The EMD SW1 was the second model produced in the SW switcher series and the last built by the Electro-Motive Corporation before it became an official division of General Motors. As with the NW2 model built during the same time period, the SW1 was very popular with railroads selling well over 600 examples although it never sold quite as well as its counterpart. Today, this little switcher, just as with the NW2, continues to soldier on in all types of applications from use on shortlines and industrial services as well as pulling excursion and tourist trains. Even the very first SW1 built in early 1939 remains preserved at the California State Railroad Museum in Sacramento. As of today, there are more than two dozen SW1s officially preserved although as more are retired from freight service this list will certainly grow.
While General Motors' Electro-Motive Division (EMD) often gets the credit for cataloging highly successful first generation switcher models like the NW2, SW1, SW9, SW1200, and numerous others the history behind these locomotives is sometimes forgotten. It actually all began with the Electro-Motive Corporation, before it was a division of GM. During the mid to latter 1930s the company began marketing various switcher designs meant for certain tasks like the SC, NW, SW, and NC. Most of EMC's designations of its switchers simply referred to how their frames were constructed and their horsepower rating. In the case of the SW this meant six hundred horsepower built with a welded frame.
The corresponding numbers that followed in later models simply regarded their place in the series. Of course, under GM, ownership some of these designations changed but in general stayed the same. The EMD SW1 was the second model in the series and while it also featured a 600 horsepower prime mover (using the new GM six-cylinder model 567, and later the 567A), the "SW" designation of future models was in name only (the "S" would come to denote "switcher"), as just the later SW600 featured 600 hp (most were more powerful). The unit retained EMC's signature short carbody of just 44-feet with tapering just short of the cab.
Once again, as with the NW2 released that year, the SW1 featured GM's own model D37 traction motors and not those built by General Electric (which was used on early EMC switchers). Even at the early date GE was now a competitor to EMD through its affiliation with the American Locomotive Company (Alco). Up to that time, the SW1 offered some of the highest tractive effort for an EMD/EMC switcher; 49,500 pounds starting effort and 34,000 pounds continuous. Interestingly, the design was even lighter than the NW2, at just a paltry 99 tons! One noticeable difference of the SW1s compared to similar models was its short, "porches" at the front and aft ends of the locomotive.
The model was one of the few EMD switcher locomotives to receive a new prime mover while in production. After World War II the SW1 was reequipped with EMD's updated 567A prime mover, which still produced 600 horsepower. During this time the model also featured a slight update to its carbody. The original switcher was designed with a double-taper near the cab while the updated version featured just a single taper. Other new additions included a better conical, exhaust stack (which became standard on all future EMD switcher locomotives) for better crew visibility, rectangular instead of curved windshields, and a two-beam headlight (the original version included simply a single light).
Production of the EMD SW1 ran between the early winter of 1939 and November, 1953. Due to their flexibility, reliability, and a cheap price tag numerous Class Is and shortlines purchased the model with some 661 in total built. Just as with many other models, it also found a lot of interest with industries (like Wheeling Steel, Warner Sand and Gravel, Republic Steel, and others) and even the U.S. Army bought four models. Two years after the model was developed, EMC and the Winton Engine Company became an official division of General Motors on January 1, 1941. Today, just as with the NW2, the EMD SW1 has stood the test of time and remains in operation in several different applications from short lines to excursion trains.Home › Diesel Locomotives › EMD SW1