Couplers, compatibility, and competition

Railway Age, August, 2000 by William C. Vantuono

Coupler manufacturers are balancing competition with cooperation to develop new equipment for interchange service.

The ubiquitous coupler is about the only piece of railroad equipment that, as regulated by the Federal Railroad Administration and supervised by the Association of American Railroads, must be fully interchangeable among suppliers. This requirement applies to just about every single part that goes into a coupler: knuckle, lock, and coupler body. Seamless locomotive and freight car interchange is dependent upon complete coupler compatibility.

This requirement has created a somewhat unusual--and rather delicate--relationship among the four major coupler manufacturers: ABC-NACO, ASF, Buckeye, and McConway & Torley. On the one hand, these four suppliers work closely together, comprising the Mechanical Committee of the Standard Coupler Manufacturers (MCSCM). On the other hand, they compete for business. So while they're striving to make their products better than that of their competitor, their improvements can't make these products incompatible.

"Couplers, though in many respects just ordinary steel castings, are precision castings," says MCSCM Chairman Terrey Hawthorne, who spent the bulk of his career with ASF and Keystone. That's why the work of the MCSCM is so critical.

"It's a good system, but it limits what you can do from an innovation standpoint," says ABC-NACO Executive Vice President-Technology Steve Becker. "We of course can design a new coupler, but it would still have to be fully compatible with everyone else's."

"There's not a lot of freedom with the basic system," says Buckeye Vice President-Sales and Marketing Jeff Laird. "About the only thing you can do is make improvements in the material and improve the coupler's service life."

One example is rotary-dump couplers. Both ASF and Buckeye recently introduced improved versions of their rotary designs (ASF's is in its fourth generation). The mechanism employed for turning a coal car upside down for dumping is proprietary, but each supplier's coupler head must conform to MCSCM-devised AAR specifications.

One of the few things a supplier can do is improve coupler metallurgy, says McConway & Torley Director-Foundry Sales Scott Mautino, but there are limits. "We can improve the appearance of our castings, because better-looking, smoother castings have a longer life under load conditions. But the railroads are reluctant to pay for any of these improvements." One of McConway & Torley's newest products is its CX coupler pin, a more flexible C-10 pin that allows coupler parts to move without fatiguing the pin, one of the weakest point in the link.

The biggest problem with couplers is "slop," or excessive slack action. MCSCM members standardized on a reduced-slack design just under two years ago that is starting to gain acceptance in the industry. Reduced-slack couplers represent 10-15% of McConway & Torley's business, for example. ABC-NACO came up with the design, which it leased to the other three suppliers.

Improving coupler knuckle service life is the next issue the MCSCM will tackle, says AEC-NACO's Becker. "If a coupler is going to fail, the knuckle is the part you want to have break first because it's the easiest to replace," he says. "But our customers don't want them breaking as frequently as they do now."

Gauging compatibility

The four suppliers on the MCSCM, which meets quarterly, are cross-licensed. The licensing agreement, which dates back to 1916, immediately followed adoption of the Type D Experimental Standard Master Car Builder's coupler.

Annually, each supplier furnishes a complete coupler representative of current production. Each unit is carefully inspected for markings and weight, and the coupler body and parts are thoroughly measured with a set of standardized AAR acceptance gauges. Each coupler knuckle is applied to each of the other couplers, and their operating functions are verified. Interchangeability is testing by disassembling all the couplers, then reassembling them using no two parts of any one supplier in any coupler. The operation of these "mix and match" units is verified.

The couplers are then subjected to a static tensile test where they are subjected to stresses until destroyed. AAR specifications demand that freight car coupler bodies must be able to withstand a 900,000-pound load; knuckles, 650,000 pounds. The growing use of high-horsepower, high-adhesion a.c.-traction locomotives and heavy-axle-load freight cars, though, will probably change these requirements. (ABC-NACO's Becker points out that draft sills on most new freight cars are being built to withstand 900,000-pound loads. The company has a new test machine that can apply loads of up to one million pounds on couplers.)

All of these testing and verification procedures are witnessed by MCSCM members, and a complete report of gauging and test results is furnished to each supplier.

A complete master set of AAR acceptance gauges is maintained by an independent company and made available for exclusive use by the committee. Each supplier, in turn, has its own set of gauges, which must be calibrated against the master set.