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Rail News Home Mechanical

November 2007



Rail News: Mechanical

Stop-gap measures



Stopping a train properly is just as important as getting it started. At the end of the brake rigging are the beams and shoes, which are critical to ensuring smooth, effective braking — particularly with today’s heavier cars. And it’s the shoes, which press against the wheel tread, that bring the train to a halt.

And those shoes, along with the brake beams, cost railroads and rail-car owners a chunk of change to repair. Last year, brake-shoe repairs cost the industry $105 million, brake-beam repairs cost $16.5 million and wheelset replacement due to tread damage cost $197 million, says Thomas Guins, Transportation Technology Center Inc.’s chief economist.

So, railroads and rail-car owners continue to push suppliers for better and more cost-effective shoes and beams. And on the brake-shoe front, for example, they’ve generally liked their experience with high-friction composition and sintered shoes during the past decade or so.

“The sintered-iron composition shoes are superior to the old cast-iron shoes in as much they are more fade resistant to the heating of the shoe,” says Dana Maryott, director of locomotive and air brake systems for BNSF Railway Co., adding that the new low-fade brake shoes do a good job of resisting fading at speeds below 30 mph.

NOT TREADING LIGHTLY
Today’s shoes also do a better job of correcting wheel tread problems. Tread-conditioning shoes “actually correct minor flat spots, avoiding the need to have to swap wheel sets,” says Maryott. The resulting reduction in wheelset replacements more than justifies the shoes’ higher cost, he believes.

“We have found that these shoes work on locomotives, as well,” says Maryott.

Union Pacific Railroad, too, embraces tread-conditioning shoes.

“The high net-to-tare ratio of the higher-capacity cars requires the use of empty/load braking devices and this has influenced our decision to use tread-conditioning brake shoes,” says Rex Beck, UP’s senior director of freight car planning.

Union Tank Car Co. has found that sintered iron and tread-guard shoes are becoming more popular “as we see more and better data coming in on the results of their use,” says Tony Warwick, project engineer.

Class Is’ “constant focus on reducing operating costs” prompted suppliers such as Wabtec Corp. to look more closely at the full cost of braking as they design and develop new products, says Tony Carpani, Wabtec vice president and group executive, friction.

“This inevitably led us to examine the mating surface of our brake shoes, which of course is the wheel,” says Carpani, who is based in Australia and responsible for Wabtec friction products worldwide. “We then looked at the cost of wheels, which is a significant component of the customer’s operating costs. We realized we could [reduce] this cost by developing products which kept freight and locomotive wheels in good condition.”

Through its Railroad Friction Products Corp. subsidiary, which manufactures Cobra® high- and low-friction composition brake shoes, Wabtec offers a “basic freight shoe” that meets all Association of American Railroads’ interchange

demands, Carpani says. The supplier also has developed several models of what Carpani terms a “value-added” tread-conditioning brake shoe under the TreadGuard® name.

“These shoes prolong the life of wheels and at the same time ensure any defects which develop, such as skid flats, are automatically removed,” he says. “They can be applied to freight cars as well as locomotives.”

The supplier also is in the process of developing a heavy-duty TreadGuard shoe that’s designed to “look after the wheels of the heaviest cars — coal cars — and at the same time provide higher levels of braking capacity,” Carpani says. “This, in turn, will assist in increasing train velocity through the system at high levels of safety.”

Suppliers also have made a few improvements in the brake-beam realm. For one, they developed the “angle-corrected” beam, says Union Tank Car’s Warwick.

Powerbrace Corp., a subsidiary of Miner Enterprises Inc., offers the Series 2000 brake beam, which is “angle corrected” — meaning “the end extensions are intentionally rotated so that the beam is tilted upwards and, when installed and the rigging is connected, the weight of the beam pushes it into a neutral position,” says Joseph Centeno, Powerbrace project engineer.

ANGLING FOR A BETTER BEAM
As a result, the entire shoe is applied against the wheel tread rather than the top of the shoe hitting the wheel tread first, which can cause uneven wear, as well as prompt the shoe to climb the tread, Centeno says.

Series 2000 Brake Beams — which include notched break heads to reduce beam binding and a reversible strut for quick beam-hand conversion — can reduce brake shoe replacement by as much as 20 percent, according to Miner’s Web site. The supplier also offers steel and plastic side frame wearplates, and other brake beam components.

