EMD F2

The EMD F2 was a diesel-electric freight locomotive produced by General Motors' Electro-Motive Division over a remarkably short window, from July 1946 through November 1946. In total, 104 units were constructed, comprising 74 cab-equipped A units and 30 cabless booster B units. The model occupied a transitional position in EMD's F-unit lineage, following the pioneering FT and preceding the more refined and commercially successful F3. Nine railroads ultimately purchased A units, with four of those roads also acquiring B units. The largest buyers were Ferrocarriles Nacionales de México, which took delivery of 28 locomotives, the Atlantic Coast Line Railroad with 24, and the Boston and Maine Railroad with 21, together accounting for the substantial majority of total production. The brief production run of the F2 was a direct consequence of its transitional nature. EMD engineers had designed a new D12 main generator intended for the successor F3, but development of that component was not complete in time for locomotives ordered in mid-1946. As a result, the F2 retained the 1,350 horsepower D8 generator carried over from the FT, even as it featured the updated carbody and revised internal layout that would define all subsequent F-unit production. Once the D12 generator became available and F3 production commenced, the rationale for continuing the F2 essentially disappeared, explaining why the model's manufacture ceased after only a few months. The F2's legacy is modest but historically significant. It served as the mechanical and structural bridge between the groundbreaking FT and the long-running F3, establishing internal arrangements and external design conventions that persisted throughout the F-unit series. Despite this engineering importance, no F2 survives in preservation, making it the only F-unit variant of which no physical example remains. All 104 locomotives were eventually retired and scrapped, leaving the F2 as something of a ghost in EMD's catalog, known primarily through documentation and photographs rather than any tangible artifact.

The F2 rode on a B-B wheel arrangement, with two two-axle trucks supporting each unit, and was powered by the EMD 567B prime mover driving a DC electrical transmission system. As noted, the main generator was the D8, a carryover from the FT rated to produce 1,350 horsepower, rather than the more advanced unit slated for the F3. One genuinely significant engineering innovation introduced with the F2 was the companion alternator, a D14 three-phase alternator integrated into the main DC generator. This device supplied alternating current to electric motors driving the radiator fans and traction motor blowers, replacing the mechanical and belt-driven systems that had been used previously. The adoption of electric drives for these accessories resulted in a distinctive external appearance, with four radiator fans grouped together near the center of the roof rather than positioned in pairs at each end of the carbody. The companion alternator concept proved so successful that EMD incorporated it into all subsequent road locomotive designs. Externally, the F2 featured what is commonly referred to as Type 1 side paneling, characterized by three portholes and an absence of filter grilles. Small number boards were positioned on the sides of the nose. These visual characteristics, however, offer little help in distinguishing an F2 from early F3 production, since EMD carried both features into the initial F3 units as well. The F2 and all later F-units can be differentiated from the older FT by the presence of two exhaust stacks rather than four, and by differences in truck placement and the elimination of the pronounced overhang at the ends of B units that had characterized the FT.

Models by: Athearn