Locomotives — Front to Back

Front to back, and side to side

A different look at European locomotives

By Ernest H. Robl

People have asked me whether European locomotives have a front and a back, as they are symmetrical.

Well, yes and no and no.

No, in the sense that they operate equally well in both directions, particularly as most modern road electrics and diesels have control cabs on both ends.

Yes, in the sense that they do have designated ends, which is necessary for a number of reasons.

And, no, they are not really symmetrical, though the cabs on both ends tend to give that appearance. Internal and under-frame components are not symmetrical.

All of these factors not only have important implications for prototype railroads; they also have important implications for model railroaders, too.


In era 2 — before WW II — as electric and diesel locomotive designs were just beginning to evolve, railroads first went with electric and diesel locomotive designs that were not that different from the steam locomotives they began with. (With steam locomotives, there never was a question about which end was the front. It was the end with the cylinders, boiler, and smokestack.)

These early designs had unpowered pilot and trailing wheels and even driving wheels connected by side rods. In part that was because early electric motors were too large to have one for each powered axle.

Though some early designs had a cab on one end, not unlike steam locomotives, it soon became apparent — at least to most European railroads — that it was necessary to designate the ends of electric and diesel locomotives. So, in German-speaking countries, by era 2, railroads began painting a large “V” (for vorne — front in German) on one end of these locomotives. Some also had an “H” (hinten — rear in German) on the other end.


Which end of this Austrian 1016 locomotive is this? And, how would you identify which pantograph is raised? Note the small number 1 on the frame under the side cab window. This is the number 1 end. And therefore, the number 1 pantograph is the one currently raised. (Click on the image for a larger version.)

Though few locomotives crossed borders at that time, the V and H designations were even problematic in multi-lingual Switzerland. So, gradually, the change was made to designating a number 1 and a number 2 end. This is now standard in Europe.

(For what it’s worth, in the U.S. and Canada, diesel locomotives have long had a small “F” on the frame on one end to designate the official front.)

On locomotives with cab doors on both sides on both ends, the numbers are usually applied to the doors; on locomotives with only one door per side, the numbers are applied to the frame below the side cab windows (or in that general area, for locomotives with no side windows).

In each cab, there is a designation of which cab the operator is in.


.The numeric system actually has many advantages over the alphabetic one.

For anything on the locomotive that exists in multiple, these items are numbered from the number 1 end.

If you only have two pantographs, the one on the number 1 end is pantograph 1; the one on the other end is number 2. But many modern multi-system (and multi-country) electric locomotives have additional pantographs for specific countries. So you may have pantographs 1-3 or 1-4.

This simplifies operation in the cab, because you have the pantograph controls labeled by both number and function. So, if the number 3 pantograph is the one to be used in a specific country, the operator simply selects that pantograph, regardless of which cab he is operating from.

But, it;s not just pantographs that exist in multiples. There are many additional internal components as well. One example is the modern genset locomotive. These are locomotives that have multiple diesel motors (and related gear, such generators/alternators), with the number of motors actually used depending on operating circumstances. When the locomotive is running light or with only a few cars, a single genset is on and the rest are shut down; with a heavier load — or on a steep grade — more motors are brought on line to handle the load. This system saves fuel compared to having one large diesel motor that is running all the time. So, these sets are numbered from the number 1 end.

Even trucks (bogies) and axles (and traction motors) are numbered from the number 1 end.

Now, you also have a means of designating the sides of locomotives. Yes, you could say one side is the right side and other the left side. But, that depends on direction of travel. So, locomotives have a 1-2 side and a 2-1 side.



The DB series 410 (later renumbered to series 184), built in only five copies in 1965, was a pioneer among multi-system locomotives, designed to operate in multiple countries with different power supplies and catenary standards. This Krupp drawing shows the 2-1 side (note the numbers on the body shell), with the following pantographs (from right to left, from the number 1 end, identified by numbers on the drawing):

  1. Dutch/Belgian pantograph
  2. German/Austrian pantograph
  3. French pantograph
  4. Dutch/Belgian pantograph

(As with most Blog illustrations, click on the image to view a larger version; use your browser’s BACK function to return to the main post.)

Both political and technical problems kept these locomotives from being used in all the countries they were designed for. Among other things, the solid state thyristor equipment caused undesired influences on the signal systems in some countries — which those countries were not willing to make adjustments for. So, by 1979, to simplify maintenance, most equipment for operating under DC power systems (not being used) was removed. That included two of the pantographs, resulting in a new roof configurations.

