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Rail News Home Mechanical

November 2008

Rail News: Mechanical

Technology Update: Tread-Conditioning Brake Shoes

By Jeff Stagl, Managing Editor

What’s the most expensive component of freight-car maintenance? Wheels, which account for about two-thirds of the lifetime cost to maintain a car.

Last year, railroads spent about $330 million to replace 320,000 wheelsets with tread damage, according to Association of American Railroads (AAR) data. In 2006, they spent $350 million to replace 350,000 tread-damaged wheelsets.

Tread damage primarily is caused by shells, spalls or slid flats that can form due to wheel sliding and other causes.

Eleven years ago, Wabtec Corp. subsidiary Railroad Friction Products Corp. (RFPC) introduced the COBRA® TreadGuard® tread-conditioning brake shoe, which is designed to prevent shells and spalls from forming, and condition the wheel tread to improve wheel/rail adhesion. Since then, several railroads and private car owners have noted longer wheel life and improved car reliability, especially on heavy-haul coal cars, while testing or using the shoe.

Similarly, Anchor Brake Shoe Co. four years ago introduced the AAR-certified Sintered tread-conditioning brake shoe, which features a mixture of iron powder and friction materials designed to remove wheel tread defects caused by shelling and spalling, and increase wheel-to-rail adhesion. Sintered shoe tests conducted by railroads and car owners since 2004 have shown brake-shoe life was extended — in some cases, more than three times — and wheel wear was maintained closely to original profiling.

Yet, only recently have the TreadGuard and Sintered shoes begun to gain wider acceptance by railroads and car owners. Why? Because the shoes typically cost three to four times more than conventional brake shoes, and railroads and car owners couldn’t overlook the upfront expense.

But now, they’re finding the overall cost savings from changing out fewer wheelsets and brake shoes justify higher initial costs, says Jim Pontious, who retired from Wabtec in 2005 and currently provides consulting services to several companies, including Wabtec.

“You get longer wheel and brake shoe wear,” he says. “You also have to factor in the labor cost to replace more shoes.”

Currently, the TreadGuard line — which includes locomotive models — has captured about 15 percent of the brake-shoe market vs. 3 percent five years ago, says Pontious.

RFPC expects to sell just shy of 1 million TreadGuards this year and 1 million of the shoes in 2009, says RFPC Vice President of Sales Ken Deceuster.

Meanwhile, Anchor Brake — which is in the process of being spun off by parent Standard Car Truck Co. because Wabtec expects to close on a deal sometime in the fourth quarter to acquire Standard Car Truck — is selling more Sintered shoes than it did in 2004.

“We’re selling about eight to 10 times more at an annual rate,” says Anchor Brake General Manager Dan Gosselin, adding that the company’s major customers are Chicago Freight Car Leasing Co. and TrinityRail.

Weighing the Benefits

To further increase the shoes’ market penetration, it’s up to RFPC and Anchor Brake to continue convincing railroads and car owners about tread-conditioning brake shoes’ benefits. The shoes provide the most wheel wear and cost-saving benefits for cars carrying heavy loads or operating in winter, when track tends to be cold and wet, reducing wheel-rail adhesion, says Pontious.

AAR rule and specification changes likely will present more sales opportunities for the shoes, as well, RFPC and Anchor Brake officials believe. In July 2006, the association revised Rule 12 of the AAR Field Manual to include tread-conditioning brake shoes as a product recognized for use in interchange applications. Plus, the AAR’s Brake Systems Committee earlier this year approved M-997 (Tread Conditioning/High Capacity), a new specification that identifies procedures for qualifying a tread-conditioning brake shoe and includes a field trial test.

The heavy grade brake dynamometer test portion of the standard is used to qualify a tread-conditioning brake shoe for high-capacity performance or fade resistance, said Steven Belport, manager-AAR brake systems committee and brake equipment standards, in an email.

The specification will enable the TreadGuard to be used at higher operating levels, says RFPC’s Deceuster.

The AAR Brake Systems Committee grandfathered the Sintered and TreadGuard shoes into the field test portion of the specification because of the shoes’ history of positive field performance, says Anchor Brake’s Gosselin.

For now, several railroads still are testing the Sintered shoe to gauge its benefits vs. their wheel maintenance needs, says Gosselin. Customers typically are interested in the Sintered shoe as a preventative or remediation measure, he says.

“Chicago Freight Car looks at it as a preventative benefit and other railroads look at a remediation approach,” says Gosselin. “It depends on your operations and how you want to handle costs.”

Under Further Examination

Several Class Is continue to test the TreadGuard, as well. CSX Transportation is testing the shoe on a small group of hopper cars that have chronic wheel problems, says Dennis Shaughnessy, CSXT’s director of car engineering, adding that the test will go on another year. The Class I already uses TreadGuards on about 3,000 cars, including coal hoppers, new coal cars and other hoppers used in heavy service.

BNSF Railway Co. is testing the shoes on 200 covered grain hoppers. The Class I, which first tested TreadGuards in 1996, already has standardized TreadGuards on its aluminum coal car fleet. Currently, 10,500 coal cars are equipped with the shoes, says BNSF Assistant Director of Mechanical Engineering Pat Whelan.

“We’ve found a reduction in the number of wheels replaced for shelling, and at wheel impact load detectors, we’ve found a lower number of wheels with shelling,” he says. “We’re replacing a lower number of brake shoes because the condition of the wheel surface is better and shoes last longer.”

Canadian National Railway Co., which has tested and used TreadGuards since 1999, also has standardized the shoe. The Class I now requires TreadGuards on all new CN-owned cars of any type and CN-owned cars that are overhauled each year, says Gerry Weber, chief mechanical officer-cars.

“We are discussing the shoes with private car owners to possibly do the same thing,” he says.

Eye on Impacts

CN changes out about 65,000 to 70,000 wheelsets per year. That figure has dropped the past few years, in part because of the TreadGuards, says Weber.

“But we don’t just want fewer wheelset changeouts, we want to reduce the number of wheels with impacts,” he says.

CN also uses TreadGuards on all new locomotives and locomotives that receive truck overhauls. The shoes have helped reduce shellouts on the high-horsepower fleet, CN officials say.

Union Pacific Railroad, Norfolk Southern Railway and Canadian Pacific Railway also use TreadGuards on certain cars, says RFPC’s Deceuster, as do car owners such as American Electric Power Co. and XCEL Energy.

Soon, TreadGuard customers will be purchasing only one model of the shoe. On Jan. 1, RFPC will stop producing the standard TreadGuard and manufacture only the DayOne TreadGuard, which was introduced in 2005, says Deceuster.

The DayOne model avoids contact with the cast iron insert during the pressing process, so the shoe — as the name suggests — functions optimally ‘”from Day 1,” he says.

At least RFPC and Anchor Brake aren’t at square one when it comes to convincing railroads and car owners to, at a minimum, consider using tread-conditioning brake shoes.

“The shoes are fairly well accepted now,” says Pontious.

Jeff Stagl, Managing Editor.


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