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The Alco RSD7

(Please note that the Alco models featured on this page are not RSD7s.)

The Alco RSD7 was a much more powerful six-axle locomotive than anything the company had previously produced. Interestingly enough, the model wasn't meant to compete with anything the Electro-Motive Division was producing but one of Fairbanks Morse designs, the incredibly powerful (for its time) H24-66 "Train Master". At the time of the RSD7's development railroads still had yet to embrace six axle diesels, let alone high horsepower models. As such, the design proved to be just another setback for the American Locomotive Company (Alco), something that unfortunately was becoming more and more than norm for the builder. With so few RSD7s produced, barely two dozen, sadly none have been preserved.

The Fairbanks Morse Company dated back to the 1830s and became highly regarded in later years for its durable marine diesel engines. However, in the mid-1940s it decided to enter the highly competitive diesel locomotive market, making a name for itself via its opposed-piston prime movers. Interestingly, when FM decided to release the H24-66 model it had been building locomotives for less than 10 years. The design was nearly a decade ahead of itself as high horsepower, six-axle locomotives had yet to catch on with railroads. However, for some reason Alco decided that it needed to offer its own version of FM's Train Master. Oddly, the company should have known the design was unpopular as its previous five six-axle models had sold a combined 666 units (the RSD1, RSC2, RSC3, RSD4, and RSD5).

While the RSD5 (a modestly successful model, in comparison to how six-axle locomotives were selling at the time) was still in production, Alco released the RSD7. The locomotive began production in 1955 and used the builder's standard prime mover of the time, the 244 model. The RSD7 was the last Alco model to use this engine as the RS11 (and later versions of the FA and PA) would use the company's newer, and much more reliable model 251. The Alco RSD7 could originally produce 2,250 horsepower although after initial sales proved to be very poor it increased this to 2,400 horsepower, which directly matched the FM's H24-66. The RSD7 saw a major change to how Alco produced road switchers. Despite having originally pioneered the design, the Schenectady builder took a cue from EMD and began producing its later road switchers, beginning with the RSD7, with long and short hoods that ran flush with the cab.

Savvy diesel spotters can easily identify Alco's version, however, by the notched corners and fewer hard angles of EMD's designs. The RSD7 proved to be one of the most powerful RS series designs Alco produced and also offered some of the highest tractive efforts; 95,600 pounds starting and 69,800 continuous, which also included dynamic braking. These later models released by Alco were some of the last to work in conjunction with GE, as by 1959 the electric giant would be producing its own line of diesels. Unfortunately, the RSD7 saw little success, selling only 29 units to three Class I railroads; Chesapeake & Ohio, Pennsylvania, and Santa Fe (along with Alco's two demonstrators, #DL600 and #DL601). Even more unfortunate, the H24-66 was also considered a failure by FM but was able to sell 127 TMs, nearly five times more than the RSD7.

Alco's six axle models were meant to provide a sizable increase in traction and be used on light branch/secondary lines allowing the locomotive's weight to be distributed more evenly over additional axles (for instance, the ten purchased by the Atchison, Topeka & Santa Fe were used exclusively in helper service along the railroad's high grades in New Mexico and Colorado, such as Raton Pass). Despite this now obvious economic advantage, railroads had yet to bite on six-axle locomotives (ironically, FM and Alco were both just a few years away from missing the market). For a total production roster of Alco RSD7s please click here. Also, for technical data of the model please click here. Finally, for more information about the RSD7 and all RS series designs please refer to the chart below.

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RS Series

Model Type	Units Built	Date Built	Horsepower
RS-1	417	1941-1960	1,000
RSD-1	257	1942-1946	1,000
RS-2	469	1946-1950	1,500-1,600
RSC-2	81	1946-1950	1,500-1,600
RS-3	1,370	1950-1956	1,600
RSD-4	36	1951-1952	1,600
RSD-5	204	1952-1955	1,600
RSD-7	29	1954-1956	2,250-2,400
RS-11	426	1956-1964	1,800
RSD-12	161	1956-1963	1,800
RSD-15	87	1955-1960	2,400
RS-27	27	1959-1962	2,400
RS-32	35	1961-1962	2,000
RS-36	40	1962-1963	1,800

(Thanks to M.J. Rodriguez for help with the information on this page.)

For a comprehensive look at the American Locomotive Company and all of the motive power types it built from steam, diesel, to electrics consider the book Alco Locomotives by Brian Solomon. Covering more than 175 pages Mr. Solomon's book details the history of Alco from its esteemed 4-6-4 Hudsons and 4-6-6-4 Challengers to vaunted RS and PA series diesel locomotives. If you have any interest in Alco this book is a must have!

Also 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 diesel locomotives in general, this book gives an excellent general history of both. If you're interested in perhaps purchasing either (or both) of these books please visit the links below which will take you to ordering information through Amazon.com, the trusted online shopping network.

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