• PA-1 traction motors

  • Discussion of products from the American Locomotive Company. A web site with current Alco 251 information can be found here: Fairbanks-Morse/Alco 251.
Discussion of products from the American Locomotive Company. A web site with current Alco 251 information can be found here: Fairbanks-Morse/Alco 251.

Moderator: Alcoman

  by Typewriters
I don't have anything official -- ie printed by maker or railroad -- that actually GIVES a minimum continuous speed for the DL-109.

HOWEVER, I do have an original NYNH&H General Notice that covers operation of all the 0700 class, which was printed by the railroad in October 1946. It does have some figures you (we) might like to note, and compare.

Operation of the units included automatic forward transition, but not automatic back transition. When current in parallel reached 850 Amps with speed decreasing, the throttle was closed and then re-opened which allowed the back transition to series to occur. After that happened, the following limits applied:

0-700 Amps: continuous
700-800 Amps: 1 1/2 Hours
800-900 Amps 20 min
900-1100 Amps 10 min
1100-1500 Amps 4 min

A note at the end of the section on currents: "Always be on the alert to watch traction motor currents when speed is less than 25 MPH."

So, then, we can probably make an educated guess from this information that the minimum continuous speed is REALLY close to 25 MPH. I'm willing to make that jump, anyway.

Later- "Do not operate locomotive faster than 70 MPH with or without power on the traction motors." That is interesting; I had thought the NYNH&H units were geared higher. It's likely a railroad-related, and not locomotive-related restriction (tracking, overturning rail on curves, etc.)

Oh - a digression, Allen - I do not know where the first reference to 726 motors in 244-engined passenger locomotives appeared. I believe, though, it might have been in a book specifically printed on these units a few years ago. I myself am of the mind that none were used in regular production units by way of that table in TP-400.

Now, I do also have several textbooks produced for use in the railroad industry, which are clearly provided with information direct from the builders for the purpose of educating those entering the field in some way or another. One of these, "Diesel Locomotives - Mechanical Equipment" has information on the twin-engine ALCO-GE units. Photos are included of both Southern A&B and NYNH&H units. It was printed the third time in 1947; this copy has a name signed in the cover (the recipient) and a date of 1/31/48.

Information by a speed-TE curve in the book indicates, for units equipped matching the curve that is, two GT-557 generators, 4 GE-730 motors, 58 to 25 gears and 40" wheels. The curve goes up to 120 MPH, and ends there. (So does the whole graph, actually.)

Later: "Find out the maximum speed limit on your particular locomotive and do not exceed it at any time under any condition. There is also a minimum speed limit which is 1/4 of the maximum speed limit. Do not go below this minimum speed with full throttle except for short periods of time, otherwise the traction motors will overheat."

The description of the (dual ammeters and) load limits are slightly different in this account.

White scale / 0 to 700 / Continuous rating
Yellow scale / 700 to 800 / 1 1/2 hours
Red scale / 800 to 1500 / 4 minutes
"Operation in the red scale is prohibited except for starting the train or for very short and intermittent periods of not more than four minutes each."

NOW, a few comments added to the facts. Many many books have been written which include phraseology about the ALCO-GE DL-109, or others, such as "with their larger freight-sized traction motors" or some such. The 730 in the DL series wasn't THAT much more powerful compared to EMD E-units (and that's really what all those authors are comparing, isn't it?) but it was enough to make a difference at the low end.

Here are some common units, geared as close to 98 or 100 MPH as possible (ie as was offered) and their minimum continuous speeds.

