• A hard-to-justify question...

  • 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
Serious technical question: if I can understand the answer's details, I'll understand more about locomotive electricals than I do now! But it's a rather weird question, so to set the scene I'll do a bit of "alternative history," a.k.a. "fantasy"…
… It's 1956. The top management of the Royal Railways of Ruritania, along with their political masters in the Ruritanian government, have decided to modenize with diesel-electric locomotives of basically American style. They have decided (shades of the roughly contemporaneous British Railways Modernization Scheme!) that the locomotives will be built in RRR workshops, to designs drawn up by Ruritanian engineers. Ruritanian heavy industry, however… has no large firms experienced in heavy electricals or diesel engine building, so they will import the engines and electrical components (about 2/3 of the locomotive by cost) from the United States. (A number of Australian state railways made similar decisions…)
But remember, they are not going to build locomotives to imported blueprints! They can mix-or-match components from different suppliers.
For the electricals (generators, traction motors, control systems…), the choice is easy: GE's stuff is the best in the business. On the other hand, the diesel engines that would go with it, if they were buying whole locomotives (Alco 251, Cooper-Bessemer FVBL), are fairly new and without much in the way of a frequency-of-repair track record. (Thats who I chose th date for the story: Dl-701 and UD18B both introduced new engines to the market.) Ruritania -- I don't know where it is, but let's imagine it sits on oil fields -- anticipated cheap oil for the foreseeable future, and so wan't terribly concerned with the efficiencies of 4-cycle engines… To make a long story short, they decided to use the EDM 567-C engine. (Pause, now, while people try to imagine what the finished locomotives will look like: maybe something like the C&O' SD-18 on Alco trucks?) After all, this is the most widely used locomotive engine in the world, and even its most recent iteration, the C crankcase, has two years of service experience.

So now the question. What traction generator will they buy from GE? General Electric designed the GT-567 for use with the Fairbanks-Morder opposed piston diesel: it was used on the Erie-Built units, and on late FM road switchers (and some of the last, Canadian, FM C-liner streamlined cabs). The FM engine seems to me to have broadly similar characteristics to the EMD diesel, including a full-power rpm in the same ballpark. And I know that railroads the re-engined Erie-builts with EMD prime movers kept (all of them?) the original generators. So, my question is: is the GT-567 a good enough fit for the EMD 567 that GE would happily supply it for several hundred new-build locomotives, or would they recommend going for a modified design that would differ enough to merit a new type-number ("GT-568"????)?
  by Pneudyne
Would EMD have sold its engines to an “own-design, own-build” overseas end-user back in 1956? My impression is that at the time, it liked to control how its engines were used and installed, and so supplied overseas only to its licensees who were bound by the terms of their agreements.

Anyway, that aside, if these locomotives were to have a GE-style control system, with main generator shunt field fed by a differentially compounded exciter, and excitation controlled through the exciter battery field, then I’d say that an updated GT567 would be used, retaining that designation but with a new suffix number, say GT567E1. In case it would be desirable that EMD fitted its engines with the PG governor with integral load control rheostat, something it wasn’t doing for its own production back then.

If an EMD-style control system were to be used, with a self-field and a battery field controlled by a (high current) load regulator, then perhaps the GT567 frame with new internals (different windings) would be used, for which GE might well have assigned a new GT-number.

It is said that “a camel is a horse designed by a committee”, so let’s hope that Ruritania is a desert country where camels have great utility....because that mixed-equipment locomotive could well turn out to be a camel, whether one hump or two being anyone’s guess.

  by Allen Hazen
Thank you for the informative response. … I should re-read the discussion about re-engining "Erie builds" (Fairbanks-Morse locomotives built under contract by GE at Erie, and equipped with GT567 generators) to see if there are relevant details.
CIE (Irish Railways) re-engined a number of its early diesel locomotives -- built with engines from a neighbouring island -- with EMD engines. The rebuilding in each case involved "rewinding" the generators. I'm don't know what "rewinding" amounts to: refurbishment to original condition, or building what is essentially a new generator with the original frame but new internals, like what you imagine for a Ruritanian unit with an EMD control system? The only information I have about this is the very brief description in an Irish rail fan book, "Locomotives & Rolling Stock of Coras Iompair Eireann and Northern Ireland Railways," by Oliver Doyle ad Stephen Hirsch (1981 second edition).

