The Alco RS27 was a late model of the Road Switcher (RS) series that
produced more than 2,000 horsepower. However, the model was
unsuccessful along with the fact that by the time it was debuted the
American Locomotive Company (Alco) was already working
on its next generation of road switcher, the Century series. As such,
the RS27 looked very much like Alco's later models and was the first to
receive the builder's new styling. By the late 1950s Alco was slipping
further behind the Electro-Motive Division in the locomotive market and
before the decade was over it would also be competing with one-time ally
Interestingly, examples of this rare Alco model can still be found, in
service on shortline Minnesota Commercial (a haven for Alcos). The
locomotives were purchased from the Green Bay & Western, which had
purchased them from the Chicago & North Western (#901 and #903).
The Alco RS27 began production in 1959 using a B-B format (two axles per
truck) and producing a hefty 2,400 horsepower for a somewhat small,
four-axle unit. As with other late-model RS designs the RS27 came in a
standard low-nose setup using Alco's much more reliable 251B prime mover.
In terms of the company's history as a locomotive builder, the RS27
offered the first glimpse of its Century series, which began production
in 1963. The model retained the flush, long hood with the cab and the
classic notched corners on the carbody remained. However, the cab
featured a slight design change with raised number boards and
headlights, and the nose was shorter giving the locomotive a more
From an exterior standpoint the RS27 began the common look of second-generation designs, as GE used a similar setup with its U25B, and EMD did the same beginning with its GP18, GP20,and GP30 models. Perhaps it was due to Alco's earlier troublesome engine designs that kept railroads away but whatever the case the builder found little success with the RS27 selling less than thirty units with the Pennsyvlania Railroad purchasing the most (15). The year 1959 was not a particularly good one for Alco. It was increasingly losing market share to EMD, had not cataloged a successful locomotive since the RS3 finished production in 1956 (although its RS11 design did sell relatively well).
Additionally, that year GE ended its five decade partnership
with the company when it released its own line of diesels beginning with
the U25B (which ironically far outsold the RS27).
From an operational standpoint, the RS27 varied little from the RS11
aside from the additional horsepower. It actually offered less
continuous tractive effort (42,000 pounds) but more starting effort
(66,000 pounds). As had been the case for nearly two decades when the
RS27 was produced, internal components like traction motors, generators,
and air brakes/compressors came in from GE and Westinghouse. For more information about the RS27 please click here.
Production Roster Of Alco RS27s
640-1, 640-2, 640-3, 640-4, 640-5
Chicago & North Western
Green Bay & Western
end the model proved another abysmal failure for Alco as just four Class I railroads ultimately purchased the RS27; the
aforementioned Pennsylvania, Soo Line, Chicago & North Western, and Green Bay
& Western. Of note, however, Union Pacific did purchase two of the
demonstrators, #640-2 and #640-3. Somewhat unsatisfied, UP returned
them to the Montreal Locomotive Works where they were later resold.
Today, the Minnesota Commercial is apparently quite happy with
its two RS27s as the railroad has kept them on its roster
for nearly three decades now. To read more about other Alco Road-Switcher (RS) models please visit the Diesel Locomotives section of the site, which can be reached from the top of this page.