EMD F-unit

EMD F-unit

EMD F-units were a line of Diesel-electric locomotives produced between November 1939 and November 1960 by General Motors Electro-Motive Division and General Motors-Diesel Division. Final assembly for all F-units was at the GM-EMD plant at La Grange, Illinois and the GMDD plant in London, Ontario, Canada. They were sold to railroads throughout the United States, Canada, Mexico and a few were exported to Saudi Arabia. The term F-unit refers to the model numbers given to each successive type, all of which began with F. The F originally meant Fourteen, as in 1,400 horsepower, not F as in Freight. Longer E-units for passenger service had twin 900 horsepower diesel engines. The E meant Eighteen as in 1,800 horsepower. Similarly for early EMD locomotives S means Six hundred and N means Nine hundred horsepower.

F-units were originally designed for freight service, although many hauled passenger trains. Almost all F-units were B-B locomotives; they ran on two Blomberg B two-axle trucks with all axles powered. The prime mover in F-units was a sixteen cylinder EMD 567 series mechanically aspirated two-stroke Diesel engine, progressing from model 16-567 through 16-567D.

Structurally, the locomotive was a carbody unit with the body as the main load-bearing structure, of a bridge-truss like design, and covered with cosmetic panels. The so-called bulldog nose was a distinguishing feature of the locomotive's appearance, and made a lasting impression in the mind of the traveling public.

The F-units were the most successful "first generation" road Diesel locomotives in North America, and were largely responsible for the replacing of the steam locomotive in road freight service.

F-units were sometimes known as covered wagons, due to the similarity in appearance of the roof of an F-unit to the canvas roof of a Conestoga wagon, an animal-drawn wagon used in the westward expansion of the United States during the late 18th and 19th centuries. When a train's locomotive consist included only F-units, the train would then be called a wagon train. These two usages are still popular with the railfan community.