California's Railroad to the U.S. 1861 - 1996

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Model Train Help EBook

Cotton Belt
EMD F7A and F7B

F7A #925 - 975

F7B #926 - 958

26 A units delivered

17 B units delivered

F7A's odd numbers only
925 927 929 931 933 935 937 939 941 943
945 947 949 951 953 955 957 959 961 963
965 967 969 971 973 975

F7B's even numbers only
926 928 930 932 934 936 938 940 942 944
946 948 950 952 954 956 958

builders photo of SSW F7A from the Rob Sarberenyi Collection (134k)

Cotton Belt received its 43 F7's over a period of time, hence they were to exhibit visual differences.

Cotton Belt's short sidings limited train length, and so they did not initially see any reason for the 'standard' 6000hp ABBA set. They therefore didn't buy a matching B unit for every A unit. However, later motive power shortages required the purchase of 6 GP9's in 1957 and 6 more in 1959. These were used as quasi B units, as SSW F7A's did not have nose MU connections, and apparently, engineers still preferred cab units over hood units.

Visual differences:

general EMD styles.

EMD changed the Cab door/frame profile in late 1950; so the first 8 F7A's had the square frame, the later 18 A units had a rounded top to the door/frame.

EMD eliminated the rear 'duck tail' overhang sometime during F7 production - not sure if this applies to SSW units...

EMD had at least 5 different styles/types of sandbox covers...

Phase designations:
according to Extra 2200 South

Phase I

F7A's #925-959 and F7B's #926-950

  • horizontal type air-intake grille and protruding horizontal type carbody louvers
  • 36" dynamic brake fan

Phase II

F7A's #961-975 and F7B's #952-958

  • vertical type (known as Farr-Air) air-intake grilles and flush vertical type carbody louvers
  • 48" dynamic brake fan

Cotton Belt options:

All were delivered in SSW version of SP's Black Widow paint, yellow carbody handrails and grabirons, and a single headlight.
The Black Widow paint was basically the same as SP's, even allowing for the 'Sunset' medallion at the bottom of the nose door, except in its place they had a reflectorized bead board with the roadnumber In the place of the upper signal light they carried a Cotton Belt medallion, .
The A units were lettered St.L.S-W (centered between the carbody doors, below the louvers), later changed to Cotton Belt in 15" lettering circa 1955. The road number appeared in the upper rear panel below the air intake circa 1958.
The B units never carried the roadname, and only carried the roadnumber in 10" script centered on the carbody side after 1958. All units had the roadnumber in black, in very small lettering centered on the red lower carbody stripe.
Judging from photographs, perhaps not many F units received scarlet and gray paint. Those that did, have basically the same lettering style as in Black Widow paint.

Most carried two opposite facing single blat horns all their life - #957 at least had a 5 chime horn fitted.

Radios with their attendant antenna were gradually added.

Cotton Belt F7A's did not have nose lifting lugs or pilot plows.

Originally delivered with 71 mph maximum, 61:16 gear ratio trucks - some evidently received 62:15 trucks to better MU with SP F units.

Various extra grabirons were fitted over the years:

  • long roof top grabs over the windshields
  • ladder type grabs above and to the rear of the class lights
  • some received a 'ladder' of grabs up the right hand side
see photos for units and placement

Nose MU connections were fitted to the right of the headlight

Originally delivered with 1200 gallon fuel tanks - over half the F7's had 1500 gallon fuel tanks fitted, with the removal of some of the skirting.

Photographs in "Cotton Belt Color Pictorial by Steve Allen Goen" would seem to indicate that perhaps spark arrestors were also carried. Photos dated 1956 show this, or at least some sort of stack extension... Later photos show the more standard EMD F unit exhaust.


  • SP Historic Diesels Vol.10 by Joe Strapac - EMD Freight F Locomotives
  • Railroad Model Craftsman, June 1972, - article entitled 'St. Louis-Southwestern by Jim Boyd.
  • 1972 SP Motive Power Annual by Joe Strapac, pages 1-21 - F unit history and photo's data etc.
  • Extra 2200 South Issue 20 Jan. 1970 - F-Unit Feature
  • Extra 2200 South Issue 21 Feb/Mar. 1970 - F-Unit Tally
  • Cotton Belt Locomotives by Joe Strapac pages 202 and 203, history, photo's etc...
  • Cotton Belt Color Pictorial by Steve Allen Goen - color photo's, data etc...

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