IMPROVING stopping distance performance for trucks and tank trailers is one of the efforts underway by brake manufacturers, according to information presented at the National Tank Truck Carriers Cargo Tank Maintenance Seminar October 16-18 in Nashville, Tennessee.
“It's gotten very complex over the years,” Larry Osborn of Consolidated Metco Inc said of truck brake systems. “NHTSA (National Highway Traffic Safety Administration) wants the stopping distance to be reduced 20% to 30%.”
Joining Osborn in the discussion was Bruce Bis of ArvinMeritor Inc. He said the company expects to see changes in the front axle steering and suspension as well as the ABS in order to implement either drum or disc brake solutions to meet more aggressive stopping distance reductions (30%). In addition, a more aggressive reduction in truck-tractor stopping distances may result in more attention to the trailer brake requirements.
Bis discussed antilock braking systems and noted their ability to reduce jackknifing because of the automatic response to sudden stops. “If you have more wheel sensors, you can adjust to what the wheel is encountering,” he pointed out. “There is an axle upcharge for adding sensors, but the sensors themselves aren't that expensive.”
Osborn said that when the new stopping distances are mandated, it's likely the rule will apply to new vehicles and won't include retrofitting requirements. For tractors to stop within 355 feet after brakes are applied will require suspensions to be redesigned. A 248-foot stop will address a 30% reduction and a 284-foot stop will apply to a 20% reduction, he said.
All of this favors disc brakes for steer axles, which is good news because their application will result in less brake maintenance. However, the parts will have to be “beefed up,” and disc brakes will add more weight and be more expensive, Osborn said.
Bis noted that warning lights are installed on the tractor dash that indicates if the ABS is in working order, and new options enable drivers to monitor and control trailer functions from the tractor.