Heavy Duty Trucking

JUL 2014

The Fleet Business Authority

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do the job anymore, about 32,000 pounds." Beefy drum brakes absorb heat and work better in many cases. "There are also parking concerns," Kay continues. "Disc brake systems are more complex, and you don't get the same power, so OEMs go with some kind of driveline brake." n 7, greater than half the buyers buy air brakes," says Meritor's Kay. "Some Class 5 buyers will spec air if they have other air systems on the truck, though the lower end of Class 5 use hydraulic discs. It depends on gross axle weight rating; there's a point where hydraulic brakes just can't The Most Innovative Technology in Sealing! A B Dynamic Edge ® pumping feature deflects contamination away from the face of the seal Four floating points of contact lock out dirt and moisture A B The National ® Oil Seals "Red" 37 Series that help keep your fleet on the road mile after mile is enhanced with National Dynamic Edge ® technology. The key to National Dynamic Edge ® technology is a patent pending sinusoidal wave that actually creates a pumping action to aggressively push dirt away from the seal. For the latest technology and engineering innovation — there's no other seal that performs like National! All trademarks shown are owned by Federal-Mogul Corporation, or one or more of its subsidiaries, in one or more countries. ©2014 Federal-Mogul Corporation 54 HDT • JULY 2014 www.truckinginfo.com Friction Materials: Be Careful with Replacements F riction materials used on drum brakes have changed to meet environmen- tal concerns and stricter stopping-distance requirements set by federal safety officials. Suppliers note that asbestos was banned due to health concerns in the 1980s and other materials took its place. Recently, more ag- gressive materials were adopted to provide better performance or long life. "Linings have been organic and non-asbestos for 10 or 15 years," says Randy Petresh, vice president, technical services at Haldex. "There are probably 15 or 20 constituents in lining materials. Each manufacturer uses a different thing. Carlisle, when they were still in business, had Kevlar fiber. Others used fiberglass or steel wool. Haldex uses mostly fiberglass plus friction modifiers, which vary drastically from one supplier over another. They're based on the property you're most interested in." "Material science in friction materials has evolved greatly and we now have the best friction materials ever," says Gary Ganaway, director of mar- keting and global customer solutions at Bendix Spicer Foundation Brake. "There was a belief that air disc brakes were the only way to meet stop- ping requirements, but that has proved untrue. Now, the 250-foot stopping requirement is done in 220 feet, due to materials." Among replacements for asbestos was copper, but now that, too, is banned in some western states. "Copper gets into ground water and into rivers and lakes, and is toxic to fish," Petresh explains. Original-equipment brakes use legal and high-performing materials, but there's little guarantee that replacement linings work as well. Suppliers who sell to original equipment manufacturers are perplexed that federal safety authorities have not regulated the aftermarket. Cheap replacements seldom have OEM quality performance. "If you change to improper materials, you undo much of the advances," says Ganaway. "Fleets are astonished — 'Who's regulating this? Why can I go and buy this sort of thing?' Fleets are extremely safety conscious. What they lack is good information. "Many suppliers are not forthright with them. They point to the legacy requirement, the dynamometer requirement. Lesser materials might meet the dyno requirement but not the performance requirement. 'FMVSS 121-certified' isn't necessarily true." OE-quality remanufactured shoes not only use the same materials designed for specific applications, he and others say, but also restore the original shape to the steel table portion of the shoes. This ensures proper contact with drums for proper stopping ability and long life. "On a new product it has to meet requirements," says Kirk Altrichter, vice president, maintenance for Crete Carrier Corp. "Why do remans not have to? If they (suppliers) can't do it themselves, some government agency is going to step in. We solve it by buying OE. If it's Meritor we buy Meritor; if it's Bendix we buy Bendix." Brake Trends

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