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EMD "SW1" Locomotives

Last revised: February 15, 2024

By: Adam Burns

The SW1 was the second switcher Electro-Motive produced that featured a welded frame and respectable 600 horsepower.  

It was the first to feature a General Motors prime mover, the 567 and 567A, and began EMD's modern line of switchers that continued through the MP15 series.

The SW1 proved quite popular, witnessing 660 sales before production ended.  While it did not sell as well as the NW2, the SW1 and it successors became EMD's primary switcher line. 

Today, examples can still be found in all types of applications, from regular freight service to industrial settings. 

In addition, you can find them hosting excursions and tourist trains. Even one of the first SW1's built, Southern Pacific #1000, is preserved at the California State Railroad Museum in Sacramento. 


283491284265265826934979748.jpgLehigh Valley SW1 #112 was photographed here at the road's terminal in Sayre, Pennsylvania on September 9, 1972. Bob Wilt photo. Warren Calloway collection.


While Electro-Motive produced a wide range of highly successful switchers such as the NW2, SW1200, SW1500, and SW9 the series can be traced back to a group of early six and nine hundred horsepower variants built during the latter 1930s.

This included the SC, SW, NC, and NW manufactured with either cast or welded frames.  For example, SC referred to Six hundred horsepower, Cast frame while SW denoted Six hundred horsepower, Welded frame.


These switchers were built during an era that predated the modern road diesels and some railroads still preferred locomotives with cast frames, harkening back to the steam era.

As the years passed, EMD's method of identifying models seemingly changed every few years; in some cases the number simply denoted its number in the series while later the horsepower rating was included.

In addition, the NW2 was the last in the short-lived "NW" line.  Following its production run, Electro-Motive dropped the first letter in identifying the horsepower rating.  It also eliminated the cast or welded designation as the latter became the preferred production method.

In their place, the builder retained the "SW" lettering, which now meant simply Switcher.   The SW1 featured a 600 horsepower prime mover and retained Electro-Motive's signature short carbody of just 44-feet with tapering near the cab for improved visibility.

The SW1's most recognizable feature is the large sandbox just under the grill.  Its location is unique to this particular model.

Reading SW1 #20 sits in the dead line at the company's shops in Reading, Pennsylvania on April 22, 1973. By this date the locomotive was being parted out to rebuild other SW1's. Author's collection.

As Jerry Pinkepank notes in his book, "Diesel Spotter's Guide," another of the switcher's noteworthy trademarks is a single, centered, conical stack. 

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 was designed with a double-taper near the cab while the updated version included a single taper.

Data Sheet and Specifications

Entered Production12/1938 (Electro-Motive #755)
Years Produced12/1938 - 11/1953
EMD ClassSW1
Engine567/567A (6 Cylinder)
Engine BuilderEMD/GM
Length44' 5"
Height (Top Of Rail To Top Of Cab)14' 5" (Built prior to January, 1945.)
Height (Top Of Rail To Top Of Cab)14' 4 5/8" (Built after January, 1945.)
Width10' 2" (Built prior to January, 1945.)
Width10' 0" (Built after January, 1945.)
Weight198,000 Lbs
Fuel Capacity600 Gallons
Air Compressor3C2C (Westinghouse)
Air Brake Schedule6-BL (Westinghouse)
Truck TypeGRS Rigid Bolster, Drop-Side Equalizer (AAR Type-A)
Truck Wheelbase8' 0"
Wheel Size40"
Traction MotorsD7* (4), EMD/GM
Traction GeneratorD4A/D4/D4D*, EMD/GM
MU (Multiple-Unit)No
Dynamic BrakesNo
Gear Ratio62:15 (Before January, 1945) or 65:12 (After January, 1945)
Tractive Effort/Starting49,500 Lbs (at 25% adhesion)
Top Speed65 mph (62:15); 55 mph (65:12)

* Only the model D4D generator was used in SW1's built between January, 1945 and December, 1949.  Electro-Motive's "Operating Manual #2303" states the D27 traction motor and D15A main generator were used in SW1 models built after December, 1949.

