Originally intended to be EMD's offering in the road-freight type diesel locomotive, and joined in that service by other maker's carbody units, the F series was only eclipsed in road freight service during production of the "9" series (GP-9 and F-9). The GP-9 was a runaway sales leader over the F-9, whereas the F-7 had outsold the GP-7 by a comfortable margin. Railroad's preferences had shifted, however, by the time the F-7 was replaced by the F-9 in EMD's catalog. Only then did the "hood" or "road-switcher" type begin to become the predominant type purchased from EMD for this service. Carbody units, because of their construction style, allowed crews to move about inside and between sections, where they could check operation of components.(But, it also alowed tinkering!) On the FT especially, this type of construction was absolutely necessary (and a part of the design philosophy behind the FT in the first place) because many components and controls were spread out all over the inside of the locomotive! As components became more reliable, and as the internal design of the F series was revised this need passed, and the greater visibility of the hood types won out.
Although replaced on first line trains by hood style units, many of these reliable locomotives soldiered on for many years in other services, for which older engines were ideal. On some railroads, F units were also preferred for long haul passenger service, and remained in this role despite availability of newer engines, or merely were supplemented by newer types. EMD's F's were the series that arguably conquered steam in the U.S., and as such are worthy of examination. We begin with the FT series, the first of the type.
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