The F7 was the Electro-Motive's four entry in its line of freight service
locomotives and proved to be one of the most successful designs of any type ever built. The
model debuted directly after the F3 in the late 1940s and with EMD's success in the market up to that point railroads quickly placed orders for the F7. Once again, the latest F model
proved efficient, rugged, and easy to maintain. Before production had ended on the F7 nearly 4,000 units were produced outselling all other manufacturers' designs, combined. The F7 proved so reliable and useful for many roads that hundreds remained in
regular freight service through the 1970s and
1980s. Today, numerous F7s remain preserved and some even continue to haul freight, a true testament to their design. The most famous set (a pair of Bs) is the fleet
owned by Class I Norfolk Southern used as part of its official
The EMD F7 began production in February of 1949. Internally, the model varied slightly from the F3 as it still carried GM's 16-cylinder, model 567B prime mover which could produce 1,500 horsepower. It did use a slightly updated generator, the model D12B, and traction motor, the model D27C, first used on the "F5", which was technically a late model
F3 (EMD did not distinguish the locomotive as an F5, instead referring to the slight variants as phases). The new
traction motor was meant to be more rugged and durable than the
previous. However, it continued to offer the locomotive the same
tractive effort as the earlier F3; 56,500 pounds starting and 40,000
pounds continuous. Using a similar frame design as the F3, F2, and FT the F7
was just over 50 feet in length and weighed 115 tons.
Once again railroads very much liked EMD's latest F model and many which
had yet to fully dieselize did so after their F7 orders were completed
(wartime restrictions had still held back some lines from either
starting or completing their change over to diesel power). The model
was easy to maintain and very reliable; coupled with a matching
1,500 horsepower cabless B unit a set of F7s could double a train's power to 3,000 hp (in
theory you could equip as many Fs to a single train as you wished, whether at the head-end or cut-in throughout the train). While
intended for use in freight service, with their clean, streamlined
design many F7s also found their way into passenger service
alongside E units (notably on the Santa Fe which
sometimes featured Fs on trains as posh as the Super Chief and El Capitan).
As with the F3, EMD slightly upgraded the F7's carbody during its
production run although most changes were primarily focused on the grille area.
The EMD F7 was the SD40-2 of its day, the first true
"common" diesel locomotive; thousands were built and could be found
powering almost any train. When production had ended some 2,366 F7As
and 1,483 F7Bs had been produced by 1953 just four years after
the locomotive was first cataloged. This was also the first instance
of the Electro-Motive Division's new General Motors Diesel (GMD) subsidiary filling orders. Located in London,
Ontario, the new plant made it much easier to sell locomotives to
Canadian lines. In all, GMD sold 127 examples to the Canadian National,
Canadian Pacific, and the Wabash for its line in southern Ontario
between Detroit and Niagara Falls/Buffalo, New York. The model was EMD's most successful in the F series as no other future design ever came close to matching the F7's sales numbers.
The EMD F7's reliability and ruggedness can still be seen today as
dozens remain preserved and in operation with a handful still work freight trains, notably on short line Grafton & Upton. Other places one can still find F7s in use include the
Conway Scenic Railway, Reading Company Technical & Historical
Society, Adirondack Scenic Railroad, Royal Gorge Railroad, Illinois
Railway Museum, Potomac Eagle Scenic, and the Fillmore & Western.
The most famous F7s are those which pull Norfolk Southern's business train
and carry a livery inspired by predecessor Southern Railway. They
include A units #4270 and #4271 as well as B units #4275 and #4276.
Related Reading You May Enjoy
Share Your Thoughts
Have your say about what you just read! Leave me a comment in the box below. Please note that while I strive to present the information as accurately as possible I am aware that there may be errors. If you have potential corrections the help is greatly appreciated.