Orchestrated stopping: High tech hits the brakes

Aug. 1, 2000
Hitting the brakes will take on a whole new meaning in the near future. That's the word from engineers, who say the trucking industry will soon be talking not about braking, but about stopping systems.And it's not semantics. The advent of electronic braking systems (EBS), also referred to as electronically controlled braking systems (ECBS), will allow trucks to be set up so that a variety of vehicle

Hitting the brakes will take on a whole new meaning in the near future. That's the word from engineers, who say the trucking industry will soon be talking not about braking, but about stopping systems.

And it's not semantics. The advent of electronic braking systems (EBS), also referred to as electronically controlled braking systems (ECBS), will allow trucks to be set up so that a variety of vehicle subsystems - not just the foundation brakes - can contribute to slowing and stopping them.

Such an advanced system, in the words of one brake-supplier executive, would amount to "orchestrated slowing and stopping."

Dennis Sandberg, president and general manager of Meritor Automotive WABCO Vehicle Control Systems, says shared data - such as rpm, wheel speed and steer angle collected from onboard monitoring devices will be used by the foundation brakes, engine, transmission and even suspension controls to manage deceleration.

On top of that, the adoption of other technologies - most notably air-disc brakes designed specifically for North American operation - will boost the performance of the service brake portion of the "stopping system."

Back when the industry was reacquainting itself with antilock brake systems (ABS), brake engineers were only comfortable talking about the arrival of advanced systems in time frames of ten or even more years away.

Now they're saying to look for smarter, even orchestrated, braking systems to hit the North American market in just two to five years.

What sped things up? The successful integration of ABS into the everyday world of equipment management has had a lot do with it. Given the pressure of razor-thin margins, there's also a greater willingness on the part of American fleet managers to at least accept the potential for technologies bred overseas to work here.

As it so happens, a lot of advanced braking concepts are coming out of Europe, where truck safety is, if anything, a bigger political football than even here.

And over here, it's not just about increased safety. As brakes evolve into stopping systems, points out Walter Frankiewicz, vp & general manager of Meritor Automotive's worldwide braking group, durability will be enhanced, and maintenance will be reduced as well.

Big things Frankiewicz is among those forecasting big things from brakes. In fact, he predicts there will be more braking system advances in the next five years than in the previous fifty.

"We see the stopping and slowing of heavy- and medium-duty commercial vehicles on its way to becoming an orchestrated system of electronic controls and maintenance-free, lightweight components," he states.

Obviously, then, EBS is the linchpin on which most if not all the developments being hinted at will swing into the market. It will certainly be the case with air-disc brakes.

That's because electronic controls will provide a cost-effective means of mating disc-braked tractors with drum-braked trailers.

That compatibility question has long hampered the adoption of disc brakes by fleets with "unmarried" tractors and trailers.

Compounding the issue is the fact that tractors might get disc brakes as new units join the fleet, but trailers - which are often held onto for years and years - would continue to have drums.

"The direction we're headed," says Jim McClelland, director of product marketing-valves & modules for Bendix Commercial Vehicle Systems, "is definitely toward EBS and air-disc brakes. These advances will make brake system performance more sophisticated while making it easier to diagnose and maintain the system."

Just last year, Bendix began offering an air-disc brake in North America that was developed through its joint venture with Europe's Knorr-Bremse and Robert Bosch.

According to Anton Schneider, Bendix's director of product marketing-ABS/EBS, the Bendix discs have demonstrated shorter stopping distances of up to 75 ft. for a tractor equipped with EBS.

Infants "Air-disc brakes are still in their infancy here," Schneider concedes, "but they are already well-proven in European operations."

As to the advantages of the design, he points out that the rotor of the disc brake expands towards the pads as heat builds, eliminating brake fade and maintaining effectiveness by keeping brake pedal pressure constant.

He says the other key benefit of discs is less maintenance, since they require no lubrication and their pads can be changed in "80% less time" than S-cam brake linings.

Schneider says the key thing to bear in mind about EBS is that it can be implemented in varying degrees. "The more you integrate electronic controls into the vehicle braking system, the more you would reduce pneumatic controls," he points out.

But he says the biggest plus may well be the ability to electronically connect the brakes to other vehicle systems, such as the engine and suspension, to boost diagnostic capabilities and enhance vehicle control.

McClelland points out that the arrival of the power line carrier (PLC) electronic technology for ABS communications between trailer and power unit will "open up an avenue to provide more vehicle information, such as brake conditions, to the driver."

He notes that beginning next March, all new vehicles will have to have PLC capability. "PLC," he adds, "links the two units so any fault with the trailer ABS is displayed to the driver in the cab of the truck."

Despite the promise held by air discs and EBS, Schneider says suppliers alone won't determine the future of braking.

"We will have to jointly identify with customers what their needs are," he contends. "Safety and productivity issues may play different roles in brake developments, depending on which particular industry segment a system is designed for."

"The U.S. will see EBS sooner than most people predict," contends John McKinley, vp-worldwide sales, marketing & product planning for Haldex Brake Systems.

"Antilock braking has paved the way," he continues. "People in trucking now accept the presence of electronics in braking. And unlike ABS, EBS will give users some operational advantages on top of the safety improvement."