Production Roster

(Total Built = 660)

Owner Road Number Serial Number Order Number Completion Date Quantity
Electro-Motive (Demonstrator)755*755E29212/19381
Seaboard Air Line1200802E2363/19391
Fort Worth Belt Railway1803E2321/19391
Electro-Motive (Demonstrator)804**804E2572/19391
Central Railroad Of New Jersey1009-1010805-806E2291/19392
New York Central600-613808-821E2172/1939-4/193914
New York Central574-579853-858E2171/19396
Great Northern5101-5102859-860E2181/19392
Lehigh Valley112874E2374/19391
New York Central614-616875-877E2395/19393
Milwaukee Road1610-1611878-879E2406/19392
Wabash Railroad101-103880-882E2476/19393
Missouri Pacific9004-9005895-896E2499/19392
Chicago, Burlington & Quincy9136-9140897-901E2596/19395
Pere Marquette10902E2627/19391
Phelps Dodge CorporationA903E2657/19391
Milwaukee Road1612904E2688/19391
Electro-Motive (Demonstrator)905***905E2878/19391
Electro-Motive (Demonstrator)906****906E2838/19391
Soo Line320907E2739/19391
Louisville & Nashville11908E2759/19391
Richmond Terminal*****1909E3079/19391
Republic Steel Corporation (Buffalo)370910E27710/19391
Electro-Motive (Demonstrator)911******911E34910/19391
Boston & Maine1109-1111912-914E28811/19393
Southern Pacific1004-1009975-980E28111/19396
Illinois Central9014-9020981-987E28412/1939-1/19407
Western Pacific502-503988-989E28312/19392
International-Great Northern (Missouri Pacific)9200-9203990-993E28912/19394
Fort Worth & Denver City (Burlington)602994E29012/19391
New York Central617-6211010-1014E28212/1939-1/19405
Elgin, Joliet & Eastern220-2241015-1019E2911/1940-2/19405
Lehigh Valley113-1151020-1022E2952/19403
Great Lakes Steel121023E3499/19401
Wabash Railroad1041024E2972/19401
Houston Belt & Terminal101025E3003/19401
Buffalo Creek Railroad421026E3033/19401
Delaware, Lackawanna & Western427-4291027-1029E3043/19403
Milwaukee Road1613-16241039-1050E2983/1940-4/194012
Delaware, Lackawanna & Western430-4371051-1058E3044/1940-5/19408
Chicago, Burlington & Quincy9141-91471068-1074E3105/1940-6/19407
Wabash Railroad1051075E3115/19401
Terminal Railroad Association Of St. Louis501-5041076-1079E3136/19404
Missouri Pacific90061083E3168/19401
St. Johns River Terminal (Southern Railway)85651085E3197/19401
Philadelphia, Bethlehem & New England2121088E3216/19401
Baltimore & Ohio200-2151098-1113E3248/1940-9/194016
Philadelphia, Bethlehem & New England213-2141160-1161E3378/19402
Elgin, Joliet & Eastern225-2301162-1167E3389/19406
Milwaukee Road1625-16331178-1186E34310/1940-11/19409
Chicago, St. Paul, Minneapolis & Omaha (Chicago & North Western)551194E34610/19401
Wabash Railroad1061197E35011/19401
Southern Railway2002-20041206-1208E35411/19403
Inland Steel Company541223E36111/19401
Philadelphia, Bethlehem & New England215-2161228-1229E36411/1940-12/19402
Central of Georgia Railway2-31230-1231E3651/19412
Elgin, Joliet & Eastern231-2371233-1239E36712/1940-1/19417
New York Central622-6411254-1273E3723/1941-9/194120
New York Central642-6441274-1276E3734/19413
New York Central645-6471277-1279E3747/19413
Chicago, Burlington & Quincy9148-91531280-1285E3752/19416
Donner-Hanna Coke Corporation11305E3781/19411
Great Lakes Steel30-311306-1307E3792/19412
Missouri Pacific90111314E3838/19411
Southern Pacific1010-10161316-1322E3854/1941-7/19417
Texas & New Orleans (Southern Pacific)111323E3857/19411
Detroit, Toledo & Ironton900-9011324-1325E3865/1941-8/19412
Great Lakes Steel14-151326-1327E3873/19412
International-Great Northern (Missouri Pacific)9204-92051338-1339E3926/19412
Milwaukee Road16341369E3999/19411
Chicago & Eastern Illinois97-981378-1379E4571/19422
Great Northern5103-51051380-1382E4369/19413
Wabash Railroad1071388E40311/19451
Elgin, Joliet & Eastern238-2461396-1404E4079/1941-11/19419
Canton Railroad211448E42510/19411
Philadelphia, Bethlehem & New England217-2181449-1450E42610/19412
Commonwealth Edison101453E42911/19411
Boston & Maine1112-11131457-1458E43011/19412
Central of Georgia Railway71459E44112/19411
Chicago & Eastern Illinois991474E4571/19421
Memphis Union Station101475E4351/19421
Nashville, Chattanooga & St. Louis151537E44312/19411
Louisville & Nashville12-151563-1566E44812/19414
New York Central648-6501582-1584E45612/19413
Inland Steel Company571588E45512/19411
New York Central651-6541589-1592E4561/1942-2/19424
Chicago, Indianapolis & Louisville (Monon)501597E4602/19421
Baltimore & Ohio Chicago Terminal217, 216, 218-2211601-1606E4625/1942-8/19426
Central Railroad of New Jersey1011-10121610-1611E4652/19422
Commonwealth Edison111632E4692/19421
Chicago Short Line2001677E4742/19421
Rock Island529-5361678-1685E4752/1942-4/19428
Pere Marquette111714E4784/19421
Chicago & North Western1207-1212, 1214-12151738-1745E4899/1942-12/19428
Canton Railroad22-231750-1751E4936/19422
Republic Steel Corporation3711778E5001/19421
Philadelphia, Bethlehem & New England220-2211853-1854E5133/19422
Chicago & Eastern Illinois95-961855-1856E5146/19422
Fort Worth & Denver City (Burlington)6041864E5178/19421
New York Central580-5841878-1882E52112/1942-3/19435
Republic Steel Corporation (Gadsden, Alabama)890-8911936-1937E5283/19422
U.S. Army70011990E5333/19421
U.S. Army7003-70042000-2001E5436/19422
