EMD SD7

An SD7 is a 6-axle road switcher diesel-electric locomotive built by General Motors Electro-Motive Division between February 1952 and November 1953. It had an EMD 567B 16-cylinder engine producing 1,500 horsepower (1.12 MW) for its six traction motors. 188 were built for United States railroads. Starting in August 1953 a total of 26 SD7s were produced which used either the 567BC engine or the 567C engine. These units are noted on the roster below.

This was the first model in EMD's SD (Special Duty) series of locomotives, a lengthened B-B GP7 with a C-C truck arrangement. The two extra axles and traction motors are useful in heavy, low speed freight service. SD series locomotives are still being produced today, with the SD70 being the most popular example in current production, and with many SD40-2s and rebuilds to SD40-2 specifications, or SD60s still in operation.

Yesterday's Special Duty eventually became today's Standard Duty, and yesterday's General Purpose has become today's Special Purpose ("time" freight and other time-sensitive lading). True GPs were discontinued after the completion of the last GP60 in 1994. Recently intermodal and other fast freights may be hauled by 6 axles locomotives with 4 powered axles, such as the SD70Ace-P4.

Many earlier model GPs, most particularly GP40s, GP39s and GP38s, also their SD equivalents, SD40s, SD39s and SD38s have been rebuilt to Dash 2 standards for another 30 to 40 years of service.

Original buyers

Owner	Quantity	Numbers	Notes
Electro-Motive Division	2	990	to Southern Pacific 5308
		991	to Baltimore and Ohio 760
Baltimore and Ohio Railroad	4	761–764	These units were built with the 567BC engine.
Bessemer and Lake Erie Railroad	8	451–455, 801–803
Chicago and North Western Railway	5	1660–1664
Chicago, Burlington and Quincy Railroad	37	300–324, 400–411	322-324 were built with the 567BC engine.
Chicago, Milwaukee, St. Paul and Pacific Railroad	24	2200–2223	Renumbered 500–523, 2215-2223 were built with the 567BC engine.
Colorado and Southern Railway	10	810–819
Central of Georgia Railway	1	201
Denver and Rio Grande Western Railroad	5	5300–5304
Fort Worth and Denver Railway	11	850–860	858-860 were built with the 567BC engine
Great Northern Railway	23	550–572
Kennecott Copper Corporation	1	903
Minneapolis and St. Louis Railway	2	852, 952	Renumbered 300–301
Nevada Northern Railway	1	401
Pennsylvania Railroad	2	8588–8589	These units were built with the 567BC engine
Southern Pacific Company	42	5279–5293, 5309–5335	5321-5323, 5334-5335 were built with the 567C engine
Union Pacific Railroad	10	775–784
Total	188

Preservation

• The first SD7 (later converted into an SD7R) built by EMD, former demonstrator #990, Southern Pacific 1518, is preserved in operational condition at the Illinois Railway Museum.
• Central of Georgia 201 is preserved at the Virginia Museum of Transportation.
• The Dakota Southern Railway rosters two SD7's, #512, and #522 (Ex-WSOR #522, Exx-MILW #522, Exxx-MILW #2222).

References

• Sarberenyi, Robert. EMD SD7 Original Owners. Retrieved on August 27, 2006