused in three areas: traction, pavement damage and vehicle dynamics.   When completed it will be a comparative effort of both track and live road testing environments as well as computer simulation and dynamic modelling.  It is expected a final report will be completed in mid to late 2018.  Next steps from a regulatory standpoint in Canada will hinge on the outcomes in the final report.

Read the complete HDT article here.



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