• What **WAS** the 5GT-590?

  • Discussion of General Electric locomotive technology. Current official information can be found here: www.getransportation.com.
Discussion of General Electric locomotive technology. Current official information can be found here: www.getransportation.com.

Moderators: AMTK84, MEC407

  by Allen Hazen
Thanks for the lengthy explanation! As you say, looking for the real facts (though hard!) is more rewarding than mere speculation.
--Re: 726 motor. Yes, I remember your bringing this out when we had our long discussion (the one on the Alco forum). Still, there ARE references to the 726 motor on PA locomotives: the December 1946 "Railway Mechanical Engineer" article for example. This suggests to me that there was at least some PLAN of equipping these locomotives with 726 motors. I'm keeping an open mind (i.e.: I don't have ANY idea one way or the other) as to whether these motors ever got into PA locomotives. If, say, ATSF 51 had 726 motors when first tested on the Lehigh Valley but had them replaced before delivery, Alco might not have bothered to mention the combination when TP-400 was drawn up.
--Re: later upgrades. I am sure (though, given the middle-aged memory, "being sure" isn't decisive) that I have seen a list showing a small number of PRR U25B as having been uprated to 2800 hp: possibly in Stauffer's "Pennsy Power II" (my copy being on the other side of the Pacific from me right now...). Not many: perhaps a half dozen or so, as if the upgrading was a program abandoned shortly after it started. ... I also recall a "Trains" magazine "Motive Power Survey" article (???from the first half of the 1970s???) that discussed the problem of what to do with "early second-generation" locomotives: the U25B was singled out as the only such model that could readily be upgraded to a higher horsepower, but I don't recall any details about who had done it or to how many.

--Re: Uprated U25B. I recall from somewhere-- possibly one of the GE documents that you have posted to your WWWebsite-- that the U28 models featured a different design of exhaust manifold from that used on U25. Do you (or anybody else reading this forum) know of other differences between
----A U25B rated (like a few New York Central units-- I think from their penultimate order, built in early 1965-- or some (perhaps all eight?) of the last units built for SL&SF) at 2800hp, and
----An early U28B (early meaning: before the rearrangement of equipment, etc, that went with the change to the "pug nosed" carbody)?

(Sorry if some of my posts seem ignorant and stubborn. I sometimes think the main value of my posts to this forum is that some of them provoke you to post more interesting details from the documents you have collected! ... If you are making a case to a publisher, tell them you know of at least one railfan who would be VERY interested in a document-based, technically detailed, history of GE locomotives!)
  by Typewriters
I'll answer what I can Allen -- but not so much as to pre-empt content of our upcoming book!

The PRR U25B units rated 2800 HP were delivered that way, as preproduction test units. They were not, to my knowledge, uprated as part of any PRR program. The units were later derated back to 2500 HP as were the NYC units also delivered that way.

There are absolutely no differences we're aware of between late U25B units rated 2800 HP as preproduction prototype / test units and early production U28B units built prior to May 1966. In fact it's perfectly accurate to say that the exact same locomotive as was tested out in the preproduction configuration was used as the production U28 until the new equipment arrangement and carbody configuration were begun in May '66.

-Will Davis
  by Super Seis
Straight from the horses mouth:

The first 1500 road freight units (GM&O) had the 726 motor applied, as did the first 2000 passenger units (ATSF).
No Alco unit was EVER equipped with 746's, as there was a VERY substantial cost penalty associated with that item, plus the fact it would have required a different truck casting.

The 752 took advantage of improved materials developed during the war effort.

The postwar instruction books (which were actually developed and created by GE) have to taken with a grain of salt when it comes to specifics of equipment applied. They were designed to be 'one size fits all'-with the locomotive schematic and the Renewal Parts being the final authority.


BTW, the horse iin question was the late Philip Hatch (of NYNH&H fame) who ordered the Alco-GE postwar 2000 hp passenger units and went on to finish his career at GE.
  by Typewriters
I'm going to say that we can finally put the last nail in the coffin for the supposed GT590 application for the U25C. In other words, it didn't happen.

Since that long-ago time when this string was active I've acquired many more manuals. One of the large format, heavy ones is GEI-92316A, Volume II - Electrical Equipment Maintenance Manual for Model U28B Diesel-Electric Locomotive, Furnished to Southern Pacific Railroad Co. on G-E Requisition No. 474-88100, for serial nos. 35852 thru 35855, Road nos. 7025 through 7028.

At tab ET2 we find GE instruction GEI-83412A, dated 8-66 which covers load testing of the locomotives. FIgure 1, "Load Test Connections," includes tables of motoring excitation and dynamic braking excitation current values, and we find something interesting in the tables. This generic manual section covers all GE domestic U series models built up through its publication date.

