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Is there a list or chart of letter/number designations for locomotives?

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  • Member since
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Is there a list or chart of letter/number designations for locomotives?
Posted by gdelmoro on Sunday, January 26, 2020 6:41 AM

Hi all,

Does anyone know of a source that lists locomotive letter/number designations like T1, Y6b, Class J, J1, K4, etc.? What do they mean? Does it relate to the wheel arangement? Type Service? Something else?

Thanks

Gary

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Posted by ndbprr on Sunday, January 26, 2020 7:50 AM

Railroads had their own nomenclature for engines. Except for USRA steam engines as I recall nearly all were custom built for specific roads. The PRR started with a class 0-4-0 switchers and ended up at Q class 4-6-4-4 engines plus some experimental S class.   After almost 50 years of model railroading their diesel classes make no sense to me.  Historical societies will probably be your best source for specific engines.

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Posted by dehusman on Sunday, January 26, 2020 9:12 AM

Every individual railroad has "class" numbers/letters for its engines.  There is no consistency.  For example a T-1 is a 4-4-4-4 on the PRR, but a 4-8-4 on the RDG.  The ATSF used numbers for classes.  Some railroads used multiple letters.  A 4-8-4 is an R on the PRR, a T on the RDG and an FEF on the UP.

Your best bet is to look for a roster of the individual railroad you are interested in.

Dave H. Painted side goes up. My website : wnbranch.com

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Posted by dknelson on Sunday, January 26, 2020 11:14 AM

The late George Drury's book for Kalmbach, A Guide to North American Steam Locomotives, would have much of the information you seek - for steam at least.

Diesels are another matter because, as pointed out, railroads such as the Pennsylvania created their own designations for diesels that differed from what EMD, ALCo or the other manufacturers used.  For example on the Pennsy, an EMD GP30 was a "EF22."  A GP25 was an "EF25."  A GE U25C was a "GF25a."  The system?  First letter stood for the maker, second letter was F for freight, P for passenger, S for switcher.  The numbers were a shorthand for horsepower.  

The Pennsylvania's system for steam made and makes sense, too, once you sit down and study it:

A is 0-4-0.  With Pennsy steam, various series would be numbered.  So you had A3, A4, A5.  

B is 0-6-0  Add a driver, go to next letter.  They went as far as B6 for their own designs.  Within a class further improvements would be designated with a letter. So you had B6a and B6b.  Actually they were B6sa and B6sb and the s stood for superheated.  Yeah confusing at first.  And the Pennsy had the habit of giving the number 28 to one-offs or experiments or locomotives that weren't their idea.  So the USRA 0-6-0 without the Belpaire firebox was a B28.  There were also J28, K28.  Perhaps other 28s.  

C is 0-8-0.  Add a driver, go to next letter.  So their huge 0-8-8-0 articulated was a CC1

D is 4-4-0.  Two axle pilot, go to next letter.  Their electric locomotive which was two 4-4-0 wheel arrangements back to back was their DD1.  

E is 4-4-2.  Two axle pilot, add a trailing wheel, go to next letter.  But it does get confusing because for some reason the E7 came before the E6 which was their last Atlantic

F is 2-6-0 One axle pilot but add a driver, go to next letter.  (moguls were fairly rare on the Pennsy)

G is 4-6-0.  Add another pilot axle go to next letter.  Again the famous electric which was 4-6-0+0-6-4 was called the GG1.  

H is 2-8-0.  So their 2-8-8-0 arriculated was an HC class.  

 

I is 2-10-0

J is 2-6-2.   BUT when the huge 2-10-4 was introduced they had to find an available letter for it and J was available, all Prairies having been long since retired.  The J1 for a 2-10-4 does break the logical pattern of the letter classes.

K of course is 4-6-2.

L is 2-8-2

M is 4-8-2

N is 2-10-2

O is 4-4-4 (electric)

P is 4-6-4 (electric)

Q they used for 4-4-6-4 and 4-6-4-4 duplexes (non articulated)

R is 4-8-4 (electric)

S was 6-4-4-6 duplex non articulated

T was 4-4-4-4 duplex non articuated

It all kind of makes sense.

Dave Nelson

 

 

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Posted by gdelmoro on Monday, January 27, 2020 6:24 AM

Thanks for the replies. Thought it was just me Tongue Tied.

Dave thanks for the list.

