Heavy Duty Trucking

SEP 2014

The Fleet Business Authority

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t 102 HDT • SEPTEMBER 2014 www.truckinginfo.com This month is a bit of a departure for Tires & Wheels, as we investigate a concern at the wheel-end — brake drum and lining wear likely related to the recent change in stopping dis- tance requirements for heavy trucks. We have heard reports of shorter- than-expected steer-axle brake drum life and of noisy, chattering brakes on trucks equipped to meet the shorter stopping distance requirements that went into effect in August 2011. Some of those models would now be coming up on a reline interval, while others may now require brake service where historically there was none. Briefly, the National Highway Traffic Safety Administration man- dated that a tractor-trailer traveling at 60 mph must come to a complete stop in 250 feet, versus the old stan- dard of 355 feet. The first trucks the rule applied to were three-axle trac- tors with a gross vehicle weight rating of 59,600 pounds — or just about every line-haul truck in the country. Fleet exposure to the symptoms seems to be tied to the OE and their choice of brake supplier. Bendix and Meritor, for example, both report that changes they made to their lining formulations and brake designs to meet the reduced stopping distance rules are manifesting them- selves on some customer trucks as chattering noises, and in other cases as shortened lining and/or drum life. "The problem is you've got these Jim Park • Equipment Editor Front-axle brakes designed to meet reduced stopping distance rules may not run hot enough under nor- mal driving conditions. Reduced stopping distance rules have some unintended consequences at the wheel-end. What's going on with my brakes? Tires&Wheels

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