Fleet Management News & Business Info | Commercial Carrier Journal
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60 COMMERCIAL CARRIER JOURNAL | JULY 2015 EQUIPMENT: AIR DISC BRAKES generally packaged in a way that better protects them in those conditions." But air disc brakes in many cases are lighter than drum brake systems, freeing up additional cargo capacity – another plus for fleets. "The weight savings are there, but fleet managers must remember that this difference depends upon the overall wheel-end components chosen as part of the complete air disc brake package," Hicks says. "There are several options, such as our SAF Integral system, that can be lighter than a comparative drum brake." Weight savings often depend on sev- eral factors, such as the air disc torque plate. "Other combinations come into play as well," Krishnan adds. "In general, the more robust the design spec'd, the heavier it is. Drum brake systems can be lighter than air discs in some instances." Still, the potential weight savings can be significant, Fitch says. "A great example of this is our Maxx22T ADB on a Hendrickson trailer suspension," he says. "This configuration offers an overall weight reduction of up to 100 pounds on a tandem axle trailer." Air disc brakes still command a higher acquisition price. "Air disc brakes are still very much a premium product in North America," Krishnan says. Meritor's experiences in the Europe- an truck market, where air disc brakes hold an 80 percent market share, show that higher volumes eventually will lead to lower prices here, he says. "From what we've seen, the tipping point generally comes in when air discs reach approximately 50 percent market share. That's when you'll start to see pricing come down." One development that is helping to bring air disc pricing down to drum brake levels is tractor OEMs offering them as a standard spec on many new models. "Air disc brakes as a standard spec gives fleet customers the opportu- nity to see the inherent benefits of superior braking performance and maintenance," Fitch says. "It also helps to improve the volume scenario and acquisition cost." Trailers: The final air disc frontier Tractors aren't alone in seeing the ben- efits of air disc braking systems. Experts say they also offer superior braking per- formance when fitted on trailers. But for many fleets, this is a much harder sell for several reasons. Looking at Meritor's experiences with air disc trailer adoption in Europe, Kay says most North American fleets today choose not to play based on their upfront expense. As a result, air discs in trailer applications only hold about an 8 percent market share in North America. "This can be a problem, because there is always going to be a compati- bility-workload balance when you have disc and drum brakes operating on a tractor-trailer together," he says. "That's why trailers in Europe eventually mi- grated to air discs as well." Kay urges North American fleets us- ing air discs on tractors and drums on trailers to make sure they balance the brake system. "If you don't, the brake load can quickly get out of sync and result in a situation where the trailer brakes are working harder – and wear- ing out faster – because they are bearing the brunt of the work trying to stop the truck," he says. That said, according to Fitch, air disc brakes in trailer applications can offer extended service intervals up to double the life of drum brakes. "As on tractors, they offer faster serviceability, with less than half the time to perform a lining change on drum brakes," he says. Another plus for fleets, he says, is that air discs typically net fewer Compliance Safety Accountability violations since the out-of-adjustment concern does not exist in their design. "There is virtually no fading, and the potential weight sav- ings can be as high as up to 100 pounds per trailer axle." Long-term trends point to eventual air disc domination in both tractors and trailers in North America, Petresh says. "They're just a much safer braking option," he says. "That's why we're see- ing fleets that look closely at their safety margins moving in that direction. As fleets recognize how air disc brakes can reduce maintenance costs and reduce downtime because of the simplicity, they will begin to see the reduced cost of ownership by equipping trailers with air disc brakes." Bendix ADB22X air disc brakes have a two-pin floating caliper design that provides a more stringent overall dimen- sion accuracy and consistent force distribution.