SD45

SD45

The SD45 was a six-axle diesel-electric locomotive built by Electro-Motive Division for North American railroads during the late 1960s and early 1970s. It combined a high-horsepower 20-cylinder prime mover with a C-C wheel arrangement to meet growing freight demands on routes served by Union Pacific Railroad, Atchison, Topeka and Santa Fe Railway, and other major carriers. The model played a pivotal role in heavy-haul freight operations alongside contemporaries such as the SD40 and GP40, influencing subsequent designs by General Motors and competitors like General Electric.

Design and Development

Electro-Motive Division developed the SD45 to compete with offerings from General Electric and to provide increased horsepower for heavy freight. The design used the 20-cylinder 645-series engine derived from earlier 16-cylinder units employed in SD35 and SD40 models, intending to deliver 3,600 horsepower for high-speed freight service. EMD incorporated a six-axle truck configuration similar to trucks used under SD40-2 and linked traction control features that addressed adhesion issues experienced on long consists on routes such as those of Southern Pacific Railroad and Norfolk and Western Railway. The SD45’s styling reflected EMD’s product line evolution, sharing carbody and radiator arrangements with units operated by Penn Central and Canadian Pacific Railway while offering distinctions in long hood length and exhaust arrangement.

Technical Specifications

The SD45 was powered by the EMD 645E3 20-cylinder diesel engine producing 3,600 bhp, paired with a DC generator and six traction motors supplied by EMD similar to those used under SD38 and SD40 platforms. The locomotive used a C-C wheel arrangement on two three-axle Blomberg-style trucks to distribute weight for heavy axle loads on mainline trackage owned by carriers like Chessie System and Seaboard Coast Line Railroad. Cooling systems, radiator sizing, and turbocharging echoed solutions found in high-horsepower contemporaries such as units purchased by Santa Fe and Union Pacific. The electrical control systems incorporated multiple-unit (MU) capabilities compatible with F40PH-era practices and featured dynamic braking packages used on mountain divisions operated by Denver and Rio Grande Western Railroad. Nominal tractive effort, fuel capacity, and weight figures varied slightly by customer options ordered by companies including Illinois Central and Missouri Pacific Railroad.

Operational History

Major North American carriers placed significant orders for the SD45 to bolster heavy manifest and intermodal traffic ahead of deregulation and traffic growth periods confronted by Conrail and regional systems. Early service deployments included fast freight routes traversing corridors controlled by Union Pacific Railroad and Atchison, Topeka and Santa Fe Railway, where crews and dispatchers evaluated the units’ horsepower advantage in multi-unit lashups. Mechanical reliability concerns emerged under extended high-power operation on mountainous divisions such as those of Southern Pacific Railroad, leading some fleets to reduce cylinder counts or reassign SD45s to flatter divisions managed by Canadian National Railway successors. Mergers and consolidations involving Penn Central into Conrail and later acquisitions by CSX Transportation and Norfolk Southern affected rosters, rebuilding programs, and retirement schedules for many SD45s in the 1980s and 1990s.

Variants and Modifications

Railroads and EMD developed several variations and rebuild programs for the SD45 platform. Notable manufacturer and shop rebuilds mirrored approaches used for SD40-2 and included conversions to 16-cylinder powerplants comparable to the 645-series used in SD40s, creating hybridized units sometimes classified under company-specific designations adopted by Southern Pacific and Santa Fe. Other modifications included head-end power retrofits for service patterns similar to those seen on passenger-contracted units with Amtrak and cab signaling equipment installed to comply with requirements of carriers such as Union Pacific on particular subdivisions. Rebuild programs conducted by shops associated with Illinois Central and CN produced remanufactured units extending service lives by replacing electrical systems and improving fuel efficiency, paralleling industry trends seen in refits of GP40 and SD50 classes.

Preservation and Surviving Units

A number of SD45s have been preserved by museums, historical societies, and tourist railroads, reflecting interest similar to preservation efforts for SD40 and E8 classes. Preserved examples are displayed and operated in settings that include state railroad museums, excursion programs tied to regional heritage organizations, and corporate collections formerly associated with Southern Pacific and Santa Fe liveries. Several units survive in operable condition following volunteer restoration projects comparable to restorations performed on F7 and GP9 units, serving as ambassadors at rail festivals and excursions. Preservation listings are maintained by organizations and archives connected to rail heritage efforts at institutions analogous to national transportation museums and regional historical societies.

Category:Electro-Motive Division locomotives Category:Diesel locomotives of the United States