The EMDSD7 is a model of 6-axle diesel locomotive built by General Motors Electro-Motive Division between May 1951 and November 1953. It had an EMD 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'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. 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]
Design and production
The SD7 was conceived as a modification of the existing EMD GP7 with two additional powered axles, one for each truck. 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, the SD9, in January 1954.
Southern Pacific #1518 (ex-EMD demonstrator #990), is preserved in operational condition at the Illinois Railway Museum. #1518 was the first SD7 (later converted into an SD7R) built by EMD.[7]
PNWR 1501 working in PNWR's yard in Albany, Oregon, on January 20, 2022Portland and Western formerly rostered SD7 #1501 (Ex-SP #5280), being retired on July 19, 2023. While it was originally going to be scrapped by PNWR parent company Genesee and Wyoming Inc. as part of a fine resolution agreement with the EPA,[11] it was acquired by Dieselmotive Company, Inc. (BUGX) and was shipped for storage on the Blackwell Northern Gateway Railroad.[12]
^"Minnesota museum acquires Great Northern SD7 | Trains Magazine". Trains. 2018-03-14. Retrieved 2024-05-16.
^"G&W locomotives to scrap or upgrade per EPA decree in 2023". Trains.com. Retrieved 27 January 2023.
^Sharfman, Alexandra (2024-02-08). "Emergency Order shuts down operations on Blackwell Northern Gateway Railroad". KOKH. Retrieved 2024-03-09.
^Franz, Justin (2021-09-29). "Nevada Northern Raising Money to Bring Two Historic Diesels Home". Railfan & Railroad Magazine. Retrieved 2024-03-09.
Further reading
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. Retrieved 2006-08-27.
Diesel Era Volume 6 Number 6 November/December 1995, "EMD's SD7" by Paul K. Withers pp 5–20; 47–50.
External links
Wikimedia Commons has media related to EMD SD7 locomotives.