EMD SD40-2

EMD SD40-2
S.L. Dixon · CC BY-SA 3.0 · source
Name	EMD SD40-2
Powertype	Diesel-electric
Builder	Electro-Motive Division
Builddate	1972–1989
Totalproduction	3,982
Aarwheel	C-C
Primemover	EMD 645E3
Enginetype	V16 two-stroke diesel
Cylinders	16
Poweroutput	3,000 hp

EMD SD40-2 The EMD SD40-2 is a six-axle, 3,000-horsepower diesel-electric freight locomotive built by Electro-Motive Division of General Motors during the 1970s and 1980s. Renowned for reliability and modular construction, it became a mainstay on North American railroads including Union Pacific Railroad, BNSF Railway, Conrail, Norfolk Southern Railway, and Canadian National Railway. The model influenced locomotive procurement across operators such as Atchison, Topeka and Santa Fe Railway, Southern Pacific Transportation Company, and Chicago and North Western Railway.

Development and Design

Development began within Electro-Motive Division as part of a lineage including the EMD SD35 and EMD SD40. The SD40-2 incorporated lessons from responses to reliability issues on units like the EMD GP40 and design trends seen in Holland and Germany for modular maintenance. Key innovations included the HT-C truck first used on EMD SD45-2 prototypes, a modular electrical cabinet inspired by practices at General Electric, and a longer frame derived from the experimental SD40X program. Designers worked with suppliers such as Westinghouse, Rectifier Corporation, and Baldwin-Lima-Hamilton to standardize components for fleets owned by Class I carriers including CSX Transportation and Illinois Central Railroad.

Production and Variants

Production totaled 3,982 units built primarily at plants in La Grange, Illinois and Joliet, Illinois. Major buyers included Southern Railway, Missouri Pacific Railroad, Seaboard Coast Line Railroad, Penn Central Transportation Company, and Texas and Pacific Railway. Derivative models and experimental variants included the SD40T-2 "tunnel motor" ordered by Southern Pacific Transportation Company and Santa Fe, and rebuilds like SD40-2W for Canadian Pacific Railway. Foreign purchasers and license-built versions appeared in countries such as Mexico, Peru, and Chile with operators including Kansas City Southern de Mexico and Ferrocarril del Pacífico. Trade and regulatory interactions involved agencies like the Surface Transportation Board and standards bodies such as the American Association of Railroads.

Technical Specifications

The SD40-2 uses the EMD 16-cylinder, 645E3 two-stroke diesel engine producing 3,000 hp, coupled to a DC generator and traction motors supplied by manufacturers like General Electric and Siemens in later rebuilds. The HT-C six-axle truck provided improved adhesion and ride quality, informed by tests conducted with Pennsylvania Railroad and New York Central Railroad research programs. Its electrical system featured modular cubicles reminiscent of designs used by Alstom and Siemens in European locomotives. Fuel capacity, braking systems, dynamic braking, and multiple-unit control conformed to specifications demanded by heavy-duty freight services operated by Union Pacific Railroad and Burlington Northern Railroad. Weight distribution and axle loadings were calibrated to interchange requirements of networks managed by Canadian National Railway and Ferrovie dello Stato Italiane-influenced freight corridors.

Service History and Operators

SD40-2s entered service with major fleets including Union Pacific Railroad, Burlington Northern Railroad, Conrail, Norfolk and Western Railway, and Amtrak-adjacent maintenance fleets. They hauled intermodal, manifest, and unit coal trains across corridors such as the Transcontinental Railroad routes and served key hubs like Chicago Union Station and Los Angeles Union Station. During mergers—most notably Burlington Northern Santa Fe merger and Conrail breakup—units were redistributed among CSX Transportation, Norfolk Southern Railway, and BNSF Railway. International operators included industrial lines owned by Grupo Mexico and state railways like Ferrocarriles Argentinos where units were adapted to local service patterns. SD40-2s also saw seasonal and specialized assignments for customers like Peabody Energy and Arch Coal.

Rebuilds, Modifications, and Preservation

Extensive rebuild programs were carried out by shops at NS Louisville Shops, Kansas City Southern Shops, and independent contractors such as Caterpillar affiliates and Progress Rail Services Corporation. Notable rebuild types included microprocessor controls retrofits paralleling work in Amtrak fleets, conversions to comply with emissions standards influenced by agencies like the Environmental Protection Agency, and cab modifications akin to those implemented on Union Pacific Big Boy program restorations. Some units were re-geared for yard service by Kansas City Southern de México, others repowered with newer prime movers by contractors associated with General Electric alumni. Preservation efforts by museums such as the National Railroad Museum, Illinois Railway Museum, and California State Railroad Museum have secured examples for static display and excursion service, while private heritage operators maintain operational units for tourist corridors like the Durango and Silverton Narrow Gauge Railroad.

Category:Diesel locomotives Category:Electro-Motive Division locomotives