RSD-compliant brakes: The great (and dangerous) Unknown

Source: The first in a multi-part series on this topic on

WASHINGTON, D.C. – Despite the federal requirements regarding reduced stopping distance (RSD) for heavy-duty truck tractors being on the books for nearly a decade, many industry experts contend there a concerning number of truck owners who do not know about the rule or do not heed the dangers of replacing RSD friction material with non-RSD friction.

“Most people today when they come in and are looking for brakes don’t even ask for the RSD friction material,” said Michael Lerach, sales manager, Blaine Brothers. “Rarely in the field does it come up. That’s the reality of it. Our team is instructed to ask the customer which material they want, RSD or not, at the onset of the conversation.”.

“Some second and third owners are not familiar with the brake friction originally on their truck and it’s different than what they have historically purchased,” said Eric Coffman, aftermarket product manager, shoes/friction, Meritor. “We’ve spent a significant amount of time and effort to educate the industry about these [RSD] materials. To say it’s totally understood would be an overstatement.”

Wheelco Product Manager Jerry Podhradsky said there are misconceptions that RSD-compliant brake products are “too expensive or reduce the lifespan of other parts, but this can be fixed with a quick conversation.”

The final rule amending Federal Motor Vehicle Safety Standards (FMVSS) No. 121, put forth by the Department of Transportation’s (DOT) National Highway Traffic Safety Administration (NHTSA), was implemented in two stages.

The first stage, which affected more than 90 percent of heavy-duty trucks went into effect in 2011 and required all new trucks to be able to stop within 250 feet after traveling at 60 miles per hour while loaded to their gross-vehicle-weight rating. The remainder of heavy-duty trucks, a very small number of severe-use tractors, had until 2013, and are required to stop within 310 ft.

“To make the stopping distance requirement, it took a lot of additional engineering by the OEMs to upgrade the vehicle,” said Randy Petresh, vice president, technical services, Haldex. “The biggest change was the mandate for larger steer axle brakes. To increase that stopping distance you get significantly more load transfer from the rear of the vehicle forward, so you have to significantly increase the performance of the steer axle to absorb that increase weight transfer and that’s why the brakes … went from a 15-in. brake to a 16.5-in. brake.

“You also have suspension, steering and structural requirements that all had to be considered and addressed by the tractor manufacturers. They had to upgrade the whole front end in order to absorb that significant increase and transfer of torque and load transfer. At the same time they also had to implement changes to the drive axle brakes to maintain overall vehicle balance.”

The entire article, with images, can be viewed by clicking HERE.

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