Alco "RSD-1" Locomotives

The Alco RSD-1 was the first road switcher of its kind to feature six-axles. However, at the time of the model's development railroads had yet to embrace the diesel locomotive for main line service let alone a six-axle curiosity that was yet to be understood for the benefits it provided.

The American Locomotive Company's six-axle RS1 came in two variations, the RSD-1 mentioned above which was a C-C setup and the RSC-1, an A1A-A1A design.

While the model only saw roughly half the sales of its four-axle counterpart it was beloved by the US Army, who interestingly enough ended up being Alco's only customer for the model (they even went so far as to requisition standard RS1s and convert them into C-C designs!). 

Today, nearly a dozen RSD-1s are known to be preserved around the country while a few are still operational including U.S. Army #8652 at the North Alabama Railway Museum (Huntsville) and former Tennessee Coal & Iron Railroad #601 (built as U.S. Army #8009) at the Orange Empire Railway Museum in Perris, California.


Department of Transportation RSD-1 #012 is seen here on the test track in Pueblo, Colorado on April 18, 1980. This unit was built as Tennessee Coal & Iron #801, circa 1941, and later became U.S. Army #8009. Robert Harmen photo.


RSD-1 History And Background

It should be noted that while historians and railfans often index the six-axle RS-1 model as either an RSD-1 or RSC-1, Alco itself made no such distinction. Instead, the builder merely included them all as RS-1s and only differentiated the three by their designation numbers.

This is further reinforced in John Kirkland's book, "The Diesel Builder's: Volume Two."  It appears railfans came up with these separate designations on their own after studying Alco construction files.  Ironically, this work was even provided to Alco department heads in 1965, for reference use only.

According to Brian Solomon's The American Diesel Locomotive RS-1s were classified as E1640, E1641, and E1641A; RSD-1s as E1645, E1646, and E1647; and RSC-1s as E1651. This can likely be explained by the fact that Alco really never intended to develop a six-axle RS-1 but did so upon request by the US Army.

The Army quickly took to the four-axle model for its lightweight and comparable horsepower, allowing it to be used in switching service within bases as well as pulling heavy loads.


Alco's Other Six-Axle Road-Switcher Models

RSC-2

RSD-4

RSD-5

RSD-7

RS-11

RSD-12

RSD-15 "Alligator"

However, after initially ordering RS1s and with World War II ongoing the Army wondered if a six-axle, C-C design (meaning all axles were powered) would not only offer more tractive effort but also be more applicable to the lighter rails used in Europe by spreading out the locomotive's 122 tons more evenly.



RSD-1 Data Sheet (Original 13, #8000-#8012)

Alco Class606-DL-319
Entered Production11/1942
Years Produced11/1942-2/1943
Model SpecificationE1640
Engine539T, 6-Cylinder In-Line, Turbocharged
Engine BuilderMcIntosh & Seymour
Horsepower1,000
Carbody StylingAlco/U.S. Army
Length (Between Coupler Faces)55' 11.75"
Weight257,000 Lbs.
Dynamic BrakesYes
TrucksC-C
Truck TypeTrimount*
Wheelbase11' 3"
Wheel Size40"
Traction MotorsGE 731 (6)
Traction GeneratorGT533
Gear Ratio16:75
Tractive Effort Rating34,000 Lbs. at 8 MPH; up to 43,000 Lbs. at 5.5 MPH.
Top Speed60 MPH

* These appear to be a version of the Trimount and probably developed by James G. Blunt based on the large journals utilized.  This truck was never replicated, even on standard production RSD-1's.

It was used solely on the original thirteen RS-1's requisitioned by the War Department since Alco had to retrofit C-C trucks on a frame designed for only four-axles.

RSD-1 Data Sheet (#8013-#8056), Construction Numbers 70634-70677

Alco Class606-DL-319
Entered Production11/1942
Years Produced11/1942-2/1943
Model SpecificationE1645
Engine539T, 6-Cylinder In-Line, Turbocharged
Engine BuilderMcIntosh & Seymour
Horsepower1,000
Carbody StylingAlco/U.S. Army
Length (Between Coupler Faces)55' 11.75"
Weight261,000 Lbs.
Dynamic BrakesYes
TrucksC-C
Truck TypeTrimount*
Wheelbase11' 3"
Wheel Size40"
Traction MotorsGE 731 (6)
Traction GeneratorGT533
Gear Ratio16:75
Tractive Effort Rating34,000 Lbs. at 8 MPH; up to 43,000 Lbs. at 5.5 MPH.
Top Speed60 MPH

RSD-1 Data Sheet (#8000-#8099), Construction Numbers 72073-72172

Alco Class606-DL-319
Entered Production10/1944
Years Produced10/1944-8/1945
Model SpecificationE1646
Engine539T, 6-Cylinder In-Line, Turbocharged
Engine BuilderMcIntosh & Seymour
Horsepower1,000
Carbody StylingAlco/U.S. Army
Length (Between Coupler Faces)55' 11.75"
Weight286,000 Lbs.
Dynamic BrakesYes
TrucksC-C
Truck TypeTrimount*
Wheelbase11' 3"
Wheel Size40"
Traction MotorsGE 731 (6)
Traction GeneratorGT533
Gear Ratio16:75
Tractive Effort Rating34,000 Lbs. at 8 MPH; up to 43,000 Lbs. at 5.5 MPH.
Top Speed60 MPH

The first 70 locomotives in this batch, #8600-8669, were built to a broad, 5-foot gauge for operation in Russia.  In all, there were 144 RSD-1's built new, in addition to the 13 RS-1's requisitioned and converted into RSD-1's, for a total of 157 units built domestically.

