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The Alco S Series

The Alco S series was by far the company’s most successful diesel locomotive line ever produced, selling well over 2,000 units by the time production ended. The American Locomotive Company (Alco) was a locomotive manufacturer icon for years before it switched to building diesels over steam,. During the steam era Alco built some of the best and well-known locomotives to ever roam the rails, many of which still survive today. These included locomotives such as the 4-6-4 Hudson, 4-8-4 Niagara, 4-6-6-4 Challenger and 4-8-8-4 Big Boy. Even when the diesel locomotive first began to see widespread use in switching service Alco did quite well selling hundreds of S and RS switcher models.

However, main line diesel locomotives began to be favored over steam (this was where the real money was made for the manufacturers) when the Electro-Motive Corporation debuted their original EA model in 1937. EMD instantly became the industry standard for first and second-generation diesel models (such as its Es, Fs and GP series) and held well over half the market share for years. However, convinced that railroads would never favor diesels over steam Alco did not invest heavily in diesel research and development for years, which cost the company dearly in the future.

While Alco held second place in the diesel locomotive market for the first twenty years from the 1ate 1930s onward, it was essentially no contender to EMD. The company’s outlook would worsen in the 1950s when General Electric not only broke ranks with Alco but also went on to debut their very own line of diesels, its ubiquitous Universal series, which was not only became quite popular but also bumped Alco into third place.

The Alco S series was the company's first true commercially and mass-produced diesel line (and for all purposes was Alco’s debut in the diesel locomotive market), although it had built and experimented in diesel locomotive technology as early as the 1920s.

While the industry as a whole was still being sold on diesels for over-the-road and heavy-haul use, they found switchers very handy and useful for yard and light duty work and the Alco S series was a sensation from the very first model, the S-1, which debuted in 1940.

The S-1 employed Alco’s 539 engine, which in the first model only produced 660 horsepower although it sold over 500 units. The S-1 was followed up by the S-2, which was by far the most successful of the series selling 1,500 units. There is virtually no difference between the S-1 and S-2 except that the later model featured an extra 340 horsepower. And, similarly, there is little difference amongst the later S-3 and S-4 (which sold over 1,000 units combined) from their previous sisters except that they included AAR trucks rather than the earlier Blunt design.

Perhaps the most successful aspects of the Alco S series were their durability and simplicity, which remains evident even today as several are still in use across the country! Unfortunately for Alco its success with its switcher line did not transfer over to its road-switchers, except for its RS series. Most were plagued by mechanical problems (and although later fixed, the damaged reputation had already been done) and did not help that management remained divided for years over steam versus diesel technology. The C636, of the company’s Century series, would also prove to be Alco’s last entry into its long and storied history book, sadly closing its doors in the fall of 1968, unable to compete with EMD and GE.

For more information on the Alco S series consider Mike Schafer’s Vintage Diesel Locomotives which looks at virtually all of the classic builders and models from Alco PAs to early EMD Geeps. If you’re interested in classic Alcos, or diesels in general, this book gives an excellent general history of both.

Also, Brian Solomon’s The American Diesel Locomotive also studies many of the same diesel models and builders as Mr. Schafer’s publication although at nearly twice the size the book goes into a bit more detail than Vintage Diesel Locomotives. All in all, though, both books are a great read and you shouldn’t be disappointed with them, not to mention that they are loaded with photos (many in color)! If you're interested in perhaps purchasing these books please visit The Railroad Diamond by clicking the tab in the menu to your left marked "TRD Store".

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