Prototype Profile: The Alco C420

alco c420

Prototype Profile: The Alco C420

Alco Logo

Alco Logo – public domain image

The American Locomotive Company, or Alco, was founded in the year 1901 from the merger of seven smaller companies. For the next 68 years, the company would produce some of the most iconic steam and diesel-electric locomotives railfans have ever known. One of those would be the subject of this month’s Prototype Profile: The Alco C420.

Alco’s first diesel-electric was built in 1924, the 300 hp 60-Ton Boxcab (built in partnership with GE and Ingersoll-Rand). Alco’s first truly successful production was the HH600 end-cab switcher, first built in 1931. Throughout the 1930s, Alco led EMD in diesel production and ranked as the preeminent designer and builder of diesel-electric locomotives, but the fact that Alco was also still building steam locomotives – something EMD never did – meant they were not only competing with EMD, but with their own steam division as well.

Alco HH600

Portland Terminal HH600 #1004, summer 1968, Public Domain photo

By the early 1940s, Alco was second to EMD, but it was still a close competition. Alco had ended its partnership with Ingersoll-Rand in 1929 and entered a sole partnership with GE in 1940, and then in 1941 the company was selected by the United States Army to produce locomotives exclusively for the Army’s use, primarily on the Trans-Iranian Railway. The RS1 (Road Switcher 1000 hp) had already been ordered by three different railroads but the Army requisitioned them all, had them converted to RSD1s (six-axle trucks instead of four-axles) and the three railroads had to reorder their RS1s. In addition, the Army prohibited Alco from selling any RSD1s to private railroads. Of all the RSD1s, the majority ended up in the Soviet Union, where many remained in service until the late 1980s.

The RSD1 deal with the Army proved to be the beginning of the end for Alco. It severally undercut their market and they lost a lot of money as a result. EMD quickly leaped ahead of Alco in the 1940s to become the preeminent diesel-electric locomotive manufacturer. By the late 1950s, GE was entering the diesel-electric locomotive market and they, too, quickly jumped past Alco, leaving Alco in a dismal third place as the 1960s began.

Alco RSD1

US Army RSD1 8679 was transferred to the US TVA in the 1950s. By 1978 it was retired. Photo by Jay T. Thomson, used with permission

To try and compete with EMD’s second generation diesel locomotives, like the SD24, SD35, GP30, and GP35, as well as GE’s first generation of locomotives, the U25B, U25C, and U28C, Alco rolled out its brand new Century series starting in 1963. Of the Century series, produced between 1963 and 1968 (when Alco folded and sold their designs to former subsidiary Montreal Locomotive Works), two stood out – the six-axle C628 (with 186 total produced) and the four-axle C420 (with 131 total produced).

The C420 was built for thirteen different railroads, including Ferrosur of southern Mexico. Most of them were built for the Long Island Railroad (30) with second most for Seaboard Air Line (27). In the end, though, it was the Louisville and Nashville Railroad that owned the most C420s. The L&N ordered 16 C420s, but it acquired all of the Monon’s C420s when it acquired that railroad, and also the two Tennessee Central C420s when it acquired that railroad, and finally almost all of the Seaboard Coast Line (successor to Seaboard Air Line) C420s were transferred to the L&N in the mid-1970s. By the late 1970s, the L&N rostered over 60 C420s, and almost all of them were in mine run duty on the EK Division of the L&N (Eastern Kentucky Division), based out of Hazard, Kentucky.

L&N C420 1371

L&N C420 #1371, Photo by Jay T. Thomson, used with permission

The Alco C420 (Century series, 4-axle, 2,000 hp) has a B-B configuration, meaning four axles per truck, or bogie. It is a 2,000 hp unit and was built in low short hood and high short hood versions. The high short hood contained a steam generator for steam heating of passenger cars and most of them were built for the Long Island Railroad, though Monon also bought a few for passenger service.

The C420 was in production for just over five years, from spring 1963 to summer 1968. After MLW acquired Alco’s designs, in 1973 they began production of the M420 (MLW series, 4-axle, 2,000 hp) which was mechanically the same as the C420 (with some modernized updates) but now had a wide-cab, of a design later to be known as the “Canadian cab”. The M420 was the first diesel-electric locomotive to come standard with a wide cab. Today, the units are often classified as M420W (W for wide cab). The M420 was in production for five years, just like the C420, with 105 being produced, most of them sold to Canadian National. A handful were built for export to Mexico and to the United States.

L&N High Short Hood C420

L&N C420 1318 was built with a high short hood to house a steam generator, photo by Jay T. Thomson, used with permission

The C420 was a tough, strong diesel-electric locomotive, and part of Alco’s desperate push to remain a player in the diesel locomotive market in North America. Sadly, it wasn’t enough. Reliability issues made the Century series a maintenance nightmare for some railroads. The new series and the company both faded away in 1968. Amazingly enough, though, roughly 30% of all C420s built still exist, preserved in various museums or operating on shortlines, and the majority of M420s that MLW built still exist, with most of them still in active service on various shortlines. The ghost of Alco lives on.

West Tennessee MR20C

West Tennessee MR20C, a rebuilt ex-CN M420, still in use on the West Tennessee short line, photo by the author










If you would like to add an Alco C420 or three to your layout, here’s a few that are available in N, HO, and O scales.

N Scale
Delaware & Hudson Low Short Hood
Iowa Interstate Low Short Hood
Delaware, Lackawanna & Western Low Short Hood

HO Scale
Guilford Low Short Hood
Long Island High Short Hood
Tennessee Central Low Short Hood

O Scale
Alaska Railroad Low Short Hood (dummy unit)
Lionel Service Station 2000 Special Train Set


NOTE: A previous version of this post incorrectly stated that Alco had ended its partnership with GE in 1940, when it actually started that partnership in 1940. The text has been edited for the correction.

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Robert Thomson

Robert W. Thomson is a life-long railfan, the son of a former L&N Railroad B&B gang foreman, and an amateur photographer. He was born and raised in southeast Tennessee but now lives in Butte, Montana with his wife, Connie and cat, Charlie. Robert has worked as a park ranger, underground mine tour guide, freelance roleplaying game writer, and ran his own roleplaying game publishing company until selling it in 2012.

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