Basic question about numbering on locomotives

Classic Trains General Discussion
1

I’m trying to catalog some old photographs of trains. Most old engines seem to have a 4-digit (sometimes 3-digit) number on them. What does this number signify?

I thought it might be the engine/locomotive number, but a quick internet search suggested that the engine/locomotive number is typically alphanumeric.

I thought it might be a route number but another quick internet search didn’t bring up support for that theory.

Are there any online resources that this community would suggest for someone who doesn’t know trains but wants to do a decent job of cataloging these photographs?

2

Almost no North American locomotive numbers were alphanumeric. The three- or four-digit number identified the specific locomotive or unit; there are complexities involved (as for example when several diesel units were combined into one “locomotive” for labor-related reasons in the 1940s, then separated with their own numbers) and not all railroads assigned sequential numbers to the same kind of locomotive in a particular class (as ATSF did with their steam power) … the Pennsylvania is one notorious example.

Some railroads, the Southern Pacific in particular, had ‘train’ number boards in addition to locomotive numbers. Where this gets perplexing to the unwary is that an ‘extra’ train, one not on the normal schedule, would receive an X code (for eXtra) followed by the locomotive number as identifier for the ‘train’. So you can tell the engine number if you see something like “X4449” but not if some other train code appears there.

It helps enormously if you know the railroad company to which a given locomotive in a picture belongs. A search on the name or abbreviation of the company plus the visible locomotive number should in most cases get you a long way toward a positive ID.

Unfortunately you can’t post scanned images in this forum, so if you want us to comment on any particular head-scratchers you can’t figure out, you’ll have to upload them to one of the free online hosting services for photos, then link the URL of the uploaded file here. (We can talk you through the procedure if you need.)

3

Basically, as railroads bought more and more engines, they would be numbered in the order of acquisition–and as locomotives of different wheel arrangements were acquired, each wheel arrangement would have its own series of numbers. For instance, Norfolk and Western Northern (4-8-4) engines were numbered in the 700 series.

4

As I understood the matter, all locomotives had number boards that were illuminated at night, and these number boards made it possible for the crews of trains that met to positively identify the trains they met for, in the days o

5

I forgot to add that both the UP and SP (and North Western?) put passenger train numbers on the number boards–and if the train was a second or higher section, that was indicated also.

6

In Timetable and Train Order territories trains are referenced by their schedule number, if any, and the lead locomotive number. If a train was not running on a timetable defined schedule it would be running as a Extra train wherein it would be referred to as Extra engine number Direction.

No 1 Engine 1444 - would indicate a train operating on the Schedule of Train Number 1 with engine 1444 in the lead.

Extra 4637 West - indicates a Extra train with engine 4637 in the lead and opeating in a Westward direction.

First Class Schedules were ‘normally’ for passenger trains. Second and Third Class schedules were normally for freight trains. First Class was superior to Second Class which was superior to Third Class. All Classes of schedules were superior to Extra trains. In the Timetable, trains were also designated as Superior by their direction of movement.

Engine numbers identify the equipment, only.

Knowledge of the numbering system each carrier uses also gave a ‘shorthand’ identification of the type of power the locomotive was. Larger railroads would buy a complete series of locomotive - 10, 20, 50, 100 or more at a time. These locomotivew would be numbered in a consecutive series. Numbering systems were not uniform between carriers.

7

In early diesel days when a brace of multiple cab units were all gven the same number (as referred to in Overmod’s post) they sometimes added letters like -A, -B, -C. etc. to distinguish the individual units.

8

As others have indicated the number painted on the engine identifies that engine, useful for train orders, keeping track of maintenance, bookkeeping and other such things. It is usually just numeric, with some exceptions mostly for cab units.

Where your internet search came up alphanumeric is probably because we usually add the reporting marks of the railroad that owned a particular locomotive. In the North American context there will be numerous railroads that chose, say, to use the 6500 series for a group of engines. CNR 6503 was a passenger FP9A, while on another railway CP 6503 was a switcher S-3. Each railroad is only concerned with its own fleet, so it does not matter to them that the numbers are duplicated elsewhere. Only if it goes off line, or railfans are looking for photos of a particular railroad’s engines, do the reporting initials become important.

9

Cab units had lot of variations. In early diesel years a set of cab units was thought of as a single “locomotive”, so the whole thing, even running units, went to the shop if one unit was down. Surprisingly, the practice of extra letters lasted right up to the end of cab units in mainline service.

