Trucks at Work

Taking aim at axle savings

So I spent a couple of days this week down in Asheville, NC, to tour Meritor’s big 504,000 square foot truck axle plant in nearby Fletcher, NC, but also to check out the company’s new “SMARTandem” 6x2 axle – a product now in the midst of a two-year field test with 15 Meritor customer trucks.

The impetus behind Meritor’s development of the SMARTandem is twofold: find ways to reduce axle weight, help boost tractor-trailer fuel economy, and attempt to bring 6x4 axle performance characteristics to a 6x2 configuration – all while keeping such a “hybrid” axle “price neutral” in comparison with traditional 6x4 offerings.

Matt Stevenson, Meritor’s general manager for North American field operations and marketing, explained what some of the biggest benefits the SMARTandem 6x2 axle should offer truckers – especially when combined with wide-base tires.

Yet fleets are understandably concerned about giving up the performance of traditional 6x4 axles – especially where traction is concerned – in order to gain the weight and fuel savings of a 6x2 package.

That’s why Meritor packed its SMARTandem with a host of traction-control features – from automatic traction control (ATC) to its electronically-controlled air suspension (ECAS) system – to try and eliminate such “trade-off” concerns. That’s one of the reasons Charles Allen, Meritor’s general manager for rear axle drives, helped craft the demonstration test you can watch below:

So, why all the fuss over axle configurations, you ask? Allen told me this is all being driven by two things: impending implementation of greenhouse gas (GHG) regulations for heavy truck, which will impose fuel economy standards on the industry, along with the ever more potent desire among truckers larger and small to reduce their fuel costs.

The ironic part of this is that a Class 8’s drivetrain – of which axles are a major component – really plays a very small role in the overall “energy consumption” picture for highway tractors. Indeed, Allen said research indicates 50% of the energy consumed by a heavy truck goes to “punching a hole in the air” as it moves down the road. Thus improvements to aerodynamics can offer the most potential for fuel savings.

Following aerodynamics are tires, which represent 34% of a Class 8’s fuel consumption, with “accessories” responsible for 10%. The drivetrain? That’s responsible for a mere 6% of the total.

“Thus where we play in the grand scheme of tractor-trailer fuel economy is the smallest area; can move the needle on fuel efficiency, of course, but not on the order of doubling fuel economy,” Allen explained. “But today, even a 1% improvement in fuel economy gets people’s attention because that can save a lot of money.”

Indeed, a 1% fuel economy improvement for a Class 8 tractor averaging 6.8 mpg over 100,000 miles per year can result in $551 to $699 in savings annually, according to Meritor's research on the subject -- depending on whether diesel is $3.80 per gallon or $4.80 per gallon. Achieve a 3% fuel efficiency gain and now we’re talking $1,654 to $2,096 per year, Allen said.

“That’s a huge payback,” he told me. “And that’s why we’re doing all of this work with axle configurations.”

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