Manufacturers Face Looming Rule Change

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.”

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