How will you stop?
By Jack Roberts
If you’re waiting for the sky to fall when the National Highway Traffic Safety Administration’s new stopping distance regulations take effect in August 2011, you’re not alone. But take heart: Any rumors that fleets will be forced to spec more expensive air disc brakes or retrofit vehicles to meet the new rules are untrue, according to brake manufacturers. They say August 2011 essentially will be a nonevent for fleets.
“We’ve been getting a lot of feedback from our customers who are very concerned that they’re going to have to fundamentally change the way they spec and maintain their vehicles, and that’s simply not true,” says Randy Petresh, vice president of technical services for Haldex. He says the new regulations can be met using existing products and technology that is tested and has been on the market and available as optional equipment for years.
The new regulations may seem draconian at first glance, mandating a 30 percent reduction in minimum stopping distance at 60 mph – meaning that a fully-loaded tractor-trailer will have to come to a full stop from 60 mph in 250 feet instead of the 355 feet required today. But experts say that criterion fits a specific set of circumstances that will not affect everyday fleet operations or driver behavior.
“This is a mandate for what is essentially a ‘panic stop’ at 60 mph in a very controlled environment,” says Doug King, aftermarket marketing manager for Bendix-Spicer Foundation Brakes. “Normal stops are still going to be in the 18 to 20 psi application range. So drivers and fleet managers aren’t going to notice any difference in the way they stop a commercial vehicle today.”
Tractor manufacturers, with support from brake component and system suppliers, ultimately are responsible for ensuring that their new vehicles comply with the new rules. “Due to the increased size and mass of the upgraded brake systems required to meet the new regulations, weight-saving components will likely receive more consideration to avoid overall vehicle weight increases,” says Jeffrey Geist, Motor Wheel’s director of product and business development.
NHTSA is adopting the new regulations in two stages: The first, taking effect next year, will apply only to tractors with 6-by-4 axle configurations weighing less than 59,600 pounds. The 2013 mandate will be for 4-by-2 vehicles and also will address some issues with heavier 4- and 5-axle tractors.
“There is no imminent program that we know of for trucks at the moment,” says Ron Plantan, principal engineer for Bendix’s wheel end group. “Basically everything we’re talking about is tractors, not trucks. But by 2013, all tractors will be taken care of, and we expect that somewhere down the road there will be some mandate addressing trucks as well.”
Retrofitting existing vehicles to meet the new rules is not mandated by the government. “Doing so is probably not a good idea anyway,” Geist says. “The brake torque on the front axle can be substantially greater, possibly exceeding the axle’s rated capacity.”
The industry has seen these mandates coming since the early 1980s when the federal government first required steer axle brakes on commercial vehicles. Prior to the introduction of anti-lock braking systems, steer axle brakes were considered bad because steer axles were prone to lock up when the brakes were applied, causing loss of vehicle control. To solve this problem, many fleets downsized or down-powered their equipment – or even removed their steer axle brakes altogether.
“It’s not like it was when the original 121 mandate came into law in the ’80s,” Plantan says. “When that mandate came into effect, everything – tractors, trailers, trucks, buses – changed at once.” ABS didn’t have the experience and reliability that it enjoys today, and brake compatibility wasn’t part of the discussion, he says. “So a lot of problems occurred out in the field that people still remember, and they say, ‘Oh my God, are we going to do this again?’ ”
“This is a mandate for what is essentially a ‘panic stop.’ “ –Doug King, Bendix-Spicer Foundation Brakes
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