NEW HORIZONS — Gold on the tracks

Increasingly, gold contacts are being used in locomotives as the use of electronic control increases.

When an engineer moves the throttle on one of the new-generation AC (alternating current) diesel-electric locomotives, his signal for action flows through gold-plated contacts and connectors, which communicate with an array of microprocessor chips. In these AC freight locomotives, chips monitor and operate systems that control the 6,000-hp, 16-cylinder diesel engine connected to the main alternator, which powers the AC-traction motors geared to each axle of these giant locomotives.

This new generation of locomotives entering service in America’s railroads brings the most significant advance in locomotive technology since the introduction of diesel power more than half a century ago. In the new Electro-Motive locomotives, each of the AC motors individually drives each of the six axles of the locomotive.

The industry’s dependence on absolutely reliable signals across gold-coated contacts and connectors, regardless of weather, temperature or load, has permitted a revolution not only in locomotive operation, but in greater fuel efficiency and service reliability. The days of massive steel components transmitting steam power to the driving wheels are gone. Now, microprocessors not only control the diesel power being transmitted to traction motors; they also monitor, through gold contacts, the motor’s speed in relation to the speed of the locomotive over the tracks. Should the monitor sense that the wheels are moving faster than the tracks can handle (indicating slipping of the wheels and potential heat-shock damage to the rail), the microprocessor reduces the power accordingly and displays the action on a computer screen in front of the engineer.

AC motors require continuous monitoring, balancing power input and speed. In today’s locomotives, these requirements are only part of the overall electronic system of sensors (many of which employ gold) that monitor every action and respond to whatever demand is made by the engineer, the load or the track. By continuous monitoring, the proper pulling power is applied consistently to the rail.

DC (direct current) motors, which had been the standard for railway power for over a century, require current to be delivered to both the internal rotating magnets and the stationary part of the motor. Carbon brushes, which carry the current to the rotating shaft, are notoriously delicate and easily destroyed by current overload. Alternating current motors, on the other hand, require a current connection only to the stationary portion of the motor, eliminating all the problems long associated with current-carrying brushes.

— The preceding is an excerpt from Gold News, published by the Washington, D.C.-based Gold Institute.