# ALCO S-1 and S-3

The ALCO S-1 and S-3 were 660 horsepower (490 kW) diesel-electric switcher locomotives produced by ALCO and their Canadian subsidiary Montreal Locomotive Works (MLW). The two locomotives differed only in trucks, with the S-1 using ALCO's own Blunt trucks, and the S-3 using AAR type A switcher trucks. The S-1 was built between April 1940 and June 1950, with a total of 543 completed, while the S-3 was constructed between February 1950 and November 1953 (MLW until 1957) with total sales of 300. A modified version, the S-10, was built by MLW only; 13 were built between January and June 1958.

## Identification

The S-1 and S-3 are distinguishable externally from the very similar S-2 and S-4 1,000 horsepower (750 kW) switchers in that they have a smaller exhaust stack with a round base and a smaller radiator shutter area on the nose sides. The S-1/S-3 radiator shutter area is taller than it is wide, while the S-2/S-4 radiator area is wider. The smaller stack is due to the lack of turbocharging.
The S-10 is not externally distinguishable from later Canadian-built S-3 locomotives; it differed mostly in electrical equipment.

## Original owners

The S-1 and S-3 models were sold to an extensive list of railroads and industrial operators, as detailed below. Major owners of the S-1 included the New York Central Railroad (NYC), with 71 locomotives; the New Haven with 65 locomotives; the L&N with 45 locomotives; the C&NW, with 29 locomotives; and the Pennsylvania Railroad (PRR) with 27 locomotives. Major customers for the S-3 included the CP, with 101; the CN, with 49; the NYC, with 43 locomotives; the B&M, with 16; and the PRR, with 13. The MLW S-10 was sold only to the CP.
The totals below include export orders and MLW-built locomotives.

