A New Step on the Brakes

"We are confident we can meet the new standards with relatively minor modifications of existing technology," says John Walsh, Mack Trucks. "We already offer disc brakes capable of meeting the standards, but our testing has not shown the need for them for the initial phase of the new regulations in 2011. Some components might have to be changed on our drum brake systems to handle the additional torque that will be applied to the axle and supporting systems."

The tractor-trailer balance also had to be considered when addressing the shorter stopping distances. "ArvinMeritor recognized the need for high-performance brake solutions on new tractors to work with existing trailers," says Pennington. "Our solutions have been developed to maintain tractor-trailer compatibility with existing trailer fleets. The tractor will incur approximately 5%  more of the braking workload, while the trailer will experience a proportionate reduction in workload."

Roll stability products should be compatible with the new braking standards, as well. "The new regulation will require only minor changes to Mack's Roll Stability Advantage," says Walsh.

Required changes increase, however, with the severity of the vehicle application. "Severe-service tractors are expected to be a greater challenge, which is the grounds for the longer implementation period and for the longer stopping distances," says Walsh. "The NHTSA is required to demonstrate technical feasibility for their new rules, so it is not impossible, just challenging."

While you may see the use of more air disc brakes on some severe-service trucks, it is technology that exists today. "In that market segment, we have already identified some optional products for our air disc brakes, such as rotor shields, pad shields and severe-service rotors," Schwass says. "In some of those applications, it is not just taken off the shelf."

Of course, the additional cost of air disc brakes means each fleet must consider if this solution makes sense. The technology may not pay for itself if you turn vehicles over every three years and are set up to run with the lowest acquisition cost. "The air disc brake doesn't fit into that cost equation," says Schwass.

Yet, the higher performance of air disc brakes will likely drive increased use. "In moving to disc brakes, clearly the operators have a different feel in the braking performance of the vehicle," Schwass comments. "Over time, you will see the cost of the air brake solution drop as the volume increases."

"I think we will see air disc brakes standard in certain wheel positions in certain vocations," King adds.

Justifiable expense
"There will be an incremental cost increase for enhanced drum brakes that meet the new regulations," Pennington acknowledges. "In studying the implications of the new regulations, the NHTSA estimates the incremental cost for drum brakes on a typical three-axle tractor would be $211, whereas the incremental costs to convert to disc brakes at all wheel positions would be $1,475."

The NHTSA believes the added cost is justified. It estimates the new braking requirement will save 227 lives annually, prevent 300 serious injuries and reduce property damage costs by over $169 million annually.

"This rule will result in a safer fleet," says Schwass, "and make it safer for everybody involved."