The SD40 and SD40-2, Standard of the Industry

EMD originally began as the Electro-Motive Corporation and has its beginnings in 1922 being based out of Cleveland, Ohio building inexpensive motorcars. With the purchase of the company in 1930 by General Motor, and more resources at its disposal the company began developing the precursor of the modern-day diesel-electric road unit (cabs and road-switchers), the streamlined trainset, which consisted of a powered car permanently attached to a few coaches (usually two or three cars). The most famous of these streamlined trainsets was the Burlington Zephyrs, a beautiful streamlined stainless steel creation (originally powered by Winton engines, which would also become a subsidiary of GM) that was extremely lightweight and fast. The original trainset, the Zephyr 9900, made headlines in 1934 when it completed a non-stop journey from Denver to Chicago in a little over 13 hours.

Because the power cars with these trainsets were permanently attached to the coaches EMC sought to design a locomotive free of this articulated setup but designed in such a manner that a railroad could still attach it to any passenger train and obtain the same, smooth streamlined look. This it did with the unveiling of the EA model in 1937, the first in a long line of passenger diesel locomotive designs that would come to be known as the E series.

Not surprisingly, soon after the EA unveiling the company decided to take things a step further and develop the first true diesel road unit, capable of pulling long freights in main line service. In 1939 it introduced the FT model (perhaps the key difference between the E and F series was that Fs rode on B-B trucks whereas Es rode on C-Cs and carried a noticeably longer carbody), the first in EMC’s F series and one of the most success diesel-electric designs of all time. The F series would go on to define American railroading for years and you can still see it in regular use today, over 60 years after it first debuted! The FT (which stood for Freight, Twenty-seven hundred horsepower) was a superb locomotive and although its 2,700 horsepower came from an A-B setup of a cab (A) and booster (B) units rated at 1,350 horsepower each, it was quickly loved by railroads for the efficiencies it held over steam such as its ruggedness and ease of maintenance.

The FT (which stood for Freight, Twenty-seven hundred horsepower) was a serious locomotive and although its 2,700 horsepower came from an A-B setup of cab (A) and booster (B) units rated at 1,350 horsepower each it would become embraced by the rail industry for the efficiencies it held over steam power as well as being rugged and easy to maintain.

Following the success of its cab units, EMD realized that there was a market to be made in the road-switchers, which at the time was mostly dominated by Alco with its RS series. Its first attempt at this type of locomotive, which gave the train crews both excellent vision all around the locomotive for switching and local service as well as enough horsepower to be used in main line operations, was the BL2. Although unsuccessful from a sales standpoint the BL2 was really a mere stepping-stone for its next model, the GP series (meaning General Purpose).

No other locomotive to date save for the earlier GP7 and GP9 has been as tremendously successful as the SD40 series, and the two models virtually became the face of EMD and what the locomotive builder stood for and represented. The series also became the standard of the industry during their time of production and because so many were built and still roam all over the country, for the most part this still holds true today, even while wide-cab units and GEs proliferate.

The SD40 series began production in 1966 with the SD40, which was built through 1972 and ended production in 1986 when the last SD40-2 rolled off of the assembly line. By the time production ended an astronomical 5,200+ units had been built! Most of these were SD40-2s as just under 4,000 were produced during its fourteen years of production while the SD40 chipped in another 1,200+.

When the series debuted it was just what railroads were after. Looking for a more powerful, reliable and gritty locomotive that could be counted on to work properly in almost any type of weather conditions the SD40 and SD40-2 were it. Rated at 3,000 hp, equipped with EMD’s standard cab design, and a C-C layout (meaning they had six axles) the units carried their builder’s 16-cylinder 645E3 diesel engine and high-traction truck. Extremely reliable the prime mover was loved by maintenance and shop crews and even many engineers have said the locomotive itself is a joy to operate as it experiences very little problems when in service.

This reliability, ruggedness, and ease of maintenance have been so fantastic with the SD40 series that the units continue to not only remain in common use on Class Is but also the big carriers have liked them so well that many are rebuilding the locomotives to keep them in active service for years to come!

Perhaps the biggest external difference between the SD40 and SD40-2 was the frame itself. The SD40 has a length of 65 feet, 9 inches whereas the SD40-2’s 68 foot, 10 inch frame is clearly noticeable with protruding platforms on the front and rear of the locomotive (sometimes called “porches”). While the SD40 is considered very successful itself what made the SD40-2 the best selling locomotive of the second-generation class was its additional upgraded features, which included things like electronics, an oblong water-level sight glass and bolted battery boxes just to name a few.

Additional features included a dynamic brake (a system for temporarily employing traction motors as generators and using the resulting electromotive force to slow the train) and an airtight hood that kept out dust, dirt, and other particles from reaching internal components (to cool these critical components the SD40 featured a single air intake for electrical cooling, with a pressurized cooling system).

A few variations of the SD40 series include an SDP40 built for passenger service (they included a steam generator) and SD40A, which at 70 feet, 8 inches were longer to accommodate bigger fuel tank and all of them operate on the Illinois Central (now Canadian National).

While one day the SD40s will slowly begin to disappear I think one can safely say that they will be around for years to come so just keep an eye out and you can routinely spot one in active service one Class Is, Regionals and shortlines.

For more information on the SD40 and SD40-2 series consider one (or both) of the books below. Mike Schafer’s Vintage Diesel Locomotives looks at virtually all of the classic builders and models from Alco PAs to early EMD Geeps. If you’re interested in classic EMDs, or diesels in general, this book gives an excellent general history of both.

Also, Brian Solomon’s The American Diesel Locomotive also studies many of the same diesel models and builders as Mr. Schafer’s publication although at nearly twice the size the book goes into a bit more detail than Vintage Diesel Locomotives and also covers newer models. All in all, though, both books are a great read and you shouldn’t be disappointed with them, not to mention that they are loaded with photos (many in color)!