U23C-AC !!

U23C locomotives for U.S. service were all built with DC transmission (GT586 generator): not TOO surprising given their early date. (Though the last domestic U23C were built after the first U23B-AC were built for C&O.) Somewhat more surprisingly -- given that they were built in the mid-1970s when AC/DC transmission (GTA-11 traction alternator) was becoming popular for domestic U23B. So apparently all U23C were built with straight DC transmission, though GE technical literature apparently mentioned AS/DC transmission as an option.

However, after-market modification... Someone with better Portuguese than mine should read this
http://vfco.brazilia.jor.br/diesel/dies ... rezzo1.htm
for the details, but apparently some number of Brazilian U23C have been modernized by GE do Brazil. From the photo, their external appearance is largely unchanged, but
----horsepower increased to 2600 with new or rebuilt FDL-12 engines
----752AF traction motors (this is the model used on B36-7, etc, with "Sentry" wheelslip control starting in 1980) and improved wheelslip control
----traction alternators: model not specified here, but GTA-24 would have been used on early domestic applications of "Sentry" with 752AF motors.

So: we had to wait, but yes, Virginia, there IS a U23C-AC!

(Also posted to GE Locos and Locomotive Enthusiast Yahoo groups: I hope other people find it as interesting as I did! I know that some are more interested in the "B18-7," but the U23C variant with AC/DC transmission is one of MY favorite unbuilt GE fantasy locomotives.)

Allen,

After I saw your post I became curious, I went to a spotters guide that I am attempting to get together for ALCO,EMD and GE.In doing this I came across the segment on GE's U23C and it gave a list of railway companies that purchased GE'S U23C. Yes,domestic only GE U23C's U.S.A.

ACL ?
AT&SF 7500-7519
CB&Q ?
CR-EX PC (CR No.'s 6900-6919) I think one was damaged and scrapped..
LS&I 2300-2304

There were 113 domestic GE U23C's built,I am not sure if there are any other railway Co's that purchased the U23C . I read and heard somewhere that the ACL -ATLANTIC COAST LINE- either purchased or had an order for some .

I see in looking at that article that the locomotives have the CHEC excitation system and Sentry wheelslip control. Also, and more interesting is the fact that the traction motors are wired in permanent parallel .. and the (10-pole) alternator output peak is listed as 10,000 Amps, roughly double the original generator's output; continuous output ratio is about the same. Note the very slight increase in allowed current per motor though (1260 A versus 1195 A) and the slight increase in continuous tractive effort (43,600 versus 41,000 kilograms force.) A major improvement is the increasee in peak dynamic brake effort (36,000 vs. 28,500 kg force).

It looks as if they're stating that they expect these modifications to allow each unit to haul up to 30% more tonnage compared to as-built, with a 10% fuel saving.

-Will Davis

Mr. S--
Only 53 (I think) domestic U23C, 20 for ATSF, 5 forLS&I,9 for CB&Q and 19 for PC. It's possible that ACL (more likely SCL, since ACL and SAL merged before the U23C was introduced) considered buying some, but in the end didn't. Plus 170 (20 built at Erie but the majority by GE do Brazil at Campinas) for Brazil. "Extra 2200 South" had a roster of U23B and U23C in issue #75: I can send you more details from it if you want.

Will Davis--
Sorry, even with my deficient Portuguese I'd seen the bit about permanent parallel connection and should have mentioned it!
Permanent parallel was, I thought, part of GE's "package" with Sentry and the GTA-24, so I would have expected it on these rebuilds. The figure of 1260 amps for the traction motors is one I've seen elsewhere (I've been looking through old "Extra 2200 South" while trying to organize my "library" in the new house, and I'm pretty sure it was mentioned in the write-up of the B36-7 or C36-7 when those models were new): U23C would originally have had 752E-something (the "E23S" rosters mentions three "forms" of traction motor: 752E6 and 752E8 were apparently used on U23C (U23B getting either these or 752E9: I assume the E9 version was introduced between the end of U23C production and the end of U23B?)), and the 1980-generation of traction motor used on the rebuilds had a higher capacity. I don't know what the tractive effort expected was, but the article seems to say that tonnage ratings went up by 11% (from 108 cars to 120 for the same number of units): perhaps this was limited more by power than by t.e.
(I think you were the person who told me that GE literature described the U23C as having an AC/DC transmission as an option, b.t.w.)

To be continued when I have some free time. I looked some more at the article (so far only a few words I can't guess: I studied Latin and French in highschool and can make headway through Spanish and Italian with a dictionary, so reading Portuguese isn't as hard as reading a foreign language would be!).
--The operational comparison (ratings over selected routes), in addition to the 11% increase in number of cars pulled, shows the elimination of at least one helper district, and reduction in number of helpers needed on another.
--There are what I take to be before-and-after continuous tractive effort figures, but stated in "kgf". Is this a unit of force equivalent to the pull of gravity on a 1-kilogram mass? (If it is, we get c.t.e. in pounds by multiplying by 2.205.)
--
Will post again when I've had some further reading and figuring time.