DL-109: 25 MPH
ALCO-GE 2000 HP Passenger: 23 MPH
ALCO-GE 2250 HP Passenger: 21.8 MPH
EMD E-7: 35 MPH
EMD E-8: 29.5 MPH

It is on such relationships that such statements originally were based "way back when," when the original authors (David P. Morgan, Don Ball, et al) wrote them. Of course, we did mention the AT&SF and its few ALCO-GE twin-engined A1A-A1A units - and they found out the following fact:

EMD F-3: 22.5 MPH

Yes, the F-3 geared for 100 MPH had a continuous speed right about the same as the post-war ALCO-GE 2000 HP 244-engined units, but also had the advantage of all weight on drivers. Although they did buy a decent number of the ALCO-GE units, we all know very well that they opted for a huge number of passenger F-3 and F-7 units. (The Great Northern, and Northern Pacific, are another two good examples of such experience and thinking.) This relationship may also be another original source of such phraseology as "freight sized traction motors" applied to ALCO-GE road units, either twin or single-engined.

How do I sum this all up?

-Only listing anywhere here for traction motors in ALCO-GE twin engine units is model 730

-Minimum speed of ALCO-GE twin engine units is 1/4 the maximum

-Current limit of ALCO-GE twin engine units both in book stating 730 motors AND in New Haven operating instructions is 700 Amps

-Minimum speed of ALCO-GE twin engine units is much closer to that of later ALCO-GE units with 752 motors than it is to contemporary EMD units

-No unit of any kind for any railroad at any time I have information for here includes ANY 726 motor. None.

Hope that isn't TOO much info for one post, but as regards the whole question of the MCS of the twin-engined ALCO-GE units, well, there you go.

-Will Davis

  by Allen Hazen
Thanks, Will!
--Continuous speed = 1/4 top speed seems like a reasonable rule of thumb. Any railroad wanting to use diesels on drag freights would probably try to be more specific, but it sounds like what you would tell an engine-man who was likely to get his first diesel assignment soon.
--Every source I've seen agrees that the New Haven's Dl-109 were geared for 80mph. I have an idea that in the 1940s enginemen new to diesels were often tempted to go to very high speeds (the ride in an E-unit or Dl-10? was smoother than on a steam locomotive, so...), and perhaps the New Haven's brass thought it would be a good idea to set a maximum with some lee-way.
--Yes, the F-3 (with 375hp per motor) had a lower continuous speed than any 2000hp A1A-A1A, but the difference between EMD and GE trqaction motors showed up there as well: in one of the posts on an earlier page of this string, a couple of years ago, I gave c.t.e./minimum continuous speeds (extracted from some source or other) for the F-3 and its Alco contemporary.

--Something I don't understand is why so many railroad managements were willing to buy passenger units with 120 (or 117) mph gearing. The Milwaukee ran trains at 100, and a few other railroads did as well, but did they really expect to go 15mph higher than thatt? Did the Santa Fe think the Super Chief was going to skitter over the Kansas plains at that speed? Did the Southern think the Tennesseean was going to be able to use that sort of speed capacity?

  by mxdata
Allen and Will, I am posting in the "wrong" string here to follow the continuity of Will's excellent discussions. I have access to some information that both of you probably have never seen, and can confirm that all the groups of DL-109s on the New Haven originally had 726 motors. I am offering this without stating the source, readers can judge this as they see fit. I have not cared much for the "prove your source" challenges that some folks are making recently on railroad dot net, I think that playing that game just forces you to advertise what you have in your collection and who you know in the industry, which is really nobody else's business.

  by Allen Hazen

Thank you for the confirmation.

I'm sorry if the "prove your sources" challenges have seemed like competitive one-up-manship. They came about because there are mistakes in the "railfan scholarship," and identifying sources is one of the useful techniques for sorting out mistakes: If I have 14 sources and you only have one, that means nothing if 13 of my sources all copied their data from the 14th-- in that case, I also EFFECTIVELY have only one source. So I try to footnote my sources so other people can judge them more efficiently.

Given the record of your past contributions to our discussions of locomotive technological history, I'm inclined to think your information is reliable even without knowing its source! (Though, if other reliable people dispute it, I will of course start to wonder....)

Anyway, thanks! You are one of the peopole whose posts I always read with special care and interest.

  by mxdata
Allen, thanks for your understanding, I did not intend to direct the comment about source challenges to you personally, but rather to offer it as a reflection on some of the other things happening on this website recently. When you view at the pure fantasy and absolute speculation that are rampant on some of the individual railroad and commuter rail discussions on this site, calls for absolute source confirmation on locomotive discussions seem ludicrous. I felt that needed to be said at this point, those of us in the industry are obviously not going to name everybody we get information from.

