Smart brakes

Electronic braking systems will soon be fact, not fantasyLong viewed as pie in the sky, full electronic braking systems (EBS) are now headed to the real world of trucking.That's the word from leading brake-system suppliers, which are already working with major vehicle OEMs to make the new technology both practical and cost-effective for fleet owners.And that means the industry can expect EBS to gain

Electronic braking systems will soon be fact, not fantasy

Long viewed as pie in the sky, full electronic braking systems (EBS) are now headed to the real world of trucking.

That's the word from leading brake-system suppliers, which are already working with major vehicle OEMs to make the new technology both practical and cost-effective for fleet owners.

And that means the industry can expect EBS to gain its initial foothold through voluntary spec'ing, not mandatory regulation.

As federal regulations now stand, an electronic brake system has to be backed up by a pneumatic system. That, of course, makes EBS a more expensive proposition and will undoubtedly dampen the enthusiasm of many fleets.

However, there's movement afoot to suggest the feds may bit by bit allow manufacturers to discard the current belts-and-suspenders approach.

But even before that happens, brake suppliers expect at least some fleets will start spec'ing EBS to grab a safety or image edge or simply to gain early experience with a technology they view as arriving inevitably. Indeed, that was the case when today's antilock braking systems (ABS) first became commercially available on trucks.

Icebreaker "ABS broke the ice," says John McKinley, vp-worldwide sales & marketing for Haldex Brake Systems. "EBS won't see the resistance that ABS did, simply because fleets have gained experience with - and confidence in - the electronics that make antilock brakes work.

"What's more," he continues, "fleets will learn how EBS will allow them to do much more than just avoid locking brakes up." Indeed, according to McKinley, the advantages of EBS cover a spectrum ranging from safety performance to driveability to maintenance costs.

"EBS can offer clear operational advantages, in terms of both performance and durability, over a pneumatic system alone," he states.

"The primary advantage is faster application of the trailer brakes on combination vehicles. This alone would eliminate imbalance between tractor and trailer brakes when either are doing more than their fair share of the stopping workload.

"Using special software and a kingpin-mounted sensor, tractor-based EBS," McKinley explains, "can maintain the correct braking relationship between the tractor and trailer. The result is safer brakes that last longer.

"And," he adds, "an EBS-equipped vehicle is more driveable - offering braking characteristics akin to a car.

That translates to braking action that is both faster and more consistent, whether or not the vehicle is loaded."

McKinley notes that EBS is making progress toward market acceptance in Europe, where at least two OEMs, DaimlerChrysler and Renault, offer heavy-truck systems.

Even if U.S. regulations don't change to allow EBS independent of a backup pneumatic system, McKinley believes smart brakes will catch on here due to their "inherent advantages" of longer lining life and improved driveability.

Biggest hurdle McKinley says valve design is the main technical hurdle to making EBS fully practical as a fleet spec. "An ABS valve," he explains, "only has to cycle during emergency braking.

"But an EBS valve goes to work every time the brakes are applied. So, the durability of these valves is an important concern as manufacturers bring EBS to market."

Adding to the design complexity of EBS, the valves must be capable of working pneumatically as well as through electronic solenoid actuation.

"The durability of valves is the toughest issue facing EBS development," McKinley emphasizes. "Developing the software and other elements of the system is certainly not easy, but it doesn't amount to the same kind of challenge the valves represent."

He lists these potential benefits of EBS: enhanced tractor-trailer compatibility (eliminating brake imbalance); automatic hill-holding (by linking EBS with engine-management systems); blending of engine retarder and service brake actuation (to cut brake wear); incorporation of lining-wear indicators (to rationalize maintenance scheduling); and equalization of lining wear (from left to right on vehicle).

"Once you have electronic control of braking," says McKinley, "you're limited only by imagination. And you can accomplish a lot without a tremendous increase in cost."

The main reason he thinks fleets will opt for EBS? "You can always sell things that save money," McKinley contends, "and EBS will deliver savings to fleets."

"We are working on EBS with our European partner, Knorr-Bremse," reports Paul Szentkiralyi, director of product marketing-control systems for AlliedSignal Truck Brake Systems Co., maker of Bendix brand products.

"We're investigating how we can best satisfy global requirements. But EBS is advancing fastest in Europe," he continues. "Most European OEMs are moving ahead with EBS because traffic congestion and different road designs make it that much more attractive. And, in general, it's easier to sell fleets on technology over there than it is here.

"In North America," says Szentkiralyi, "fleets first say 'Show me the payback.' That's why we don't foresee EBS catching on in large volumes for at least five or ten years from now."

"Overall," he predicts, "we expect trucking to first embrace a base EBS system with other subsystems added on later." Such systems might include electronic yaw control, which would utilize engine intervention and careful brake application if the vehicle is not headed where the driver intends. The same electronic techniques can be used to help prevent rollovers."

Along with those safety advantages, other EBS benefits he lists involve better vehicle performance, lower maintenance costs, and less unscheduled downtime.

"EBS improves braking performance by eliminating pneumatic balance problems," Szentkiralyi explains. "A built-in capability for 'smart' diagnostic functions will also allow fleets to conduct predictive maintenance of brakes. And because EBS can give trucks the brake 'feel' of a passenger car, it should help with recruiting and retaining drivers."

Despite all its pluses, EBS won't be an easy sell to many fleets. "Today, it's difficult to quantify the benefits financially," Szentkiralyi comments. "However, like ABS, advanced features of EBS will be easy to demonstrate. Just switching the features on and off will make it easy to see the advantages on the road."