While the U25B, U50 and all U28 models are listed with the GT-598 main generator, the U25C is listed with either the GT-586 or the GT-598. To my way of thinking, this means probably two things:

1. The GT590 reference in the PRR documents is a mistake. This was supposed to be GT-598.
2. The chance now exists that some U25C locomotives which were not preproduction U28C locomotives had GT-598 main generators.

Number two above is not necessarily obvious, as one might just guess that this refers to preproduction U28C test beds, but becomes possible when one examines the figures in the charts, which upon analysis reveal different excitation values for the U25 and U28 units using the GT-598. (Braking values are the same.) This could only mean that the U25 units with the GT598 as described in this chart are running at 2500 HP.

As with most GE manuals, there's no explanation for, or expansion of, this information. It exists in a vacuum on this page. Careful searching of the manual reveals many other interesting pieces of information (for example, the differences between submodels of the GT-598 generator in the following designations -- GT598A1, B1, B2, C1, C2, C3, C4, D5) but nothing as to the question of generators in the U25C manuals. This isn't surprising because SP had no U25C units, and so such delineation isn't necessary in this manual. (I will note again the large Conrail diesel engine manual that covers everything Conrail had, which does by way of necessity include many explanations of variances.)

So we do have an answer to the original premise of this string in one sense; the 5GT590 wasn't used in U25C units. But we do have another; which straight U25C units used the GT598 (properly 5GT598 of course just as the diesel engine is properly the 7FDL-16) instead of the GT586?

I'm looking into this possibility and will get back with details when I think I've figured it out. The answer might actually be easier than we'd think.

-Will Davis
  by Allen Hazen
Thank you, Will! ... I've thought that it was a bit strange that GE didn't adopt the 598 as standard on the U25C right from the start: why, when "stretching" the U25B to a six-axle model, did they change something they didn't have to change? (If it ain't broke...)
---The title question for this string was "What WAS the 5GT-590?" and I'm still a bit curious about that even now we are confident that it wasn't something used on the PRR's U25C. The 590 was something that GE designed for use by Baldwin when Westinghouse abandoned their former partner. Did they stat with a clean sheet of paper? or (what seems à priori more likely) did they take one of their existing generator designs and modify it to match the characteristics of the Baldwin engine? ... I've ASSUMED (with no documentary evidence to back me up) that the GT-587 used on Fairbanks-Morse diesels was a fairly close cousin of the GT-586 (and its predecessor, the GT-566 used on early Alco PA locomotives... and, if Kirkland didn't make a slip-of-the-pen error in his Alco book, on the RSD-5). My GUESS would be that the GT-590 was similar. (The other obvious starting point would be the GT-581, but this was not a generator type in much favor for CC diesels-- in the event Baldwin didn't build any six-motor units with the GT-590, but their six-motor road-switcher was in their catalogue when they asked GE to come up with a generator for them.)

My ***GUESS*** is -- do you have maintenance manual that list the weights of generators? -- that the GT-586, GT-587 and GT-590 would all be dimensionally similar. I think they are somewhat bigger and heavier than a GT-581 (or GT-564), but a bit smaller than a GT-598.

Thanks again for your continued research! (I look forward to the book!)
  by Typewriters
This is just one of a number of responses I'll have to your very good questions, Allen!

GENERATOR WEIGHTS GE models without auxiliaries

GT-552 7,000

GT-553 9,200

GT-564 10,450

GT-566 11,500

Below are with auxiliaries

GT-564 11,675

GT-566 12,725

GT-581 12,100

GT-586 12,900

GT-598 18,700




Below are submodels of the GT-598.

GT598A1 17,040
GT598B1 18,505
GT598B2 18,505
GT598C1 18,298
GT598C2 18,298
GT598C3 18,298
GT598C4 18,298
GT598D1 18,786
GT598D2 18,786

Without auxiliaries, the GT598 weighs between 15,714 lbs and 16,992 lbs. The armature increases from 7,377 lbs to 7701 lbs.

Westinghouse (for comparison) without auxiliary generator

471A 13,200 early

471A 15,580 later

471B 15,625

480F 12,175

The weights for the Westinghouse 471B and 480F are from a 1953 600 Series engine manual revision.

GE Specification 3090A dated 3/64 for the U25C lists only the GT-586 as the main generator. There's no optional upgrade in the "Available Modifications" section. Load testing instructions in all available manuals include a separate generator characteristic curve for the U25C ("GT586B1") along with GT598 at 2500 HP and GT598 at 2800 HP.

SOURCES for this post include GE Training manual for P&LE Locomotive School; ALCO-GE manuals TP-400, TP-500; GEI-92316A; BLW/BLH Operating manuals and Diesel Engine manuals, various.

