Why was the F2 ?

The F2 was apparently an F3 EXCEPT that it had the lower capacity main generator of the FT (and the engine downrated to 1350hp to match).
All published accounts I have seen agree that the F@ was introduced AFTER the first F# was built. (BUT: are they independent or did they copy one another?)

The old "Diesel Spotter's Guide" (not, as we know, an infallible source, but where many people interested in locomotive issues got their first course) says that the F2 was built because EMD was unable to produce the higher-rated generator.
Assuming the first (test? demonstrator?) F3 had an F3 generator, the new design must have been ready BEFORE the F2 was built. The war was over, so there shouldn't have been a problem with scarcity (& gov't regulation) of materials.

Is there a story here? Does anyone know what it is?

They had a problem with one component of the new generator which required additional time to correct, as an interim measure they adapted the companion alternator to fit the previous generator. This allowed production of the "new" locomotive design, but with a lower rating, resulting in the F2 model.

And to dovetail and speculate a bit on what mxdata has written. EMD most likely felt some pressure to get the production line for freight units going again. The last FTs were built in November 1945 and the F2s started the production of F units again in July 1946. You will remember that ALCO-GE had started producing their FA line in January 1946. It is entirely likely to me that EMD already had orders for freight units and asked its customers who was willing to wait for the higher rated units and who wanted freight units right now. I don't think there was a dimes difference in the carbodies between the F2 and early F3. It was the generator that was holding up production of the 1500 horsepower unit, but a lower rated generator was available. What say you?

That sounds quite reasonable to me.

Thanks, both of you!

SSW9389-- Sounds plausible to me. I've always wondered at the gap between FT and F2 production (seven months with no freight units delivered to coustomers? immediately postwar? COME ON!). It makes sense if tests of the F# prtotype showed that the generator needed more work, producing a desperate scramble to get some sort of stopgap into place!

mxdata-- Just to make sure I understand you correctly... There was some additional design work to be done on the new generator ("design" in a broad sense-- maybe tightened material specification, maybe changes to manufacturing methods...). (Discovered in testing the prototype F3?) And the additional work took long enought that a kludge design was shipped for a few months while it was going on?
... And (purely for curiosity-- your track record for historical/technical details is so good that I don't doubt you at all!) what is your source: is there something in print?

Thanks again, both. It had been niggling at the back of my mind for years, and "Model Railroader"'s recent feature on F-unit "phases" reminded me. (It also agrees with your impression, SSW, that the F2 and early F3 had identical external appearance.)

Yes, this is all in print, published in Railfan & Railroad Magazine December 1989, part three of the FT article by Preston Cook, this specific discussion takes up the bottom of page 77 and the left side of page 78. The same article discusses production priorities and defense contracts, and the effect they had on locomotive manufacturing at EMD. Keep in mind that nobody knew very far in advance when Japan was going to surrender. Most people expected the war to go on much longer.

mxdata--
Thanks for the reference! I undoubtedly read it in 1989, and will re-read when I am visiting the family home (where a lot of my books and magazine back issues still are) next month.
Presston Cook has to be one of the best things that ever happened to locomotive history!
--For the record: the "Model Railroader" article on F-unit "phases" I referred to is in the October 2006 issue. Dates and illustrations, but (sensibly enough for a model magazine) not much about the actual innards of the locomotives. And what there is isn't reliable: they say the F-9 had D-67 traction motors!

Allen, thanks for your kind words. I wish I had more time to put into historical research, but the last few years have been very busy. There are lots of projects that still need to be done and unfortunately every year the remaining group of people who were first hand witnesses to the events several decades ago gets smaller.

Preston

Allen Hazen wrote:The F2 was apparently an F3 EXCEPT that it had the lower capacity main generator of the FT (and the engine downrated to 1350hp to match).
All published accounts I have seen agree that the F@ was introduced AFTER the first F# was built. (BUT: are they independent or did they copy one another?)

The old "Diesel Spotter's Guide" (not, as we know, an infallible source, but where many people interested in locomotive issues got their first course) says that the F2 was built because EMD was unable to produce the higher-rated generator.
Assuming the first (test? demonstrator?) F3 had an F3 generator, the new design must have been ready BEFORE the F2 was built. The war was over, so there shouldn't have been a problem with scarcity (& gov't regulation) of materials.

Is there a story here? Does anyone know what it is?

I had read somewhere that the F2 was the result a request of several railroads to have a stand alone "A" that was compatible with the FTs. That way the railroads that had ABBA sets of FTs could break them up into ABA sets of FT/F2. As built the FTs were not compatible with any other locomotives. The F2 provided a solution for flexibility.

There is a valid point here because of MU compatability, the standard MU arrangement for the F2 was 21 point and they were manual transition. The standard MU arrangement for the F3 was 27 point with automatic transition. However, the F2's were not the only locomotives that could MU with an FT, the guys from Schenectady also built some locomotives that were MU compatible with the FT.

Having different MU receptacles did not preclude operating units together. To operate the later F-units, GPs and SDs that had 27 point receptacles with an FT or F2 (or an ALCO with 21 point receptacles) you just needed the standard EMD 8-foot conversion jumper from 27 to 21 point listed in the parts book.

However, if the purpose of building the F2 was to provide additional "A" units to work with FT sets, it doesn't explain the reason for the delivery of A-B sets of F2's and A-B-B-A sets of F2's to some customers. I am working from memory here without the benefit of a delivery list, but I seem to recall ACL, B&M, M&StL, and NdeM as having taken delivery of F2's in multiple unit sets. Please feel free to offer corrections if I have made a mistake in the railroads mentioned.

Visiting my mother's house where many of my books still are...
Had a chance to re-read the Preston Cook article in "Railfan & Railroad": VERY impressive! (Somebody at Carstens should think hard about collecting a bunch of the locomotive history articles "R&R" and "Railroad Model Craftsman" have published over the past couple of decades and reprinting them as a book!)
----Had I remembered the article, I wouldn't have posted on this topic: it answers my original question! Which would be a pity, because I learn much more from people on this forum than the answers to my specific questions!
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The production F3 differed from the F2 in at least one other respect (additional to the new generator and changed engine rating): a different system of engine control, as I recall. This SOUNDS like a new technological development, so-- if I were asked to bet-- I'd guess that the original 1500 hp prototype built before the F2 stopgap was put into production probably DIDN'T have it.
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I'm away from my normal home and office (until late January) and have only intermittent e-mail connection. So let me wish you all a Merry Christmas (&c) now!

Allen, thanks for the nice compliment. I wish I had the time to do more writing projects, but time is an a premium right now. There are several urgent historical preservation tasks I am working on that have a much greater long term importance than any articles I can presently write. Their significance may become more evident sometime in the distant future. When they are closer to completion I am hopeful that I can get more time to work on writing railroad history articles again.