The ALCO S-1 and S-3 were diesel-electric

switcher locomotive A switcher locomotive (American English), shunter locomotive (British English), station pilot (British English), or shifter locomotive (Pennsylvania Railroad terminology) is a locomotive used for maneuvering railway vehicles over short distanc ...

s produced by

ALCO The American Locomotive Company (often shortened to ALCO, ALCo or Alco) was an American manufacturer that operated from 1901 to 1969, initially specializing in the production of locomotives but later diversifying and fabricating at various time ...

and their Canadian subsidiary

Montreal Locomotive Works Montreal Locomotive Works (MLW) was a Canadian railway locomotive manufacturer that existed under several names from 1883 to 1985, producing both Steam locomotive, steam and diesel locomotives. For many years it was a subsidiary of the American ...

(MLW). The two locomotives differed only in

trucks A truck or lorry is a motor vehicle designed to transport freight, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction ...

, 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 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 In an internal combustion engine, a turbocharger (also known as a turbo or a turbosupercharger) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake air, forcing more air into the ...

. 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 The New York Central Railroad was a railroad primarily operating in the Great Lakes region, Great Lakes and Mid-Atlantic (United States), Mid-Atlantic regions of the United States. The railroad primarily connected New York metropolitan area, gr ...

(NYC), with 71 locomotives; the

New Haven New Haven is a city of the U.S. state of Connecticut. It is located on New Haven Harbor on the northern shore of Long Island Sound. With a population of 135,081 as determined by the 2020 U.S. census, New Haven is the third largest city in Co ...

with 65 locomotives; the L&N with 45 locomotives; the C&NW, with 29 locomotives; and the

Pennsylvania Railroad The Pennsylvania Railroad ( reporting mark PRR), legal name as the Pennsylvania Railroad Company, also known as the "Pennsy," was an American Class I railroad that was established in 1846 and headquartered in Philadelphia, Pennsylvania. At its ...

(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.

S-3

ALCO and the Montreal Locomotive Works constructed approximately 300 S-3s for the North American market between 1950 and 1957.

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 7372 is at the Western Pacific Railroad Museum and painted in Western Pacific colors. * Ex-Canadian Pacific MLW S-3 6568 is at the

Saskatchewan Railway Museum The Saskatchewan Railway Museum is a railway museum located west of Saskatoon, Saskatchewan at the intersection of the Pike Lake Highway (Hwy 60) and the Canadian National Railway tracks (on "Hawker" siding). It is operated by the Saskatchewan R ...

. *Two Ex-Steel Company of Wales S-1s are preserved and are being restored to working order at the

Nene Valley Railway The Nene Valley Railway (NVR) is a Heritage railway, preserved railway in Cambridgeshire, England, running between and Yarwell Junction. The line is in length. There are stations at each terminus, and three stops en route: , and . History ...

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 The New York Central Railroad was a railroad primarily operating in the Great Lakes and Mid-Atlantic regions of the United States. The railroad primarily connected greater New York and Boston in the east with Chicago and St. Louis in the Midw ...

No. 872, later Bath and Hammondsport No. 5, was acquired by the Rochester & Genesee Valley Railroad Museum in March 2025. * Ex- South Omaha Terminal No. 1, later Hutchinson Northern Railroad No. 4, is owned by the Abilene and Smokey Valley Railroad. Number 4 was donated in 1993 and still runs excursions.

References

External links

Alco/MLW S-1 Roster

Alco/MLW S-3 Roster
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