Alco "RSC2" Locomotives: Data Sheet, Roster, Specs

Last revised: December 27, 2024

The RSC2 was the Alco's six-axle version of its RS2. It's purpose, as with all of the builder's RSC models, was to decrease the locomotive's axle loading for light branch line work.

In other words, the weight was spread over a wider area (six axles instead of four). A number of railroads were pleased with the concept as the locomotives could handle duties on secondary corridors where track was typically under 100 pounds.

Overview

Interestingly, American Locomotive may have never developed a six-axle road switcher had it not been for the US Army, which requested such as a variant of RS1 model known as an RSD-1.

When Alco cataloged the RSC2 many railroads saw little use for a six-axle locomotive and as such, few sold.

The RSC3 of the early 1950s was the final A1A-A1A design the builder offered to domestic railroads (its Montreal Locomotive Works branch did catalog an RSC13 and RSC24 for Canadian lines through the late 1950s).

Today, at least one RSC2 is preserved, Milwaukee Road #988 at the Mid-Continent Railroad Museum in North Freedom, Wisconsin.

Photos

Union Pacific RSC2 #1282 is seen here in St. Joseph, Missouri on August 30, 1970. This unit was originally #1182 and renumbered in 1955. American-Rails.com collection.

The RSC2 began production alongside its sister model, the RS2, in 1946 using the same model 244 prime mover. Railroads still had yet to embrace such a design and even market leader Electro-Motive had difficulty selling its six-motored SD7 and SD9.

Nevertheless, following the Army's interest in the RSD-1, Alco pursued the concept for domestic production. At 1,500 horsepower, the RSC2's primary advantage was weight distribution.

Model Confusion

From a historical perspective, Alco initially never cataloged an RSC-2 model during production. This point is explicitly stated in John Kirkland's book, "The Diesel Builders Volume Two." If you are able, locate a copy of this out-of-print resource.

It not only offers an in-depth look on Alco's diesel production but also how railfans of the era came up with model designations the builder never actually used.

In the RSC-2's case, the model was initially part of Alco's RS2 class (specification E1661) with little distinction made between the two aside from their specific model numbers. As Kirkland points out, the "RSC-2" designation was added two years after the model had ended production.

The advantage of the A1A-A1A design meant that the already lightweight model (at just 117.5 tons) could more easily negotiate secondary and branch lines that were laid with lighter rail.

One railroad that found the model quite useful was the Milwaukee Road. The Milwaukee was the first railroad to begin receiving its batch of RSC2s in November, 1946 wishing to test its usefulness and effectiveness on secondary lines; in this case its Valley Division in north-central Wisconsin (and headquartered in Wausau).

Milwaukee Road RSC-2 #490 with a single boxcar and caboose at a rural grade crossing near Welch, Minnesota on the CGW (trackage rights) in December, 1965. Rick Burn photo.

Advantages

Interested in the maintenance savings, as well as retire its fleet of steam locomotives, the Milwaukee employed its first eighteen RSC2s on the route where they proved quite effective.

The railroad would go on to roster twenty-two RSC2s and in future years returned to Alco for many of its six-axle Road Switcher models.

In later years the locomotives were replaced by Electro-Motive's SDL39, a special variant built only for the Milwaukee that was used in a similar fashion. The Seaboard Air Line turned out to be the largest buyer of the RSC2.

However, unlike the Milwaukee, the SAL assigned theirs to various tasks. The first thirty-one delivered between 1947 and 1949 (#1500-1530) were used in light branch work. The rest, however, including #1531-1536 were all equipped with steam generators and used in passenger service.