U.S. Army70022012E5485/19421
Broward County Port Authority (Fort Lauderdale, Florida)4002384E5952/19431
Commonwealth Edison142864E6386/19461
Great Lakes Steel16-183182-3184E6569/1945-10/19453
Republic Steel (Canton, Ohio)50-543219-3223E66110/19455
Republic Steel (Youngstown, Ohio)300-3013224-3225E66110/19452
Illinois Central9021-90303289-3298E6686/194610
Wheeling Steel1001-10023769-3770E72010/19462
Boston & Maine1114-11163884-3886E72710/19463
Boston & Maine11173895E72710/19461
Electro-Motive (Demonstrator)700*******3896E73010/19461
Maryland & Pennsylvania704162E77112/19461
Mathieson Chemical Corporation14479E8041/19471
Chicago District Electric Generating Company34492E8061/19471
Manufacturers Junction Railway64498E8101/19471
Atlantic & East Carolina Railroad94582E8124/19471
Southern Railway2007-20114743-4747E8274/1947-8/19475
St. Joseph Belt Railway (Missouri)124793E8314/19471
Republic Steel (Buffalo, New York)3724804E8354/19471
Chattanooga Traction Company44840E8374/19471
Commonwealth Edison124995E8569/19471
Terminal Railroad Association of St. Louis505-5085022-5025E8599/1947-10/19474
Pennsylvania9138, 9137, 9139-91515370-5384E8984/1948-7/194815
Angelina & Neches River Railroad105656E9319/19471
Georgia Marble Company15663E9339/19471
Tennessee Coal, Iron & Railroad1000-10035753-5756E9453/19484
Wheeling Steel1003-10045764-5765E9478/19482
Commonwealth Edison135767E9493/19481
Allis-Chalmers Manufacturing Company (West Allis, Wisconsin)85920E9599/19471
Erie Railroad3606148E9777/19481
Inland Steel70-736169-6172E9803/1948-4/19484
Hanna Furnace Company14-156258-6259E9904/1948, 4/19492
New York Central585-6096391-6415E9994/1949-6/194925
Mathieson Chemical Corporation26466E10034/19491
Great Lakes Steel33-346753-6754E10237/1948, 4/19492
Chicago District Electric Generating Company46769E10258/19481
Great Lakes Steel227402E10234/19491
Roscoe, Snyder & Pacific Railway1007458E10618/19491
Rock Island537-5467473-7482E10647/194910
Union Railroad455-4687502-7515E10706/1949-8/194914
Canton Railroad24-257744-7745E10678/19492
Detroit Edison210-2118152-8153E11394/19492
Chicago Short Line2018154E11404/19491
Boston & Maine11188321E11544/19491
Chicago, Indianapolis & Louisville (Monon)5-68423-8424E12548/19492
Union Railroad469-4708531-8532E11851/1950-2/19502
Galveston Wharves201-2028613-8614E11944/19492
Galveston Wharves203-20410083-10084604112/19492
Central Indiana Railway11011160057/19491
Great Northern80-8210118-1012040271/19503
Commonwealth Edison151053840349/19501
Union Railroad471-47610900-1090540427/19506
Conemaugh & Black Lick Railroad60-6111009-11010606012/19492
Great Northern831102540471/19501
Georgia & Florida Railroad70-7211097-1109960707/19503
Public Service Company Of Northern Illinois91122760831/19501
McLouth Steel31131660861/19501
St. Joseph Terminal1-211378-1137960892/19502
New York Central610-61411767-11771611510/19505
New York Central (Chicago River & Indiana)615-62111782-1178861166/1950-10/19507
Conemaugh & Black Lick Railroad62-6511938-11941406010/19504
Detroit Edison21212087613310/19501
Lehigh Valley118-11912212-12213406712/19502
Republic Steel (Youngstown, Ohio)302-30312734, 131396167, 618310/1950-11/19502
Inland Steel (East Chicago, Indiana)76-7713547-13548621511/1950-12/19502
Inland Steel (East Chicago, Indiana)78-8013575-1357740943/19513
New York, Chicago & St. Louis (Nickel Plate Road)105-10613705-13706621312/19502
Allegheny & South Side Railway1011405841013/19511
Republic Steel3041409862403/19511
Illinois Central9031-903214388-1438941198/19512
Republic Steel (Youngstown, Ohio)3051439162623/19511
Public Service Company Of Northern Illinois101447862618/19511
McLouth Steel41450762673/19511
Republic Steel3061455962668/19511
Republic Steel (Cleveland, Ohio)340-34114560-1456163178/19512
Chihuahua Forests Company (Mexico)5001465462968/19511
Granite City Steel600-60114721-1472262928/19512
Inland Steel811474140943/19511
Republic Steel (Gadsden, Alabama)8931474263168/19511
Galveston Wharves2051498563248/19511
Electro-Motive (Demonstrator)152********1555741526/19511
Republic Steel (Youngstown, Ohio)3521611663792/19521
Republic Steel (Gadsden, Alabama)8941611763942/19521
Great Western Railway of Colorado611644663912/19521
Public Service Company Of Northern Illinois111670463716/19521
Portland Traction Company1001688963992/19521
Great Lakes Steel361711464353/19531
Great Lakes Steel3517137642112/19521
Louisiana Midland Railway111714364376/19521
Metropolitan Sanitary District of Greater Chicago1-317235-1723764177/1952-12/19523
Garden City Western20117564647210/19521
Portland Traction Company2001770942103/19531
McLouth Steel51789564783/19531
Chicago & North Western1268-1270, 1272-127318101-1810541775/19535
Chicago & North Western12711811142275/19531
Chicago & North Western1274-127918106-18110, 18112-1811342285/19536
Boston & Maine1119-113218186-1819942147/1953-8/195314
Warner Sand & Gravel Company151827965085/19531
Hanna Furnace Company161829965105/19531
Lehigh Portland Cement Company51844165195/19531
Sahara Coal CompanyNo Number1872142379/19531
Great Lakes Steel381878342429/19531
Cleveland Quarries Company219304425411/19531