Such details as I have:
Class "A" locomotives (A1-A60), converted in 1968-1971 with EMD 12-645E engines, downrated to 1350hp gross, 1250 for traction, at 800rpm, having been built originally (by Metropolitan-Vickers) with Crossley HST V8 engines of 1200hp gross. "The original electrical equipment was retained but the main generator was rewound." (Geared for a maximum speed of 75mph.) … A further note adds that "a number of locomotives have the GM engine developing full power of 1,650 hp gross at 900 rpm, 1500 traction. These locomotives have their traction motors rewound and their maximum speed is 85mph."

Class "C" locomotives (C201-C234). Originally built (in 1956) by Met-Vic with 550 hp Crossley engines, four MV137CW traction motors. Two were experimentally re-engined in 1965 with Maybach engines, but the definitive rebuild (applied to the whole class, including the two that temporarily had Maybachs) was done 1969-1978, with 8-645E engines developing 1,100 hp gross at 900 rpm, 1040 hp traction. "In all conversions the original electrical equipment was retained, with the main generator and traction motors being rewound." (When I lived in Dublin in the late 1970s, Dublin suburban trains were operated by these locomotives, working push-pull.)

(Sorry-- topic creep: there is no GE connection with the CIE locomotives, just an electrical engineering issue related to my original curiosity question.)
  by Pneudyne
Well, one may actually make a GE connection with the CIE A and C class cases. Electrical equipment supplier MetroVick was part of the AEI group (along with BTH, British Thomson Houston), and AEI did have some kind of arrangement with GE for the exchange of ideas. That probably came from the BTH side of AEI. An obvious manifestation of the connection was AEI’s emergence as a second electrical equipment supplier to Alco in 1959, offering machines that in many cases were directly interchangeable with their GE counterparts. But there were other examples. The BTH PCM control system for EMUs, used by London Transport on new builds for about four decades, derived directly from the GE original of the same name. And the simple Lemp 1924 form of “engine stalling” load control, as used by GE on the 70-tonner and the small Universals, was found on some of the smaller BTH-equipped diesel-electric locomotives, including the WAGR Y, NSWGR 41 and NZR Dsc classes. An amusing thing there; one Australian commentary on the NSWGR 40 and 41 classes noted that British control systems, as on the 41, were less sophisticated than American control systems, as on the 40 (Alco-GE with Amplidyne control). Well, the 41 control system was virtually pure GE. BTH’s first diesel-electric locomotive dynamic brake installation, on its 1959 Explorer prototype, essentially followed that used on GE’s export Universals, with the brake control rheostat in series with the exciter battery field.

Nonetheless, MetroVick and BTH at times also did differently. MetroVick was something of a maverick, and for example was very antithetical to the PCC streetcar multinotch control system, and also, apparently, to anything from competitor English Electric. It spoiled BR’s (laudable) plan to have a uniform control and MU system (of mixed English Electric and Sulzer origins) for all of its pilot plan diesel-electric locomotives. BTH passed on GE’s MRC trolleycoach control system and later developed a better design of its own.

