EMD "SD9" Locomotives

Last revised: December 29, 2022

By: Adam Burns

The EMD SD9, also referred to as a "Cadillac" for the smooth, soft ride, was the builder's second model in its six-axle series and looked virtually identical to the SD7.

Slightly more powerful than its predecessor and using an updated version of General Motors' proven prime mover of the time, the model 567, the SD9 was the most successful first-generation six-axle locomotive EMD produced, selling more than 500 examples (which included sales to foreign railroads).


Apparently, the bump up in horsepower convinced more lines to try the locomotive. Still, the Electro-Motive Division found sales difficult with numerous future six-axle models. Until the SD40 was released in 1966 only the SD24 and SD35 sold more than 100 units for the company.

As with many early model EMDs the SD9 soldiers on today, finding use in regular service on shortlines and industrial settings. There are also several units officially preserved including Colorado & Southern #839 and Southern Pacific #5428, #5363, #5468, and #5472.


A handsome quartet of Southern Pacific SD9's in the "Black Widow" livery, led by #5472, have freight #805 on the San Joaquin Line, circa 1958. Gordon Glattenberg photo. American-Rails.com collection.


The SD9 began production in early 1954, soon after the SD7 line was closed. The model used GM's latest prime mover of the time, the 16-cylinder model 567C which provided the SD9 a 1,750 horsepower rating, 250 more horsepower than the earlier SD7.

Also, using GM's model D47 traction motors the C-C truck setup provided for a continuous tractive effort of 75,000 pounds (its starting tractive effort was nearly 91,000 pounds), which also closely mirrored the SD7.

While the locomotive had the option of an added steam boiler for use in passenger service only a few railroads would include the feature with their SD9s including the Duluth, Missabe & Iron Range Railroad, Burlington, and Southern Pacific.

Baltimore & Ohio SD9 #1837 is seen here in Cumberland, Maryland during March, 1975. The unit was assigned to hump yard service during this time. American-Rails.com collection.

The Southern Pacific was one of the first railroads to take notice of the extra tractive effort EMD's Special Duty line provided, especially in mountainous operations, and purchased the most SD7s by a single company.

They likewise purchased the most SD9s, buying 150 of the 471 total sold to domestic railroads (another 44 were purchased by foreign lines).

While the 515 SD9s ultimately sold paled in comparison to the more than 4,000 four-axle GP9s outshopped, more railroads took notice of the latest six-axle design with more than a dozen Class Is purchasing the model.   Many of the companies that purchased the SD9 had also bought or tested at least one SD7.

Colorado & Southern (Burlington) SD9 #838 passes the depot and Purina grain elevator in Loveland, Colorado with southbound loads of limestone for the Great Western Sugar factory during the 1960s. American-Rails.com collection.

In any event, buyers included the Atlanta & St. Andrews Bay Railroad (3, numbered 503–505), Baltimore & Ohio (10, numbered 765–774), Burlington (80, numbered 325–374, 430–459), Colorado & Southern/CB&Q (23, numbered 820–842), Central of Georgia (6, numbered 202–207), Chicago & Illinois Midland (5, numbered 50–54), Chicago & North Western (14, numbered 1701–1710, 1721–1724), Milwaukee Road (14, numbered 2224–2237), DM&IR (73, numbered 101–109, 111–174 although just two came equipped with steam generators), Rio Grande (10, numbered 5305–5314), Elgin, Joliet & Eastern (3, numbered 600–602), Great Northern (27, numbered 573–599), Nickel Plate Road (20, numbered 340–359), Pennsylvania Railroad (25, numbered 7600–7624), Reserve Mining (6, numbered 1220–1225), Soo Line #2381, and SP's 150 (numbered 5340–5444, 5449–5493).

Data Sheet and Specifications

Entered Production1/1954 (Milwaukee Road #2224)
Years Produced1/1954 - 6/1959
Engine BuilderGM
Length60' 8 ½"
Height (Top Of Rail To Top Of Cab)15' 0"
Weight360,000 Lbs
Fuel Capacity2400 Gallons
Air CompressorGardner-Denver
Air Compressor ModelWBO
Air Brake ManufacturerWestinghouse
Air Brake Schedule24RL
Truck TypeFlexicoil
Truck Wheelbase13' 7"
Wheel Size40"
Traction MotorsD47 (6), GM
Primary GeneratorD22, GM
Auxiliary GeneratorDelco (A8102)
Steam Generator (Optional)Vapor-Clarkson (Model OK4625)
MU (Multiple-Unit)Yes
Dynamic BrakesYes
Gear Ratio62:15
Tractive Effort (Starting)90,800 Lbs at 25%
Tractive Effort (Continuous)75,000 Lbs at 9.3 mph
Top Speed65 mph

Production Roster

Owner Road Number(s) Quantity Date Built
Atlanta & St. Andrews Bay503-50531956-1958
Baltimore & Ohio765-774101954-1955
Burlington325-374, 430-459801954-1957
Central Of Georgia202-20761955
Chicago & Illinois Midland50-5451955
Chicago & North Western1701-1710, 1721-1724141954-1955
Colorado & Southern Railway (CB&Q)820-842231957-1959
Denver & Rio Grande Western5305-5314101957
Duluth, Missable & Iron Range101-174751955-1959
Electro-Motive (Demo)559111955
Elgin, Joliet & Eastern600-60231957
Great Northern573-599271954-1958
Milwaukee Road2224-2237141954
Nickel Plate Road340-359201957
Reserve Mining Company1220-122561955-1959
Southern Pacific5340-5417, 5424-5444, 5449-54931441954-1956
Wisconsin Central (Soo Line)238111954

Rio Grande SD9 #5309 was only a few months old when photographed here by Jackson Thode between assignments at the engine terminal in Provo, Utah in 1957. Author's collection.

Foreign lines to purchase the SD9 included Orinoco Mining of Venezuela, Korail of Korea, and Chile Exploration. Additionally, EMD demonstrator #5591 went to the Missabe Road. You can still find SD9s in service on the Algers, Winslow & Western, Nevada Northern Railway, South Branch Valley Railroad, Montana Rail Link, Port of Tillamook Bay Railroad, Black River & Western, Squaw Creek Southern Railroad, Escanaba & Lake Superior Railroad, Portland & Western, Dakota Southern, Independent Locomotive Service, Indiana Eastern Railroad, Trona Railroad, and even BNSF Railway still operates a few. 


  • Foster, Gerald. A Field Guide To Trains. New York: Houghton Mifflin, 1996.
  • Hayden, Bob. Diesel Locomotives: Cyclopedia, Volume 2 (Model Railroader). Milwaukee: Kalmbach Publishing Company, 1980.
  • Marre, Louis A. Diesel Locomotives: The First 50 Years, A Guide To Diesels Built Before 1972.  Milwaukee: Kalmbach Publishing Company, 1995.
  • Pinkepank, Jerry A. Diesel Spotter's Guide.  Milwaukee: Kalmbach Publishing Company, 1967.
  • Solomon, Brian.  EMD Locomotives.  Minneapolis: MBI Publishing Company, 2006.
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