### S-1

ALCO constructed approximately 535 S-1s for the US market between 1940 and 1950.
| Railroad | Quantity | Road numbers |
| Alabama Great Southern Railroad | 2 | 6501–6502 |
| Alameda Belt Line | 3 | D-1–D-3 |
| Alco (demonstrator) | 1 | 660 |
| Alco (plant switcher) | 1 | 5 |
| Alco/War Department | 1 | GT-1304 |
| American Steel & Wire | 1 | 2 |
| Ann Arbor Railroad | 2 | 2–3 |
| ARMCO Steel | 3 | E106–E108 |
| Atchison, Topeka and Santa Fe Railway | 2 | 2303–2304 |
| Baltimore and Ohio Railroad | 6 | 223–227, 250 |
| Belt Railway of Chicago | 3 | 304–306 |
| Birmingham Southern Railroad | 2 | 100, 101 |
| Boston and Maine Railroad | 10 | 1163–1172 |
| Broward County Port Authority | 1 | 410 |
| Canadian Car and Munitions | 1 | 5 |
| Estrada de Ferro Central do Brasil | 5 | 3001–3005 |
| Central of Georgia Railway | 2 | 4, 6 |
| Central Railroad of New Jersey | 2 | 1024, 1025 |
| Champlain Paper and Fibre | 1 | 25 |
| Chicago and Eastern Illinois Railroad | 3 | 103–105 |
| Chicago and North Western Railway | 29 | 1202–1205, 1213, 1223–1229, 1232–1236, 1247–1258 |
| Chicago Great Western Railway | 5 | 11–15 |
| Chicago, St. Paul, Minneapolis and Omaha Railway | 3 | 56, 57, 69 |
| Cincinnati, New Orleans and Texas Pacific Railway | 2 | 6000–6001 |
| City of Prineville Railway | 1 | 101 |
| Donner Hanna Coal Company | 1 | 2 |
| Day and Zimmerman (Iowa Army Ammunition Depot) | 1 | 3-100 |
| Defense Plant Corporation | 2 | DPC25.23, DPC25.24 |
| Delray Connecting Railroad | 4 | 66, 68, 70, 72 |
| Des Moines Union Railway | 4 | 1–4 |
| Detroit and Mackinac Railway | 1 | 646 |
| East St. Louis Junction Railroad | 1 | 100 |
| Elgin, Joliet and Eastern Railway | 5 | 213–217 |
| Erie Railroad | 16 | 306–321 |
| Ford Motor Company | 4 | 6601–6604 |
| Great Lakes Steel Corporation | 1 | 32 |
| Green Bay and Western Railroad | 1 | 102 |
| Gulf, Mobile and Ohio Railroad | 4 | 661–664 |
| Hunken Conkey Construction | 2 | 1001–1002 |
| Inland Steel | 7 | 53, 56, 61, 62, 64–66 |
| Inland Waterways Corporation | 1 | 1 |
| Iowa Transfer Railroad | 1 | 2 |
| John Morrell & Co. | 1 | 7 |
| Kansas City Terminal Railway | 5 | 40–44 |
| Kewaunee, Green Bay and Western Railroad | 1 | 103 |
| Lehigh Valley Railroad | 1 | 117 |
| Long Island Rail Road | 14 | 404–408, 413–420, 421 |
| Louisville and Nashville Railroad | 45 | 16–29, 34–68 |
| Maine Central Railroad | 8 | 953–960 |
| Massena Terminal Railroad | 2 | 8, 9 |
| Minnesota Transfer Railway | 5 | 60–64 |
| Missouri Pacific Railroad | 2 | 9007, 9008 |
| Nashville, Chattanooga and St. Louis Railway | 4 | 1–4 |
| Ferrocarriles Nacionales de México | 5 | 5000-5004 |
| Newburgh and South Shore Railway | 7 | 3–7, 9, 10 |
| New Orleans and Lower Coast Railroad | 3 | 9013-9015 |
| New York, New Haven and Hartford Railroad | 65 | 0931–0995 |
| New Jersey, Indiana and Illinois Railroad | 1 | 1 |
| New York Central Railroad | 71 | 590, 685–744, 864–873 |
| New York, Chicago and St. Louis Railroad | 1 | 85 |
| Northern Pacific Railway | 1 | 131 |
| Northern Pacific Terminal | 5 | 30–34 |
| Pennsylvania Railroad | 27 | 5661–5670, 5954–5956, 9100–9103, 9237–9246 |
| Point Comfort and Northern Railway | 1 | 5 |
| Port Huron and Detroit Railroad | 2 | 51, 52 |
| Portland Terminal Company | 4 | 1005-1008 |
| Procter & Gamble | 1 | 9 |
| Pullman Railroad | 2 | 20, 21 |
| Reading Company | 5 | 50-54 |
| Red River Ordnance Depot | 1 | 7372 |
| Republic Steel | 9 | 15–17, 312–314, D840, D841, D810 |
| River Terminal Railway | 1 | 52 |
| St. Louis and O'Fallon Railway | 1 | 51 |
| Seaboard Air Line | 1 | 1201 |
| Sheffield Steel Corporation | 3 | 11–13 |
| Solvay Processing Division, Allied Chemical | 3 | 1–3 |
| South Buffalo Railway | 4 | 51, 52, 60, 61 |
| Southern Pacific Company | 4 | 1017–1020 |
| Southern Railway | 3 | 2000, 2001, 2006 |
| South Omaha Terminal Railway | 5 | 1–5 |
| Spokane, Portland and Seattle Railway | 2 | 10, 11, 10 Sold to City of Prineville 102, 11 to Burlington Northern 11 |
| Steel Company of Wales (UK) | 5 | 801–805 |
| Studebaker | 2 | 2, 3 |
| Tennessee Central Railway | 1 | 51 |
| Tennessee Coal, Iron and Railroad Company | 3 | 700–702 |
| Tennessee Copper | 2 | 104, 105 |
| Terminal Railroad Association of St. Louis | 4 | 521–524 |
| Texas and New Orleans Railroad | 1 | 10 |
| Texaco | 1 | 19 |
| Texas City Terminal Railway | 2 | 30, 31 |
| Texas Pacific-Missouri Pacific Terminal Railroad of New Orleans | 2 | 3, 4 |
| Timken Rolling Bearing Company | 2 | 5911, 5912 |
| Toledo, Angola and Western Railway | 1 | 101 |
| Traux Truer Coal | 1 | 10 |
| Union Railroad | 4 | 451–454 |
| Upper Merion and Plymouth Railroad | 1 | 54 |
| U.S. Army | 11 | 7132-7136, 7141-7142, 7374-7375, 7459-7460 |
| Wabash Railroad | 9 | 151–159 |
| Weirton Steel | 3 | 200, 203, 204 |
| Western Maryland Railway | 1 | 102 |
| Western Pacific Railroad | 8 | 504–511 |
| Youngstown Sheet and Tube | 5 | 661–665 |
| Total | 543 | |