Regarding the CIE A and C class re-engining, I recall reading somewhere many moons ago that CIE had to do a bit of arm-twisting to gain EMD’s participation. I don’t know the details of the electrical equipment rework, other than that the control system was changed from 10-notch to 8-notch. MetroVick’s control system was evidently informed by Sulzer practice from its involvement with the two CIE prototypes #1100 and #1101. Originally the main generators were separately excited with differential compounding. The latter looks to have been relatively mild, as, unlike say in the GE case, the curves did not drop right down on to the standstill line of their own accord, as it were, and current limit relays were required for the lower notches. Excitation control was by a (high-current) load regulator rheostat in the main field circuit. I’d guess that the rewinding involved replacing the single main field winding with a pair, battery and self, per usual EMD practice, and possibly dispensing with the decompounding winding (although that may have been part of the starting winding). That probably sounds more difficult than it was in practice. For example, in the early 1950s, English Electric used main generators with both battery and self-field windings, but changed over to single field windings in the mid-1950s. The later machines retained the same basic (frame-size) numbers, and I think conversion between the two was possible. So GE would have been able to reconfigure its GT567 if required, although it might have wondered why anyone would want to do differently to its own ideas.

  by Allen Hazen
Thanks again!

I tried to find out a bit more by looking up things elsewhere in the archipelago. The CIE "A" class seems to have been similar to the British Rail Class 28 (that's the unusual five-axle diesel, the prototype of the character Boco fromThomas the Tank Engine…): same engine, same rating. Apparently the Crossley engine operated at the very low speed of 625 rpm: am I right in thinking that generators are not happy if asked to operate at vastly different speeds, and that even if nothing else changed the generator would have needed modifications to run at 800 or 900 rpm? (The "A" is reveal tons lighter than a Class 28, but spreads its weight over six axles: Irelan is more thinly populated than Great Britain, and its railways were apparently built to accommodate even lighter axle-loadings!)

The "C" doesn't correspond to anything on British Rail. Re-engined with the much more powerful EMD engine, it was perhaps comparable to BR classes in the low 20s, but BR didn't have any full-width carbody type with the very low original rating of the "C".

Re: "CIE had to do a bit of arm-twisting to gain EMD’s participation." Of course, EMD would have MUCH preferred to sell whole new locomotives to CIE: another order of the 161 class instead of re-engining the "C" class, for example! And they would undoubtedly have told the CIE people "Look, we helped a number of U.S. railroads with re-engining projects in the late 1950s, and they've all since decided that new engines and old electrical systems are a bad combination." But in the end maybe it was worth their while to "play nice" with CIE: their next big order for new locomotives, the "71" class of the late 1970s, was for EMD JT22C.
  by Allen Hazen
The BR Class 28 had a ten notch control: so one more similarity to the Irish "A" class as built.
And, in my speculation about what EMD would have preferred instead of re-enigining the CIE units: for "161" class read "181."
(The first batch of twin-cab EMD JL8W, with 8-567CR engines, were the 141 class: 141 to 177. The subsequent batch with 8-645 engines were the 181 class: 181 to something in the 190s. I misremembered when writing my previous post.)
  by Pneudyne
It’s true that generators generally do not like being asked to run much above their design maximum rotational speed, and ideally a generator would be designed around its associated engine rated speed. But in practice it seems that generators come in fewer frame sizes than do engines, so matching is not always exact. For example, GE used the GT581 for both its 8-cylinder (U12 through U15) and 12-cylinder (U20 and U22) export models, covering a power input range from 1200 to 2000 hp, although all at 1000 rev/min. And it also happened that generators were sometimes used in applications below their nominal rated speed. For example, I understand that the AEI TG5302W main generator used with an 800 rev/min Sulzer engine in the Commonwealth Railways NT class and Nigerian Railways 1400 class was essentially just a variant of the TG5301 used in Alco locomotives, such as the DL541, at 1000 rev/min.

The main generator used with the 625 rev/min Crossley HSTV8 engine in the CIE C class and the preceding Western Australian Government Railways (WAGR) X class locomotives was the MetroVick TG4203. Almost certainly, this was also used in the BR 28 class. I don’t have the type number for the generator used with the 1000 rev/min Crossley ESTV8 engine in the CIE C class, but it was described as being very similar to that in the CIE A. The photographic evidence seems to confirm that it was of very similar frame size, and so just a variant of the TG4203. That would also explain why the C class could handle an approximate doubling of engine power when it was retrofitted with the EMD 8-645E.

