[?] OK I know what the F7A unit is, and what a F7B unit is but ,what is a F7C unit?
I saw them in a pic of a Great Northern F7 engine on number boards.
Also it was on the side where the engine numbers are painted on the front side of the cab.
A C unit is another name for Cab.
Some Railroads use the letters A and C to designate Cab Units. GN numbered its F units in For Unit sets. Like 305 ABDC, the A and the C are the Locos with Cabs.
James
Thanks James! I’m trying to learn everything I can on F7 and F3 units and the Great Northern. I’m going to try and build a set with just the Great Northern Rail Road theme.[:)]
F units were A (with cab) and B (without cab) In the ‘50s General Motors (EMD) sold F units to many railroads as ABBA sets which were considered as one locomotive. All 4 units in a locomotive set were given the same number with “A”, "B’ , “'C” and “D” added to distingui***he specific unit. On some railroads the units “A” was a cab (A) unit, “B” and “C” were B units (cabless) and “D” was an cab (A) unit. In some cases the letter would tell wheather or not a unit had a steam generator for passenger train heating. For instance “A” no steam generator, “D” steam generator.
Some railroads had AB, AA, ABB sets or ABA sets instead of or in addition to ABBA sets.
You need to check the roster of your favorite railroad for the time period of interest to determine their specific numbering system.
Eventually the railroads realized it was not necessary to keep the units together as a set. Many of them renumbered their locos with individual numbers. Often with A units often in one number series and B units in another.
GNRR, to add to what DSmitt noted, “Rocky” carried their numbering one step further. In the early days, late 40’s and thru the 50’s The series denoted how the units were bought. Remember at first the concept was to split the ‘E’ units so the ‘B’ units were connected to the ‘A’ unit with a drawbar, and there were no steps or side ladder at the joint. The rear truck on the ‘A’ and front truck on the ‘B’ was closer to the end and they were a foot closer together. Anyway, the 200’s series was bought as an AB, 300’s were bought as ABA, and 400’s were bought as ABBA. Later on they (EMD) extended the body so that both ends of the ‘B’ were the same and the rear of the ‘A’ matched. They added the coupler, steps and side ladder, and provided for MU’ing (Multiple Unit) So they were able to more closely match power to load, sometimes going to 5 or 6 units in any combination, as long as there was an ‘A’ in front, who cared?
Darn you guy’s are good. I love this place!!! I never though I would find a place with people older like me that was so crazy about trains!!! Is there any where on the net (I tried a search and came up empty) where there is any information on the old f units and there distinguishing characteristics between them. I really love the late 40’s and 50’s Great Northern stuff too. We lived right next the GN tracks in Fergus Falls Minnesota and I never got tired or running up to the tracks and watching. Sorry to say now those tracks between there and the twin cities are gone. I miss my old goat… 
Oh for the days gone by. I saw in all those old days back then some really strange trains back then.
Hey, GNRR, Who you callin’ a old goat? I’m only 66. I was raised on SP in the SF Bay area, but now retired to the NW so decided to model GN in the Cascades. My major yard is the imaginary “Cascade” located where the big tunnel actually is. So my sorting is track 2: Seattle south, trk 3: Seattle north, trk 4: Spokane and east, trk 5: Wenatchee and south, trk 6: overflow, and trk 7: runaround with engine service on west end and refer icing on east end. I am doing Free-mo modules up to 8’ long of 2" blue foam, yet to be framed with plywood. Ain’t we got fun?
I hope Im not outcast of from the rest of you guys in the GN club. I missed the GN by about 15 years. I am only 21 years old, but the scheme that I got attracted to is the Big Sky Blue colors of 1967-1970.
I hope you old fogeys [8D] have room for the Big Sky Blueness.
James
OH no John not calling you an old goat. I just miss my old goat the Great Northern…LOL
Wish I had the pleasure of seeing your layoutwhen it finneshed. I’m just now getting into the hobby but do want to do it in the GN theme of the NW Minnestoa landscape.
Hi Big sky Blue no outcast at all. I love to see all GN people but sorry I’m partial to the old green/brown -orange though. : )