The EMD SD9 is a model of diesel locomotive built by General Motors Electro-Motive Division between January 1954 and June 1959. An EMD 567C 16-cylinder engine generated 1,750 horsepower (1.30MW). Externally similar to its predecessor, the SD7, the SD9 was built with the improved and much more maintainable 567C engine.
471 SD9s were built for American railroads, while a further 44 were produced for export.
Many SD9s, both high and short hood variants, can still be found in service today on shortline railroads and with industrial operators. Although most Class I railroads stopped using these locomotives by the 1970s and 1980s, some remain on major Class I railroads in rebuilt form, as switcher locomotives.
The SD9 was the second model of EMD's SD (special duty) line of locomotives, following the SD7. Just as the SD7 was a lengthened GP7 with two additional axles, the SD9 was a corresponding modification of the GP9. The additional axles in SD series locomotives provide more tractive effort and more even distribution of locomotive weight compared to the four axle GP series locomotives.
SD9s can be distinguished from the similar looking SD7s by observing the position of the classification lights on the ends of the locomotive, above the number board. The SD9's classification lights are on a small pod, canted outward, while the SD7's classification lights are closer to the centerline and flush with the hood.
EMD produced a lightweight variant of the SD9, named the SD9s. This locomotive had its weight reduced for service on lighter tracks with modifications such as a smaller fuel tank.
SD9E
Between August 1970 and March 1980, the Southern Pacific Transportation Company had rebuilt 144 of their units into EMD SD9E locomotives under their own rebuild program known as the General Rehabilitation and Improvement Program (G.R.I.P). 142 of their rebuilt units were renumbered as 4300-4441 and two additional rebuilt units being renumbered as 4450 and 4451. These 142 units were also reclassified as EF618E-1, with their two units #4450 and #4451 as EF618E-2, which had left six other SD9 locomotives un-rebuilt.
BNSF #1730 (ex-GN #598) is preserved at the Inland Northwest Rail Museum at Reardan, Washington, having been donated in 2020. It is being restored into its original Great Northern appearance. Sister locomotive Great Northern #599 is also preserved by the same museum and will undergo a cosmetic restoration, with mechanical parts used for the restoration of #598. The 599 was previously donated to the city of Skykomish, WA and was on display until 2019-2022.
Escanaba & Lake Superior Railroad #1221 and #1224 are active assigned to Channing Michigan's Upper Peninsula and NE Wisconsin. Units #1222 stored. Unit #1220 ran for about a year and then was stored OOS, stored for parts. #1223 ran for a week in 2026 before checking fire fate unknown. Despite rumors, Reserve Mining unit #1225 was never purchased by the ELS RR.
12Marre, Louis A. (1995). Diesel locomotives: the first 50 years: a guide to diesels built before 1972. Waukesha, WI: Kalmbach Pub. Co. pp.66–67. ISBN0-89024-258-5. OCLC34531120.
12Glischinski, Steve (May 15, 2007). Regional Railroads of the Midwest (MBI Railroad Color History). St. Paul, Minn: Voyageur Press. p.45. ISBN978-0-7603-2351-9.
![[icon]](https://en.wikipedia.org/wiki/File:Wiki_letter_w_cropped.svg){kind=small}
