EMD SD35

EMD SD35 The EMD SD35 was a six-axle, diesel-electric locomotive introduced in the mid-1960s by General Motors Electro-Motive Division for heavy freight service. It saw use on North American railroads including Southern Pacific Railroad, Atchison, Topeka and Santa Fe Railway, Union Pacific Railroad, and Great Northern Railway, evolving alongside contemporaries such as the EMD GP35, Alco C-628, and Baldwin SD45.

Development and Design

EMD developed the SD35 during a period of intense competition among manufacturers including General Electric, American Locomotive Company, and Fairbanks-Morse, responding to operational demands from carriers such as Pennsylvania Railroad, New York Central Railroad, and Chicago and North Western Transportation Company. The design built on lessons from earlier models like the EMD SD24 and EMD SD28, incorporating the Roots-type supercharger heritage traceable to EMD 567 family developments influenced by research at General Motors Research Laboratories and procurement policies shaped by committees in organizations such as the Association of American Railroads. Styling and mechanical layout reflected practices seen on units operated by Southern Railway (U.S.) and Seaboard Air Line Railroad.

Technical Specifications

The SD35 used the EMD 567D3A 16-cylinder two-stroke diesel engine producing 2,500 horsepower, part of a lineage including the EMD 567B and EMD 567C variants; electrical equipment was supplied by EMD’s traction system similar to that on the EMD GP38. Tractive effort, adhesion features, and six-axle C-C trucks paralleled engineering choices used by carriers like Canadian National Railway and Canadian Pacific Railway for heavy coal and manifest trains. Locomotive systems—cooling, dynamic braking, and fuel capacity—matched operational profiles established by railroads such as Burlington Northern Railroad, Illinois Central Railroad, and Conrail, while cab ergonomics and controls showed lineage with units serving Chessie System and Norfolk and Western Railway operations.

Production and Service History

EMD produced 360 SD35s between 1964 and 1966, with orders coming from Class I roads including Santa Fe, Southern Pacific, Illinois Central, and regional carriers like Missouri Pacific Railroad and Baltimore and Ohio Railroad. The locomotives entered service amid infrastructure and traffic shifts involving ports like Long Beach, California and terminals such as Chicago Union Station, handling manifest freight, unit coal, and intermodal duties alongside fleets from Southern Railway (U.S.) and Louisville and Nashville Railroad. Through mergers and consolidations involving Burlington Northern Santa Fe Corporation, Conrail, and the St. Louis–San Francisco Railway, many SD35s saw rebuilt careers, lease service, and secondary-market transfers to regional and shortline operators including Illinois Terminal Railroad and Iowa Interstate Railroad.

Variants and Modifications

Railroads and shops such as National Railway Equipment Company, Progress Rail Services, and railroad repair facilities at Alco (plant) performed modifications including turbocharger retrofits, dynamic braking adjustments, and cab upgrades reminiscent of alterations on EMD SD40 and EMD SD45 classes. Some units received control systems compatible with MU standards used by Union Pacific Railroad and Southern Pacific Railroad and were rebuilt with components from series like the EMD 645 family during mid-life overhauls. Industry programs for emissions and fuel efficiency from contractors such as General Electric (company) influenced experimental retrofits, while private shops undertook conversions to booster or slug configurations as seen in projects for Conrail and Chessie System.

Preservation and Surviving Units

Several SD35s survive in museums and on tourist railroads, preserved by organizations including the Illinois Railway Museum, California State Railroad Museum, and regional heritage groups such as the Mid-Continent Railway Museum and North Carolina Transportation Museum. Preserved examples often operate on excursion services alongside equipment from Southern Pacific, Atchison, Topeka and Santa Fe Railway, and Union Pacific Railroad historical fleets, or are displayed in collections curated by institutions like the National Railroad Museum and Gold Coast Railroad Museum. Enthusiast societies, historical commissions, and restoration volunteers from groups linked to Railway & Locomotive Historical Society and Historic Railways continue to maintain operational examples for interpretive programs and rail heritage events.

Category:Diesel-electric locomotives of the United States