The EMD SW1200 is a diesel switcher locomotive built by General Motors Electro-Motive Division between January 1954 and May 1966. Power was provided by an EMD 567C 12-cylinder engine which generated 1,200 hp (895 kW). Late SW1200s built in 1966 were built with the 567E 12-cylinder engine. Additional SW1200 production was completed by General Motors Diesel (EMC) in London, Ontario, Canada between September 1955 and June 1964.
737 examples of this locomotive model were built for American railroads, 287 were built for Canadian railroads 4 were built for Brazilian Railroads, 25 were built for a Chilean Industrial firm, and 3 were built for the Panama Canal Railway.
A cow-calf variation, the TR12, was cataloged, but none were built.
A few units were built with dynamic brakes, featuring large square box with a fan on top of the hood, right in front of the cab.
An SW1200RS is a variation of the standard SW1200 that featured large front and rear (on some units) numberboard housings, EMD Flexicoil B-B trucks, and larger fuel tanks for roadswitcher service. The majority of the Canadian National and Canadian Pacific SW1200 fleets were purchased as SW1200RS units.
Many are still in use today, parts are still readily available and considering their low running cost and high reliability it looks like they will continue to be used for the forseeable future.
The locomotives are mostly equipped with variants of the EMD 12-567 bar 9 which were shipped fitted with a single phase electric motor instead of a diesel engine. These engines are capable of producing 1200hp, hence SW1200, and most were fitted with Flexicoil trucks, however some(SW1200Rs) were supplied with Blomberg B trucks for road service.