The Alco S2 was the second model
of switcher the company produced although it was constructed at the same
time as the earlier S1. One of the significant differences between the
two models was the increased horsepower of the S2, which was a 40% increase over the previous design. The model
had a ten year production run and railroads apparently liked the
increased power as the S2 went on to being Alco's best selling small
switcher. While the large Class I systems tended to purchase the most
S2s numerous smaller lines and industries also found the locomotive
quite useful. Today, the S2 is one of the most preserved Alco models in
existence and can be found throughout the country many of which are
still operational. Additionally, a handful of these locomotives still find a place on shortline rosters who find the units easy to maintain, rugged, with a knack to pull just about anything.
Like its S1 sister, the Alco S2 was first produced in 1940 featuring an end-cab design using McIntosh & Seymore's 539 diesel engine.
However, unlike the S1 the S2 was more powerful and came equipped with
a 1,000 horsepower rating. With this increased power the S2 was more
suitable for a wide range of duties from yard and switching services to
freight operations (normally on branch and secondary lines). The adept
little switcher and its ability to seriously pull (an Alco trademark
with all of its diesels) made it a favorite amongst industries as well
because it could lug around heavy cuts of cars while also being able to
negotiate the sharp curves and tight clearances found in these settings.
The Alco S2, like the S1, was born out of the company's long history (even by 1940) of studying and developing small diesel locomotives that dated back to 1918. Their first true diesel line came with the HH (High Hood) series that began in 1931. These switchers were developed in conjunction with McIntosh & Seymore and Westinghouse, the former providing the prime mover and the latter air components and a revolutionary cab design (the "Visibility Cab") that enabled crews maximum visibility. With the help of famed industrial designer Otto Kuhler, Alco gave the High Hood models (which included the HH300, HH600, HH660, HH900, and HH1000) a clean look with beveled edges to the hood and cab.
When Alco released the S series in 1940 it carried over many of the
Kuhler design recommendations. As mentioned above the builder also
carried over the McIntosh & Seymour prime mover and also continued to work
with General Electric (which provided traction motors and generators)
and Westinghouse (which provided air components such as brakes and
compressors). Easily the most popular design of the S series the S2
sold more than 1,500 units to various Class Is, shortlines, and
industries by the time production had ended in June, 1950. Of note, the
company's Montreal Locomotive Works branch also sold a number of S2s.
Several Canadian lines including the Canadian National, Canadian
Pacific, Alma & Janquiere, Ontario Northland as well as industry
Aluminum Company of Canada all purchased the MLW version of the S2.
In total, MLW built 114 examples of the model for these
companies. The S2 was also the last in the S series to be equipped with
Alco's Blunt trucks, as all future designs used the more standard AAR
type 1 or type 2 trucks. The S2 also offered some serious tractive
effort, another reason it sold very well. For weighing only about 115
tons the locomotive could produce 69,000 pounds of starting tractive
effort and around 30,000 pounds continuous. The S2 was the same length as the S1 and one of the few noticeable
differences was the size of the radiator grill, which was smaller on the
S1, as well as the smoke stack (the S2 featured a flared stack at its
bottom while the S1's stack was more conical). These were not all of
the slight design differences of the two but some of the more
noticeable. For more information about the S2 please click here.
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. To read more about other Alco switchers please visit the Diesel Locomotives section of the site, which can be reached from the top of this page.
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