WORTH A LOOK?: Mack officials claim the latest disc brakes offer advantages over drums.
DALLAS, Texas – Mack Trucks was at the Great American Trucking Show in August, highlighting the recent availability of air disc brakes and dispelling some myths about the product.
Jerry Warmkessel of Mack Trucks said there has been a lot of interest in disc brakes, especially with new stopping distance requirements under development by the National Highway Traffic Safety Administration. He said disc brakes can stop a truck 20-30% sooner than drum brakes, adding “The faster the truck is going, the more effective disc brakes are.”
However, he admitted customers still express concerns about the cost of disc brakes as well as the increased weight. Addressing the weight issue, Warmkessel said while disc brakes weigh slightly more than today’s drum brakes, they are actually lighter than the larger drum brakes that will be required to meet the impending shortened stopping distances.
Equipping a tractor with today’s disc brakes can save 158 lbs versus the larger drum brakes that will be required to meet the new stopping distance requirements, Warmkessel explained. Specifically, a tractor with 16.5″x5″ drums on the front and 16.5″x8.6″ drums on the drive axles will carry 1,594 lbs in brake weight while the same truck with the ADB22X disc brake from Bendix on the front and rear axles will carry only 1,436 lbs, for a net savings of 158 lbs.
Opting for the disc brake on the front axle only can still save a truck owner 47 lbs, Warmkessel said. He said that disc brakes also result in less maintenance, a more user-friendly passenger car-type feel, improved stability while stopping and they are not subject to brake fade.
Warmkessel said one customer has found that 90% of its trucks equipped with disc brakes had the same pads on them at 600,000 miles.
As far as cost is concerned, Warmkessel admitted they are more expensive than drums, with the OEs setting the price. However, he added “In the long run, it’s well worth the value added by the products.”
Air disc brakes are currently available on Mack trucks with 12,000-lb front and 40,000-lb rear axles.
“We will be working up to the heavier axles as customer demand increases,”Warmkessel said.