So a working hypothesis based upon the empirical evidence is that the core TG4302 design was capable of handling 1000 rev/min, in which case accommodating the 900 rev/min of the EMD 645E engine would not have been a problem.

Then you could parlay that into a strong case that GE would have chosen to work with the GT567 main generator frame for mating with the EMD engine unless there was an overwhelming reason to start again with a new design. I am not aware that GE had any other main generator extant that was a closer match.

Addressing control systems in this context is really stepping into a barrel of writhing serpents, as well as getting us off-topic. The 10-notch system used in the BR 28 (later designated as BR’s “red circle” system) was not quite the same as that used in the CIE A and C, and before that the WAGR X. And these three used MetroVick’s own adaptation of the Sulzer 10-notch system used on the CIE prototypes. BR didn’t want a second control system, but MetroVick won the first round of that battle, having found allies – for the time being - in Brush and GEC, who had previously developed similar systems. If anything the resultant BR 10-notch system was probably most like the existing Brush system.

  by Allen Hazen
Many, many thanks for lots and lots of information! … I'll be away from my computer for a few days, but if I can think of anything to say or ask next week… I will!
  by Pneudyne
Pneudyne wrote:For example, I understand that the AEI TG5302W main generator used with an 800 rev/min Sulzer engine in the Commonwealth Railways NT class and Nigerian Railways 1400 class was essentially just a variant of the TG5301 used in Alco locomotives, such as the DL541, at 1000 rev/min.
In fact both the AEI TG3501 and TG5302 were used in Alco locomotives. And GEC Traction, into which organization AEI was absorbed, grouped them as TG3501/2 in its lists. So the fourth digits in their designations are probably in the nature of suffixes denoting detail differences. The TG3501/2 was the AEI counterpart to, and I understand interchangeable with the GE GT581 as used in Alco equipment. From there one might deduce that the TG5302W was a variant matched to the Sulzer 6-cylinder engine.

The TG5301 was also adopted in 1962 by Heavy Electricals (India) limited, Bhopal, to whom AEI was technical consultant, as the main generator for the heavy 2400 hp broad gauge locomotives (Alco DL560 type) built by DLW Varanasi.

The AEI TG5303 was another apparent variant used in the 1962 AEI/Sulzer/Birmingham prototype for BR. It ran at 1150 rev/min, this being the speed from the output gears of the Sulzer 12-cylinder twin-bank engine. Of course one never knows with manufacturers’ designation systems, but the “3" fourth digit does not seem as if it would denote a major change as compared with the “1” and “2”.

Now I am wondering whether the GE GT567 was, for example, simply a variant of its GT564 or GT566, the latter more likely I think.

  by Allen Hazen
Re: "Now I am wondering whether the GE GT567 was, for example, simply a variant of its GT564 or GT566, the latter more likely I think."
I've wondered about that myself. The 566 was introduced on the Alco-GE 2000 (better known by its later designation, PA-1). The 567 was introduced on the Fairbanks-Morse Erie-built, with the same nominal power rating. It wouldn't be surprising if GE used similar designs of generator on these two comparable (and roughly contemporaneous) applications. I'll look at what I have and see if there is anything giving a suggestion about the details of the two generators.
  by Allen Hazen
Well, looking at engine-room photos of Alco PA and FM-GE Erie-built locomotives… the 566 and 567 ***LOOK*** fairly similar, but this is no more than the family resemblance you would expect from a pair of GE designs. The (reprinted) trade press articles I have from when these locomotives were new give no useful comparative information.