Data Sheet and Specifications

Alco Class	606-DL-250
Entered Production	10/2/1946 (Milwaukee Road #975)
Years Produced	10/2/1946-4/11/1950
Model Specification	E1661/A/B/C
Engine	244, V-12
Horsepower	1,500 (Increased to 1,600 HP in variant E1661C.)
Carbody Styling	Alco
Length (Between Coupler Pulling Faces)	55' 11.75"
Weight	250,000 Lbs.
Dynamic Brakes	Optional
Trucks	A1A-A1A
Truck Type	C-Type
Truck Wheelbase	10' 6"
Wheel Size	40"
Traction Motors	GE 726 (4): (Later upgraded to GE 752 [4].)
Traction Generator	GT564 (Upgraded to GT564C in variant E1661A.)
Steam Generator	Optional
Gear Ratio	74:18
Tractive Effort Rating	34,000 lbs. at 13.5 MPH (Later increased to 42,500 lbs. at 11 MPH.)
Top Speed	65 MPH

Production Roster

Alco

Owner	Road Number(s)	Serial Number(s)	Date Built
Alco (Demonstrator)	1190 (became Union Pacific #1190)	75136	11/1947
Milwaukee Road	975, 976	73643, 73644	11/1946
Milwaukee Road	977, 978	73647, 73648	11/1946
Milwaukee Road	979, 980	74989, 74990	11/1946 - 12/1946
Milwaukee Road	981-983	74994-74996	11/1946 - 12/1946
Milwaukee Road	984	74999	1/1947
Milwaukee Road	985, 986	75129, 75130	12/1946 - 4/1947
Milwaukee Road	987-989	75133-75135	12/1946 - 4/1947
Milwaukee Road	990-992	75138-75140	12/1946 - 4/1947
Milwaukee Road	993-996	76639-76642	2/1949
Minneapolis, St. Paul & Soo Ste. Marie (Soo Line)	368, 369	76977, 76978	11/1949
Minneapolis, St. Paul & Soo Ste. Marie (Soo Line)	370, 371	77558, 77559	11/1949
Seaboard Air Line	1500-1503	75397-75400	10/1947 - 11/1947
Seaboard Air Line	1504-1516	76806-76818	4/1949 - 5/1949
Seaboard Air Line	1517-1525	77176-77184	8/1949
Seaboard Air Line	1526-1531	77408-77413	9/1949
Seaboard Air Line	1532-1535	77967-77970	4/1950
Seaboard Air Line	1536	77966	4/1950
Union Pacific	1180	75693	3/1948
Union Pacific	1181-1186	75936-75941	4/1948
Union Pacific	1187-1189	75947-75949	4/1948 - 6/1948

* #1532 - #1536 were of the E1661C variant boasting 1,600 horsepower. These were the only RSC2's manufactured with the additional 100 horsepower rating.

Export

Owner	Road Number(s)	Serial Number(s)	Date Built
Comboios de Portugal (Portugal)	1501-1506	75872-75877	11/1948
Comboios de Portugal (Portugal)	1507-1512	75878-75883	11/1948

Sources

Foster, Gerald. A Field Guide To Trains. New York: Houghton Mifflin, 1996.

Kirkland, John F. Diesel Builders, The: Volume Two, American Locomotive Company And Montreal Locomotive Works. Glendale: Interurban Press, 1989.

Pinkepank, Jerry A. Diesel Spotter's Guide. Milwaukee: Kalmbach Publishing Company, 1967.

Solomon, Brian. Alco Locomotives. Minneapolis: Voyageur Press, 2009.

Interestingly, after less than a decade of service the Seaboard re-trucked several to four axles after they began experiencing wheel slip issues. Only eleven remained in service after 1965 and all were retired by the Seaboard Coast Line after 1974.

Mechanically, the RSC2 was all but identical to its four-axle cousin save for just a slight increase in length at 55 feet, 11 inches. The RSC2 was produced until 1950 but sold less than 100 units (whereas the RS2 sold over 400).

Still, four Class I railroads purchased the RSC2 with the Seaboard Air Line owning the most, 37 (the Soo Line owned four units and the Union Pacific purchased another 10 with the rest purchased by foreign lines).

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