• EMD BL1 and BL2

  • Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.
Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.

Moderator: GOLDEN-ARM

  by EDM5970
Mxdata- Thanks for the information on the air throttle. It seems like kind of a side step away from the normal ABCD that a Geep or F unit would have, but I can see them offering it as an option on locomotives designed to operate alone. And ships don't have 21 or 27 pin MU-

AmtrakFan- They weren't the most aesthetically pleasing units to look at by todays standards, but as a stepping stone between the cab units and the GP-7, they were historically important and quite worthy of preservation. It is also been said that Dick Dilworth was (figuratively) holding his nose as he was finishing up the GP-7 design. A very utililitarian, maybe even crude looking design, as compared to the E, F and even BL-2 units of the day, but we've all gotten used to them, right? Tastes change over time-

  by Typewriters
The post about "too much misinformation" in railfan press, circles and websites is right on. If you're going to publish a book, or put up a website, do your homework.

My brother and I are here looking through his manuals on this subject. It's true that a pneumatic throttle arrangement was available for years on EMD switchers which did not have multiple unit control. Manual 252B for the Model 567B engine, on pages 1103/1104, displays a Woodward governor with an internal diaphragm arrangement, very similar to that used on Baldwin-Lima-Hamilton units later on (modified Woodward PG; BLH manual DE-111A, Feb 1955.) The info we have on the EMD units notes that the pulling of the throttle away from idle actuates a cam switch to close the shunt and battery field contactors, applying power to the traction motors (again, more similar to the Westinghouse CE-100 controller than to the D-1 which required an external air-actuated throttle switch.) Note, of course, that Baldwin units frequently used air throttles with multiple unit controls; it isn't ruled out theoretically overall, just on EMD's. (Oh.. and don't forget F-M units with air throttles.)

The BL2 did, of course, have an electric throttle arrangement which could be used with other EMD units with MU. The BL2 was essentially like the F-3 electrically; however, the throttle lever itself in the BL2 does not have an escapement latch, which allows rapid opening.

(The previous comes from the 'Supplement to Manual 2308A for use with model BL-2 locomotives, which is a 5/48 manual without the 10/48 updates.) The BL-2 had automatic transition without the the transition forstalling feature found on F-3 units. BL-2 also had a Load Regulator Control Switch on the control stand, which had "Road" and "Switching" positions. The Road position allowed modified maximum field start, as in the contemporary F-3. In Switching, a shunt resistance is inserted, which bypasses the load regulator, allowing more rapid starting. (This is very similar conceptually to the 'teaser starting' employed on the GP-7 later, and was done with a single 7.5 ohm resistor.)

One thing of interest. Where, exactly, does the "BL-1" label come from? As we've looked through all of this (which isn't exactly new to us) we find NO use of the BL-1 designation in any of the original EMD materials. We find two designations: BL, and BL-2. This is not, in fact, surprising. After all, we all know that the FT was followed by the F-2 (yes, yes, we know about the F-3 being tried first and all that.) My point is that there was no F-1. (There was also no F-5, either, and nowhere in any official material will you EVER, EVER find this; it's a railfan creation, and that's it.)

If you look only at original manufacturer materials, you find two types. BL, which is the original prototype with air throttle, and BL-2, which includes production units with electric throttle, whether or not they had MU. The supplement in 2308A is very clear in the diagrams given for single control/no MU and dual control/MU that both are model BL-2. As a specific example, if one looks at manual 252C, 12/56, page 1119 gives a listing of settings for governors to be used on 567C engines when backfitted and operated at original unit horsepower. Right there in that table is a listing for "BL." No number. (In fact, this listing gives a replacement pneumatic governor.)

That's what we have for now; if anyone has further questions which can be answered from these manuals, let us know.

Will & Dave Davis

  by mxdata
The "model" designation could differ somewhat depending on which department at EMD was involved. Some locomotives were developed by Engineering with a different designation than what was adopted by the Sales Department. In addition, There was tinkering with some of the model designations as the product line progressed. A good example is the locomotive we know as the FT, which is the "Model F" on many of the original engineering drawings. There are some EMD sales and service documents which break the production of this product down into a number of model designations depending on its draft gear arrangement and safety appliances.

