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EMD "SW7" Locomotives

Last revised: March 2, 2024

By: Adam Burns

The SW7 was Electro-Motive third in its modern switcher line and the first produced after World War II.

EMD had halted production on new models until after the war due to restrictions brought about the War Production Board, which directed companies to focus on materiel for the war effort.

Outwardly, the SW7 was virtually identical to the NW2 and later "SW" models through the SW1200. Once again, there were a wide range of buyers for this locomotive from large Class I's to short lines and private industries.

Both builders and railroads alike came to realize the 1,000-1,500 horsepower switcher was the ideal rating; it offered plenty of beef, yet remained small enough to handle the assignments required of these locomotives (such as tight clearances and sharp curves).

As with many early EMD switcher models, the SW7 continues to see use today.  It remains in operation at some private industries and also on short lines. 


62273912941274521351564236725367278.jpgChesapeake & Ohio SW7 #5224 pushes cars into the "S.S. Badger" carferry at Ludington, Michigan in July, 1960. Rick Burn photo.

History and Background

The SW7 debuted in October, 1949 as Electro-Motived looked to continue the strong sales of its earlier SW1 and NW2 models.  

These two switchers had been a massive success, combining for 1,775 units during a production run that spanned fifteen years (1938-1953).  The NW2, alone, had sold 1,115 units. 

The history of the SW line dates back to the Electro-Motive Corporation a series of cast and welded-framed models built between 1935-1939.

This switchers sported 600 horsepower and, coupled with their 900 horsepower counterparts (NW/NC), convinced the builder there was a market for such a locomotive.

The SW7 used the traditional EMC/EMD carbody design, that was tapered near the cab and featured EMD's classic conical exhaust stacks. Length remained the same at just over 44-feet and the model continued to use GM's D37 traction motors.  

2689498124726346257236893907.jpgKansas City Southern SW7 #1312 is seen here in Kansas City, Missouri, circa 1973. Mac Owen photo. American-Rails.com collection.

12-Cylinder, 567A

The biggest difference was a bump in horsepower; sporting an updated, 12-cylinder model 567A prime mover, the SW7 could produce a hefty 1,200 horsepower with a starting tractive effort of 62,000 pounds.

By the time the switcher was cataloged, the "SW" designation had changed: "S" no longer stood for six-hundred horsepower and "W" did not mean welded frame.

Data Sheet and Specifications

Entered Production10/1949 (Indiana Harbor Belt #8835)
Years Produced10/1949 - 1/1951
EMD ClassSW7
Engine567A (12 Cylinder)
Engine BuilderEMD/GM
Length44' 5"
Height (Top Of Rail To Top Of Cab)14' 6"
Width10' 2"
Weight248,000 Lbs
Fuel Capacity600 Gallons
Air CompressorWXO (Gardner-Denver)
Air Brake Schedule14EL (Westinghouse)
Truck TypeGRS Rigid Bolster, Drop-Side Equalizer (AAR Type-A)
Truck Wheelbase8' 0"
Wheel Size40"
Traction MotorsD37 (4), EMD/GM
Traction GeneratorD15C, EMD/GM
Auxiliary GeneratorEMD/GM
MU (Multiple-Unit)Optional
Dynamic BrakesNo
Gear Ratio62:15
Tractive Effort/Starting62,000 Lbs
Tractive Effort/Continuous36,000 Lbs at 11.0 mph
Top Speed65 mph

Production Roster

(Total Built = 489)

