Alco "S-1" Locomotives

Last revised: May 30, 2023

By: Adam Burns

The Alco S-1 was one of the first switcher models the company produced and debuted just after the company had released its first ever main line design, the DL series.

The American Locomotive Company's history with switchers actually dated as far back as the boxcab design it had developed in conjunction with General Electric and Ingersoll-Rand in 1918 for the Jay Street Connecting Railroad (#4).

In 1931 it began constructing more standard designs beginning with a 300 horsepower variant (despite railfans classifying these switchers as "High Hood" types, Alco never used such terminology as John Kirkland notes in his book, "The Diesel Builders: Volume Two").

Along with this model Alco built 600, 660, 900, and 1,000 horsepower versions through July, 1940.  Convinced that it could successfully market a line of switchers, the builder released its "S" series (Switcher) soon after.  

The dichotomy of Alco is fascinating; the builder proved quite successful with its switchers and light road-switcher models (RS-1, RS-2, and RS-3). 

However, it struggled to catalog an effective and rugged road-switcher design that could handle the stresses and beating of daily freight service.  Today, numerous S1's are preserved around the country, many of which are still operational.


It's the early Erie Lackawanna era as a former Erie Railroad S1 works local service along the old Delaware, Lackawanna & Western main line at Nichols, New York on a beautiful October day in 1963. Photographer unknown. collection.


The Alco S1 was first produced in 1940 featuring an end-cab design using McIntosh & Seymore's 539 model prime mover. The model came equipped with 660 horsepower and was well liked by short lines and Class Is for yard work and light branch line duties.

The engine the S1 employed proved quite adept in this capacity although the builder would come to find that producing a reliable main line design was a far trickier task.

This was mostly due to the fact that the Schenectady manufacturer did not see diesel locomotives as standard freight and passenger power, a fatal decision that would haunt the company for years.  In any event, to its credit Alco correctly foresaw the demand for switchers, at least early with first-generation examples.

New Haven Railroad S-1 #0939 and a mate layover near the massive coaling tower at the Charles Street Roundhouse in Providence, Rhode Island during the early 1950s. collection.


The S1 employed many design characteristics that the company had refined during its early years of collaborating with Ingersoll-Rand and GE, particularly during the construction of its initial switcher line.

This series was produced in conjunction with Westinghouse and McIntosh & Seymore featuring the former's "Visibility Cab" design, which was wider and, usually, taller (unless the hood was mounted flush with the top of the cab) than the trailing hood to give crews maximum visibility.

Alco would make this cab the standard for its S series and early RS (Road Switcher) locomotives. The manufacturer also carried over the carbody design features Otto Kuhler had employed on the HH locomotives, primarily in the way of soft bevels and curves.

A former Erie S1, #318, totes a short of cut of cars at Binghamton, New York in December, 1962. Author's collection.

The Alco S1 was classed by Alco as its E1530 design and was quite similar to its later S3 model (actually, all of the S series locomotives were very similar in appearance, externally).

It featured four, General Electric model 731 traction motors and also used main/secondary generators from the company. Additionally, Westinghouse supplied all air components (both companies supplied Alco with these parts virtually through the end of its time as a locomotive manufacturer).

For a small switcher that only weighed 105 tons it could produce quite a bit of tractive effort; 57,500 pounds starting and 46,000 pounds continuous (a trait certainly not missed by railroads).   

Data Sheet and Specifications

Entered Production5/16/1940 (Des Moines Union Railway #1)
Years Produced5/16/1940-6//29/1950
Model SpecificationE1530
Engine539, 6-Cylinder In-Line
Carbody StylingAlco
Length (Between Coupler Pulling Faces)45' 5.75"
Height Above Rail Head14' 6"
Weight196,000 Lbs.
Truck TypeBlunt
Truck Wheelbase8'
Wheel Size40"
Traction MotorsGE 731 (4)
Traction GeneratorGT552
Gear Ratio75:16
Tractive Effort Rating29,200 Lbs. at 6.1 MPH.
Top Speed60 MPH