Szentkiralyi believes the first to gravitate to EBS will be managers of safety-conscious fleets and other "progressive operations who want to be prepared for what's coming."

The arrival of EBS is sooner than many expect. For example, AlliedSignal is working with Navistar International now and is discussing with other OEMs how to implement EBS.

"Electronic braking will initially be a low-volume item," says Szentkiralyi, "but the OEMs still have to dedicate engineering work to incorporate the systems brake suppliers develop." He notes that AlliedSignal has thus far installed EBS on some vehicles for "extensive evaluation."

At least one U.S.-based OEM has already jumped into EBS with both feet. Freightliner has been offering an electronic braking system supplied by Meritor WABCO optionally on its Century Class line of premium Class 8s.

According to Tony Moore, Freightliner's engineering manager-axle & brake systems, a chief advantage of the OEM's EBS is deceleration control, which automatically adjusts to a vehicle's load and then proportions braking pedal effort accordingly.

"Whether a truck is hauling an empty trailer or is max'ed out at 80,000 lb.," Moore points out, "pedal effort to stop that vehicle at a particular speed will be the same."

Other benefits, he notes, include the ability to detect brake fade as it occurs and instantly compensate for safer downhill descents. The system will also alert drivers so they can take additional precautions in such a situation.

And by eliminating delays in air-brake actuation, Moore says EBS results in "surer, more confident stops - giving drivers brake feel similar to a car while providing a shorter stopping distance."

Moore also says EBS equalizes pressure on all brakes so that linings wear out at the same time. "That way, a one-time service stop is all that's needed for total brake-lining replacement."

Yet other advantages he lists are the improved performance and diagnostics that can be attained when EBS integrates ABS and traction control into one unit.

Evolution at work Even though Meritor Automotive and its joint venture Meritor WABCO have already developed the electronic braking system available on the Century Class, executives at the two firms caution EBS has a ways to go before becoming a commonplace spec in North America.

"There's no specific date in mind as to when EBS will come into widespread use," says Denny Sandberg, Meritor WABCO's director of electronics products. "We see it arriving more as an evolution in the marketplace."

And Prakash Jain, Meritor Automotive's director of technical support-stopping systems, says to expect "basic EBS to gain favor first, followed by the addition of various add-on functions."

They both point out that a major obstacle to EBS acceptance is the way FMVSS-121 - the federal braking safety standard - now stands.

"Full redundancy of the braking system, EBS plus pneumatic actuation, is now required," says Sandberg.

"For EBS to gain a wide following," he continues, "the industry will have to address changing the regs to remove at least some degree of the current redundancy requirements. As far as we know, NHTSA has not yet focused specifically on this issue."

Nudge the feds The feds, then, will need a nudge - if not more -from trucking to make that happen. In the meantime, according to Sandberg and Jain, work continues apace to bring EBS into wider use.

"A major piece of EBS evolution is already under way," Sandberg points out. "Freightliner has been out there with our system since introducing it as a Century Class option. They're working one-on-one with interested customers to engineer the system into their vehicles.

"Our EBS has been fully tested and we feel it's a reliable product," he continues. "It's a relatively complex system because it has built-in redundancy with back-up valves to guarantee it's fail-safe."

According to Jain, features that may be added to a base EBS could become standard or optional, depending on market acceptance.

Such add-ons might include advanced diagnostics, for the entire braking system, and a "suspension interface" that Jain says would allow electronic braking to manage brake balance no matter how the vehicle is loaded.

Both engineers note that EBS will also function as another electronic communications link onboard the vehicle.

"With EBS," says Jain, "there will be more opportunities to combine much of the communications capability already on vehicles into a common system."

Sandberg points out that the SAE J1939 electronic data link has become familiar to the industry. "The link is used now to enable traction control on ABS-equipped trucks. In effect, a J1939 can serve as a 'skeleton' to support communications interfaces between a variety of electronic systems."

A potential example he cites is tying engine or driveline retarders in with the braking-control system. "That way you'd gain much higher retarder application, which will save on brake wear and increase vehicle safety.

"At this point," he continues, "on the whole the industry is only using bits and pieces of what the data link can do. In the near future, we'll see more and more systems become integrated onboard."

And, Jain adds, "With engines, retarders, brakes, and other systems working together, it won't be far-fetched at all to get to a true million-mile truck. EBS alone will ensure longer brake life with no loss in vehicle performance."

Speaking of performance, Jain and Sandberg contend that EBS may pave the way for wider use of disc brakes on trucks.

"Another benefit of EBS we feel strongly about is how it can lead to a rebirth of air-disc brakes," says Sandberg.

"Discs offer a tremendous performance advantage," he continues, "but fleets have been reluctant to adopt them due to the compatibility issue that results when running them on tractors that must interchange with trailers fitted with drum brakes."

According to Sandberg, EBS makes tractor-disc/ trailer-drum compatibility a non-issue. "In Europe," he notes, "the combination of EBS and discs is increasing the stopping ability of tractor-trailers by a quantum leap."

Although Freightliner is already offering a Meritor WABCO electronic braking system, Sandberg and Jain remain guarded about how quickly the rest of the industry will follow that lead.

"We don't expect the redundancy requirements to be completely eliminated," says Jain, "but we feel they will be relaxed based on what trucking and the government accomplish working together to address this issue.

"In the end," he concludes, "what we'll see arrive are systems that are both fail-safe and cost-effective for fleets to use."

Obviously, if fleets can't afford EBS they and the motoring public won't benefit from them. No matter how smart they are.

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