EMD SD7

EMD SD7
SP 1518 at the Illinois Railway Museum
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 ft 2 3⁄4 in (18.66 m) Width 10 ft 8 in (3.25 m) Height 15 ft 4 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 EMD 567B RPM range 800 Engine type V16 diesel 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 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

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.

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 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

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).
• Great Northern No. 558, one of the first 20 SD7s to be built in 1952, is preserved and in restoration at the Minnesota Transportation Museum.

Wikimedia Commons has media related to EMD SD7 locomotives.

References

• 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.