Encyclopedia of Trains, Rail and Locomotives: F Unit

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The first diesel freight locomotive was not a General Motors F Unit, nor did the technology of its car body styling and relatively primitive engineering become the industry standard, but this timeless design was the first of its kind to be powerful enough, reliable enough, and versatile enough to per form to its owners’ satisfaction on a daily basis. Over the previous decade, other designs were produced that could do the job sporadically, but the rugged depend ability and attendant operating economy of the F’s forced North American railroads to reconsider their remaining commitment to steam and the traditional locomotive builders.

By 1938, the newly formed Electro Motive Division (EMD) of GM had opened their brand-new plant at La Grange, Illinois, and was ready for production of GM’s own two-cycle diesel engine, which was intended to supersede the four-cycle Winton diesel then in use, designated model 567 for the cubic inch displacement of each cylinder. The sixteen-cylinder version of this engine, developing 1,350 hp, was installed in the first road freight prototype, model FT.

The FT differed from the earlier passenger-hauling E Units in that the freight locos were powered by a single engine and rode on four-wheel power trucks, while the passenger loco had dual engines on six-wheel trucks. Instead of the rakishly slanting nose that had been the hallmark of the E Unit, the FTs were blessed with the first of the soon-to-be-classic “bulldog” noses that were to become the signature of EMD locomotives for the next two decades. Rearrangements, variations, improvements, and options would evolve, but the F Unit was always a standard product of mass production.


ABOVE: We are along for the ride on Adirondack F10 #1502 inside the carbody as we roll north from ...

By late 1939, the FT demonstrator, a pair of cab units spliced by a pair of booster units and designated as a single 5,400-hp locomotive numbered 103, was ready to embark on a barnstorming tour across America. Resplendent in dark green with buff trim and lettered Electro-Motive, No. 103 spent the next eleven months hauling freight on twenty Class I railroads in thirty-five states under all sorts of conditions. The tour was hailed as a grand success, and the Santa Fe was the first to place an order, intending to assign them to their “bad water” routes in the Southwest. The Southern purchased the reconditioned 103, and was always proud to have the first F Unit ever built.

Originally built for the New York, New Haven & Hartford Railroad, the EMD FL9 was a unique locomotive that could switch from its own diesel-powered generator to third-rail power when it entered electrified territory. Metro North, the New YorkState—managed commuter system, now operates twenty-nine of these units.

The onset of World War II had a major impact on the entire locomotive-building business. Only GM was building diesel road units, and the War Production Board was forced to assign the construction of all new units to them, leaving the switchers and steamers to the competition. This gave EMD a lead in technology and mass- production techniques that they would hold for forty years.

Following the close of hostilities, the scramble to replace the war-weary locomotive fleet began in earnest. By the end of 1946, thirty roads had placed orders for F Units, which were to have higher horse power, optional high-speed gearing for passenger train use, and an improved electrical system. The first postwar successor to the FT was the F2, built for only five months until the F3 went into production at the rate of seventy per month.

Other builders tried to copy the GM techniques and frequently improved on them, but it was more of a risk for officials to commit to other units over the well- proven Fs. Dependability combined with the established GM service organization backed with years of experience was too much to overcome, and the F7 model swept the marketplace in the early 1950s. There were 1,084 F Units on twenty-five railroads in January 1946, and in the next nine years some forty-six additional rail roads invested in F’s.

In order to counter the competition’s road switchers, EMD introduced the GP7 (General Purpose) in 1949, which shared the F7’s 567 power plant and other components. While the F7 outsold the “Geep” 7 until introduction of the 1954 models F9 and GP9, the versatility of the road-switcher body won over the railroads and F Unit production wound down .The final units were dual-service FL9s, designed to run on both internally generated and overhead electricity, which were delivered to the New Haven in 1960.

Over 7,600 F Units had been built and the 567 power plant continued to be produced for new locomotives until 1966. F Units still serve on a number of railroads: in commuter service; on director’s specials; and even rebuilt into road switchers such as the Santa Fe’s CF7s, which would not be recognized by their original builders unless they looked in the engine compartment! Like the ubiquitous 4-4-0 Americans of the previous century, the pioneering F Units eventually found their way to virtually every depot in North America.

The EMD F Unit’s obvious impact on railroad transportation entitles it to a place in history, ranking with the Concord coach, Conestoga wagon. Clipper ship, Model T Ford, and the DC-3 as a mile stone in design.


Above, top: The California State Railroad Museum includes a pair of EMD F Units in the exquisite Santa Fe “war bonnet” paint scheme. No. 347Cisa 1,500-bpF7, while the trailing B Unit is a 1,350-hp F3; both were built by General Motors in 1949. Above: Bangor & Aroostock GP7 No. 68 maintains the original design on the cab, where a short hood was placed flush with the roof The GP7 road switchers produced 1,500 hp and were built by EMD from 1949 to 1954.


Above: The New Haven operated the F7 in passenger service; No. 6691 carries the multicolor “billboard “paint scheme of the 1960s.

See also: Electrification, EMD; Diesel Locomotives.

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