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EMD SD7
SP#1518 inside Barn 9 at theIllinois Railway Museum inUnion, Illinois on May 27, 2023.
Type and origin Power type Diesel-electric Builder General Motors Electro-Motive Division (EMD) Model SD7 Build date May 1951 – November 1953 Total produced 188
Specifications Configuration: ​  • AAR C-C Gauge 4 ft 8+1⁄2 in (1,435 mm)standard gauge Trucks EMD Flexicoil C Wheel diameter 40 in (1,016 mm) Minimum curve 23° (250 ft (76.20 m) radius) Wheelbase 48 ft 7 in (14.81 m) Length 61 ft2+3⁄4 in (18.66 m) Width 10 ft 8 in (3.25 m) Height 15 ft4+1⁄2 in (4.69 m) Loco weight 309,000 lb (140,000 kg) Fuel capacity 1,200 US gal (4,500 L; 1,000 imp gal) Prime mover EMD16-567B RPM range 800 Engine type V16diesel engine Aspiration Roots-type supercharger Displacement 9,072 cu in (148.66 L) Generator D-12-C Traction motors (6) D-27-B Cylinders 16
Performance figures Maximum speed 65 mph (105 km/h) Power output 1,500 hp (1.12 MW) Tractive effort 77,250 lbf (343,600 N)
Career Locale United States Disposition Some still in service, others preserved

TheEMDSD7 is a model of 6-axlediesel locomotive built byGeneral Motors Electro-Motive Division between May 1951 and November 1953. It had anEMD 567B 16-cylinder engine producing 1,500 horsepower (1.12 MW) for its six traction motors. United States railroads bought 188 units.^[1]

This was the first model in EMD'sSD(SpecialDuty) series of locomotives, a lengthened B-BGP7 with a C-C truck arrangement. The two extra axles and traction motors are useful in heavy, low-speed freight service. EMD continues to produce SD series locomotives to this day. Some SD7s both high and short-hood can still be found in service today on shortline railroads and industrial operators, although most Class I roads stopped using these locomotives by the 1970s and 1980s.^[2][3]

The SD7 was conceived as a modification of the existingEMD GP7 with two additional powered axles, one for eachtruck. Providing two more axles served two purposes: it gave the locomotive more tractive effort compared to the four-axle GP7, and it distributed the locomotive's weight more evenly.^[4]

EMD produced its first examples of the SD7 in May 1951, using the 567B engine. Starting in August 1953 a total of 26 SD7s were produced which used either the 567BC engine or the 567C engine.

SD7s were originally set up to run long hood forward, usually noted by the letter "F" painted adjacent to the top step of the long hood boarding steps. Many were later changed or upgraded to run short hood forward as is today's Association of American Railroads standard.

EMD ended production in November 1953 and began producing the SD7's successor, theSD9, in January 1954.

TheSouthern Pacific Transportation Company had rebuilt a total of 42 of their SD7 locomotives into the EMD SD7R. They were numbered 1500–1542. The rebuilds had also included upgrades to theelectrical systems,traction motors, as well as a changeout of the prime movers swapping the 16-cylinder 567B prime movers with 16-cylinder 645CE prime movers.^[5][6]

Image	Owner	Quantity	Numbers	Notes	Ref.
	Electro-Motive Division	2	990	to Southern Pacific 5308 then to 2715 to 1415 and finally 1518. Preserved at theIllinois Railway Museum.	[7]
			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. ToBurlington Northern 6023-6059
	Chicago, Burlington and Quincy Railroad (Colorado and Southern Railway)	10	810–819	ToBurlington Northern 6070-6079
	Chicago, Burlington and Quincy Railroad (Fort Worth and Denver Railway)	11	850–860	858-860 were built with the 567BC engine. ToBurlington Northern 6080-6090
	Chicago, Milwaukee, St. Paul and Pacific Railroad	24	2200–2223	Renumbered 500–523, 2215-2223 were built with the 567BC engine.
	Central of Georgia Railway	1	201
	Denver and Rio Grande Western Railroad	5	5300–5304
	Great Northern Railway	23	550–572	ToBurlington Northern 6000-6022	[8]
	Kennecott Copper Corporation	1	903
	Minneapolis and St. Louis Railway	2	852, 952	Renumbered 300–301. To Chicago and North Western Railway.
	Nevada Northern Railway	1	401	Sold to LADWP in the 1980s; reacquired by Nevada Northern in 2021, along with RSD-4 #201.	[9]
	Pennsylvania Railroad	2	8588–8589	These units were built with the 567BC engine. Later renumbered to 6950-6951, toPenn Central 6998-6999, and toConrail 6998-6999
	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