Production Roster

Owner Road Number(s) Quantity Date Built
Alco (Demo)660 (To Tacoma Municipal Belt Line Railway, #905)11950
Alco (Plant Switcher)511947
Alco (U.S. War Department)GT-130411942
Alabama Great Southern (Southern)6501-650221941
Alameda Belt LineD-1, D-2, D-331942-1946
American Steel & Wire211941
Ann Arbor2-321944
Armco SteelE106, E107, E10831949-1950
Baltimore & Ohio222-22761944
Belt Railway Of Chicago304-30631941-1942
Birmingham Southern100-10121941
Boston & Maine1163-1172101944-1949
Broward County Port Authority41011943
Canadian Car & Munitions (Canada)5112/1941
Central Of Georgia4, 621940-1941
Central Railroad Of New Jersey (CNJ)1024-102521941
Champlain Paper & Fibre2511947
Chicago & Eastern Illinois103-10531941-1942
Chicago & North Western1202-1205, 1213, 1223-1229, 1232-1236, 1247-1258291941-1948
Chicago Great Western11-1551948
Chicago, St. Paul, Minneapolis & Omaha (C&NW)56, 57, 6931944-1948
Cincinnati, New Orleans & Texas Pacific (Southern)6000-600121941
City of Prineville (Oregon)10111950
Danner Hanna Coal Company211941
Day & Zimmerman (U.S. Army Munitions Depot, Iowa)3-10011941
Defense Plant CorporationDPC25.23, DPC25.2421943
Delray Connecting66, 68, 70, 7241945
Des Moines Union1-441940-1946
Detroit & Mackinac64611946
East St. Louis Junction10011948
Elgin, Joliet & Eastern213-21751940-1941
Erie Railroad306-321161946-1950
Estrada de Ferro Central do Brasil (Brazil)3001-3005511/1942
Ferrocarriles Nacionales de México (Mexico)5000-500459/1944
Ford Motor Company6601-660441946
Great Lakes Steel3211945
Green Bay & Western10211949
Gulf, Mobile & Ohio661-66441940
Hunken Conkey Construction1001-100221941
Inland Steel53, 56, 61-62, 64-6671940-1945
Inland Waterway111942
Iowa Transfer211950
John Morrel Company711941
kalamazoo, Green Bay & Western10311941
Kansas City Terminal40-4451940-1941
Lehigh Valley11711950
Long Island Rail Road404-408, 413-421141946-1949
Louisville & Nashville16-19, 24-39, 34-68551941-1950
Maine Central953-96081941-1949
Margam Steel Works (Wales/United Kingdom)801-805510/1949-2/1950
Massena Terminal8-921940-1943
Minnesota Transfer60-6451941-1946
Missouri Pacific9007-900821940
Nashville, Chattanooga & St. Louis1-441941-1946
Newburg & South Shore3-7, 9-1071940-1942
New Jersey, Indiana & Illinois111940
New Orleans & Lower Coast (MP)9013-901531947
New York Central811-873, 950-957711941-1950
Nickel Plate Road8511950
New Haven931-995651941-1949
Northern Pacific13111945
Northern Pacific Terminal30-3451940-1941
Pennsylvania5661-5670, 5954-5956, 9100-9103, 9137-9146271947-1950
Point Comfort & Northern511945
Port Huron & Detroit51-5221945
Portland Terminal1005-100841945-1949
Proctor & Gamble911948
Red River Ordnance Depot (U.S. Army)737211941
Republic Steel15-17, 312-314, RSCX-D840, RSCX-D841, RSCX-D81091943-1945
River Terminal5211941
Santa Fe2303-230421944
St. Louis & O'Fallon5111946
Seaboard Air Line120111941
Sheffield Steel Corporation11-1331943-1949
Solvay Process Corporation1-331946
South Buffalo Railway51-52, 60-6141940-1941
South Omaha Terminal1-551945-1947
Southern Pacific1017-102041941
Southern Railway2000-2001, 200631940-1941
Spokane, Portland & Seattle10-1121941
Studebaker Corporation2-321945
Tennessee Central5111941
Tennessee Coal & Iron700-70231942-1946
Tennessee Copper104-10521947
Terminal Railroad Association Of St. Louis (TRRA)521-52441940-1941
Texas & New Orleans (SP)1011941
Texas City Terminal30-3121947
Texas Pacific-Missouri Pacific Terminal3-421940-1941
Timken Roller Bearing COmpany5911-591221950
Toledo, Angola & Western10111949
Truax-Traer Coal Company1011944
Union Railroad451-45441947
Upper Merion & Plymouth Railroad5411945
U.S. Army7132-7136, 7141-7142, 7374-7375, 7459-7460111941-1943
Wabash Railroad151-15991941-1948
Weirton Steel200, 203-20431945-1946
Western Maryland Railway10211941
Western Pacific504-51181942
Youngstown Sheet & Tube Company661-66551947


  • Foster, Gerald. A Field Guide To Trains. New York: Houghton Mifflin, 1996.
  • Kirkland, John F. Diesel Builders, The:  Volume Two, American Locomotive Company And Montreal Locomotive Works. Glendale: Interurban Press, 1989.
  • Pinkepank, Jerry A. Diesel Spotter's Guide.  Milwaukee: Kalmbach Publishing Company, 1967.
  • Solomon, Brian. Alco Locomotives. Minneapolis: Voyageur Press, 2009.

El Dorado & Wesson Railway S1 #19 lays over at the engine house in El Dorado, Arkansas. This unit was built as Messena Terminal #8 in 1940. Ed Lewis photo. collection.


A reliable and agile locomotive, railroads found the S1 incredibly useful. In all, the locomotive would sell more than 500 examples to numerous Class I companies, smaller railroads, and a handful of private industries.

Alco itself even used an S1 for switching duties at its plant, #5. While the Montreal Locomotive Works also produced the S1 few were built, just one was constructed for the Canadian Car & Munitions located in Quebec.

Additionally, foreign lines purchased the model including Central do Brazil, National de Mexico, Polish State Railway, and Margam Steel Works of Britain although amongst all four only 55 were built.  For more information about the S1 please refer to the chart above, which provides a full production roster of U.S. sales. 

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