EMD SD7

An SD7 is a 6-axle road switcher diesel-electric 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. 188 were built for United States railroads.[1] 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.

EMD SD7
Type and origin
Power typeDiesel-electric
BuilderGeneral Motors Electro-Motive Division (EMD)
ModelSD7
Build dateMay 1951 November 1953
Total produced188
Specifications
Configuration:
  AARC-C
Gauge4 ft 8 12 in (1,435 mm) standard gauge
TrucksEMD Flexicoil C
Wheel diameter40 in (1,016 mm)
Minimum curve23° (250 ft (76.20 m) radius)
Wheelbase48 ft 7 in (14.81 m)
Length61 ft 2 34 in (18.66 m)
Width10 ft 8 in (3.25 m)
Height15 ft 4 12 in (4.69 m)
Loco weight309,000 lb (140,000 kg)
Fuel capacity1,200 US gal (4,500 L; 1,000 imp gal)
Prime moverEMD 567B
RPM range800
Engine typeV16 diesel engine
AspirationRoots-type supercharger
Displacement9,072 cu in (148.66 L)
GeneratorD-12-C
Traction motors(6) D-27-B
Cylinders16
Performance figures
Power output1,500 hp (1.12 MW)
Tractive effort77,250 lbf (343,600 N)
Career
LocaleUnited States
Dispositionsome still in service

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,[2] 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 SD7s both high and short-hood can still be found in service today on shortline railroads and industral 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..

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


OwnerQuantityNumbersNotes
Electro-Motive Division
2
990
to Southern Pacific 5308 then 2715 to 1415 ne 1518
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. To Burlington Northern 6023-6059
Chicago, Burlington and Quincy Railroad (Colorado and Southern Railway)
10
810–819
To Burlington Northern same numbers
Chicago, Burlington and Quincy Railroad (Fort Worth and Denver Railway)
11
850–860
858-860 were built with the 567BC engine. To Burlington Northern Same numbers.
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
To Burlington Northern 6000-6022
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
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
Total188

Preservation

Former Pennsylvania RR SD7 8589 is in operation at Red Trail Energy in Richardton ND as 1751 with a chopped nose.

References

  1. Pinkpank, Jerry A (1973). The Second Diesel Spotter’s Guide. Kalmbach Books. p. 71. LCCN 66-22894.
  2. Ross, David, ed. (2003). The Encyclopedia of Trains and Locomotives. pp. 281, 364, 368–369. ISBN 978-0-7607-9679-5.
  • Dorin, Patrick C. (1972). Chicago and North Western Power. Burbank, California: Superior Publishing. p. 114. ISBN 0-87564-715-4.
  • Pinkpank, 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. Retrieved on August 27, 2006
  • Diesel Era Volume 6 Number 6 November/December 1995, "EMD's SD7" by Paul K. Withers pp 5-20; 47-50.
  • EMD Product Reference Data Card dated January 1, 1959 has the 567BC and 567C engine data used in the as-built roster.


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