By the way your comment on the other string was great: "Now, "Railfan scholarship" has a somewhat dubious reputation...."

Indeed, just look at all the deluge of recent "fluff" books where the text is nothing but copied (sometimes very poorly) articles from Trains and Railfan & Railroad.

  by Typewriters
Thanks for the information, mxdata and for your kind words. I appreciate it very much.

I myself had actually greatly reduced visits here, and posts, for essentially the same reason.

We do now have something interesting, don't we? We have what appears to be good information that the units with 730 motors were limited continuously to 700 Amps, and now have proof that the units with 726 motors also were limited to 700 Amps (speaking strictly about the twin-engined 2000 HP units.) There are nuances though in the short-time ratings; on the units with 730 motors, it appears (taking the ratings all quite literally) as if any time you're over 800 Amps you only have 4 minutes - but on the 726 motors, at 800 to 900 Amps you have 20 minutes or five times longer.

{I should make a point here; I am not convinced yet that any of the later single-engined 244 powered 2000 HP ALCO-GE passenger locomotives had 726 motors. I am certain of both 746 with 42" wheels and 752 with either 42" or 40 " wheels, as they're quite clearly indicated in the TP-400.

We do have the odd old black cover ALCO-GE 1500 RO manual which gives a continuous limit of 750 AMPS; this manual is an early one for 1500 HP road freight units. That's one indication of motors other than 752, and the preponderance of evidence seems to indicate they were 726 motors.

So far we do not have any such corresponding manual for 2000 HP passenger units to indicate the same (all of the units with 752 motors will have ammeters marked with a continuous current limit of 900 Amps.)}

Of course, we might just suppose that the rating given associative with the 730 motors is just more conservative, but then again that's an assumption, isn't it? The ratings as given are what they are, and it does appear from those that the 726 had more room in the short-time ratings. One might easily suppose it had better insulation than the 730, or heavier windings - there would have to be SOME reason, if the ratings and our reading of them are correct, that the 726 would have that extra room in the short time rating area. Perhaps that single fact is indicative of it being more closely related to later, larger motors (like the 752 with which we know it had at least some parts commonality) than it was to earlier smaller motors.

We also now know that the NYNH&H General Instruction on 0700-0759 reference to "watch traction motor currents any time speed is below 25 MPH" is likely five MPH above the minimum continuous speed to give a buffer. That's based on the 1/4 rule given in the textbook and the 80 MPH max speed, limited by gear ratio (the 70 MPH stated in that same general instruction being applied by the railroad later.)

Thanks again for the info, mxdata and glad to see you're still around.

-Will Davis

  by mxdata
Will and Allen, I should add one additional interesting piece of information to this puzzle. In all in-company reference materials on the New Haven DL-109s that I have seen, they were descriped as "combination passenger and freight locomotives". That differs from other ALCO references I have seen for similar DL-100 series units (Rock Island for example) which describe them as "passenger locomotives". I believe the distinction has significance in the selection of traction motors.

  by mxdata
Will, I checked with some friends, the corresponding black cover manual for the PA-1 is 2000RM, and unfortunately they used a "generic" traction motor bulletin in that volume that shows both the 726 and the 752 (in fact it even shows the two axle swing hanger truck, so you can really tell it is generic). However, the ratings shown for the 752 are indeed 900 amps. No other models of traction motor are mentioned or shown.

  by Allen Hazen
So, belatedly trying to practice what I preach... One of my main sources has been the marvelous collection of stuff at the "Fallen Flags" WWWebsite: pages from the PRR and NYC locomotive diagram books (it used to have some E-L diagrams, but I couldn't find them after the most recent reorganization) and a collection of "Operastor's Manuals" (which includes maintenance manuals, but is richer in EMD than Alco or GE stuff).

