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 1750 hp. Externally similar to its predecessor, the SD7, the SD9 was built with the improved and much more maintainable 567C engine. Four hundred and seventy-one SD9s were built for American railroads, while a further 44 were produced for export. Many SD9s both high and short hood can still be found in service today on shortline railroads and industrial operators. Although most Class 1 roads stopped using these locomotives by the 1970s and 1980s, some remain in rebuilt form on some major Class I railroads, as switcher locomotives.

History

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. The last phase of construction had a carbody similar to the SD18 and SD24, and used two 48 in cooling fans instead of four 36 in cooling fans. EMD ended SD9 production in June 1959. It was succeeded by the SD18 which began production in 1960.

Variants

SD9s

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.

SD9m

The SD9m was a rebuild from SD7s and SD9s mostly by Norfolk Southern Railway. NS rebuilt a total of ten units and used them in service between 1989 and 2010.

Original buyers

Preservation

Some SD9 locomotives can be found in museums and on tourist lines, and at least two are in service on a working railroad.