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July 1, 2004 5:00 AM, EDT

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hile the National Highway Traffic Safety Administration has yet to release a proposed rule, fleets and suppliers are resigned to the fact that Class 8 trucks built after 2007 will have to be able to stop in a shorter distance than do today’s models.

Less certain is how the en-hanced braking will be achieved. Air disc brakes provide superior performance over standard drum brakes, particularly when brakes are applied frequently at higher speeds. But larger-capacity drum brakes may be able to meet the new requirements.

“The rules are expected to require up to a 30% reduction in stopping distance at 60 miles per hour,” said Jim Clark, chief engineer for commercial vehicle systems at Dana Corp. “That would require a bigger brake on the front axle and it could be either a drum or disc brake. We’ll need to increase braking torque up front because that’s where the vehicle’s weight transfers to.”

For the full story, see the June 28 print edition of Transport Topics. Subscribe today.

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