So. The FA1/RS2/PA1 manual there is "TP-400": I couldn't find a date on it. (The "TP-800" there, on RS3 and FA2, has a date of, i.i.r.c., 1950.) Amazingly difficult to find anything about traction motors in it, though I finally did tract down the table of motor/gear-ratio options that I think Will was referring to: it's NOT in the electrical systems section, but at the end of the diesel engine section (though I'm not sure whether that reflects the original layout of the book or the organization when it was scanned for the WWWeb).

There is also an "Alco Electrical Maintenance" manual (first item on the "Operating Manuals" t.o.c.), "TP-501." This seems to be basically a guide to the care of early 752 motors: specifically, 5GE752A1 and 5GE752C1. (The main difference seems to be that the A had wool-waste for applying axle-bearing lubrication, where the C had felt applicators: mention is made of motors originally built as A being modified with felt brushes, and apparently such motors have the same maintenance instructions as the C form.)

Something (I think it was lubrication at the pinion end) was described as sealed, do not lubricate, but in terms suggesting that earlier motors had a different system requiring periodic top-up of lubricant at that location. The TP-400 mentions -- this may be in the "Chassis" section, but I don't remember clearly and don't have time to check now -- what you should do to lubricate this point on motors that don't have it sealed.

The only mention of any other traction motor model I found in skimming the TP-501 was a note about some bearing that specified a couple of things as being good for 752 or 726 motors.

Two miscellaneous things from TP-501: weight (of bare motor including pinion) is given as 7000 lbs, and the maximum rotational speed is listed as 2280 rpm. (117mph with 40" wheels and 58:25 gearing works out to 2281, which may be why 117 mph was given as the max for this option instead of rounding it up: the gear ratios for 80, 90 and 100mph top speeds (40" wheels) all have a bit of leeway in terms of motor speed.)

Anyway.... I'm sorry I am unable to contribute more! I feel I am learning a lot from both of you (Will and mxdata). I like particularly Will's suggestion that, though 730 and 726 motors were given the same nominal continuous rating, the 726 was perhaps more "forgiving" in its short-time ratings.

  by mxdata
The advancing technology of the electronic storage and retrieval of documents is a wonderful thing, it is a significant help in doing research when dozens of documents are available immediately on your computer. Too bad it came along so far after the departure of ALCO from the locomotive business, as getting the documents collected and scanned now is a sizeable task. Several former EMD employees have been working on private electronic archive projects relating to the company they worked for. Unfortunately the national railroad related "historical" societies haven't taken more of an interest in the central collection and electronic archiving of builders and suppliers documents, their focus continues to be on photography, not on documents or the knowledge base. Meanwhile the time for doing this is rapidly running out.

I recently purchased an ALCO maintenance manual from a paper dealer. On opening the manual I was surprised to find the name of a railroad employee, a person I used to work with, who has now passed away. Above his name, lined out, was the name of an ALCO employee, also someone I worked with, who passed away more recently than the second owner, so he apparently gave his book to the railroad man. This industry is indeed a very small "club" when one document carries the names of two previous owners and you know them both.

  by Typewriters
Interesting stuff, mxdata and Allen!

I take note that the black cover 2000 RM manual indicates a continuous limit of 900 A, indicative again of 752 motors; that's a good piece of info.

Allen, the table you mention is actually in order as you described it. It's at the end of the section wherein load testing is performed, and it's there to verify pickup / dropout of relays either for transition or overspeed function and where applicable to check multipoint shunter operation.

Although I don't know if it helps, I did note that TP-700 which is the electrical maintenance manual for 660 HP and 1000 HP switchers and 1000 HP road switchers lists the maximum permissible speed for the 731D traction motors as 2360 RPM. Perhaps that will help, Allen, in some way with your calculations and estimates for some of the motors other than the 752.

Weight of the 731D3 and 731D5 in that manual is given as 5600 lbs; my TP-400 gives me 7190 lbs for the 752 itself. The textbook I mentioned gives the approximate lifting weight of the 730 motor as 6500 lbs, and the weight of one truck as 55,000 lbs. (TP-400 gives weight of six-wheel two-motor passenger truck for 2000 HP units with 244 engine as approximately 56,000 lbs, which is what you'd expect given the preceding truck and traction motor weights.)

