EMD E-units

EMD E-units
Name	EMD E-units
Powertype	Diesel-electric
Builder	Electro-Motive Corporation/General Motors Electro-Motive Division
Builddate	1937–1963
Totalproduction	748 A units, 367 B units
Disposition	Museum, excursion, scrap

EMD E-units were a family of streamlined diesel-electric passenger locomotives built by Electro-Motive Corporation and later General Motors Electro-Motive Division for North American railroads. Introduced in the late 1930s, they replaced steam power on premier trains for carriers such as the Atchison, Topeka and Santa Fe Railway, Pennsylvania Railroad, and New York Central Railroad. Their distinctive bulldog nose, twin-engined layout, and long careers made them icons of Streamliner era passenger service and subjects of preservation by museums like the Illinois Railway Museum and the RailGiants Train Museum.

Development and design

EMC developed the E-unit series during an era when companies such as Burlington Route, Southern Pacific Railroad, and Baltimore and Ohio Railroad sought reliable diesel motive power for named trains like the Zephyr and the 20th Century Limited. Designers at EMC drew on prior experimental units and the success of the E1 demonstrator to produce a family characterized by dual 12-cylinder and 16-cylinder EMD 567 engines and the iconic sloping nose influenced by styling firms and industrial designers who worked with Norman Bel Geddes and Raymond Loewy on train streamlining. The units balanced aesthetics with operational needs dictated by non-EMC stakeholders including executives from Union Pacific Railroad and Chicago and North Western Railway.

Models and variants

The series included a succession of models named E1 through E9, with subvariants for different gear ratios, train heating systems, and customer-specified fittings. Railroads ordered custom sets for consists on services such as the Super Chief, Broadway Limited, Twentieth Century Limited, and the Crescent Limited, resulting in cosmetic differences tied to owners like Santa Fe, Penn Central, and Southern Railway. Some orders included B units without cabs supplied to operators including Northern Pacific Railway and Great Northern Railway, while deluxe versions served streamlined consists for Rock Island Lines and Chicago, Rock Island and Pacific Railroad.

Mechanical and electrical systems

E-units used two prime movers coupled to individual generators feeding electric traction motors on each powered truck, a layout influenced by early diesel-electric pioneers including H. H. Franklin and practices at Alco and Baldwin Locomotive Works. The engines were variants of the EMD 567 family, later models moving to improvements akin to those in EMD 645 development programs. Electrical control employed multiple-unit control systems compatible with other EMC/EMD road units and was refined through operational feedback from railroads such as Illinois Central and Missouri–Kansas–Texas Railroad. Trucks and suspension designs reflected inputs from North American interchange practices overseen by bodies including the Association of American Railroads.

Operations and service history

E-units entered service on high-profile named trains and long-distance services across routes like the Santa Fe Chief, Pennsylvania Railroad Broadway Limited, and New York Central 20th Century Limited routes connecting Chicago, Los Angeles, New York City, and St. Louis. During World War II, deployments expanded on transcontinental and troop movements overseen by War Shipping Administration-era transportation coordination, and postwar showings included exhibitions at venues tied to World's Fair events. Over time many units were rebuilt or modified in shops run by operators including Atchison, Topeka and Santa Fe Railway and Southern Pacific Railroad; some units later transferred into freight or commuter service with railroads like Conrail and Amtrak by the 1970s.

Preservation and preservation units

Numerous examples survive in museums and tourist operations, with preserved units displayed by institutions such as the California State Railroad Museum, National Museum of Transportation (St. Louis), National Railroad Museum (Green Bay), and the Colorado Railroad Museum. Preservation efforts have been led by organizations including the Railway & Locomotive Historical Society, volunteer groups at the California State Railroad Museum Foundation, and private owners who restored E-units for excursion service on hosts like Union Pacific Railroad and regional heritage lines. Notable preserved locomotives have appeared at events organized by the Railfair and NRHS gatherings, and some units have been cosmetically restored to their original railroad liveries for static display or operation.

Technical specifications and performance

Typical E-unit specifications included twin diesel engines producing combined outputs from approximately 1,800 hp in early models to 3,600 hp in later variants, driving multiple DC traction motors to achieve top speeds intended for passenger timetables of 80–120 mph on mainline routes such as those run by New York Central and Santa Fe. Locomotive weights, axle loads, and fuel capacities were specified to meet interchange rules administered by the Association of American Railroads and to accommodate features like steam generators for passenger heating preferred by carriers such as Pennsylvania Railroad. Overhaul practices adopted standards from heavy maintenance facilities operated by Atchison, Topeka and Santa Fe Railway and Southern Pacific Railroad, extending service lives through rebuild programs documented in corporate records and railroad historical societies.

Category:Diesel-electric locomotives Category:Passenger locomotives