Owner Road Number Serial Number Order Number Completion Date Quantity
Nashville, Chattanooga & St Louis24-297433-743860317/1950-8/19506
Indiana Harbor Belt8836-88458127-8136E11361/195010
Chicago, Burlington & Quincy9249-92608493-8504E11965/195012
Chicago & Eastern Illinois126-1318882-8887E12282/19506
Wabash Railroad355-3629037-9044E12427/19508
Indiana Harbor Belt8856-88769121-914140002/1950-4/195021
Kansas City Southern1300-13019159-9160405710/19502
Atlantic Coast Line643-6519173-918140024/19509
Indiana Harbor Belt8877-88799215-921740004/19503
New York Central8880-88839221-922440405/19504
New York Central8884-88979418-943140405/1950-6/195014
Indiana Harbor Belt8846-88509446-9450E11361/1950-2/19505
New York Central8851-88559451-9455E11362/19505
Indiana Harbor Belt88359460E126710/19491
Great Northern163-1709569-957640053/19508
Chicago, Burlington & Quincy9261-92689718-972540067/19508
Conemaugh & Black Lick107-1119752-975640076/19505
Louisville & Nashville2245-22509772-977740093/19506
Kansas City Southern (Louisiana & Arkansas)1310-13159792-979740081/19516
Louisiana Midland Railway10979862381/19511
Conemaugh & Black Lick112-1159915-991840119/19504
New York Central8911-89219950-996040121/195111
Illinois Central9300-930910032-1004160082/1950-4/195010
Illinois Central9400-940910042-1005140164/1950-6/195010
Peoria & Pekin Union4061008560012/19501
Peoria & Pekin Union408-41010086-1008840248/19503
Peoria & Pekin Union4071011660012/19501
St. Louis-San Francisco Railway (Frisco)300-30410182-10186402812/1950-1/19515
Union Railroad573-57410235-10236404111/19502
Detroit, Toledo & Ironton920-92210242-1024440399/19503
Chesapeake & Ohio5214-523910273-1029860751/1950-3/195026
Conemaugh & Black Lick103-10510303-10305602012/19493
Pennsylvania9364-9368, 9373-939510387-1041460223/1950-5/195028
Pennsylvania9358-9363, 9369-937210431-1044040316/1950-7/195010
Chicago & Eastern Illinois (Chicago Heights Terminal & Transfer)132-13310526-1052760396/19502
Union Pacific1800-182410752-1077640388/1950-11/195025
Detroit, Toledo & Ironton923-92410801-10802403910/19502
Great Northern11-1310869-1087160506/19503
Union Railroad571-57210898-10899404111/19502
Northern Pacific107-11410932-10939605411/1949-12/19498
Southern Railway (Cincinnati, New Orleans & Texas Pacific)6060-607310942-1095560562/1950-3/195014
Southern Railway (New Orleans & North Eastern)6852-686310956-10967606412/1949-1/195012
Southern Railway (Alabama Great Southern)6505-650910968-1097260651/1950-2/19505
Southern Railway (Georgia Southern & Florida)8200-820310973-1097660665/19504
Lehigh Valley2201118560761/19501
Lakeside & Marblehead Railroad121118660773/19501
Arkansas & Louisiana Missouri Railway111123260853/19501
Louisville & Nashville2251-226511301-11315404712/195015
Cornwall Railroad120-12111372-1137360873/19502
Philadelphia, Bethlehem & New England31-3211374-1137560943/19502
Conemaugh & Black Lick1061137661064/19501
Chicago & Illinois Western1011137760884/19501
St. Louis Southwestern Railway (Southern Pacific)1054-105711383-1138660904/19504
Detroit & Toledo Shore Line116-11711399-1140060924/19502
Milwaukee Road16461140140499/19501
Colorado & Southern Railway (Burlington)1541147540508/19501
Missouri Pacific9142-914611554-1155861026/19505
Central Railroad of New Jersey (Central Railroad Of Pennsylvania)1080-108311629-1163261085/19504
Illinois Central9310-931911648-11657405310/1950-12/195010
Illinois Central9410-942911658-1167740548/1950-12/195020
Detroit & Toledo Shore Line1181173260924/19501
Chicago River & Indiana (New York Central)8898-890311774-1177940586/19506
Erie Railroad4281182561205/19501
Nashville, Chattanooga & St. Louis30-3311924-1192760318/19504
Texas & Pacific1020-102311996-1199961337/19504
Erie Railroad429-43012022-12023406111/19502
Erie Railroad432-43312024-12025406911/19502
Erie Railroad43112026407011/19501
New York, Chicago & St. Louis (Nickel Plate Road)230-23212307-1230961399/1950-10/19503
Maine Central331-33312370-1237261489/19503
Lehigh Valley221-22412467-12470406812/19504
Woodward Iron Company50-5112720-1272161639/19502
Chicago & Illinois Western102-10312895-12896616912/19502
Conemaugh & Black Lick116-11712917-12918401110/19502
Peoria & Eastern (New York Central)8904-891013012-13018617411/19507
Youngstown & Southern70-7113019-13020617511/19502
Montour Railroad7213021617511/19501
Charleston & Western Carolina800-80113022-13023617611/19502
Pennsylvania Railroad8861-8868, 8871-887213063-1307262301/195110
Kansas City Southern1302-130913420-13427405710/1950-11/19508
Louisville & Nashville226613532404712/19501
Cornwall Railroad12213540619911/19501
Philadelphia, Bethlehem & New England33-3413565-1356662019/1950-10/19502
Weyerhaeuser Timber Company300-30113571-13572622512/1950-1/19512
Monessen Southwestern Railroad2113573621110/19501
River Terminal61-6213674-1367562331/19512
Phelps Dodge Corporation (New Cornelia Branch Mine)61398162411/19511
Detroit Terminal1161409762391/19511


  • EMD. Operating Manual #2303: 600 & 1200 HP Switching Locomotives (Models SW1 & SW7; 567 Series Engines). La Grange: Electro-Motive Division (General Motors Corporation), January, 1950 (5th Edition).
  • Foster, Gerald. A Field Guide To Trains. New York: Houghton Mifflin, 1996.
  • Hayden, Bob. Diesel Locomotives: Cyclopedia, Volume 2 (Model Railroader). Milwaukee: Kalmbach Publishing Company, 1980.
  • Marre, Louis A. Diesel Locomotives: The First 50 Years, A Guide To Diesels Built Before 1972.  Milwaukee: Kalmbach Publishing Company, 1995.
  • Pinkepank, Jerry A. Diesel Spotter's Guide.  Milwaukee: Kalmbach Publishing Company, 1967.
  • Solomon, Brian.  EMD Locomotives.  Minneapolis: MBI Publishing Company, 2006.

009157171761892690390790387.jpgMaine Central SW7's #333 and #331 carries out switching work in Bangor, Maine during June of 1980. American-Rails.com collection.

Instead, the company apparently decided to simply use the two letters  as short for "Switcher."  Once again, railroads were impressed with this latest EMD product and sales were strong.

Once again, the SW7 found use in yard work, light branch service, and a myriad of industrial applications.  When production had ended some 489 units had been produced during only a two year production run. 

It should noted that EMD also produced a 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.

In his book, "Diesel Spotter's Guide," author Jerry Pinkepank notes the SW7 is distinguished from the SW9 and SW1200 by a single feature, an upper set of short vents on the carbody access doors.  These are not present on the other two variants.

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