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The 6x2s are coming

FLETCHER, N.C. -- Truck, engine and component manufacturers have exhausted almost all the simplest ways to improve productivity for fleet owners and owner/operators. With the low-hanging fruit harvested, what will be the next big breakthrough...

Meritor's SMARTandem 6x2 axle configuration can save a fleet 400 lbs and improve fuel efficiency by 2%.
Meritor's SMARTandem 6x2 axle configuration can save a fleet 400 lbs and improve fuel efficiency by 2%.

FLETCHER, N.C. — Truck, engine and component manufacturers have exhausted almost all the simplest ways to improve productivity for fleet owners and owner/operators. With the low-hanging fruit harvested, what will be the next big breakthrough to increase payload and improve fuel mileage?

The answer may lie in spec’ing 6×2 configuration tractors, an industry norm in many parts of Europe, where disc brakes, automated transmissions and other technologies that make life better for drivers and fleet managers have been deployed and perfected before finally arriving on these shores.

Axle manufacturer Meritor believes there is a place for 6×2 configurations here in North America – including Canada – and is bringing to market a new offering designed for this market. A 6×2 configuration, a rather foreign concept to Canadian truckers, consists of a vehicle where only two of six wheel positions are powered. The second tandem drive axle is sometimes referred to as a “dead” axle, because it carries load but doesn’t help propel the vehicle.

This concept may seem at first to be a nice, but impractical idea in Canada, where slick conditions are hard to avoid for much of the year. However, when coupled with sophisticated electronics, 6×2 axles are surprisingly capable, even on the slickest of surfaces.

Meritor recently demonstrated its 6×2 axle capabilities at a press event at its Fletcher, N.C. axle plant. The company launched its SoloDrive series of 6×2 axles at this year’s Mid-America Trucking Show with the introduction of its FUELite tandem axle, based on its 160-Series drive axle. Its next offering in the 6×2 category, scheduled for launch in 2013, is the SMARTandem, which combines elements of the FUELite with other characteristics borrowed from Meritor’s popular 14X tandem drive axle. The SMARTandem provides the fuel and weight savings offered by the FUELite, along with greater traction that rivals that of the 14X tandem.

The SMARTandem uses advanced electronics to prevent wheel slippage and offers an automatic differential lock, making it more operator-friendly than the FUELite, while also extending tire life. Since it essentially takes the driver out of the equation, this newest option will be well-suited for large truckload fleets with high driver turnover. The FUELite performs well, while in the hands of a trained, experienced and skilled driver, but isn’t entirely foolproof.

So, why the sudden interest in 6×2 axles? Matthew Stevenson, general manager of North American field operations and marketing with Meritor, said customers are beginning to ask more questions about Meritor’s future plans for 6×2 offerings.

“We are hearing the demand out in the field and trying to get a handle on how large this market can grow,” Stevenson said.

To find out, the company surveyed 500 fleets to gauge their level of interest in, and knowledge of, 6×2 configurations. Of those responding fleets, about 60% had no, or little, knowledge of the benefits of 6×2 axles.

Respondents who were familiar with the concept cited loss of traction and poor resale value as their chief impediments to 6×2 adoption. Meritor’s research also found that fleets would be interested in exploring the viability of 6×2 axles if they could gain fuel efficiency, reduce weight and decrease maintenance. Only 10% of the fleets surveyed that run more than 100 trucks, and 13% of those running less than 100 trucks operate some portion of their fleets as 6x2s. Only 20% of fleets indicated they were “likely” or “very likely” to spec’ 6×2 drive axles today. However, Meritor figures that with the price of diesel expected to remain high, and with increased education on the benefits of running a dead axle, that the market penetration of 6×2 axles could grow from 3% today to 18% within five years. That’s a sizeable chunk of the market, and one that Meritor has decided is worth investing in.

As with any new technology, however, Meritor officials acknowledge there’s a learning curve. They’re beginning to educate customers on how to properly introduce 6×2 tractors into their fleets without making some common mistakes that would be sure to leave a sour taste in their mouths.

Stevenson stressed fleets can’t simply spec’ a 6×2 tractor without also considering the impact tires, axle ratios and other spec’s will have on the performance of the vehicle.

“It has to be spec’d as a system,” Stevenson warned. “Otherwise, it will not work and you will not be happy as a customer with that configuration.”

For example, open lug tires with aggressive tread patterns should be spec’d on the powered axle, while more fuel-efficient low rolling resistance tires can go on the tag axle. A load transfer system, which shifts weight onto the powered axle upon acceleration in low traction scenarios to prevent the tires from spinning, is also highly recommended. Meritor Wabco’s ECAS (electronically controlled air suspension) is one such offering, which is slated to hit the market in 2013.

“If you don’t have ECAS, it’s going to affect tire life,” Stevenson admitted. With ECAS, he said, “You can get tire life that’s darn close to what a fleet would see in a 6×4 application.”

The weight savings provided by a 6×2 amount to about 400 lbs, which translates to additional payload in applications that maximize their gross vehicle weights. Meritor promises fuel savings of 2-4% when spec’ing its FUELite or SMARTandem 6x2s. It’s that fuel-saving potential that’s garnering the most interest from fleets. Even a 2% fuel savings can translate to up to $1,120 per year in savings at today’s fuel prices, which extrapolated over an entire fleet amounts to big bucks.