So, on to the next document: a GE internal document (that came my way awhile back) from 1971 listing generator types with advice about what can be substituted for what…

In the relevant period (late 1940s and 1950s), GE seems to have had six numbered generator models suitable for use on mainline North American locomotives. (Well, technically, I guess, seven, since the first prototypes of the GT598-equipped U25B were built in the very late 1950s…):
--GT564 (for early 12-244 equipped Alcos)
--GT581 (replacing the GT564 in 12-cylinder Alco applications about 1950… and used on many, many, Alco and GE locomotives of power ratings LESS than 2500 hp into the 1970s)
My guess is that these are irrelevant for the current discussion.
--GT590, developed for use with Baldwin engines when Westinghouse dropped out of the heavy traction market: a grand total of TWO generators of this type made it into locomotives before Baldwin dropped out of the locomotive market, and the GE document doesn't mention this model. (There is a long discussion of this model number elsewhere on the GE forum: conclusion was that the Pennsylvania Railroad diagram suggesting that this model of generator was used on some PRR U25C locomotives was most likely an error.)

Getting us to the models in question.
--GT566, introduced for use with the 16-244 engine on 2000 hp Alco passenger locomotives (NB: these locomotives had four traction motors). Late in its career (early 1950s) it was also used on the 1600hp (12-244 engined) Alco RSD-5 locomotive. The RSD-5 and the RSD-4 were six-traction-motor analogues of the four-motor RS-3 roadswitcher: the first iteration of this idea, the RSD-4, shared the GT581 generator with the four motor unit. Apparently this was o.k. for low-speed operations (meaning, I guess, that the GT581 could put out lots of amps), but limited the locomotive's performance at higher speeds (so, maybe the GT581 had trouble keeping the volts up in this part of its operating envelope?). The RSD-5 addressed this problem by substituting the GT566 generator.
--GT586. This seems to have been an evolutionary development of the GT566, introduced on some of the later (2250hp) Alco 16-244 engined passenger units. Close enough to a GT-566 that some GT566 generators were remanufactured as GT586. (The list says that the GT586 can safely replace the GT566 anywhere, but cautions against replacing the higher-rated GT586 with a GT566.) … The GT586 was used on many Alco and GE six-traction-motor freight units, both 1800hp 12-251 engined and 16-cylinder-engined units up to 2750 hp (i.e., U25C).

And finally,
--GT567. Document doesn't remark on similarity to any other Generator model. This was introduced for the Erie-builts: 2000hp, 10-cylinder F-M engine. F-M then switched to Westinghouse as an electrical supplier, but when Westinghouse dropped out of the heavy traction motor had to come back to GE. So, after several years gap. GE started supplying the GT567 again: both for 1600hp (eight-cyinder engine) and 2400hp (twelve-cylinder) units.

One difference between the GT567 and the generators used on Alco and GE locomotives. The GT564 was introduced for 1500 hp units, the GT581 for 1800hp, with engines operating at 1000rpm. This operating speed stayed the same for (at least the earlier versions of) the Alco 251 and CB/GE FDL engines, and when old Alcos started getting traded in on second generation diesels in the early 1960s both of these generators were used on Alco locomotives up to 2400hp. (RS-27 and/or C424: so, four-traction-motor units). The GT567, however, was designed to mate with the FM engine, operating at 850rpm. At some point a few 2400hp FM six-motor units were re-engined with Alco 16-251 engines, and the original generators (modified) were used… but limited to 900 rpm and 2250 hp. So it would appear that allow most of these GE generators could be used at significantly higher power ratings than their original applications, but that the GT567 had limited tolerance for higher rotational speeds.

(Apologies for using lots of words to convey not much information.)
  by Pneudyne
Yes, that does look like a machinery rotational speed limitation.

The original GT567A1, B1 and C1 were quoted by GE as having an input capacity of 2000 hp at 850 rev/min.

The GT567D1 was a remanufactured GT567C1 for use with the Alco 16-251 engine.

I suppose one could develop two theories here:

1. That 900 rev/min was as fast as it could go, and at that engine speed the Alco 16-251 could provide 2250 hp, which it was capable of absorbing.

2. That 2250 hp was as much as it could absorb, and the Alco 16-251 could provide that at 900 rev/min, so there was no need for it to run any faster.