McKinley says thanks to the more precise control afforded by electronics, fleets will realize better overall braking performance, less lining and tire wear, and more equalized brake wear. EBS will also make imbalance issues "go away."

"Electronic controls," he notes, "will keep track of lining wear and will put less pressure on those that are wearing faster."

Small step In McKinley's view, it's a "small step" from ABS to EBS. "Fleets will be able to quantify the advantages of EBS, whereas ABS was simply legislated. That's why I think we'll all be pleasantly surprised by the rate of adoption."

As for the orchestration concept, he asserts "those kinds of things" will happen. "A sophisticated electronic brake system may direct the engine retarder to apply first. In that scenario, the treadle valve in effect becomes a transducer that will 'ask' the system for deceleration - instead of simply actuating the foundation brakes as it does now. In other words, the system will find the best way to slow or stop the truck in response to the driver's actions."

McKinley notes that Haldex already sells a system in Europe that can determine when the truck is decelerating. It uses the "free horsepower" of coasting to run the compressor so the brakes will always be operating with full pressure available.

This system, offered on M-A-N trucks, also automatically completes a diagnostic check for leakage at startup.

"The Europeans feel the maximum benefit of EBS can be derived by using air-disc brakes," McKinley continues. "In this country, the most likely combination will be disc-braked tractors hooked up to trailers with drum brakes. That's because we use a lot of new tractors and old trailers. EBS eliminates imbalance between the two brake types without compromising brake life on either end."

According to Rick Youngblood, Eaton Corp.'s business manager for ABS, air-disc brakes will surely prove an avenue to reducing heavy-truck stopping distances. (Editor's note: The Roadranger organization markets Dana air-disc brakes alongside Eaton ABS/EBS products.)

"Discs have a good potential to become a mainstream product in the next five to ten years - if fleets want the improved performance they offer," says Youngblood.

"There has to be a rationale, though," he continues. "Trucking's too competitive for fleets to put on a technology for its own sake. Payback might be derived by looking at the impact from fewer accidents or how offering better brakes might help in recruiting drivers."

Youngblood says the "general interest" in braking advances among fleets is low but thinks that would change if truckers were better educated on the advantages of discs and EBS.

Brake show He notes that The Maintenance Council (TMC) of the American Trucking Assns. is "working to put new brake technology in front of the fleets." TMC, in fact, will be holding a special day-long brake-education event at its fall meeting, October 16-19 in Columbus, Ohio. (For more information, contact TMC at 703-838-1763.)

"TMC attendees will get to pore over a group of vehicles outfitted with brake systems from various suppliers," Youngblood reports. "Included will be production units equipped with both EBS and disc brakes."

The whole idea behind all these advances, according to Prakash Jain, Meritor Automotive's director of technical support-braking systems, is to gain "car-like braking performance" as well as lower maintenance costs and extended brake life.

"The stopping-distance gap between cars and heavy trucks is currently between 60 and 100 ft.," Jain reports. "This gap can be closed by using air-disc brakes on at least the front axle and incorporating electronically controlled braking systems.

"Disc brakes provide higher torque at higher speeds to prevent brake pull," he continues," and EBS will take care of balancing the system and apportioning brake workload. Think of EBS as the manager of the brake system."

Alan Korn, chief engineer for Meritor WABCO Vehicle Control Systems, says that some modification to the FMVSS-121 brake regs may be needed before EBS comes fully into play.

"EBS is predated by 121," Korn explains, "so the rules may have to be rewritten to cover its adoption. That's not the same as mandating it. It will only be a matter of making EBS viable for this market."

Orchestration Korn says braking will become orchestrated as more and more systems on board the truck become connected electronically. "A tremendous amount of data can be shared over a J1939 data link," he asserts.

Orchestrated stopping would be achieved by having an onboard computer direct the brakes to apply, or the engine retarder to engage, or even to have the transmission shift to a lower gear.

"The other advantage to adding all this intelligence to the vehicle," says Korn, is that the level of system diagnostics can be vastly improved for greater maintenance savings."

According to Korn, EBS may even evolve to the point of providing "active braking." Such a system would kick in independently of driver action once a vehicle goes out of safe control.

"EBS would be the platform for such a system," Korn explains, "which would provide stable vehicle control via special sensors and software."

Down the road, drivers will still be hitting the brakes and fleet managers will still be paying for them. The real hope, then, is that technology can make braking less costly all around.

Along with EBS and disc brakes, engineers at Meritor Automotive report they are working on a new application-specific approach to brake linings and pads dubbed "friction coupling" that promises to cut stopping distances for trucks.

The scientific explanation goes like this: Optimizing the composition of friction materials and drum/rotor surfaces will provide a co-efficient of friction that creates adhesion - instead of just friction and heat from abrasion.

At this point, says Paul Johnson, director of engineering for the Meritor Automotive braking systems group, friction coupling is still a research project.

"Working with friction-material suppliers and the Rockwell Science Center," says Johnson, "we will be able to control all of the major elements in both the friction material and the drum or disc so that they work together more effectively.

"For example," he continues, "we can change the metallurgical composition of our drums and discs with various additives so when they are coupled with an appropriate friction material, optimum adhesion and braking performance can be achieved for specific applications."

According to Johnson, Meritor Automotive expects to introduce these "friction couples" within the next five years to the OEM market, and shortly afterward to the aftermarket.

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