It (the textbook) also gives the following data, again on the twin-engine ALCO-GE 2000 HP units:

Standard motor gearing 58/25; 120 MPH
Special motor gearing 61/22; 100 MPH
Special motor gearing 64/19; 80 MPH

Quite interesting - the 730 motor does appear "in between" the 731 switching motor and the 752 road unit motor of later on, and it does also appear at least in terms of current limit very similar to the 726 (at least in the twin-engine units - the continuous limit in 1500 HP road freight units with 244 engine appearing to be about 50 A higher but naturally there's a whole different electrical system to consider in those units as well.) Maybe it isn't safe to make any assumptions about the 726 per se, although I think we're certainly getting a much better across-the-board picture of things than has been available anywhere else previously.

-Will Davis

  by Allen Hazen
Thanks for the details, Will!

--When I get a chance I'll see what the gear ratios and top speeds for Alco switchers on the NYC diagram do for that maximum r.p.m. for the 731.

--Trying to see a system to the assignment of model numbers to GE traction motors is fool's work, but... I note that the 730 and the 731 were very roughly contemporary: MAYBE they were intended as part of a series of models. And that 726 is ten more than 716, making 726 a sort of obvious number for a successor to the 716 used on early EMD locomotives (there is at least one other case where GE derived a number for an updated model by adding a multiple of ten: 733 and 763, I think, are very similar motors). And, of course, 52 is twice 26.

--The New york Central diagram cards show a variety of GE generators-- including the 566 used in the PA1 AND the generators used on S1 and S2 switchers as having fairly similar "full load" voltages: 700 to 750. So it seems likely that the (model 542) generators used on the "Dl-100" units would have had a similar full-load voltage. This is nice: it looks as if ONE of the variables in the quations we are trying to solve is a sort of almost constant!
  by Typewriters
This may be a record for "long-dead message string resurrection."

Relative to the GE 726 motor in the ALCO-GE freight locomotives....

I now have in my collection an advertising brochure for "The New ALCO-GE '1500' " locomotives. This was published by General Electric, is publication number GED-1148 and has a print date of 11-46.

On the page with the heading "Motored for Top Performance" we find the following text:

"The stamina and reliability of the GE-726 traction motor have been proved in service on major railroads in all parts of the United States. Its record on the New Haven is typical of the results.

"Hauling 16 car passenger trains by day and 4500 ton freight trains by night between Boston and New Haven, 10 ALCO-GE diesel-electrics ran up more than 10 million motor-miles before classified repairs. In fact their performance was such that the New Haven was able to materially increase the mileage between major overhauls. On regular schedule, these motors now run more than 10 times around the earth with only routine attention!"

It is important for us to note that this cannot refer to 1500 HP freight units on the New Haven, since they hadn't been built yet. It refers instead to the DL-109 units.

On the opposite page we find more about pulling power, and this paragraph:

"The unusually high continuous and short time tractive rating of this GE-726 traction motor allows you to haul more tonnage over a given profile. Optional gearing permits you to select the range of speed best suited to your operating conditions. The combined result is a motor - and a locomotive - that will enable you to move more tons over greater distances in less time and enable you to get more work from fewer motive power units. The "1500" is really built to increase railroad earning power."

The "1500" units that had been built prior to the 11/46 date of this brochure were all for the GM&O.

Now, my NYC manual that covers all makes and models of diesel locomotive and covers all NYC ALCO-GE freighters has a 900 A limit. These units were built beginning in 2/47. 900 A means 752 motors if I read back in this string correctly.

We may have the rough cutoff here for 726 and 752 motors in the ALCO-GE freighters between 11-46 and 2-47.

-Will Davis
  by Allen Hazen
Will Davis--
An old, but interesting, string! Well worth reviving when new information becomes available: thank you!
There is a string on this forum called "Alco 244A engine" (at the moment it is about six down from this string). Contains some interesting information about the early FA/FB-1 locomotives built for the GM&O: an Alco data card for one attests that it was equipped with 726 motors.