The SMARTandem has been used in Europe, where 6x2s are commonplace, for four years and has been in testing here in North America for the last two years. Charlie Allen, general manager, rear drive axles with Meritor, said there are 15 SMARTandems undergoing field-testing in North America, and they’re performing well even in wintery conditions.

Stevenson said Canadian fleets that run north-south could benefit from the fuel and weight savings, but it wouldn’t be recommended for operations that run predominantly in winter conditions; ie. regional fleets in northern Manitoba. This is primarily a mainstream, linehaul specification.

While Canadian customers will be skeptical of a 6×2’s practicality in the great white north, a demonstration by Meritor revealed a remarkably capable system. A Freightliner Cascadia with 53-ft. trailer was parked on a subtle grade with its drive tires placed on a slippery surface (think hockey board material), which was then sprayed with a soapy substance to further reduce what little traction there was. The test truck was rigged so that the operator could switch between traditional 6×2 and SMARTandem performance. In traditional 6×2 mode, the powered axle’s wheels spun hopelessly, but with SMARTandem’s electronics activated, the truck pulled forward with very little wheel spin at all. It’s one of those demonstrations, like electronic stability, that has to be seen to be fully appreciated.

Meritor wouldn’t comment on the price of the SMARTandem, due out sometime next year, because the OEMs will ultimately determine the price. However, it’s expected to be in line with the cost of a conventional 14X tandem drive axle. Resale value may initially be a concern, particularly in Canada. Meritor’s research showed a $5,000 penalty at resale time may be incurred, but in some fleets, owner/operators are actually willing to pay as much or more for the 6x2s the fleet has put up for sale, because they have seen the benefits first-hand. Some carriers that are among the early adopters are getting well over 8 mpg, officials claimed.

As for Canada, with t
he snowy, icy conditions we all know and love, don’t discount the possibility of the 6×2 trend catching on with some progressive fleets with dedicated trucks running north-south lanes. It would seem improbable, but with advancements made on the electronics side of the equation, it just may happen. Fuel savings aren’t going to come easy anymore, with so much that’s been done in recent years, so 6×2 axles are something that at the very least, may merit some investigation.

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7 Comments » for The 6x2s are coming
  1. Josh says:

    Hey, they can have their 6x2s, automatic transmissions, 300 horsepower engines, and bubble shaped cabs. For me, I’ll take a 13 speed overdrive with a 500 horsepwoer Cummins, a classic Peterbilt or Kenworth exterior design, and a 6×4: 6 miles to the gallon and all. And I’ll meet them at the next hill.

  2. Mark Sarty says:

    We won’t know how this will work out if we never try! I can certainly understand the positive side, maybe more +’s than -‘s ie. how many tire chains will I have to throw!? 2! Also maybe able to run a trailer like tire on the rear axle. On the drive axle run a more exspensive drive winter tire!

  3. Ulf says:

    Here in Sweden the tag axle has single wheels, like the front axle, with twins on the drive axle only. With a legal max weight of 19 metric tonnes the drive carries 11.5t and the tag 7.5t. The tag axle is of course liftable as well, so if you get stuck in the winter you just raise it so the drive axle gets all the weight. The same is true when running empty or lightly loaded, so you save fuel, tires, and minimize the risk of a puncture.

    BTW, I haven’t seen a 300hp tractor in a long time. They tend to be around 500hp, with a few 700+hp if the owner makes too much money… Less than that is uneconomical with 60t gross.

  4. Dave Again says:

    ECAS…electronically controlled rear suspension? Shifts weight between axles? Hmmm…where does that fit into the Ontario SPIF regulations calling for “self equalizing?” Will this option even be in compliance with Ontario law?
    All that aside, the 6X2 option may work very well in Ontario for freight operators, unless they park in those gravel lot truckstops along the way. Their tag axle will be hung on a pothole, and the drives spinning in the breeze.
    Call me a skeptic, but I think American test track conditions won’t necessarily make a successful leap to real world Canadian conditions.

  5. Angelo Diplacido says:

    I don’t understand how this can be considered a breakthrough. In the early 1980’s , I ran a tandem straight job with a 26 ft box and an air lift tag axle. Same concept but with the marked advantage over merritors concept that the rear or front axle could be raised clear off the ground and the variable of rolling resistance eliminated. The air lift tag could be manipulated up and down as an aid for situations when I got stuck. I can’t explain why this helped but it did. As for any electronic traction control, posi-traction and air lock differentials have been around for decades. Most air lift axles ran trailer tires as it acted only as a follower. This would alter the pivot point naturally , and cause the tag axle to scrub and wear prematurely but I believe merritors design is subject to the same rigours. Depending on the application , I believe that the old design is still superior provided that the driver understands the air lift and is willing to make it work. Merritors design is “idiot-proof”.

  6. Michael says:

    This is hardly “Breaking News”. Kleysen Transport did this back in the late 80’s with some of their Kenworth T600 tractors that were hauling mail for Canada Post.

    The rear axle should be the drive axle and the forward axle be the dead axle. It just makes sense.

  7. claud cagle says:

    Rear tag in snow will not work ! Tag must be in front . Been there will not work .

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