In addition to being angle-corrected, today’s beams are lighter, making replacement easier.

“Some of the new lightweight beams can now be changed in the field rather than having to bring the car to a repair track,” BNSF’s Maryott says.

One drawback: The lighter beams may not be strong enough to withstand the vibrations, which could lead to early failure, according to Maryott.

Miner “addressed the fatigue issue” in the design of the 2000 series, Centeno says: A guide prevents the brake shoe key slot from sliding behind the shoes while the key lock works as a detent — a restraint that checks motion — to secure the key in place.

“[Because] the beam is weld free, we have not found this to be a problem,” he adds.

A. Stucki Co., too, continues to push the envelope on the brake-beam front.

“Railroads and car owners continue to motivate us to provide a longer lasting, safer to handle and apply, and cost-contained product,” says Jeff Vodar, vice president of sales and marketing for A. Stucki, which has supplied brake beam designs to most North American railroads and rail-car builders, and is actively developing variations for specific international and other custom applications. “We have responded to these needs and more by providing a flexible product in which the struts can be easily reversed without the need for torching off huck bolts and using replacement fasteners as well as a product with easily replaced brake heads.”

INTRODUCING ... REPLACEABLE HEADS
In 2001, Stucki introduced the reversible strut and in 2002, the angle-corrected brake head design. Today’s RC Beam incorporates both of these features, as well as provides the industry’s only brake beam with replaceable heads, a design that “addresses another of the industry’s top reasons for removal of brake beams,” Vodar says.

“Today, an investment in a Stucki brake beam with replaceable brake heads can reduce the time and cost of replacing the entire brake beam as was done in the past for burnt brake heads,” he adds.

In the meantime, Stucki continues to strive to meet customers’ need to reduce maintenance costs “with the advent of reversible struts to reduce inventory, lighter weights for ease of handling and improved safety, vibration tested designs to ensure long life and reliability in service, fully hardened struts to eliminate lost bushings, and increased wear areas in the strut’s brake lever slots to extend service life,” Vodar says.

Extending the life of brake shoes and beams reduces the cost of rail-car ownership, which in turn helps improve car-owners’ returns on their investment.

“This is a common goal for us all,” Vodar says.

NO STOPPING THE EVOLUTION
Of course, railroads and rail-car owners expect to see more improvements at every link in the braking-system chain. Take truck-mounted air brakes.

“We are using truck-mounted brakes on those cars where there are clearance problems due to insulation, or where body mounting is not practical,” says Union Tank Car’s Warwick. “We find this a better solution. However, there is one area which I would like to see corrected. When the hand brake is set, the application is only on the ‘B’ end and not on both wheels.”

Meanwhile, UP’s Beck would like to see “the development of reliable systems that brake evenly at the brake shoe to the wheel interface,” adding that wayside detectors sometimes pick up higher wheel temperatures due to improper brake pressure. Researchers are looking into the problem, says Harry Tournay, TTCI senior scientist.

“We see that cold and hot wheel detectors are being implemented on the railroads and the AAR is suggesting algorithms to identify poorly performing brakes, including valves, hand brakes, rigging and stuck beams, and these promise to highlight brake issues, including those related to shoes and beams,” Tournay adds.

Meanwhile, AAR last year introduced a “strategic research initiative” to address such brake-related issues as brake-beam specifications, which currently are being updated to include “resistance to the effects of high- impact wheels,” Tournay says.

“We have examined the stress factors in connection with brake beams and high-stress wheels in both body-mounted and truck-mounted brakes, and the report should be completed by the end of this year,” he adds.

The next big thing in braking technology — electronically controlled pneumatic (ECP) brakes — also could help reduce component wear, railroads and car owners say. Last month, Norfolk Southern Corp. operated an ECP brake-equipped coal train in Pennsylvania — the first U.S. revenue service train to feature the braking system (see page 6). And sometime this month, BNSF will become the second U.S. Class I to operate an ECP brake-equipped train in revenue service.

“I think ECP will provide longer brake shoe life, particularly as this system provides for both quicker application and release,” says BNSF’s Maryott, adding that the quick release will avoid “dragging” a train with only partially released brakes.

Walter Weart is a Denver-based free-lance writer.



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