Saw a B&M 4-8-2 R1b, it was numbered 4105. I’m wondering how loco numbering came about, now I’m sure B&M did not have 4,105 locomotives, (or more) why did they not number them in consecutive order from initial purchase? I would assume this loco should have a number like 46 or 3 or 164.
This rule seems to apply to the present, anyone know why they use this system and what is it’s purpose?
It has been a lot of years since I gew up in a railroad family, and worked for Santa Fe in EDP in Topeka in the 60’s, but I can give you a short answer, others may have other info. Locomotives, steam or diesel, are numbered in classes, as example, Santa Fe F units were in 100, 200, 300, etc. classes. GP’s were not numbered in the same classes, they had their own. I can tell you that maintenance records would probably be a mess trying to determine out of 5000 diesels (example) which ones were of a certain type for a maintenance upgrade if they were just randomly numbered as they were purchased.
Another example, if you were storing kits in one big box for future building, would you just throw them into the container as you purchased them with no order, or would you separate by manufacturer, or by type, ie. box, tank, etc.? If they were in random order and you were looking for a particular car to build or put on the layout, you might have to dig and dig and dig. But if they are arranged in some order, type, or manufacturer and placed in boxes, life would be much easier.
Bob
Most locomotive numbering systems are ‘class’ based. For example, a railroad may choose to place all 6 axle engines in the 6000 series. They will put older SD7/9 engines in the 6300 series, SD40-2’s in the 6600 series and SD70ACe engines in the 6700 series.
Other railroads may choose a horsepower based system, where SD70ACE’s are in the 4300 series, ES44AC’s are in the 4400 series, GP38’s are in the 2000 series.
Have types of engines in ‘blocks’ allows for additional purchases, and makes easy calculation of selecting road power to meet a train requirement.
Jim
There is no one answer to this question that applies to all railroads, or even to the same railroad.
But for most railroads, locomotives (steam and diesel) came in classes and those classes would have a number. So for example there might a “4000” class consisting of 25 engines: Number 4000, number 4001, number 4002 and so on. Sometimes railfans mention getting a photo of “the class engine” – the lowest numbered of the class.
Now imagine a railroad that had a 4000 class of engines, and then a 4100 class of entirely different engines. If it happened that they acquired “too many” of the 4000 class they might have to renumber or invent new class numbers. Many steam locomotives, and the Milwaukee Road is a particular example of this, renumbered their engines many times during their service lives. Thus a real exacting Milwaukee Road modeler with a specific era in mind might have to repaint or renumber a model that is otherwise perfect for their layout.
Some railroads were small enough and acquired so few engines that the number system was keyed to when they got the engine, so for example an engine acquired in March of 1945 would be 345. What if they got more than one engine in the same month? Frankly I do not know but i gather the kinds of railroads that used this “system” tended not to have that problem. By the way some model railroaders with their own layout name use that same system to keep track of when they got an engine.
The Pennsylvania Railroad was an example of a huge railroad with distinct and very precise classes of engines, but a numbering system that at time seems purely chaotic. I have read that there was indeed a system of some kind to the numbering, but I have never read an explanation that I could actually track (no pun intended) in my mind.
One problem of course is that a truly huge railroad might soon run out of numbers. For a variety of reasons four digits seems to be the max. In
Then there was the Pennsylvania Railroad which until the 1920’s gave each new locomotive the next available number, so the 425 K4 Pacifics had numbers from the single digits to the 9000’s. Some of the later purchases were put in a block but the majority were spread across the spectrum of numbers. The classes that were put in blocks were the M1’s, J1’s, Q2’'s and T1’s and some of the K4’s and I1’s.
Rick[2c]
Locomotive numbering is purely a management decision and is totally arbitrary depending on what the management goals are trying to do with the numbering system.
Sometimes it designates the horsepower, sometimes the series of engine, sometimes the model, sometimes the service, sometimes the order the engines were bought, sometimes whatever number was available.
Most likely in your case it was based on the type or class of engine. All engines of that type would be numbered in the 4100 series. The next series of engines might be the 4200 series engines. That doesn’t mean there are 100 4100’s, just that the 4100’s and 4200’s are distinct types of engines in some way (4100’s might have 62" drivers and 4200’s might be the exact same engines with 55" drivers).
Or if it’s a shortline railroad with all secondhand engines from varying sources, the numbers could be all over the map if they just keep the original number.
Generally, if a railroad has more than just a few engines of a certain type, they’ll be numbered into a common group.
All railway equipment, whether locomotives, freight cars, passenger cars, cabooses, etc. are uniquely identified by reporting mark and number. The numbering scheme (or lack thereof) is totally up to the specific railroad’s management. Generally, similar equipment will be grouped together.
Another twist to the engine numbering is when a railroad buys used units from another railroad. For instance, when Rock Island went bankrupt, Maine Central bought a number of their U-25b locomotives. In this case, MEC kept the RI road numbers; they just as well have renumbered them.
When Guilford bought MEC, B&M, and D&H, they started moving locomotives around the former 3 RRs. Some were renumbered and some were not. An example was a number of D&H U-23bs that were sent to MEC, and other locomotives that were transferred to Springfield Terminal RR, a former B&M subsidary. (I would have to look up in one of my references to see the details of what happened to the road numbers of these. [*-)])
Numbering locomotives in blocks isn’t exactly a new idea. Santa Fe was doing it when they were experimenting with jointed-boiler Mallets.
In my case, numbers are assigned consecutively, in order of acquisition - BUT! The first digits of the number, one or two alphas and the first two numerics, identify the class. So you could have C621 through C6249 (YOU could. I don’t run those big 4-6-4s), ED161 through ED1618, DD131 through DD13(and here the system begins to break down. There were blocks of DD13 class diesel-hydraulics, with gaps between)
An earlier system assigned numbers in blocks of 100. The classes that exceeded 100 units (most of them) then got a prefix number, so the numbering went from 9600 to 9699 to 19600 and on. That was one reason for the change in class designations.
The one key factor in the entire mosaic is that each locomotive has to have a unique number specific to it alone - for record-keeping purposes.
Chuck (Modeling Central Japan in September, 1964)