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.

It proved quite successful and the Army ordered several batches of RSD-1s beginning in 1942. Interestingly enough, with World War II ongoing and desperately in need of locomotives for the war effort, the Army took the first 13 RS-1s built for the Rock Island, Milwaukee Road, New York, Susquehanna & Western, Atlanta & St. Andrews Bay, and the Tennessee Coal, Iron & Railroad and had Alco convert them all into RSD-1s.

Preserved U.S. Army RSD1 #8677 at the Tennessee Valley Railroad Museum. Harvey Henkelman. photo.

Internally, the Alco RSD1 was essentially the same as the RS1 featuring the turbocharged McIntosh & Seymore model 539T prime mover and was also about the same length, 54 feet, 11 inches (although some were 55 feet, 5 inches).

As usual, still working in conjunction with General Electric and Westinghouse many of the model's internal components like air brakes, air compressors, and traction motors came from these companies. Interestingly, Alco stuck with the six-axle design producing later versions (although some featured an A1A design, or the center-axle unpowered) like the RSC-2, RSD-4, and RSD-7.


Prior to the start of World War II there were thirteen RS1's produced for five different railroads.  Please refer to the table below.  These locomotives were later requisitioned by the U.S. Army for use on the Trans-Iranian Railway to supply Russia with war materiel during the conflict.  

New locomotives were later built for the original railroads (paid for by the U.S. government) to replace those requisitioned, in April and May of 1943 (1946 for the Tennessee Coal, Iron & Railroad).


Original 13 RSD-1's Requisitioned By U.S. Army

Railroad Road Number Construction Number Date Built Date Rebuilt U.S. War Department Number Replacement Construction Number
Rock Island748694243/194111/1942800570816
Rock Island749694253/194112/1942800670817
Atlanta & St. Andrews Bay901694263/19411/1943801070810
Atlanta & St. Andrews Bay902694273/19411/1943801170811
Tennessee Coal, Iron & Railroad600694284/194112/1942800875203
Tennessee Coal, Iron & Railroad601695664/19411/1943800975204
Milwaukee Road1678695676/194111/1942800270814
Milwaukee Road1679695686/194111/1942800370815
Rock Island746695698/194112/1942800770818
Rock Island747695708/194111/1942800470819
Atlanta & St. Andrews Bay903698006/19421/1943801270821
New York, Susquehanna & Western231699926/194211/1942800070812
New York, Susquehanna & Western233699936/194211/1942800170813

Total Production Of Alco RSD-1s

Owner Road Number(s) Quantity Date Built
U.S. Army8000-8012, 8013-8056, 8600-86991571942-1946
National de Mexico5700-570561946

Total Production Roster Of MRS-1s

Owner Road Number(s) Quantity Date Built
U.S. ArmyB2041-B2084, 2085-2123831953

Total Production Roster Of RSC-1s

Owner Road Number(s) Quantity Date Built
Sao Paulo Railway (Brazil)500-50341946


A handful of Alaska Railroad's fleet of RSD-1's are seen here, all former U.S. Army units.

Unfortunately, the six-axle RS models, while providing more traction and greater weight distribution (making them ideal for heavy drag service, even on light branch lines), were never as popular as their B-B counterparts.  

In, all some 250+ six-axle RS-1's were produced; 247 for the US Army (including the 83 MRS-1s the Army purchased in 1953), 4 for Sao Paulo Railway of Brazil (which purchased the A1A-A1A RSC-1), and 6 for National de Mexico. 

More information about these locomotives can be found in the production roster listed above.  Of the dozen units preserved four are known to be operational:

  • U.S. Army #8018 at the Orange Empire Railway Museum

  • U.S. Army RSD-1 #8652 at the North Alabama Railroad Museum 

  • U.S. Army #8669 and #8677 at the Tennessee Valley Railroad Museum.  
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SteamLocomotive.com

Wes Barris's SteamLocomotive.com is simply the best web resource in the study of steam locomotives. 

The amount of information found there is quite staggering; historical backgrounds of wheel arrangements, types used by virtually every railroad, preserved and operational examples, and even those used in other countries (North America and beyond). 

It is difficult to truly articulate just how much material can be found at this website.  It is a must visit!



Researching Rights-Of-Way

A popular pastime for many is studying and/or exploring abandoned rights-of-way. 

Today, there are tens of thousands of miles scattered throughout the country.  Many were pulled up in the 1970's and 1980's although others were removed long before that. 

If you are researching active or abandoned corridors you might want to check out the United States Geological Survey's (USGS) Historical Topographic Map Explorer

It is an excellent resource with thousands of historic maps on file throughout the country.  Just type in a town or city and click on the timeline of maps at the bottom of the page!