Signals

Real train operations are often controlled by signals, using either color lights or semaphores (which have colored lenses combined with a blade arm).  These signals are a colorful feature of real railroad operations.  So, too, signals can also control train movements and offer additional detail to the model railroad. 

Many European modelers control their model trains with signals.  This is a reflection of the operating philosophy of model railroad operation in Europe, where the model railroader usually views themselves as a signal tower operator.  In the North American market, the model railroader views themselves as a locomotive engineer, a different approach to train control.  In either case, railroad signals can improve the realism of your model railroad.  This can be automated if the modeler desires, and the process of such automation is made much easier by computer programs such as Railroad & Co.

The topic of model railroad signaling is a complicated one, but if you break things down into their component parts, the process becomes easier.  Operation of an individual signal combines a control device connected to the signal.  This control device can be a simple pushbutton. In turn, train control is achieved by creating a segment of track that is defined by isolating one rail at two locations.

As mentioned earlier, there are two general types of signals:

  • Color Light
  • Semaphore

Color light signals are the more modern of railroad control signals, while semaphores date back to the late 1800’s. In parts of southern Germany, semaphores are still in use, although they are now slated for removal. Semaphores give both a color indication and have an arm which gives additional indication.  Color lights, however, are generally immune to the effects of ice and snow, which can jam a semaphore arm.

For many years, the only signals in Z-Scale were manufactured by Märklin.  Starting in 2010, American prototype signals became available from Custom Signal Systems.  More about them in a moment.

When Z-Scale was introduced, Märklin included a color light signal, the 8939 in the product line.  In 1973, the 8993 grade crossing signal was added to the line.  Later, in 1979, Märklin added the 8940 semaphore signal.

These earlier signals have been replaced with a series of German prototype color light signals and semaphores which are more realistic. The earlier signals are still in the marketplace and may be more than sufficient for your purposes.

1st Generation Märklin Signals

The 8939 color light signal shows a red and a green indication. 

Courtesy Märklin

The signal has two light bulbs in its base; fiber optic pieces guide the light from the bulbs into the lenses in the head of the signal.

The 8939 requires either the 8945 relay or 8946 manual signal controller to operate.  These controls also provide for automatic stopping of trains at a red signal.

Here is a wiring diagram for a single color light signal with the 8946 manual signal controller:

Courtesy Märklin

In this wiring situation, the train is operating from the right side of the diagram to the left. At the right, the transformer feeds track power to the rails.  A yellow wire is run to the yellow connection of the signal.  Note the two 8598 Isolating Track pieces, which define a segment of track (marked “X”).  Note: “8598” is an earlier track piece number; the current track piece is No. 8588.

The two Isolating tracks create a segment of track which is not directly connected to the rest of the railroad.  Instead, one of the Isolating tracks has two red wires which are connected to two terminals on the manual signal controller.  On the right side of the 8946, one wire is connected to the gray terminal on the transformer; the other two wires are connected individually to the two light bulb connections of the signal.  A schematic appears below:

In this diagram, the 8946 manual signal controller is in the “Red” position. Current flows from the center (gray) contact of three contacts on the right to the red bulb of the signal. At the same time, no current flows to the isolated track segment. 

As the train approaches the red signal, it stops. Note the the distance of “X” needs to be long enough to stop a moving train yet not so long that the casual viewer does not associate the stopped train with the red signal. When the 8946 is turned to “Green”, current flows to the green bulb instead of the red and also connects the isolating section to the red rail track current.

The color light signal and manual signal controller combination can be used on small Z-Scale layout to effectively control several trains.  Not immediately apparent is the fact that in the above track diagram, if a train is moving from left to right (against “traffic”) as soon as it enters the controlled section and the signal is set to “red”.  Under normal circumstances, the signal only governs traffic moving right to left, so this is a problem which can be solved by adding a diode oriented to allow electricity flow when the track polarity is set for trains moving from left to right. 

Needless to say, this complicates matters considerably from a signal logic standpoint, so it may be easier to have all train traffic moving in one direction only (as on the Noch “Cortina” factory made layout).  The signal & controller combination can also be used for train control on dead end sidings, where a train is backed into the siding when the signal is green, the switch is then turned to red, which turns off track power to the siding. Another siding could now be turned on and another train can operate on the railroad.

A more common application used with the color light signal employs the 8945 Relay instead of the manual controller. The 8945 is like a switch machine in that it has a pair of solenoid coils, but instead of moving the points of a track turnout, it moves electrical contacts. The 8945 relay is wired internally the same as the 8946, but the two solenoid coils operate the electrical contacts. The 8945 relay also has a manual lever, but the coils allow for remote operation of the relay.  At this juncture, it would seem that the 8945 relay is overkill in simple signal applications, but all will become apparent in the Automatic Operation segment of these pages.

The 8940 Semaphore performs the same start/stop functions as the color light signal, but it has a both pair of solenoid coils which operate the semaphore blade and also operate an internal set of electrical contacts. These contacts provide the same train control function as the 8945.

Here, the installation of the 8940 semaphore.

The 8940 has the following connections:

Red - The 8940 has two red wires which are connected to an 8588 Isolation Track; either a second 8588 is used to define the segment or an insulated rail joiner can be used on the “red” rail.