Regarding the torrent of disinformation which seems to be engulfing the hobby in recent years, I also agree with the comments in an earlier posting. I think things went downhill when the publishing market attracted some people who are trying to make a living exclusively by turning out large numbers of books and magazine articles, on a wide variety of subjects, with the absolute minimum of research needed to get the document into print. I have encountered a few of these mass-production "authors" at railroad enthusiast events, and when you suggest that they do some researching in EMD Pointers, Maintenance Instructions, and General Service Bulletins, they are sometimes not even aware that these documents exist.

  by Leo_Ames
You guys ever read any of these rail books published by Motorbooks? Prime example of what you're complaining about with misinformation. It also affects their racing books they publish, and probably every other subject they publish books about as well.

  by mxdata
Yes indeed, Leo.

Regarding the question "Where does the BL-1 designation come from", which Will and Dave asked, it seems to originate from an article in the EMD Field Service News, dated December 8, 1951. This is the earliest reference I have been able to find that breaks the BL production into distinct BL-1 and BL-2 models.

As Will and Dave noted in their excellent posting, using an air signal for throttle control involves more than just a different governor. You still have electrical devices that have to be operated even if the governor speed signal is done with air pressure, and that requires appropriate electrical interlocks to tell the control system what you are doing with the air throttle.

  by Typewriters
Very interesting, mxdata! Thanks, too, for your kind words; they're very much appreciated here. We at present don't have that publication here; in fact, all the things we consulted in making that BL-2 post were materials printed while the locomotive was in production, with the exception of the 567C manual (which only gives BL as a model.)

Interesting, isn't it, that this publication postdates production of the locomotive? Naturally, it wouldn't be the first retrospective renaming of a locomotive BY THE ORIGINAL MANUFACTURER, which of course legitimizes the redesignation.

You note the internal variance in designation, or subdesignation of models; anyone who has looked at a GP-7 manual knows about the subdesignations for those as well. Never printed in any railfan magazine article yet, but there they are in the manual.

It sounds like we aren't alone in this. And, to stretch it out a little -- why do you think that all this "imagineering" is going on? I'll tell you. It's because technically minded young railfans have NO real mechanical data or reading material to wrap their brains around. They want to know how things work; when they get so far, the info runs out, so their natural energy and curiosity is used in designing things, or modifying things. Things of fantasy.

The real world actually DOES have plenty to hold their interest, if only it would be found, read, UNDERSTOOD, and published. There isn't a whole lot of that going on right now. So then we get typical regurgitation of misinformation and myth, such as one finds in the mainstream railfan press at the moment. (We're actually writing a letter to the editors of one major magazine about all of the total misinformation, which is totally unsubstantiated or just wrong, in a recent magazine issue.)

One final note on this topic. A while back, I developed a 12-page website about the development of the GE U-series locomotives. Put a link to it on the GE forum. Used only official materials and the annual meeting minutes of the RF&OOA to create it, and NOTHING else. It gets lots of hits; you can't see the hit counters and site stats, but I can. Point is that there is a need indicated for real reading material and diagrams, instead of flashy color pictures and "golly gee whiz" commentary.

-Will Davis

  by 498
Accuracy seems to be an optional feature in the railfan press at the moment. It appears that making money takes precidence over any need to get the facts correct.
  by Allen Hazen
As you know, I'm a GE fan. I think the link to your 12 page site on the U-series may have vanished the last time the Railroad.Net site had to be rebuilt... could you post it again?
(Accurate technical stuff about GE locomotives seems, if anything, harder to come by than EMD stuff: my posting "GEVO numbers" to the GE forum came after a LOT of Google-seraches and a consultation with the librarian at my university's engineering library....)
On the "BL-X" front... do any of your printed sources say anything about the frame weakness and m.u. limitations mentioned earlier in this string?

  by mxdata
During the time period the BL2 was in production the standard EMD technical reference publication was the General Service Bulletin, and the field notification publication was the Field Service News. I have not seen anything in the GSB's or the FSN about frame weaknesses or MU restrictions on these locomotives. Many of the GSB subjects were carried into the subsequent Maintenance Instruction (MI) system, and there is nothing in the MI's about these topics related to the BL2 either.

There were some issues regarding draft gear and draft gear pockets on EMD locomotives in the late 1940s, but these were not specific to the BL2 locomotive, they involved any model of locomotive which used the particular type of draft gear. Considering the current environment where regurgitation of partially misunderstood information has been accepted as "journalism" it would not surprise me very much if these programs were the basis for some of the reports of underframe problems.