• Burlington Northern #6008 (ex-Great Northern #558) is preserved at theMinnesota Transportation Museum inSaint Paul, Minnesota. #6008 was one of the first 20 SD7s to be built in 1952; it's currently under restoration to its original appearance asGreat Northern #558.^[10]
• Southern #197 is preserved at theVirginia Museum of Transportation. It was originally built asCentral of Georgia #201.
• Southern Pacific #1518 (ex-EMD demonstrator #990), is preserved in operational condition at theIllinois Railway Museum. #1518 was the first SD7 (later converted into anSD7R) built by EMD.^[7]
• Portland and Western formerly rostered SD7 #1501 (Ex-SP #5280), which was retired in 2023 as part of a fine resolution agreement with the EPA.^[11]
• TheDakota Southern Railway rosters one SD7, #512 (ex-MILW #2212)
• ILSX #1751 (ex-Pennsylvania Railroad #8589) is in operation at Red Trail Energy inRichardton, ND.
• Nevada Northern Railway 401 is in service at theIntermountain Power Plant inDelta, Utah. When retired, it will be donated to theNevada Northern Railway Museum, as part of an agreement with the museum.^[12]

• Solomon, Brian.American Diesel Locomotives. Voyageur Press. p. 69.ISBN 978-1-61060-605-9.
• Strapac, Joseph A. (1997).Southern Pacific Historic Diesels Volume 4, SD7 and SD9 Locomotives (1st ed.).Shade Tree Books,Bellflower, California.ISBN 9780930742171.OL 8360777M.
• Withers, Paul K. (1995).Diesel Era, November/December 1995, Volume 6 Number 6. Withers Publishing.
• Shine, Joseph (1991).SP into the '90's. Four Ways West Publications.ISBN 9780685752104.
• Shine, Joseph (1988).SP 1987/88 Motive Power Pictorial (1st ed.). Four-Ways West Publications.ISBN 9780961687434.
• Signor, John R. (2005).SP Trainline - Issues 83-93 (1st ed.). Southern Pacific Historical & Technical Society.
• Dorin, Patrick C. (1972).Chicago and North Western Power. Burbank, California: Superior Publishing. p. 114.ISBN 0-87564-715-4.
• Pinkepank, Jerry A (1973).The Second Diesel Spotter's Guide. Kalmbach Books. pp. 17, 26,71–72.ISBN 0-89024-026-4.LCCN 66-22894.
• Sarberenyi, Robert."EMD SD7 Original Owners".www.trainweb.org. Retrieved2006-08-27.
• Diesel Era Volume 6 Number 6 November/December 1995, "EMD's SD7" by Paul K. Withers pp 5–20; 47–50.

Wikimedia Commons has media related toEMD SD7 locomotives.

• Locomotive Truck EMD FlexiCoil C

• Electro-Motive Division locomotives
• C-C locomotives
• Diesel–electric locomotives of the United States
• Railway locomotives introduced in 1952
• Freight locomotives
• Standard-gauge locomotives of the United States
• Baltimore and Ohio locomotives
• Chicago and North Western Railway locomotives
• Chicago, Burlington and Quincy locomotives
• Denver and Rio Grande Western Railroad locomotives
• Great Northern Railway (United States) locomotives
• Milwaukee Road locomotives
• Pennsylvania Railroad locomotives
• Southern Pacific Railroad locomotives
• Union Pacific Railroad locomotives

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