The EMD GP7 is a four-axle (B-B) road switcher diesel-electric locomotive built by General Motors Electro-Motive Division (EMD) and General Motors Diesel between 1949 and 1954. The locomotive had an EMD 567B 16-cylinder engine which generated 1,500 horsepower (1,119 kW). The GP7 was offered with and without control cabs. The locomotives built without control cabs were called a GP7B. Five GP7B’s were built in 1953. The GP7 was the first EMD locomotive to use a hood unit design instead of a car-body design. The hood unit design cost less to build, was cheaper and easier to maintain, and had much better visibility for switching.
Of the 2,734 GP7’s built, 2,620 were for American railroads (including 5 GP7B units built for the Atchison, Topeka and Santa Fe Railway), 112 were built for Canada, and two were built for Mexico.
This was the first model in EMD’s GP (General Purpose) series of locomotives. Also, EMD offered a six-axle (C-C) SD (Special Duty) locomotive, the SD7.
EMD introduce their road switcher after ALCO, Fairbanks-Morse, and Baldwin. EMD’s first attempt at the road-switcher was the BL2 which unsuccessful in the market, selling only 58 units. The GP7 swapped the truss-framed stressed car body for an un-stressed body on a frame made from flat, formed and rolled structural steel members and steel forgings welded into a single structure or a weldment, a design still used today. Unfortunately, in heavy service, the GP7’s frame would give but the defect was corrected in later models. The GP7 proved very popular, and EMD was barely able to meet demand, even after opening a second assembly plant in Cleveland, Ohio. Locomotives in EMD’s GP-series came to be nicknamed ‘Geeps’. Many GP7s can still be found in service today, although most Class 1 roads stopped using these locomotives by the early 1980s. The GP designation stood for “general purpose”, while the “7” had no meaning other than matching the EMD F7 cab unit then in production. 74 Rail Roads in the US used the EMD GP7 and 7 in Canada.
For more information about EMD GP7 go to American Rails at http://www.american-rails.com/gp7.html
For more information about EMD GP7 CNJ No. 1523 go to the Jersey Central Chapter of NMRS at http://www.jcrhs.org/cnj1523trip.html . The line was called the Flemington Branch Special.
Micro-Mark sells several EMD GP7 locomotives for modeling. Go to http://www.micromark.com/search?keywords=EMD%20GP7
GM Demonstrator 100 73022