Intelligent Design
By Lane M. Latto, Bishop & Associates, Inc.

One might contend that the rail industry is built on muscle as opposed to finesse, as diesel locomotives can deliver up 6,500 horsepower over the rails hauling freight or passengers.

But today’s technologically advanced locomotive is put into motion by electro-mechanical hand controls that provide drive voltages to relays, rheostats, and all manner of other devices. So much for the diesel locomotive’s muscle; after all, it is the 21^st century. Let’s address aspects of connector application finesse instead.

Of maximum concern are the precision systems that handle the myriad signals that collect or send data for processing and action, both internally and externally, to the locomotive. A typical locomotive contains onboard computers, both stand-alone and in the form of modules that share space in backplanes along with other specialized modules that control speed, report location, talk to the tracks, and monitor every conceivable aspect of the vehicle’s operation.

The Bishop Report, “Rail Industry Market for Connectors,” takes an in-depth look at the role connectors play in the modern rail system. One interesting thing about the rail industry is that connectors that are considered mature and limited in capacity by other industries actually work quite well for rail.

For example, the most common locomotive backplane employs an Ethernet format incorporating the typical 3-row Eurocard (DIN 41612 style) printed circuit board interconnect for these modules/PCBs.

The Eurocard interface has been proven over time and has become a staple part of many connector manufacturers’ offerings from the past 25 years.

In tandem with the backplane connector system are accommodations for high-density, rack and panel  rectangular connectors that distribute signals into and away from the backplane. One of the more common formats, as evidenced in the application above, is TE Connectivity’s former AMP brand, M-Series connectors. The M-Series connector has been part of the interconnect scene for more than 40 years, which matches the age of some diesel locomotives still in service around the world.

Why are these older connectors still in service in a vital part of our transportation infrastructure? Because the rail industry seeks to minimize risk when choosing connectors. They chose components with proven application worthiness, since they are required to maintain their effectiveness for 20-30 years, the typical life expectancy of a diesel locomotive.

In addition to high-density rectangular connectors, many variations of circular connectors prevail in diesel locomotive design. One can find plastic, threaded commercial MIL-5015 styles, and reverse-bayonet type coupling devices applied to both signal and power applications throughout the locomotive circuitry.

With only a few newer and subtle adaptations, the standard circular connector format has not changed within the same locomotive operational timeframe described earlier.

One must also recognize the contribution of traditional terminal and barrier blocks within the overall locomotive design. Many of these original applications have evolved into DIN levels of complexity. These applications take advantage of 21^st century advancements in terminal block technology, but conceptually perform the same functions they were originally intended to satisfy nearly 80 years ago.

Finally, the solderless terminal, that most basic of connector building blocks, permeates diesel locomotive circuitry. All variations of the traditional “reds, blues, and yellows” are found in vast numbers connecting electro-mechanical components to the sophisticated processing devices and backplanes in point-to-point wiring schemes. So, simple is better, at least in the rail industry.

This analysis is not an indictment of the engineering capabilities of the rail industry. Obviously, we are seeing rail expand its reach around the world, and achieve new standards in comfort, speed, and efficiency. Instead, we respect and marvel at the levels of sophistication that can be accomplished using products that have established the credibility of the entire interconnect industry over time. When interconnect products are designed well in the first place, they can have a very long and successful lifespan, even as the industry updates and evolves with the changing times.

Lane M. Latto Market Segment Director — Rail Industry, Bishop & Associates Inc. Lane Latto joined Bishop & Associates in 2011 as market segment director with a focus on the global rail industry. He has particular expertise in applications and participating OEMs. His more than 20 years of experience in the interconnect industry includes positions as account manager and district sales manager with AMP Incorporated/TE Connectivity, and work as a sales trainer at the AMP Institute. He can be reached at llatto@bishopinc.com.