The system of identifying ends and parts of locomotives is so well established that, most cases, no one bothers to mention it. For example (a made-up example) if a description shows that a particular group of locomotives has the following pantographs — Austrian/German, Swiss, Italian, and French — the assumption is that these are being listed in order from the number 1 end of the locomotive.

Model implications

You may not have realized it, but this also has major implications for model or locomotives, particularly in digital operation.

You may be aware that the NEM/NMRA DC standards specify which wires go to which pin on a decoder socket. The left and right track pickups — for European locomotives — of course apply to the number 1 end of the locomotive.

But, though, as far as I know this is not an official standard yet, digital locomotives with separately switchable red end lights (and no other special functions) now typically use F1 and F2 to turn on those tail lights. Guess which end of the locomotive each applies to?

And, on high-end digital locomotives that have interior cab lights, these are now usually assigned to F11 and F12, again, matching the ends of the locomotive.

Back to the past

Before we go further, we need to make a side trip to look at some background related to digital operation and the history of model railroading — and its relation to the prototype.

Both prototype European locomotives and their models typically have two sets of lights on each end. One set is the headlights, which are on in the direction of operation. The other set of lights are red tail lights — which, on the prototype, are used only when a locomotive is running solo or is at the actual end of a train, such as a pusher assisting a freight train or the locomotive on a push-pull passenger train when it is in push mode, being run from a cab control car.

A solo locomotive parked on a through track in a station may display red tail lights on both sides.

Unfortunately, for much of the history of model railroading, analog models have only had lights that changed with direction of operation. That meant that headlights were on on one end of the locomotive; the red tail lights were on on the other end, regardless of whether the locomotive was coupled to a train or not. Again, on the prototype, red tail lights would be allowed only on the actual end of a train.

This is among the key items that are checked when a running inspection is made of a train. If the end-of-train indicators are in place, the train is complete. If not, there is a problem, such as the train having broken in two.

So, for many years, the always-on red tail lights have been a frustration for those model railroaders who wanted their operations to be more prototypical.

This was, of course, one of the “problems” that could be solved with digital operation, though not all digital models initially implemented a fix.

In the beginning (early 20th century) many models in the smaller scales either had no lights or only headlights on each end. (The then-available technology made it difficult to produce small-enough bulbs for the models.) Actually, many early prototype locomotives did not have tail lights. When necessary, an end-of-train indication was accomplished by clipping a red filter over one or both of the lights on the rear of the locomotive.

By the middle of the 20th century, some model manufacturers, such as Roco, solved the space problem by having two small light bulbs centrally located on a circuit board and having plastic light guides take the light to the actual lenses on each end. When, based on direction, one bulb was on, the light guides sent light to the headlights on one end and the tail lights on the other end. When the direction changed, the other light bulb came on and sent light to opposite combination of headlights and tail lights.

More digital considerations

When digital locomotives became available at the end of the 20th century, manufacturers simply redesigned their circuit boards to accept a decoder — but kept the two-bulb with light guides concept.

Then, as LED lighting became possible and affordable, many manufacturers again kept their light guide configuration, simply replacing the two bulbs on the circuit board with two LEDs. That continued the frustration with unwanted tail lights when a locomotive was coupled to a train.

Then, finally, as LEDs shrank in size and became even more affordable, it became possible to place a tiny LED behind each headlight and tail light lens. That finally made it possible to have lights individually switchable on digital locomotives.

But, again, there was a lag in implementing this technology. While individually switchable lights were possible with 8-pin decoders, it took the widespread implementation of 16- and 22-pin decoders (and the required redesign of circuit boards) to finally implement the individual light controls.

Finally, there are two further considerations:

  • On many models, the body shell can be installed in either direction, which, can, of course, cause problems the light functions if the number 1 end on the body does not match the number 1 end on the locomotive frame. (There are some practical considerations for making the shell fit both ways.) So, pay attention when replacing the body shell. Fortunately, most models now identify the number 1 end on the circuit board or body frame, making it easy to reinstall the body shell correctly. And, the number 1 and 2 ends are typically also identified in the instructions.
  • Eight-pin decoders can be installed backwards (I’m not sure about some of the other pin configurations). This can also cause some problems with light functions. So, we need to pay attention to the decoder plug orientation, as explained in the locomotive and decoder instructions.

So, now you can not only identify which is the number 3 pantograph, but also efficiently use light and other functions that are dependent on locomotive end designations.


I hope this post has provided useful information — or at least something to think about. As always, comments are welcome.


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