Powering Frogs?

Model Railroader General Discussion (Model Railroader)
1

Hi all- I’ve installed several Atlas #6 turnouts and was just starting to install the Deluxe Under Table Switch machines. Since I have a couple locos w/ short wheel bases, I thought it would be a good idea to utilize the feature of the “deluxe” machine to power the frog based on the turnout setting.

However when I read the machine instructions, I realized a potential problem: If the turnout is set to the “through” position and a loco approaches the turnout from the diverging track, the frog would be set at the wrong polarity and the loco would create a short.

Maybe that’s not a problem if you’re on your toes and always check the turnout settings, but I’ll be playing w/ my 7-year old and chances are good that one of us will miss this.

Is there a fail safe system to prevent this problem? I don’t think indicator lights would solve it. Or am I missing something?

Thanks in advance for your suggestions.

2

And the problem is?

If the switch is lined the wrong way the train may derail at the switch. So which do prefer a short or a derailment? Your choice. :sunglasses:

Dave H.

3

Well actually I would prefer a derailment over a short. But I believe the points on the turnout will move just enough to let the loco coming in from the diverging route to enter the straight section without derailing.

4

you will need to do some wiring magic and make a section of dead track before the frog so the trains stop before flying into danger.

This can happen with the switch machine contacts.

Like always tho, you the engineer must be alert so you don’t do this.

5

Why would you prefer damaging your equipment to a short? If your power supply is properly protected when you short the breaker will trip and everything will safely stop. If you derail things you can damage grab irons sill steps, coupler springs, etc.

But then its your railroad. If you don’t want to short then you can install auto reversers for each switch that change the polarity of the frog to match the train ($30-60 a switch plus you have to have DCC). Or you can create a detection block ahead of each switch detects the presence of an engine or cars, and changes the polarity to match the frog (once again $10-30 per switch depending on how much you want to build yourself.) Or you can build the detection circuits so they throw the switch depending on which route is activated ($10-30 per switch)

Or you can pay attention for free. :sunglasses:

Dave H.

6

Actually, we like the shorts they stop the locomotive from dragging a train backwards throught the turnout. Actually the locomotive usually pushes through the turnout just fine. It is the cars after it that go on the ground.

But, yes, there is a fail safe system. Actually there are probably more ways than one could think of in an evening. All most all of them would involve making isolated sections of track on frog side of the turnouts, putting detection circuits on them, and then making a circuit that either changes the turnout toward the oncoming train, or cutting power to the oncoming train. All of this would be required for each turnout. It would cost $3-$7 of components (not counting the switch motor or power supplies) if the circuits are built from scratch, and probably $15-$50 using pre-built components. Also depends if you are running DC or DCC.