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.