Fleets Slow to Adopt 6x2 Axles

This story appears in the Feb. 9 print edition of Transport Topics' Equipment & Maintenance Update.

Are the 6x2 axle configuration’s fuel savings and reduced weight worth its traction issues, greater tire wear and the difficulties that are always involved with change — especially with diesel prices declining?

Not yet, say most fleets.

Though 6x2s are common in Europe, a report released last year by the North American Council for Freight Efficiency found the configuration accounts for about 4% of new linehaul sales in America, with total market penetration rates at about 2.3%.

But NACFE’s executive director, Michael Roeth, said more fleets should consider it because they can save fuel costs of $2,100 per truck per year.

In a 6x2 configuration, only one of the tractor’s rear axles is powered, rather than both axles in the traditional 6x4 configuration.

That means there is less rolling resistance and parasitic drag, resulting in fuel savings of about 2.5%, NACFE said in its report. Fewer mechanical parts reduces the weight of the tractor by about 370 pounds, said Karl Mayer, Meritor Inc.’s director of product line management for North American axles, allowing carriers to add cargo capacity or other fuelsaving technologies.

The trade-offs? Having only one set of tires reduces traction on slippery and uneven surfaces. Not surprisingly, sales are higher in warm-weather areas, said Mayer. And the added stress on the drive-axle tires causes them to wear faster and requires fleets to rethink their rotation schedules. NACFE’s report found that tire life on the drive axle is about a third of that for a 6x4 drive tire, resulting in added tire costs of $466 per year per truck.

Finally, it’s harder to resell a 6x2, and driver acceptance can be a problem.

Steve Slesinski, director of product planning for Dana Commercial Vehicle Driveline Technologies, said some industry calculations have found average 6x2 resale values during the past 10 years to be about $5,500 less than 6x4s.

Because of all that, most fleets are doing what they’ve always done — sticking with the 6x4s.

Meritor’s Mayer said that when his company launched its FUELite tandem axle system in 2012, it expected sales would double annually to an undefined point — eventually in the neighborhood of 15% to 20% of the market. It has grown to about 4% of the company’s sales — not quite as fast as expected, but growing nonetheless.

“I think our industry in general is typically slow to adopt change sometimes,” Mayer explained. “I think there’s still some bad perceptions out there from the old days of loss of traction, residual values, etc. But I think the good news is that we’re starting to see more and more fleets try these, have success with them, and now we’re actually starting to see some major fleets start repeat orders.”

Dana, manufacturer of the Spicer EconoTrek tandem axle, sees a similar dynamic. Slesinski stated in a written response that the estimated take rate of his company’s 6x2 offering is about 3%.

“Fleets are traditionally conservative and they are most comfortable relying on proven technologies that have performed over the long term,” Slesinski said. “However, as fleets become increasingly metrics- driven and fully understand the benefits of 6x2, we see the popularity of this option rising. For example, the overall acceptance continues to be popular in dedicated bulk-haul operations.”

Mayer doesn’t believe that lower diesel prices will hurt sales growth of 6x2s. He said most in the industry believe the lower prices are temporary and that original equipment manufacturers and fleets are always looking for improvements.

“I think whether fuel is $3.80 a gallon, or $4.10 or $4.20, if you can save 2½, 2% fuel economy, it’s still money in the fleet’s pocket,” he said.

NACFE’s Roeth also doesn’t believe the lower fuel prices will hurt the growth of 6x2s. Unlike gasoline, which in some places is below $2 a gallon, diesel has not dropped that far. Moreover, trucking executives have long memories. Fuel prices have gone up and down in recent years, but the long-term arc is upward, so fleets are always investigating many different fuel-saving technologies.

“I don’t see people saying, ‘I’m going to stop testing things because of the lower fuel prices.’ . . . Even at $3.50 a gallon, a lot of these technologies will still pay for themselves,” he said.

Among manufacturers, Volvo Trucks and Mack Trucks said demand for 6x2s is increasing, while Anthony Gansle, Peterbilt’s marketing manager for on-highway products, said in a written statement that his company is seeing “modest interest and growth in 6x2 configurations.” Brad Williamson, manager, powertrain marketing for Daimler Trucks North America, said, “The overall perception of 6x2s in the industry has been improving, and we expect this trend to continue with the ever-increasing emphasis on fuel economy.”

