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GENERAL MOTORS - ELECTRO MOTIVE DIVISION In February 1949 the Electro Motive Division of General Motors introduced the Model F-7A (cab) and F-7B (booster) locomotives. Based on the previous F-3A and F-3B models, the locomotives were completely evolutionary in design. Equipped with two trucks (usually referred to LFM or "Blomberg" trucks), these car body units contained a 1500-horsepower 16 cylinder, Model 576B GM diesel, driving a DC generator. The current generated by the power plant was sent to four traction motors via a control system that was more automatically controlled than the previous models. The EMD F7 could be equipped with a number of options, ranging from steam generators, which can be spotted by the water fill caps and steam generator vents and exhausts at the rear of the roof, an extra nose light mounted on the cab door and dynamic brakes (noted by an extra roof fan). Other options included varying traction motor gear ratios for various kinds of service. Unlike the earlier cab models, which seemed to change observable details often enough to cause considerable difficulty with locomotive spotting, the F7's did not change much in appearance over their period of manufacture, which ended in December 1953. The A units had two portholes on the side panels, while B units had three. All units had Far-Air painted or stainless steel filter grills at the top of the sides. As it turned out, the F7 was built in both the United States and Canada - 2,341 F7A and 1,467 F7B units were built during the construction period of this locomotive. This makes the F7A one of the most successful models ever constructed by General Motors, being exceeded only by the very popular SD40-2 model in later years. By way of comparison, ALCO products sold 394 FA-2 and 227 FB-2 models of their cab units that were more or less contemporary with the F7's. The F7 was succeeded by the 1750HP F9 in 1954, but by this time most railroaders were buying the more flexible road switcher and the later model never approached the F7 in numbers of sales. Virtually every North American railroad operated some number of F7 units. Not only were the units used for freight service, in building blocks ranging from a single unit up to six or more, but a number of roads purchased F7's equipped with steam generators for passenger service. Some roads even bought nominal freight units with steam boilers so that they could be used in emergency or seasonal passenger service. The design proved a very durable and popular one, as it could be used for virtually any type of road service. The F7 was even used for way freight and switching service, but the limited vision of the engineer did not make the model a popular unit for this type of work. Most F7's operated for their owners for 15-25 years, and some units are still in operation. For the most part, the F7's were the units that allowed the complete replacement of the steam locomotive on many roads that operated them, and as such provided a link to the older days of railroading. The many bright and innovative decorative designs that were put on the F7's provided considerable contrast to the mostly black and box car red colors that were in use during the steam days. Because of these factors, the F7's will always be thought of as one of the most modern and innovative machinery items that have ever operated on a railroad. Their days may be over, but the F-units will always be remembered. EMD FP-7 In 1949, along with the F-7A and F-7B type, EMD offered the FP-7 (freight passenger) A unit, which was the F-7A extended by 4 feet between the trucks in the area just ahead of the engine. This was in order to accommodate more than twice as much boiler water internally for passenger train heat than the standard F-7 equipped with a steam generator - a total of 1750 versus 700-800 gallons. 314 FP-7's were sold to 27 different railroads.
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