Here are some examples:

Passenger units could have A and B cabs, or an A cab and B booster.

Four-unit F-series (FT, F3, F7) cab-booster-booster-cab had A,B,C,D suffixes, so there would be a 913A and a 913D cab unit.

Santa Fe lettered a similar setup L,A,B,C but never put the actual L (lead) on the engine. Some of AT&SF’s FT sets were A-B-B-B so there was no “C” cab unit.

Three unit sets (cab, booster, cab) were either sublettered A,B,C (most eastern roads) or A,C,B (Soo Line) or even L,A,C (Santa Fe PAs) . Most of Soo’s freight sets were two unit (A,B). The first Soo passenger cab-booster sets were sublettered A,B, then quickly changed to A,C. The Soo’s FP7 units bought as singles had no subletter.

Southern Pacific (and some others) numbered boosters, including switcher “calfs” with no cabs, in separate series and never used sublettering.

10

This led to an amusing situation with the original ATSF PA sets, because railfans expected cab units to have an “A” number and boosters a “B”.

I must be getting too old because I remember seeing PAs with the “L” suffix.

11

First thing you have to figure out: are you looking at the engine’s own number (every engine has one) or, if it’s an SP or UP engine, are you looking at the number of the train it’s pulling?

If it is an SP/UP engine, you might see “1” or “27” or “486” in the changeable numberboards on each side of the engine. Those are train schedule designations, unrelated to the engine’s own number, which you can probably see elsewhere in the pic.

Or an SP/UP engine might show “X4202” in the changeable numberboards if it’s engine 4202 pulling an unscheduled train.

But most railroads didn’t show any numbers on the engine except the engine’s own number.

12

I’ve never seen a picture of one. The tiny number boards over the center windshield pillar and the side number panels (like the ones on the FTs) just seem to show the number with no subletters. On later F units with larger numberboards seeing numbers with a “C” was pretty common, but the “L” was always left off.

Here are PA 74L and F3A 34C side by side in Chicago:

http://www.rrpicturearchives.net/showPicture.aspx?id=544479

13

Right. I am not certain, but the C&NW may also have shown the passenger train number on the original City of Portland, for the engine was articualted to the rest of the train, and thus ran over the entire route. The engines of the later city trains were not articulated with the cars, yet may have remained coupled to the cars for the entire trips.

14

Milwaukee put “City” train numbers in the indicators until about 1968. For their own trains, just the engine number. Not all Milwaukee passenger engines had changeable number indicators.

15

I believe in the early diesel years, the M&StL used the prefix D before the number. Later on that was dropped. The Milwaukee Road had an E prefix for their electric locomotives.

I have some Rock Island train orders from the 1940s. On the orders, but not on the locomotives themselves, diesel engines are identified as such. Example, “No 5 Diesel 627.” Eventually that practice was discontinued.

Jeff

16

New Haven prefixed non-steam numbers with “0”. The DL-109s were delivered as 0700-0759. If memory serves, the first class of diesels without leading 0s were delivered in 1950 from Alco (RS3) and F-M (H-16-44).

17

Railroads - at least, larger railroads - usually numbered similar engines in the same numbering range…so for example a railroad might have all it’s Pacific steam engines numbered in the 4000’s, usually with the first group of engines having the lowest numbers. Later, if it bought Northerns, those might be 4100’s.

BTW working railroaders generally referred to engines by the number range rather than wheel arrangement or nickname, so a New York Central engineer or fireman might refer to a “5300” type engine, rather than calling it a 4-6-4 or J-1 or Hudson.

18

Sometimes the number schemes were more accidental. Among other railroads, both Soo Line and Southern Pacific simply numbered the next batch of diesels after the last batch - the result ended up mixing EMD and Alco/GE series (and some SP Baldwins) with no particular grouping by make or model. SP did a system-wide renumbering in 1964-65 to (mostly) correct this, but Soo’s units ran with the original numbers until retired. Tack on that both systems had units numbered in different series for subsidiaries (3-digit for SP’s T&NO, 4 digit for Soo’s Wisconsin Central).

19

It’s still that way today.

20

Keep in mind also that it wasn’t unusual for an engine to be renumbered several times during it’s productive life, sometimes due to mergers or sometimes just to the railroad setting up a new numbering system.