NEARLY ONE-FIFTH OF ALL TRUCKS are operating with 20% of their brakes defective — a pattern that has existed for over 30 years.
“That's a staggering statistic,” said Gene Damron in “New Developments in the HD Brake Business,” a panel discussion on new technology and regulatory issues and their impact on the aftermarket in the coming 10 years.
Damron, general manager of Page Brake Warehouse, said that research has shown this condition increases stopping distances between 4% and 23%, “which tends to undercut and undermine any proven gains we might see with new vehicles in as-designed or as-manufactured condition. So all of the work that we as OEs do to produce well-performing products is going out the door.”
He said a significant portion of proposed rulemaking by the National Highway Traffic Safety Administration (NHTSA) will be lost if vehicles are not maintained. NHTSA last December proposed a 20%-30% reduction in stopping distance for both service and emergency brakes, requesting comments on the feasibility of achieving it, along with information on dyno performance requirements that exist now.
“Looking ahead, when all the dust has settled and this rule becomes a final rule, what is the practical effect?” Damron asked. “I think that regardless of what the stopping-performance requirements are, we'll see a shift to either large S-cam or disc brakes, primarily on steer axles, and a possible shift to other axles.
“In the emissions arena, we are seeing mandatory regulatory requirements for onboard diagnostic systems to monitor the performance of new emissions systems and to latch failures recorded on vehicles. It's certain that the same systems could be developed for some safety-related systems — and brakes could be one of them.”
He said the potential exists to develop systems to detect when individual wheel/brake systems are not performing adequately. Information could be conveyed to the driver and either recorded and/or wirelessly transmitted to the carrier. Corrective actions could be scheduled and taken at the soonest practical opportunity, reducing down time.
Damron said carriers might want those systems for: improved highway safety; improved productivity (no roadside breakdowns or surprises, plus the ability to plan and schedule repairs in between trips, and no out-of-service roadside inspections); and the possibility that government officials might allow trucks to completely bypass roadside inspections.
Today's advantages
Haldex's Randy Petresh said the NHTSA proposal is similar to Federal Motor Vehicle Safety Standard (FMVSS) 121 of the 1970s, but there are a number of things available today that weren't then: non-asbestos, long-life brake linings; reliable automatic brake adjusters; S-cam brakes produced to much closer tolerances; advanced digital ABS systems complete with various stability programs and advanced diagnostics; and air-disc brakes.
The objective, he said, is to improve compatibility between automobiles and commercial vehicles, but the laws of physics make this a challenge because automobiles have four tires and weigh 4000 lb, while HD commercial vehicles have 18 tires and weigh 80,000 lb.
“Producing enough torque to slide the tire is no problem,” he said. “Brakes stop tire rotation and tires stop trucks, so tire-to-road traction is the key. The improvement paths are better utilization of available front-tire traction, better utilization of existing tire traction, improved tires, and better utilization of front-axle traction capability — increased drum brake torque to 16.5 × 5, as opposed to 15 × 4, air-disc brakes with higher torque than 15 × 4 camp, and an upgrade in suspension and steering components.
“Tire traction can be better utilized on all axles. Lower hysteresis brakes — i e disc brakes — allow ABS systems to be more precise and more effective. ECBS allows faster brake application.”
He said the downside is that these improvements and changes could generate issues and service parts considerations that the industry will have to deal with in the future.
“Improved performance of OEM brake parts may be easily compromised,” he said. “Some of today's lower performance parts will likely interchange mechanically. If new vehicle targets are met with improved tires, replacement-tire selection will be critical. The industry will develop replacements parts for any new technology that is used. Simply fitting will not be enough to maintain performance, and larger gaps between new and used vehicles would be likely.”
Council at work
ArvinMeritor's Paul Johnston, chairman of the Heavy Duty Brake Manufacturers Council (HDBMC), said the council is working on implementing an air-disc brake profile standard within the Society of Automotive Engineers (SAE) to address the new brake packages and how they fit into the commercial industry. HDBMC consists of top engineering representatives from 14 braking-system manufacturers and works closely with government and other industry organizations on design standards and regulatory and safety issues.
Addressing the proposed stopping distance of 248' at 60 mph for tractors (52,000 GVWR) — a 30% reduction on the current rule of 355' — he said: “That's going to be done mostly by improving or increasing the amount of braking on the steer axle of tractors. Since the reversal of brake regulations in the ‘70s, the primary steer axle brake has been the 15" cam brake. There have been a few larger ones. Going forward with rulemaking, you'll see less and less of 15" cam brakes and more and more of air-disc brakes as well as larger 16½" cam brakes on steer axles. We're looking at a range of 200 feet of stopping distance at 200 mph, which is pretty comparable to a passenger car.”
He said the following aftermarket changes are needed to support stopping-distance rulemaking: drum-brake lining alternatives to maintain OE performance; passenger-car pad and rotor replacement model for ADB (no standard designs, new steel required); and brake hard parts; and caliper remanufacturing.
“Clearly from a technical perspective, there is going to be change as it relates to the aftermarket supplier base,” he said. “We'll definitely have to limit or at least modify some lining materials if it's going to be a drum brake. With air-disc brakes, it's going to be more like a passenger-car friction material, where they won't be many standard designs.”
He said the net impact will be: revised lining recommendations; a proliferation of air-disc brake service pads; complex internal caliper components (simple kits for some components, while critical settings may require the remanufacture process); and rotors specific to brake and wheel-end installation (a proliferation of service parts).
Increased use of onboard sensors and off-board communications will require more agile aftermarket providers, he said, adding that brake stroke monitoring systems are a prominent example.
“It monitors the foundation brake stroke,” he said. “It provides the opportunity to notify the driver of the situation, take that data and use an ECU of some sort to look at the data and make a judgment to start communicating or preparing for service on the wheel end to make it an on-time or special stop for service. It's looking at the stroke. Certain chambers have a limited amount of stroke available to them, so the system is looking for exactly where in the condition of the stroke with regard to vehicle performance.”
He said on-time service will translate into fleet satisfaction.
“There's a vision out there that there will be a drivetrain or chassis information network where these sensors will become a continuous loop of information that the vehicle will be able to accept and start acting on,” he said. “Clearly, there will be more and more data and information that has to be interrogated by the service provider. Onboard sensors and on-vehicle networking systems of the future will have endless availability of data to work with. It will require a more agile aftermarket provider so that he has the right information, the right parts, and the expertise to take action to service the vehicle.
“Tip of the day: Faster, more complex systems are going to be coming into the vehicle for the future. It definitely will be necessary for the service provider to be able to act on this information. But the end result will be that we'll continue to satisfy our fleet customer and provide the right service and support that he needs.”