### S-3

ALCO and the Montreal Locomotive Works constructed approximately 300 S-3s for the North American market between 1950 and 1957.
| Railroad | Quantity | Road numbers |
| Manufactured by ALCO |||
| Aluminum Company of America | 1 | 8 |
| Ann Arbor Railroad | 4 | 4–7 |
| Boston and Maine Railroad | 16 | 1173–1188 |
| Brooks and Scanlon | 2 | 101, 102 |
| Champion Paper | 1 | 2104 |
| Chicago and North Western Railway | 6 | 1262–1267 |
| Davenport, Rock Island and North Western Railway | 7 | 1–7 |
| Davidson Chemical Division, W.R. Grace and Company | 1 | 101 |
| El Dorado and Wesson Railway | 1 | 18 |
| Ford Motor Company | 7 | 6605–6611 |
| Frederick Snare Corporation | 1 | 7 |
| General Portland Cement | 1 | 1 |
| Graysonia, Nashville and Ashdown Railroad | 1 | 51 |
| Greater Portland Public Development Corporation | 1 | 661 |
| Humble Oil | 1 | 997 |
| Louisville and Nashville Railroad | 7 | 69–75 |
| Maine Central Railroad | 2 | 961, 962 |
| Manistique and Lake Superior Railroad | 1 | 1 |
| Mount Hood Railroad | 1 | 50 |
| New York Central Railroad | 43 | 874–916 |
| Pennsylvania Railroad | 13 | 8873–8885 |
| Solvay Processing Division, Allied Chemical and Dye Corporation | 1 | 2 |
| Southern Pacific Company | 10 | 1023–1032 |
| Swift and Company | 1 | 664 |
| Texas and Northern Railway | 2 | 3, 4 |
| Texas City Terminal Railway | 1 | 32 |
| Texaco | 2 | 21, 22 |
| Washington, Idaho and Montana Railway | 1 | 30 |
| West Pittston and Exeter Railway | 1 | 6 |
| ALCO total | 137 | |
| Manufactured by MLW |||
| Bathhurst Power and Paper | 1 | 3 |
| Canadian Arsenals | 1 | 1 |
| Canadian National Railway | 49 | 8450–8498 |
| Canadian Pacific Railway | 101 | 6500–6600 |
| Essex Terminal Railway | 1 | 103 |
| LaSalle Coke | 1 | 4 |
| National Harbours Board | 8 | D2–D9 |
| Price Brothers | 1 | 106 |
| MLW subtotal | 163 | |
| Total | 300 | |

### S-10

MLW constructed 13 S-10s in 1958, all for the Canadian Pacific Railway, numbered 6601–6613. These units were essentially similar to late-built S3s, though with minor updates to the electrical gear.

### S-11

In 1959, MLW built a final order of 660 horsepower switchers for the Canadian Pacific, as model S-11, numbered 6614–6623. The internal machinery of these units was essentially the same as that of the S-10, but the car body was radically redesigned, with the radiator on the front end of the hood instead of on the sides.

## Preservation

Numerous S-1 and S-3 locomotives remain in use, and several are preserved:
* Ex-U.S. Army S-1 No. 7372 is at the Western Pacific Railroad Museum and painted in Western Pacific colors.
* Ex-Canadian Pacific MLW S-3 No. 6568 is at the Saskatchewan Railway Museum.
* Two Ex-Steel Company of Wales S-1s are preserved and are being restored to working order at the Nene Valley Railway in England.
* Ex-Erie Railroad S-1 No. 307 is preserved at Riverside Park, Manhattan and painted in New York Central colors.
* Ex-Tennessee Central No. 51, later Cadiz Railroad No. 8, was on display in Trigg County, KY near exit 65 of Interstate 24. The unit is now currently in private ownership in nearby Christian County.
* Ex-New York Central No. 872, later Bath and Hammondsport No. 5, was acquired by the Rochester & Genesee Valley Railroad Museum in March 2025.