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.  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 roads 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.

EMD SW7 Production Roster

Owner Road Number(s) Quantity Date Built
Alabama Great Southern Railroad (Southern)6505-650951950
Arkansas & Louisiana Missouri Railway1111950
Atlantic Coast Line643-65191950
Burlington9249-9268201950
Central Railroad Of Pennsylvania (CNJ)1080-108341950
Charleston & Western Carolina Railway800-80121950
Chesapeake & Ohio5214-5239261950
Chicago & Eastern Illinois126-13161950
Chicago & Illinois Western101-10331950
Chicago Heights Terminal & Transfer (C&EI)132-13321950
Chicago River & Indiana Railroad (NYC)8898-890361950
Cincinnati, New Orleans & Texas Pacific (Southern)6060-6073141950
Clinchfield Railroad350-35561950
Colorado & Southern Railway (CB&Q)15411950
Conemaugh & Black Lick Railroad103-117151949-1950
Cornwall Railroad120-12231950
Detroit & Toledo Short Line116-11831950
Detroit, Toledo & Ironton920-92451950
Detroit Terminal Railroad11611951
Erie Railroad428-43361950
Illinois Central9300-9319, 9400-9429501950
Indiana Harbor Belt8835-8850, 8856-8879401949-1950
Georgia Southern & Florida Railway (Southern)8200-820341950
Great Northern11-13, 163-170111950
Kansas City Southern1300-1309101950
Lakeside & Marblehead Railroad1211950
Lehigh Valley220-22451950
Louisiana & Arkansas Railway (KCS)1310-131561951
Louisiana Midland Railway1011951
Louisville & Nashville2245-2266221950
Maine Central331-33331950
Milwaukee Road164611950
Missouri Pacific9142-914651950
Monessen Southwestern Railway2111950
Montour Railroad7211950
Nashville, Chattanooga & St. Louis24-33101950
New Orleans & Northeastern Railroad (Southern)6852-6863121950
New York Central8851-8855, 8884-8897, 8911-8921301950-1951
Nickel Plate Road230-23231950
Northern Pacific107-11481949
Pennsylvania8861-8868, 8871-8872, 9358-9395481950-1951
Peoria & Eastern Railway (NYC)8404-841071950
Peoria & Pekin Union Railroad406-41051950
Phelps Dodge Corporation611951
Philadelphia, Bethlehem & New England Railroad31-3441950
River Terminal Railway61-6221951
St. Louis San Francisco Railway (Frisco)300-30451950-1951
St. Louis Southwestern Railway (Cotton Belt/SP)1054-105741950
Texas & Pacific Railway (MP)1020-102341950
Union Pacific1800-1824251950
Union Railroad571-57451950
Wabash Railroad355-36271950
Weyerhaeuser Timber Company300-30121950-1951
Woodward Iron Company50-5121950
Youngstown & Southern Railroad70-7121950


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, 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 museums, as mentioned above, and because of their ease of maintenance several also are used in excursion train service. 

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