Editing EMD F-unit (section)

== Model development ==
The [[EMD FT|FT]], introduced in 1939 with the new {{convert|1350|hp|MW|abbr=on|lk=in}} [[EMD 567|567]] engine and Blomberg B trucks, was a successful design, and remained in production during WWII.

The [[EMD F3|F3]] (1946) had a different roof arrangement that included the replacement of the FT's boxy dynamic brake structure with two under-roof grids, two exhaust stacks instead of four, and four cooling fans grouped together instead of separated pairs of cooling fans. The F3 was also {{convert|2|ft}} longer than the FT to allow a standard draft gear to be installed at the rear of the unit. The 567B engine was uprated to {{convert|1500|hp|MW|abbr=on}}. Some F3s were nicknamed "chickenwire" for the type of engine room air-intake structure along the sides.

The [[EMD F7|F7]] (1949) and [[EMD F9|F9]] (1954) were evolutionary: the F7 had improved traction motors, the F9 had a {{convert|1750|hp|MW|abbr=on}} 567C engine. A louver arrangement over the vents changed their appearance from the F3.

There were also {{convert|4|ft||adj=mid|-longer}} versions, the [[EMD FP7|FP7]] and [[EMD FP9|FP9]], the extra length being used to house a tank for extra water capacity. Only one F model did not have Blomberg B trucks: the [[EMD FL9|FL9]] [[electro-diesel]] locomotive had a lightweight Flexicoil B in front and a standard passenger A-1-A at the rear.

Model descriptions are as built, but EMC/EMD locomotives are often rebuilt to newer standards. 
<ref>{{cite book|last=Pinkpank|first=Jerry A|title=The Second Diesel Spotter's Guide|year=1973|publisher=Kalmbach Books|isbn=0-89024-026-4|pages=13, 26 90–95, 99–101}}</ref>
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