TROY, Mich. — ArvinMeritor’s Commercial Vehicle Systems business supports the intent of braking systems improvements proposed by the National Highway Traffic Safety Administration that would reduce stopping distances by 20-30 percent, says Paul Johnston, senior director, North American Foundation Brake Business.

The company also agrees with the finding that truck-tractor vehicles represent the largest opportunity to reduce stopping distances with specific focus on increasing the level of braking on the front steer axle.

Johnston expects to see changes in the front axle steering and suspension as well as the ABS system in order to implement either drum or disc brake solutions to meet more aggressive stopping distance reductions. In addition, a more aggressive reduction in truck-tractor stopping distances may result in more attention to the trailer brake requirements. “We must keep an eye on the resulting compatibility with existing fleet equipment,” he says.

ArvinMeritor expects changes to ABS systems in order to meet
either drum or disc brake solutions for NHTSA rule

Depending on the exact percent reduction in the final rule, the stopping distance reduction could be achieved by increasing the brake torque on just the steer axle. Larger front drum brakes or air disc brakes could accomplish the requirement for many typical vehicle combinations. If reductions can be achieved with steer axle brake upgrade only, tractor/trailer compatibility should not be impacted.

The proposed new rule would only affect new tractors, although ongoing research by NHTSA may impact future stopping distance requirements for all air-braked vehicles. NHTSA has requested additional comments regarding revisions to dynamometer test procedures and requirements that could impact trailer brakes sometime after the new rule takes affect.

Because of new developments in air disc brakes, enhanced larger-capacity drum brakes, electronically controlled brake systems (ECBS), and advanced ABS, the NHTS concludes that tractors can achieve these new conditions with existing available technology, with modifications only to the foundation brake systems.

NHTSA is also researching and requesting comment concerning improving the braking performance of other types of heavy vehicles, such as trailers, straight trucks, and buses. The agency says it may address improved braking performance for these other vehicles in a future rulemaking.

The proposal and comments are available on the Department of Transportation Document Management System website, http://dms.dot.gov. Search for Docket #NHTSA-2005-21462.