Yellow - A yellow connection is made to provide power to the two solenoid coils inside the 8940.

Blue - Two blue wires connect the 8940 to the control box which operates the semaphore. As with the relay & color light combination, more information about using the semaphore in automatic operation is located elsewhere on this site.

Gray - Because the semaphore has an internal light bulb to illuminate the colored lenses of the semaphore blade, a gray wire provides the necessary ground.

Both the 8939 and 8940 signals are “Home” signals, meaning that when a train approaches such a signal in the “red” position, it must stop & stay there until the signal is set to “green”.  In railroad usage, “red” is usually referred to as “Stop” and green is referred to as “Clear” or “Proceed”.

2nd Generation Märklin Signals

Märklin has introduced a series of color light and semaphore signals which are considerably more sophisticated than the 8939 and 8940.  These signals have finer detail and use LED’s for reliable lighting.

The 89391 (left) is a Block Signal, typically found on main line railroads away from stations.  Red means “Stop”; green indicates “Proceed”.

The 89392 (right) is an Entry Signal, found at the entrance to station areas. Red means “stop”, green means “proceed” and green/yellow indicates “proceed slowly”.

The 89393 (left) is an Exit Signal, governing trains departing from stations.  Red means “Stop”, green means “Proceed”, green/yellow means “Proceed Slowly” and the two white lights indicate “Switching Allowed”.

The 89390 (right) is a “Distant Signal”.  It is located some distance before the other color light signals, and advises the train engineer of the indication of the next signal, allow the train crew to prepare to stop if necessary.

In addition to these color light signals, there are two semaphores:

The 89401 (left) is similar in function to the 1st Generation 8940, but with better detail.

The 89402 (right) indicates “Stop” & “Proceed Slowly”.

The new Märklin Z-Scale signal line includes three “Yard Signals”, which are used to govern switching movements within railroad car marshaling yards.

The 89395 (left) is a high mounted signal.  Red indicates “Do not proceed” while white indicates “Proceed [prepared to stop]”

The 89394 (right) is a ground level mounted signal.  Red indicates “Do not proceed” while white indicates “Proceed [prepared to stop]”

Dating back to the semaphore era, the 89403 (right) is an earlier Yard Signal. A horizontal bar indicates “Stop”.  The signal currently indicates “Proceed [prepared to stop]”.

Operation of the Märklin Z-Scale 2ndGeneration Signals

Because these new signals have LED’s, the accessory voltage provided by the Märklin transformer is more than sufficient to illuminate them.  Operating them is another matter.  Because these signals are more complicated than the earlier 8939 and 8940, providing signal logic for the different indications can be complex. In the case of the 89391 and other two indication signals, the 8945 relay remains sufficient for the job.  But with the more complicated 89392 (which has three indications) and the 89393 (which offers four indications) mean more complicated wiring.

This problem becomes more apparent with the Märklin Factory recommendation of the 7244 Universal Relay:

The 7244 is a relay from the Märklin H0 product line, and it requires 16 volts to operate unlike the 10 volts of the Z-Scale relay.  Obviously, it has many more contacts than the 8945, which are necessary for operating the more complicated 2nd Generation Z-Scale signals.  Using the 7244 relay also means that you will need a separate power supply to provide the necessary voltage to drive its solenoids yet you still connect to the 10-volt AC tap of the Z-Scale power supply if you are using it with the 8939 color light signal or 8940 semaphore. Both of these earlier signals use lower voltage light bulbs from the early days of the Märklin Z-Scale line.

And, with several of these color light signals (such as the 89392), you need two 7244’s and in the case of the 89393 you need an astonishing four.  In all cases, only two or three of the contact sets are used for each relay.

In short, this wiring arrangement is the culmination of electromechanical technology, with the attendant complicated wiring of trying do so little with so much.  I am not completely versed with the new signal technology, but it seems that the current instruction sheet that uses this approach is simply occupational therapy for the model railroad enthusiast until digital logic becomes available.

Of course, there have been persistent rumors about Z-Scale command control; I wrote about them in the Greenberg book in 1988.  Rob Albritton is using it on his huge Swiss Z-Scale railroad

Yet, we seem to be no closer to digital control of Z-Scale trains but I’m probably being a bit pessimistic here. In fact, given that the signals use LED’s, it seems quite possible that the model railroad enthusiast seeking to create a complicated signal system on their railroad could use off-the-shelf Märklin Digital or DCC (Digital Command Control). This would be combined with a computer program such as Railroad & Co. to provide signal logic.  The Z-Scale railroad itself would remain pure, operating on the necessary 8 volts DC while the signals are operating in their own environment, receiving data from the railroad via circuit tracks. This one is your call, and a lot of this remains a question of what will be coming next from Märklin or other manufacturers.

American Z-Scale Signals

As mentioned earlier, Custom Signal Systems is now offering Z-Scale color light signals which are compatible in appearance with North American Z-Scale model railroads. These signals are a very nice addition to the world of Z-Scale:

As stated at the outset, the topic of railroad signals is a complicated one. Here are a couple web sites that might help:

German Railroad Signals

American Railroad Signals

It’s an interesting topic, and signals will make your Z-Scale model railroad much more interesting.

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