EMD E2A/E2B

The EMD E2A and E2B were diesel-electric passenger locomotives built by the Electro-Motive Corporation in 1937, representing an evolution of the early streamliner power units that had begun to transform American passenger railroading in the mid-1930s. Only three units were constructed in total, comprising two A units and one B unit, and all three were built specifically to power the upgraded consist of the Union Pacific's City of San Francisco. They entered revenue service on January 2, 1938, when the original 1936 City of San Francisco trainset was replaced by an entirely new and substantially larger seventeen-car consist. The locomotives carried road numbers SF 1, 2, and 3, assigned jointly by the Chicago and North Western, Union Pacific, and Southern Pacific railroads, which operated the train cooperatively over the Overland Route between Chicago and Oakland. The introduction of the E2 locomotives marked a significant step up in power and capacity for the City of San Francisco service. The original 1936 trainset had relied on a pair of Pullman-built power car units producing a combined 2,400 horsepower, while the new E2 consist delivered 1,800 horsepower per A unit configuration, now hauling a much longer and heavier train that could accommodate 222 passengers and featured an elaborate range of sleeping accommodations and onboard amenities. The new train was capable of speeds reportedly reaching 110 miles per hour and represented an investment of over two million dollars. The E2 units thus helped usher in a new standard for transcontinental luxury passenger travel at a time when competition among western streamliners was intensifying. The E2A and E2B were among the rarest of EMD's early E-series production, their small build quantity reflecting their tailored purpose for a single named service rather than general catalog sales. Their legacy is largely tied to that of the City of San Francisco itself, a train that went on to operate for decades and became one of the most celebrated transcontinental passenger trains in American railroad history before Amtrak assumed intercity operations on May 1, 1971.

Each of the E2 locomotives was powered by a pair of Winton 201-A diesel engines, the same prime mover that had been used in several earlier Electro-Motive streamliner applications. Together the two engines produced 1,800 horsepower per cab unit, transmitted to the rails through a direct-current electrical system driving traction motors. The wheel arrangement was A1A-A1A on both the A and B units, meaning each three-axle truck had powered outer axles with an unpowered center axle, a configuration suited to spreading the locomotive's weight while keeping axle loading within acceptable limits for high-speed passenger operation. The B unit, designated E2B, was a cabless booster designed to work in multiple with the two A units, allowing the combined locomotive set to handle the substantial weight of the new seventeen-car articulated and semi-articulated consist. The E2 design was closely related to the E1 series that had preceded it, sharing the same basic carbody and mechanical architecture while refining certain details for production. The use of twin Winton 201-A engines in each unit was characteristic of EMD's approach during this period before the introduction of its own in-house 567 series prime mover, which would arrive in subsequent E-series models. The locomotives were built to match the stainless-steel and streamlined aesthetic of the Pullman-constructed passenger cars they hauled, presenting a unified visual appearance consistent with the design standards that railroads and their industrial designers were applying to prestige named trains throughout the late 1930s.

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