-Will Davis
  by Allen Hazen
Ask and ye shall receive! Thank you, Will, very much!
The close similarity in weight between the 566 and 586 confirms my thought that they were "cousins." It has been said (on a Railroad.net forum, some years back) that the 581 was a "product ionized" version of the 564-- from the weights, it seems that the 581 was less similar to the 564 than the 586 was to the 566. And... the 598 was a whopper!
...The book "Alco's Century Series: volume one - four-axle models" (by "Diesel Era with Stephen McMillan", Withers Publishing, 2003) has, on pages 71 and 105, (Alco-produced?) general arrangements/location of equipment drawings of the C-424 and C-425, locomotive models that differed largely in that the C-424 had the 5GT581 generator whereas the C-425 hd the 5GT598. Even in these fairly small diagrams (as reproduced they are roughly 1/120 scale) the difference in size between the two generator types is very visible: the 598 is perhaps a foot and a half longer than the 581.
  by Allen Hazen
People my age should NEVER trust their memories!

When I referred (three posts up) to the GE traction generator supplied for F-M diesel locomotives, I called it the "587." WRONG! It was the 567. Introduced for use onthe "Erie-built" cab units GE put together for F-M in the late 1940s before F-M had a full-size locomotive erecting hall. After that came several years when F-M went "off-brand" for their locomotive electicals. (Westinghouse, with F-M's own smaller components and switcher traction motors.) When W'house abandoned its locomotive-building customers, F-M came back to GE, and the 567 was used on both 4-motor and 6-motor 1600 hp types, and also on the 2400 hp "Train Master."
Reasons for thinking the 567 was a close cousin of the 566:
(1) Introduced for a near contemporary, 2000 hp, 4-motor, analogue of the 566-using PA-1.
(2) Model number differs by one. (It's hard to see any general rationale to GE's assignment of model numbers to generator and traction motor types, but when two generator models are introduced at close to the same time and get numbers that close...)
  by Allen Hazen
George Elwood's marvelous "Fallen Flags" rail image site has a number of locomotive manuals up. The first on the list is an Alco electrical manual (I think I saw a 1950 date) for 244-engined types:
http://www.rr-fallenflags.org/manual/manual.html" onclick="window.open(this.href);return false;

(Pdf files: load fairly slowly. Downloading the traction generator section of this manual takes enough time to boil water and make instant coffee.)

This has details (including dimensioned drawings: I don't know if they can be enlarged enough to make the dimensions legible) on the 564B, 564C, 566C and 581A generators. (564 variants were used on FA/FB-1 and RS-2 types from their introduction to end of production in 1950. 566 was used on PA-1. 581 was used on FA/FB-2 and RS-3... as well as many later Alco and GE locomotives.)

564 and 581 were ten-pole generators, 566 twelve-pole. There are similarities with regard to things like brush size between all of them: as one would expect for generators from the same builder at about the same period. 564B was grease-lubricated and had belt-driven auxiliaries, the 564C (like the 566C) was oil-lubricated and had gear-driven auxiliaries.

Weights are given. Not QUITE the same as those Will (two posts up) found, but close (I don't know if the differences reflect slightly different subvariants of the generator types or the inclusion of different fittings):
Code: Select all
------------------------------ 564B...........564C..........566C...........581A 

Complete assembly:            11,400..........12,360........13,368.........11,945 (pounds)
Generator only:                10,120..........10,080........11,087...........9,660 
Armature+fan:                  5,075...........5,040.........5,430............4,040
So GE apparently managed, in going from the 564 to the 581, to reduce the weight significantly. Assuming the cost was roughly proportional to the amount of various materials (copper being the one that probably most influenced the cost), the 581 was probably cheaper: which could have helped Alco's competitive position vis-à-vis EMD, Baldwin and F-M a bit.

(No mystery why the manual doesn't cover the 586: the 586 was introduced on the RSD-5 and late PA units, starting in 1953.)
Last edited by MEC407 on Tue Sep 03, 2013 8:26 am, edited 1 time in total. Reason: attempting to make columns line up more legibly using "code" function
  by Allen Hazen
(Minor complaint. All the dashes and dots in my last post were put in VERY carefully to get the columns to line up neatly. What you see is not what you get. ... Annoying, but only a small complaint about a service -- the Railroad.net forums -- that I VERY much appreciate!)
  by MEC407
Allen Hazen wrote:(Minor complaint. All the dashes and dots in my last post were put in VERY carefully to get the columns to line up neatly. What you see is not what you get. ... Annoying, but only a small complaint about a service -- the Railroad.net forums -- that I VERY much appreciate!)
Unfortunately this has been a longstanding problem/complaint. Even though the site's software was recently upgraded, the phpBB system still functions like web sites of the late 1990s in many ways.

There is one way to "sort of" work around this problem when one wants to display columns of data: that is to highlight the data with your mouse cursor and click the "Code" button (it's between the "Quote" and "List" buttons). Doing this will force the site to display the data in a monospace font. It's not perfect but it does make the data slightly easier to read.