The first seems more likely.

The GE list makes no mention of a 2400 hp input version of the GT567, as used on the F-M Train Master (T-M). Or perhaps that was the GT567C1, and GE simply omitted mention of its uprating. In that case, then theory (1) would definitely apply.

It would appear that the Erie-built models used the GT567 with Amplidyne excitation and with both belt- and gear-driven auxiliaries, I think GT567A1 and GT567B1 respectively.

The T-M used the GT567 with both Amplidyne and static excitation, the latter at least with belt-drive, the former I don’t know. The GT567C1 appears to have been a belt-driven Amplidyne machine, so maybe that was used on the Amplidyne-fitted T-Ms.

  by Allen Hazen
Pneudyne-- I'm not sure I have anything useful to add! But…

(1) I think the article on one of the early Erie-built orders has a diagram that certainly LOOKS as if it had belt-driven auxiliaries.
(2) Since the generators had accepted 2400 hp from the original F-M engines, I would certainly think that the derating on the re-engined Train Masters was a rotational speed issue.
(3) "Extra 2200 South," issue 61 (*), has an article on the Train Master with a roster. The units re-engined with Alco 16-251 engines (in 1964) were those belonging to the Wabash (**). Six (I think-- the unit numbering and renumbering is confusing) were built with GE transmissions (static excitation). Two were originally F-M demonstrators, built in 1953 with Westinghouse electricals (WH 498 generators). Of those two, one got a GE generator when re-engined, the other didn't: no indication what the power rating with an Alco engine and a WH generator was! … And-- error SOMEWHERE-- the "E22S" article says the re-engined units were rated at 2350hp, not the 2250 mentioned in the GE document.
(4) According to "E22S", all Train Masters built with GE electricals -- both the Amplidyne and the Static excitation ones-- got GT567C1 generators (and 752E motors).

(*) Cover date July-September 1977, but contains news photographs at least as late as October 1977. Actual publication date anybody's guess: "E22S" was notorious for late appearance of issues.
(**) Deep trivia: one of the Wabash re-engined units was scrapped, and the propulsion equipment (Alco engine and NEW -- since it was the WH equipped unit that got a new generator -- GE generator) were used to re-power an ex-Virginian Railway unit.
  by Allen Hazen
Just for the record… I've checked John F. Kirkland's book, "The Diesel Builders: Fairbanks-Morse and Lima-Hamilton" (Interurban press, 1985). It doesn't add much to what we already have.
---Confirms that on the Erie-builts, the three non-main generators (Amplidyne generator, 76-volt auxiliary generator for lighting, control and battery charging, variable voltage auxiliary generator for radiator fan and traction motor blowers (both of these items were run by DC motors on the Eries)) were run by a Vee-belt drive from an extension of the main generator shaft.
(Comment: my guess is that this was the initial design, used on early units. It ***might*** have been changed later: belt drives on locomotives are, I think, a maintenance and engine-room access pain.)

On later GE equipped FM units… Confirms that the belt returned on Static Excitation units: the exciter current was provided by a belt driven alternator with solid-state rectification.

(((ON A TANGENT… One might naively think that the rotational speed of the traction generator is determined by that of the engine, but there ARE exceptions. There is currently a locomotive rebuilder in the U.S. -- Knoxville Locomotive Works -- that rebuilds old EMD locomotives with a higher-speed German engine (a descendent of the engine used on various diesel-hydraulic locomotives of the 1950s…), connected to the original EMD traction alternator through reduction gears. From something I read, I got the impression that the British Rail Class 47 was another exception: these locomotives had a twin-bank Sulzer engine, and since gearing was needed anyway to connect the two crankshafts to to the generator, they used it to allow a higher generator rpm. Am I right about this?)))
  by talltim
To throw a spanner in the works, I'd have thought that the Ruritainians would have gone for electrification, with only maybe a limited number of diesels