I am incredibly amused by the observations of some writers that these were "unsuccessful" locomotives. Considering that some of them are still around more than fifty years after they were built, and they hauled a lot of freight in those years, you have to wonder what these folks criteria for a "successful" locomotive would be.

By the way, many years ago (1980s) I did a draft manuscript for an article explaining the EMD publications, the types of documents which were produced, when each system started and ended, how they were organized, and the scope of what they covered. I submitted it several times to railfan magazines, and was told nobody was interested in that "stuff". I have no idea where the draft is now. If I have the time one of these years maybe I will try to reconstruct it.

  by Typewriters
Our sources here give no mention of this problem. There is a prety well done book, fairly scant on matters highly technical, about the C&O's BL-2 units which mentions this phenomenon as well. Don't have it right here; lent it to my brother.

That U-boat article is here:


Mxdata, you oughta dig up that article. Perhaps now, or very soon, will be the time for it to finally get published!

-Will Davis
  by Allen Hazen
Thanks for the URL, Will Davis!
The mass market railfan publications ("Trains", "Railfan and Railroad") are lighter on technical details than I would like: I assume their publishers know what the market wants, and that a railroad magazine that appealed to me would be a smaller circulation magazine. Is there one? I don't often get to see the magazine put out by the R&LHS: should I subscribe to it?
MEANWHILE, forums like this one are ... a source of joy. I try to be a responsible contributor: in particular, I make an effort to give sources for anything I claim that isn't common knowledge. I just wish I **HAD** enough sources to be able to post the sorts of things "Typewriters" and "mxdata" do!
(Thanks, guys!)

  by mxdata
Finding detailed technical reference books requires a lot of searching but is well worth the effort in the long term, particularly if you plan on writing any articles for publication. I believe that EMD Pointers and MI's are still available through Rail System Inc., in Houma, Louisiana, although they are expensive to purchase and the assortment offered in recent years covers the Dash Two line up through the present, there is very little information applicable to older units.

The reference documents sometimes show up on eBay but you will have to fight it out item by item with many others who also want them, a lot of the competitors on eBay are our friends who participate in this forum.

Bookstores are sometimes a good source but it requires a lot of time and effort searching. I would recommend that you do not call in advance, because you are likely to find the items of interest specially marked up for your visit when you get there. Many years ago I walked, totally at ramdom, into a small bookstore in a very large city, and in the technical book section I found several shelves of leather bound reference books with embossed covers having the logos of several GM divisions and the name of a very famous GM executive both embossed and lettered in gold leaf. I spent a lot of money that day!

  by AlcoMD

The mass-market publications claim that their readership are not interested in the technical nuances of locomotives.

IMHO, the best book ever published on the subject came from down under. It is a single-marque book about the A-7 class.

Have you ever seen it ?
  by Allen Hazen
You wouldn't be referring by any chance to "The A-7 Era," by Peter Birmingham, published 1995 by Horsepower Histories (of P.O. Box 60, Ferntree Gully, Vic 3156, Australia), ISBN 0 646 25614 9, would you? (Grin!)
Do you know the same author's earlier (1982) "The ML2 Story", ISBN 0 9598392 9? Very similar format, similar sorts of information, with-- as a treat for American readers-- a bit about the development of the SD truck, with a photo of the road slug (only word to describe it) that EMD used to test six-wheel trucks on before introducing the SD-7.
I'm not sure about the current publisher, but I think both books may still be available: the "Railfan Shop" in Melbourne, which I think has a web-page at
would be able to tell anyone interested (and sell by mailorder, though I have no particular reason to think this would be the cheapest way for someone outside Oz to get the books).
(For those not familiar with Australian EMDs, an A-7 is a slightly elongated F unit with six-wheel trucks, built in a number of subvariants for several Australian railroads. The ML-2 was a version with a cab at each end used by the Victorian Railways: if Birmingham's story is to be believed, VR's request for CC trucks led EMD to develope them, and so to the SD series.)
  by Allen Hazen
Sorry, the URL I gave for the "Railfan Shop" in Melbourne seems to be a dead link. (I visit the shop most weeks, and can ask questions and check book availability if anyone wants to e-mail me.)
And, rereading, it's not clear that the Flexicoil test vehicle was a slug: it may have been used simly to test the new truck's tracking properties without the motors being powered.