The much maligned Dl-109 was a success on the New Haven, and in 1946 the only major road-diesel success the Alco-GE team could point to in their efforts to convince potential customers.
  by Allen Hazen
Another… footnote? … to an ancient string. I've found another source of documentation.
The Kansas Historical Society has scanned the diagrams from a Santa Fe motive power book, covering steam, diesel, and railcar types from some time in the steam era to the mid 1950s:
with thumbnails that can be clicked to enlarge to readable size. I haven't looked at all of them-- I think there are something like 200 pages-- but I did look at a few relevant to my … obsession.
Page 6 (so the full URL for this diagram has "page/6" after the final slash in the one three lines up) is for their earlier PA-1: it is titled "Class 51, diesel-electric locomotive, unit 51 to 58" with "63 to 74" added later (after the units originally given only letter designations in multiple unit sets with a single number were renumbered). The diagram is dated "10-21-46" and has revision dates marked "4-3-48" to "5-3-54." As expected, it shows these units as having type "746" motors, with 64-23 gearing for a maximum speed of 100mph.. (There is also a page for the corresponding booster units.)

O.k., we knew that Santa Fe's earlier PA-1 units had 746 motors. One question that comes to mind is, "Did the Santa Fe remoter them later, given that the 752 was common and the 746 after the 1940s a rare item, likely no longer manufactured?" Well, Page 3 is for "Class 51, diesel-electric locomotive, unit now. 51 and 51C": no date on the diagram, but this is for these units AFTER their heart transplants: the diagram notes that they were "Built by American Locomotive Co., 1946, new power plant & remodelled in 1955 by E M D of General Motors." The engine is noted as a "16-567C," but the electrical equipment is GE: 566 main generator, GY-27A1 auxiliary, Amplidyne exciter AM 608 A1, and-- what we are looking for-- 746 traction motors with the original gearing and top speed. So: Units delivered with 746 motors kept them… at least until 1955.

Page 41 (12-29-48, with four revision dates, from 4-14-48 to 6-20-55) is for "Class 52, diesel-electric locomotives 59 to 62, 75 to 78." (The "52" in the title is in a slightly different lettering style from the "Class": how much do you want to bet that the June 1955 revision was to change this from"51" when the 51 herself was … altered?) This covers the later PA-1 (all built in 1948). 5GT566C1 main generator, as in the earlier units, but this time with 752 motors, geared 61:22 for the same 100mph top speed.

(All three of the PA-1 diagrams, b.t.w., say they had 42 inch wheels.)

Jim Boyd's "Passenger Alcos" (Morning Sun Books, 2000) says that Santa Fe, desiring standardization, ordered all its PA-1 units to specification DL304 (and Dl-305 for PB-1), including these 1948-built units, even though other railroads had received Dl-304A and Dl-304B units before the last Santa Fe units were built. Suggesting that, whatever the differences between the subtypes were, the choice of traction motor was NOT reflected in the suffix letter on the specification number.

And, for a couple of other locomotives relevant to this story…
Page 82 is for Class 90: the Fairbanks-Morse/GE "Erie Built": it shows these units as having 746 motors, geared 64-23 for 100 mph (with 42 inch wheels). (At least one other source says that Santa Fe's Erie-builts had a different gear ratio, which I found puzzling. I'm now inclined to believe the Santa Fe's own diagram, which shows them as having the same gear ration as the 746-equipped PA-1.)

And, finally, Page 75 is for "Class 50, Diesel Electric, Loco. 50": the Dl-10? unit from 1941. (This diagram is dated May 27,1941: there are four revisions noted with dates I can't read, but the last one LOOKS like 1952 or 1953.) 721-F1 traction motors, geared 58-25 for (with 40 inch wheels) a top speed of 120 mph. Which is fine, except that Kirkland's Alco book says that this gear ratio was available with the 730 motor and not the 726.