Gary

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Posted by ndbprr on Monday, January 27, 2020 12:15 PM

One other thing about the PRR is that the first letter is the class. The number is a variation or improvement of the original engine and the s means superheated. This was dropped later as all engines were superheated as time went on

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Posted by rrinker on Monday, January 27, 2020 3:09 PM

 FOr any given railroad, they tend to make sense. It's when you look at the industry as a whole that you start to wonder, ie Dave's example of the T class locos across the different railroads being vastly different wheel arrangments. Just as you make the argument for the PRR classes, the Reading ones also make reasonable sense, starting with A class 0-4-0, B class 0-6-0, on through I class 2-8-2, M class 2-8-2, etc. Like wheel arrangments together, letters not always in order, but in general the letter is the wheel arrangement, few exceptions. Some oddballs jumped way ahead, like the Q clase 2-6-4T commuter locos. Ending with the last new design, the T 4-8-4s. Not the last steam locos built by/for Reading, those would be the G3 4-6-2s, but there already were G1 and G2 class for that wheel arrangement.

 Now SP was a bit off - or else the commonly held belief that AC stood for Articulated Consolidation is completely wrong (which makes sense - the initial ones were Mallet compounds even if the later ones were simple engines, so the AC may really have meant Articulated Compound). They were 2-8-8-4 for the conventional ones and 4-8-8-2 for the cab forward ones - to truly be an articulated consolidation, it would want to be more like a pair of consolidations, so 2-8-8-2.  But at least they were consistent, all the AC classes had the same wheel arrangemnt, except for the back cab ones, which were flipped around. Or maybe it was the cab forwards that were the flipped around ones. Which is more likely, becuase of the way the cylinders faced.

 Where is gets complicated is with diesels. Ealry on, they were often called oil-electrics (possibly to keep the German name 'Diesel') out of it during and immediately following WWI). So many roads classed them OE-something. Many early switchers carried OE designations. Reading, they had DF for the F frient units, DP for the FP7s, and RS for the various road switchers, originally numbered in order they were purchased. So the Alco RS3 was, on the Reading, a class RS-1, first road switcher purchased. The GP-7 was class RS-3, third type purchased. (Baldwin AS16's were RS-2). Later on, the manufacturer was added, so an RSE was an EMD road switcher, an RSA was an Alco road switcher, and an SWE was an EMD switcher. They got lazy with the last two new diesels delivered, the GP39-2 and GP40-2 were simply class GP-39-2 and GP-40-2 - although this may just have been to follow B&O practice.

                            --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by gmpullman on Monday, January 27, 2020 4:23 PM

You could keep a "scorecard" of locomotive types by starting with the Whyte system and make your own notes for each railroad you are interested in.

 Whyte1 by Edmund, on Flickr

Print these out and keep them in a binder for quick reference.

Regards, Ed

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Posted by Overmod on Monday, January 27, 2020 5:06 PM

rrinker
Now SP was a bit off - or else the commonly held belief that AC stood for Articulated Consolidation is completely wrong (which makes sense - the initial ones were Mallet compounds even if the later ones were simple engines, so the AC may really have meant Articulated Compound).

The problem with this is that all the initial ones, and technically any 'Mallets', were compound engines -- that's why the convention is to use 'simple articulated'.  (In no small part this is because Anatole Mallet himself violently objected to any engine of 'his' configuration not being compound)

The explanation would make better sense if there also weren't AMs (for 'articulated Mogul') in the picture.  You could always say that "AC" was 'articulated compound' and "AM" was 'articulated Mogul' but this rapidly ceases to make much objective sense...

The four-wheel 'lead' truck was a later improvement, and SP chose not to change the name behind the AC class designation (in somewhat the same way as ATSF called its early 4-8-4s "heavy Mountains").  To me this is no more a violation of common sense than, say, continuing to call an E unit by that name after it made more than Eighteen hundred horsepower...

 

As a nomenclatural suggestion:  www.steamlocomotive.com has sections titled something like "Pacific locomotives of the Reading" or "4-6-4 locomotives of the New York Central" and these will handily list all the different codes for that wheel arrangement on that railroad -- they also have 'catchall' pages for a given wheel arrangement that show all the different locomotives with their classes.  With the very slight and possibly unimportant caveat that sometimes they get the use of dashes vs no space in the designators confused (a Reading is a T-1, a PRR engine a T1, for example, not that they got that one wrong) this is a good primary reference when doing the 'notebook fill-out' exercise Mel and Ed have suggested...

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Posted by gdelmoro on Wednesday, January 29, 2020 6:48 AM

WOW. Thanks for all the information!  

And I thought there was a standard Confused

At some point i will research all locomotives on my layout.

Gary

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Posted by gregc on Thursday, January 30, 2020 3:56 AM

North East Rails is a collection of photos of northeast RR locomotives categorized by designation

greg - Philadelphia & Reading / Reading

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Posted by gdelmoro on Friday, January 31, 2020 7:12 AM

gregc

North East Rails is a collection of photos of northeast RR locomotives categorized by designation

 

Thanks Greg

Gary

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