*        Became Inland Steel Company #51 in January, 1940.

**       Became Southern Pacific #1000.

***      Became Central of Georgia #1.

****     Became Western Pacific #501.

*****  This unit was built as Atlantic Coast Line #1901 but ultimately rejected and returned to EMD where it was resold to Richmond Terminal.

******   Became Great Lakes Steel #11.

*******  Became Manufacturers Junction Railway #7.

******** Became Scullin Steel #6.

199483746261262635728699026793.jpgPennsylvania SW1 #8590 (Class ES-6) was photographed here in Cincinnati, Ohio, circa 1967. The switcher was originally built as #5990 in March, 1948 and had been renumbered here in preparation for the upcoming Penn Central merger. Fred Byerly photo. American-Rails.com collection.


  • EMD. Operating Manual #2303: 600 & 1000 HP Switching Locomotives (Models SW1 & NW2; 567 & 567A Engines). La Grange: Electro-Motive Division (General Motors Corporation).
  • 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.

1799772uhb268992716g1676813.jpgA handsome Monon Railroad SW1 in a scene probably dating to the 1950's. Date, location, and photographer not listed. American-Rails.com collection.

Other new additions included a lower exhaust stack (which became standard on all future EMD switcher locomotives) for better crew visibility, rectangular instead of curved windshields above the hood (beginning in the mid-1950s), and twin sealed-beam headlights.

The SW1 enjoyed a long production run, from December, 1938 through November, 1953. Due to their flexibility, reliability and cheap price, numerous Class Is and short lines purchased switcher with some 660 manufactured over thirteen years.

It also found great interest in the private sector where companies like Wheeling Steel, Warner Sand & Gravel, Republic Steel, Cleveland Quarries, and even the U.S. Army bought the model.

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