But two manufacturers said that lower fuel prices are having an effect. Jodi Presswood, Navistar’s vice president and general manager for its heavy-truck product line, said growth has been steady year-over-year and is expected to continue in 2015. “However, lowering fuel prices and residual values could impact near-term increased adoption,” Presswood said.

Kurt Swihart, Kenworth marketing director, said his company sold about the same number of 6x2s in 2013 and 2014. “We expect to see some growth in this market segment over the next few years, but with the recent decrease in fuel prices, customers will be slow in adopting the technology,” he said.

About 1% of Ryder System’s 50,000 tractors are fitted with the 6x2 configuration, said Scott Perry, vice president of supply management. While usage has increased in recent years, it’s always done in partnership with customers for specific applications in leased fleets, not in general rentals. The configuration works best for longhaul, over-the-road routes, he said. For regional fleets that make a lot of deliveries, it’s often not the best choice because of curb cuts and other uneven terrain features that can expose the truck to traction issues.

“I’m not seeing a tremendous amount of adoption of the 6x2 at a rate that would tell me, ‘Hey, this is an emerging trend,’ or ‘This is something that’s becoming more commonplace.’ I still think it’s a very targeted, very specific, niche configuration,” Perry said.

Perry also said he is not hearing from customers that lower fuel prices are discouraging them from considering the configuration. However, he’s also not seeing new fleets requesting it.

“It may make some fleets say, ‘Well, that 2% to 5% or 6% may not be worth it if my fuel costs have gone down by 25% year-overyear,’ ” he said.

Royal Jones, president and CEO of Las Cruces, New Mexico- based Mesilla Valley Transportation, is perhaps the carrier industry’s most vocal 6x2 advocate. Virtually all of the fleet’s 1,300 trucks use that configuration, which it has been purchasing exclusively since 2007. He estimated the configuration increases his mileage by 0.3 to 0.5 mile per gallon.

The fleet’s long-term use of the configuration has taught it to work around some of the trade-offs. For example, the fleet programs most of the torque out of its motors in the early gears, which is where he said most tire damage occurs. Driver acceptance is not a problem because the fleet doesn’t use anything else. As for the resale issue, Jones solves that by simply selling the trucks himself through two company-owned dealerships.

“Anything can be a negative if you don’t thoroughly understand it and learn how to work with it,” Jones said.

Among the other fleets committed to the configuration is Hudson, Illinois-based Nussbaum Transportation, which hauls mostly dry van loads in all 48 states. The fleet began transitioning to a 6x2 configuration during its 2011 model-year purchase, when it bought about 10 trucks and then the next year bought only 6x2s. Phil Braker, vice president of operations, said the configuration has led to about 3% fuel savings.

Like Mesilla Valley Transportation, Nussbaum has created a number of solutions for some of the issues associated with 6x2s. Tire wear was reduced when the company shifted to Detroit Transmission’s 12-speed DT12, which allowed for smoother gear shifting than the company’s previous package. Drivers do complain about the configuration, but the company tries to prepare them during training, and it has made improved fuel economy part of the company’s culture by paying drivers extra for better mileage. As for the traction issue, it’s real, but Nussbaum said 6x2s actually are less likely to jackknife because the non-powered trailing axle acts as a rudder.

Furthermore, traction issues have been lessened by changing technology. Many early 6x2 configurations used manual dump valves so the driver could transfer air from the dead axle to the drive axle when he or she felt the load begin to shift, putting more weight on that axle. Now that’s often done automatically.

“A manual dump-valve system is certainly better than nothing, and I would say that any fleet, if they’re going to order a 6x2, must have some type of load-transfer system,” said Meritor’s Mayer. “Otherwise, they’re not going to be happy. They’re going to get into some events where they get stuck and have traction [problems] and then get tow bills.”

Roeth said technologies related to coasting, downspeeding and powertrains will further increase fuel savings associated with 6x2 configurations. It’s possible to lift the dead axle off the ground completely on return trips, though that does add complexity to the system.

“Make this the new norm. If you believe in it, go do it and . . . try hard not to turn back,” Roeth said. He later added, “I think this is one that has some real challenges to adoption, but if you’ve got some guts, this is a good one to look at.”