EMD EA/EB

The EA and EB were among the earliest passenger diesel locomotives produced by the Electro-Motive Corporation of La Grange, Illinois, entering production in May 1937 for the Baltimore and Ohio Railroad. The order comprised six complete two-unit sets, each pairing a cab-equipped EA A unit with a cabless EB booster unit, numbered 51 through 56, with the B units carrying the corresponding number followed by the letter X. This made for a total of six A units and five B units built, with the production run extending into 1938. The locomotives were assigned to some of the B&O's premier named passenger services, including the Royal Blue and the Capitol Limited, hauling trains that were outwardly styled as streamliners but were largely composed of rebuilt heavyweight cars given modernized interiors, smooth exterior sheathing, and air conditioning. One unit, B&O 52, was sold to the Alton Railroad in 1940, later passing to the Gulf, Mobile and Ohio Railroad in 1947. The EA and EB occupy a notable position in the broader development of American passenger diesel motive power. Appearing at roughly the same time as the E1 built for the Atchison, Topeka and Santa Fe Railway and the E2 produced for the Union Pacific and associated railroads, the EA represented a meaningful transition away from the fully custom-integrated diesel streamliner sets toward a more standardized, road-locomotive approach. While each of these early E-unit variants was tailored to a specific railroad customer, their shared mechanical underpinnings pointed toward the fully production-line passenger diesels that would follow with models such as the E3 and E6. The EA and E1 in particular shared a distinctive slant-nosed styling that reflected General Motors' influence on its newly acquired Electro-Motive subsidiary, with an emphasis on visual modernity alongside technical capability. That nose design was carried forward through several subsequent E-unit variants. The first EA built, B&O number 51, survived into preservation and is held at the Baltimore and Ohio Railroad Museum in Baltimore, Maryland, where it has undergone cosmetic restoration and is displayed as a representative example of this foundational chapter in diesel locomotive history.

Each EA or EB unit was powered by a pair of Winton 201-A diesel engines, each rated at 900 horsepower, giving a combined output of 1,800 horsepower per unit. The two-unit EA and EB sets therefore produced a combined 3,600 horsepower when operated together. Power was transmitted to the wheels through a DC electric transmission, in which each engine drove a generator that in turn supplied current to axle-mounted traction motors. The wheel arrangement was A1A-A1A, meaning each unit rode on two three-axle trucks in which only the outer axles of each truck were powered, with the center axle of each truck unpowered and present to help distribute the locomotive's weight across the rail. This arrangement was well suited to the lighter axle loadings preferred on passenger mainlines while still providing sufficient traction for high-speed service. The external design of the EA and EB was protected under United States design patent D106,918 and featured the characteristic slant nose that became closely associated with the early EMD E-unit family. This styling distinguished the EA and E1 from the somewhat different bulldog nose treatment applied to the contemporary E2, and it established a visual language that persisted through the E3, E4, E5, and E6 models before the nose profile evolved again with the later E7 series.

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