Heavy Duty Trucking

JUL 2014

The Fleet Business Authority

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On trailers it's 8 to 10%, on trucks and tractors it's 12 to 15%. The usual configuration for tractors is discs front and drums rear. Brake adjustment is another reason for disc brake growth. Out-of- adjustment brakes are often an issue in roadside inspections, and citations now affect a fleet's Compliance, Safety and Accountability ratings, Hansen adds. "Disc brakes are encapsulated and have fewer moving parts, so out-of-stroke is not an issue. Some fleets are looking at disc brakes so they don't have the concern over adjustment." Disc brakes are inherently self-adjust- ing and have no "stroke" to measure, so are difficult for inspectors to gauge unless they have dynamometers to measure performance. Some states do. Aside from refuse fleets, firms adopting discs are those sensitive to safety, like haulers of petroleum, chemicals and industrial gases. Freight haulers who are squeezed more by costs are more likely to stick with drums. "Customers have to choose among disc brakes and elec- tronic aids like lane-departure warn- ings, electronic stability control and so on, and they have only so many dollars to spend on safety," says Meri- tor's Kay. "There are also automated transmissions, for driver ease and fuel economy." One who's staying with drums is Kirk Altrichter, vice president, main- tenance for Crete Carrier Corp. "Cost and weight" argue against discs, he says. He wasn't clear on price, but puts the weight penalty at 100 or more pounds per axle. "We're struggling constantly to take weight off," he says. "The cost for that is $1.50 per pound — that's a figure we use. So there's not enough justification to make discs worth it. Drums meet the stopping distance but the jury's still out as far as how they're lasting. I don't think there's extra life." Air disc brakes might some day account for 25% of sales, says Gan- away. More bullish is Randy Petresh, vice president, technical services, at Haldex Commercial Vehicle Systems, which sells a variety of components for brakes and air systems. He thinks disc brake usage might go to 70% in 10 years. Even so, "There's never going to be a complete conversion. There's always going to be segments Circle 276 on Reader Action Card that will stick to drums no matter what. And cost — drums have been in production for 30, 40 years and tooling has been amortized, so drum- brake parts are dirt cheap." Parts pricing is one reason air drum brakes are popular among buyers of medium-duty trucks. "In Class 6 and www.truckinginfo.com JULY 2014 • HDT 53

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