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The EMD SW7

The EMD SW7 was the third diesel locomotive switcher the builder produced in the SW series and the first new design following World War II in the late 1940s (EMD halted production and development on new models until after the war, mostly due to war restrictions ongoing at the time). Outwardly, the SW7 was virtually identical to future SW models and related NW designs of the time although it did differ slightly from the earlier SW1 in that it featured a more streamlined hood without the "step" in front of the nose. The most striking difference between the SW1 and SW7 was the latter's additional horsepower, which was twice that of the former. As with many early EMD switcher locomotive models the SW7 continues to see use today in many various settings from industrial and shortline operations to tourist and excursion trains. There are currently two models officially known to be preserved (CB&Q #9255 at the Illinois Railway Museum and Southern #8202 at the Southeastern Railway Museum) although more are sure to follow as they are retired from freight service.

The EMD SW7 debuted in October, 1949 and looked to follow the success of the previous SW1 and NW2 models, which combined, sold more than 1,800 units between 1939 and 1953. The history of the SW line, of course, dates back to the Electro-Motive Corporation of the mid-1930s which began releasing a whole series of small switchers for use in light duty and industrial work. They almost instantly became successful and after the company became a division of General Motors it continued to expand on the series. To learn more about the history of those early switchers please click here. In any event, all EMD switcher locomotives after the SW7 are very hard to tell apart. The SW7 used the traditional EMC/EMD carbody design, that was tapered near the cab and featured EMD's classic conical exhaust stacks above the hood. Length remained the same at just over 44-feet and it continued to use GM's model D37 traction motors.

The biggest difference, to date, with the EMD SW7 over any previous model was simply horsepower. Using the updated V12 567A prime mover the SW7 could produce a hefty 1,200 horsepower for such a small switcher of its size (almost a tug boat on steel wheels!), and produced 36,000 pounds of continuous tractive effort and 62,000 pounds starting. Overall, the locomotive weighed just 124 tons and remained about 44 feet in length. Also, by the time the SW7 was developed the "SW" designation EMC originally used, which stood for six-hundred horsepower, welded frame had long since been dropped with EMD simply having refer to "switcher."

Once again, railroads were impressed and orders for the SW7 quickly began to pile up. As with previous models the SW7 was meant to be used in yard, light branch, and industrial settings which also helped in finding many buyers. With a very reasonable price tag some 489 SW7s were produced in less than a two year time span, through January, 1951. The railroads to purchase the SW7 are far too numerous to mention here. However, some of the industries to purchase the locomotive included Weyerhaueser Timber Company and the Phelps Dodge Corporation. It should noted that EMD also produced another cow/calf version of the SW7 known as the TR4. This model sold 15 total sets to the Santa Fe, Belt Railway of Chicago, Chesapeake & Ohio, and Milwaukee Road.

Just as with previous EMC/EMD switcher locomotive designs of the time, it's somewhat amazing that several SW7s remain in use in all types of applications from industrial to shortline settings more than 60 years since the last one rolled out of the assembly line. Places were you can still find the SW7 in operation include the Conemaugh & Black Lick Railroad, Lehigh Valley Rail Management, Mansbach Metal Company, Independent Locomotive Service, Midwest Steel and Alloy, Turtle Creek Industrial, Chicago-Chemung Railroad Company, Heritage Railroad, J&L Consulting, New York New Jersey Rail, Seaview Railroad, Peoria and Pekin Union Railway, STRATA Corporation, and the Chesapeake Auto Terminal, Inc. You can also find many preserved at railroad museums, as mentioned above, and because of their ease of maintenance several also are used in excursion train service. For technical data regarding the EMD SW7 please click here. Also, for information about EMD's various switchers please refer to the chart below.

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Electro-Motive Division Switchers

Model Type	Units Built	Date Built	Horsepower
NW2	1,145	1939-1949	1,000
NW3	7	1939-1942	1,000
NW5	13	1946-1947	1,000
SW1	661	1939-1953	600
RS1325	2	1960	1,325
SW600	15	1954-1962	600
SW7	489	1949-1951	1,200
SW8	374	1950-1954	800
SW9	815	1950-1953	1,200
SW900	371	1953-1969	900
SW1000	119	1966-1972	1,000
SW1001	230	1968-1986	1,000
SW1200	1,056	1954-1966	1,200
SW1500	808	1966-1974	1,500
SW1504	60	1973	1,500
MP15/DC/AC/T	640	1974-1987	1,500

For more reading about EMD SW7s and related diesel locomotives built by General Motors consider Mike Schafer’s Vintage Diesel Locomotives which 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.

You might want to also consider the book EMD Locomotives from author Brian Solomon. Solomon's book highlights the history of EMD from its earliest beginnings in the 1920s, to its phenomenal successes in the mid-20th century, and finally its decline into second spot behind General Electric in the late 20th century and eventual sale by General Motors in 2005. The book features 176 pages of EMD history and is filled with excellent photography and illustrations. If you're interested in perhaps purchasing either (or both) of these books please visit the links below which will take you to ordering information through Amazon.com, the trusted online shopping network.

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