EMD's F Unit:
The Champion


In 1939, the Electro-Mechanical Division (EMD) of General Motors challenged the steam locomotive in what many thought was an impossible battle, the hauling of huge loads of freight. The diesel had proven itself to some skeptics as a capable passenger locomotive, but many doubted that it could pull freight as well. Those doubters were in for quite a shock.
In an 11 month tour of 35 states and 20 Class 1 railroads, EMD FT (The F for freight and the T for 2700 horsepower with a 2 unit set) unit demonstrators #103A, 103, and 2 boosters, dealt a deathblow to the steam locomotive. The "bulldog" F proved it could pull freight well and beat the steam locomotive in efficiency in almost every category. The F could haul more freight, with less fuel, than a steamer. Diesels could be arranged in a "building-block" fashion, the number of units adjusted for the horsepower needed. In addition, a "lash-up" of diesels, thanks to MU controls, could be run by a single crew in one cab, greatly cutting down on labor cost. Maintenance requirements were much lower and railroads could dispense with the costly coaling and water facilities needed by steam locomotives. Over the next 6 years, 1096 FTs were built. One railroad, Santa Fe, purchased 320 units! Santa Fe operated rather extensively in desert territory, where water for steamers was hard to come by, therefore it saw the advantages of diesel power. It is not an exaggeration to say that the FT, along with later F models, almost single-handidly ended over 100 years of steam dominance on the tracks.
In all, over 7600 F units (both A units and boosters) were built between 1939-1960. The FT was followed by the F2, F3, F7, FP7, F9, FP9, and production ended in 1960 with the FL9. The F was easily the top selling cab unit of all time.

F Unit Technical Data: (F7)

Model: F7
Horsepower: 1500
Tractive Effort: 57,500lbs.
Engine: EMD 567B
16 Cylinders

Units Sold:
2366 (A units)
1483 (B units)
Total: 3849
Produced: 1949-1953

F unit models: FT, F2, F3, F7, FP7, F9, FP9, FL9
(and B units)
A units: 4708
B units: 2904
Total: 7612

Technical Features:

1. Most F units were almost 51 feet long and weighed 230,000 pounds. The A unit was 15 feet high and 10 and-a-half feet wide. The F7 had a tractive effort of 57,500 lbs.
2. Horsepower eventually reached 1800 with the FL9.
3. The truck design was BO-BO.
4. Normal maximum speed was 65 m.p.h. on a standard gear ratio of 62:15. A ratio of 65:12 allowed 55 m.p.h., 71 m.p.h. on 61:16, 77 m.p.h. on 60:17, 83 m.p.h. on 59:18, 89 m.p.h. on 58:19, 95 m.p.h. on 57:20, and 102 m.p.h. on 56:21.
5. Although designed for freight, the F was quite suitable as a passenger hauler. Many units were fitted with steam boilers for this purpose. The higher tractive effort of the F, in comparison to the E, and better adhesion on flat terrain, made it attractive to companies that did not operate in areas with steep grades. Santa Fe used Fs to pull one of the finest passenger trains ever, the Super Chief.
6. The F carried 1200 gallons of fuel oil. In addition, 200 gallons of lubricating oil was carried, 230 gallons of cooling water, and over 1000 gallons of water could be carried for the steam generator.
7. The original model, the FT, was designed to operate in sets that were semi-permanently coupled with drawbars. This inflexible arrangement was unacceptable to railroads and EMD was forced to re-design the FT and later models with standard couplers.
8. The FP7 and FP9 models (The P for Passenger) were also offered by EMD. These units were 4 feet longer than the standard F and this additional space was used for more water tanks to supply the steam generator.
9. Dynamic braking was optional.
10. Most F units served 15 years or more before being retired.

The FL9: A 5 axle F

The FL9 was the final variant of the F unit. It arose because of a need by the New Haven Railroad (and others) for a dual-mode locomotive that could be powered by either an internal diesel engine, or from a third rail carrying electricity. New Haven operated passenger trains in New York City and other nearby cities. Many cities had laws that banned smoke emissions within city limits. The only way for a train to operate was to be able to switch to third rail power once it neared the city limits. Before the diesel, steamers had pulled passenger trains part of the way and then were replaced by electric locomotives for the remainder of the journey. The FL9 was designed to do both these jobs with one locomotive.
The FL9 was fitted with the EMD 567C or 567DI engine, generating 1750 and 1800 hp, respectively. An extra axle was added on the rear trucks to more evenly distribute the weight of the unit and contain the third rail shoes. When called upon, the shoes deployed and contacted the third rail. This powered the traction motors instead of the diesel engine. New Haven, Penn Central, the Metropolitan Transportation Authority, Conrail, Amtrak, and the Connecticut Department of Transportation, owned and operated the FL9. FL9s were 4 feet longer than the FP7 and 8 feet longer than the standard F. A total of 60 FL9s were built. Most of them still exist, either in operation or in storage. The recent arrival of the GE P-32 dual-mode Genesis units may mean the days of the FL9 are numbered.

Historical Perspective:

The F unit has been referred to as "the diesel that did it" by the editor of Trains magazine. The F unit changed an entire industry almost beyond recognition. Who could have guessed that the humble F unit would play a large role in the demise of the steam locomotive in less than 20 years?
The F also established EMD as the leader in diesel locomotive construction for nearly 50 years. Only recently has EMD slipped to second place behind GE. Over 7000 F units were sold. The F outsold the FA, its closest competitor, by almost 6 to 1. It was no contest.


About 250 F units still exist across North America. Some pull excursion and dinner trains, others sit as static displays in museums, while some await a rebuilding and return to service. A few even still serve in mainline freight and passenger service. They are out there.

Railfan Perspective:

The F has become one of the all time favorites of the railfan. The attractive, bull-dog nose and fine lines have come to represent the diesel locomotive itself. So many Fs were built that they showed up in every part of the country and became a common sight to millions of people. Many have survived far longer than designed. The F helped usher in the era of the colorful railroad, with countless paint schemes and variety. This contrasted sharply with the almost uniform black or gray of the steam locomotive. The image of the vibrant railroad, ready to meet the challenges of the 20th Century and beyond, was created. And that image is still with us.

A 1995 picture of FP9#1753. Algoma Central still operates some Fs on passenger and freight runs. Picture by Dan Dawdy.



 "The American Diesel Locomotive" Brian Soloman. MBI Publishing. 2000.

 "Modern Diesel Locomotives" Hans Halberstadt. MBI Publishing. 1996

"Vintage Diesel Locomotives" Mike Schafer. MBI Publishing. 1998

"A Field Guide to Trains" Gerald Foster. Houghton-Mifflin. 1996

 "Diesel Locomotives: The First 50 Years" Louis A. Marre. Kalmback Books. 1995

 "The Encyclopedia of Trains and Locomotives" C.J. Riley. MetroBooks. 1995

 "The Railroad Encyclopedia" Edited by Anthony Lambert. Eaglemoss Productions. 1996

Diesel Era Magazine

 LocoNotes Mailing List

"The Revolutionary Diesel: EMC's FT" Diesel Era. Withers Pub. 1996

 "F Units: The diesels that did it" Jeff Wilson. Kalmback Books. 2000

 "F-Units: The Locomotives that Revolutionized Railroading" Daniel J. Mulhearn & John R. Taibi. Quadrant Press. 1982


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