The National Highway Traffic Safety Administration estimates that shorter stops will save 227 lives a year.

It’s possible that tractors built to meet a new braking standard would be able to use the same specs as today’s equipment, but at a minimum, better friction materials would be required. That seems to be the consensus of some leading suppliers as the truck building industry looks down the road at a mandate for a 30 percent reduction in minimum stopping distance at 60 mph as required by a recent National Highway Traffic Safety Administration regulation.

In most combinations of vehicle configuration and gross vehicle weight rating, NHTSA will require that a loaded tractor-trailer stop within 250 feet as opposed to 355 feet today. Full implementation is expected by August 2013, though most configurations are subject to it by August 2011.

NHTSA initially had proposed a reduction in the range of 20 to 30 percent to be settled during the rulemaking process. Compliance falls strictly on the vehicle supplier, not the fleet, and the regulation applies only to new equipment; there is no retrofit requirement. (For more on the specifics of the NHTSA rule, including what axle/GVWR combinations must comply when, see Journal, CCJ, August 2009, or go to www.regulations.gov and search NHTSA-2009-0083.)

Several parties, including the Truck Manufacturers Association and the Heavy Duty Manufacturers Association’s Heavy Duty Brake Manufacturers Council, have filed petitions for reconsideration on several technical elements of the rule, but it doesn’t appear that any significant party is objecting to the rule in broad terms.

Staying the course?
While a standard on-highway spec today – 15- x 4-inch steer axle/16.5- x 7-inch drive axle drum brake package – might meet NHTSA’s performance standard, that will need to be confirmed, Mac Whittemore, regional manager for ArvinMeritor Commercial Vehicle Systems, told attendees in a session at last month’s Technology & Maintenance Council. It’s fairly clear, however, that moving a step up to a 16- x 5-inch steer/16.5- x 8 5/8-inch drive package not only would meet the standard comfortably but also provide some benefits in terms of longer life, he said.

The next step would be to install air disc brakes on the steer axle with 16.5- x 7- or 8 5/8-inch drums on the drive axle, Whittemore said, adding that the premium solution would be air disc brakes all around. Each step gains stopping capability, braking consistency and the potential for longer life, but also increased purchase cost and changes in maintenance practices, Whittemore said.

Vince Lindley, manager of national account fleet service for Volvo Group North America, agreed that a 15- x 4-inch steer axle/16.5- x 7-inch drive axle drum brake package might prove to meet the NHTSA standard, but there would need to be lining and drum changes.