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Eliminate problems when you forget to throw the switch

The End of "Switch-Busting"?
Here's a circuit that might do it!


by Stephen Lowens

It's a crummy feeling.   You've invited the entire neighborhood over for a show, and your trains are running beautifully...     until you hear that clunk, clunk, rattle, rattle, rattle that says four cars are on the ground.    In all the excitement, you forgot to set a turnout, and your faithful locomotive burst right through it!    I call this phenomenon switch-busting...  in polite company.

If you, like me, remember the "good old days" of Lionel trains, when they invented circuitry that would detect a turnout set the wrong way and automatically set it right, maybe you also wonder if you should ever have left tinplate behind.   The standard texts don't give us a way to solve this problem, which on my layout, and probably yours, happens over and over again.

Here are a couple of circuits that won't reset an incorrectly set turnout, but they will do the next best thing.   If the turnout is set the wrong way, they will bring the train to a dead stop until you reset the turnout.    No, it isn't realistic in bringing the train to a slow, normal stop; but it will save you the re-railing blues.    It is especially helpful for those locations on the layout where you can't maintain eye contact with the turnout.

The concept works best for Atlas turnouts right out of the box, but can be adapted for Micro-Engineering and Shinohara turnouts using a Tortoise switch motor.     In operation, it requires only that you set your turnouts the way you always do - no extra steps are required after installation and wiring.   This is a "DC" concept - I haven't graduated to DCC yet.

Fig. 1 - Click to Enlarge
Atlas Switch Buster

Figure 1 (AtlasSwitchbuster.jpg) shows the materials and wiring for an all-Atlas setup.   This will work with any Atlas turnout, including Snap-track, Custom-line and Super-Track.   The diagram shows six gaps.   The 4 gaps that separate Block A from Blocks B and C are standard wiring that is used to create a block system.   The "new" idea is identified by "Note A".    In the locations shown, create an isolated section of track long enough to hold your longest engine. Note that this isolated section is gapped only on the inner rails leading from the turnout.

Connect the wiring as shown in Figure 1 and test it.     If wired properly, you will find that any engine approaching the turnout from right to left (as shown in the diagram) will be stopped if the turnout is set incorrectly.    If the turnout is set correctly, the train will pass on through.    Any train passing from left to right will be directed onto the proper spur by the turnout and will not be stopped.

There is one possible "gotcha" in this diagram.   Depending on whether you are using the "under - the table" or the "on the table" Atlas switch motor, you may find with your first test that the train does not stop for an incorrectly set switch.    If so, exchange the wires on the switch motor marked "1" and "3" in the diagram.    The system should then work properly.

Some Atlas turnouts include plastic frogs, and some include insulated metal frogs.    If you have very short engines (or only a single truck powered), you may wish to add power to a metal frog. This design has a limitation in that it is possible to only power the frog in one direction.    If you need to power the frog with this concept, I recommend that you power the leg that gets the heaviest traffic (your "main line").    See Note "C" for the proper connection.

Micro-Engineering or Shinohara (Walthers) turnouts are wired differently, and so I have prepared two options. One option requires significant modifications to the turnout to essentially make them work like Atlas turnouts. The other uses the turnouts "as-is," but only "protects one leg; the remaining contacts are used to power the frog and connected components.

Fig. 2 - Click to Enlarge
Tortoise Switch Buster 1

Figure 2 (TortoiseSwitchBuster1.jpg) illustrates the "complete protection" concept using either Micro-Engineering or Shinohara (Walthers) turnouts with a Tortoise switch motor. The Tortoise is a combination of the Atlas switch motor and Snap Relay in a single package. There are a number of ways to power the moving parts of the Tortoise; I have shown one of the three shown in the wiring diagram that is packaged with each Tortoise. Any of the three will work, depending on your power source. The power to the Tortoise motor passes through connection pins 1 and 8, as shown in the diagram.

The wiring for connections to the track pass through Tortoise pins 2, 4, 5 and 7, as shown in Figure 2. When wired this way, the trains will run just as described for the Atlas combination above.


As with the Atlas system, you may find upon testing that the system doesn't work. In this event, interchange the wires to pins 1 and 8. (It is impossible for me to guess which way you will physically orient the Tortoise; and for this concept, this detail must be worked turnout-by-turnout.)

There are a few extra concerns with the Micro-Engineering and Shinohara turnouts beyond what I have described for the Atlas. These two brands of turnout do not have an isolated frog, and power is distributed in a different manner. There are two options. If you use the turnouts "out of the box," you will be depending on a connection between the stock rail and the switch-point rails for your electrical connection. This is not considered reliable, and I can assure you that your engines will stall on the turnout. The option is to isolate the frog as shown in the diagram, converting it electrically so that it effectively works just as the Atlas turnouts work.


Fig. 3 - Click to Enlarge
Tortoise Switch Buster 2


A second option for Micro-Engineering or Shinohara (Walthers) turnouts is to treat one leg of the turnout as the main line, and one leg as a siding. The concept shown in Figure 3 (.jpg) "protects" the main line and also powers the frog and connected components.   My testing of Micro-Engineering turnouts with Tortoise motors indicates that it is mandatory to power the frog in order to keep your engines running through the turnout.   Thus, since there are only two switches internal to the Tortoise, you'll have to make a choice between protecting only one direction, or else modifying the turnout.



Fig. 4 - Click to Enlarge
Tortoise Switch Buster 3

Finally, I've shown in Figure 4 (TortoiseSwitchBuster3.jpg) a concept for using this technique on a cross-over.   This is really the same circuit as Figure 3, used twice for the two turnouts.   Since there is no "siding," there are sufficient internal switches to protect all approaches to the turnout.   No modifications to the turnouts are required for this scheme.

I suggest some careful testing and experimenting with the various combinations to make this system work.   It is worth the effort to achieve a far more trouble-free operating layout.


If you find any of the ideas in this article worthwhile, please drop me an e-mail.    It takes a bit of time to write these articles, and I don't want to spend the time if they're not useful.

Steve Lowens
United Pacific Railroad
e-mail: unitedpacific44@hotmail.com


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