I am building a layout using 1121 switches. My question is, how do I install the switches on a loop that comes back on itself without shorting out? This is an old school style layout, no fancy modern stuff here. Thanks for any info!
No problem. That's one of the advantages of three-rail track, not shared by postwar American Flyer and most HO. The outside rails are already connected together, so it doesn't matter if they get swapped in a loop.
Bob Nelson
Lionelsoni- Are you saying that the center rail that supplies the power can loop back onto the switch itself and my train will still run? Looks to me like it will cause a short. Also what is the purpose of the insulating track pins?
Yes it can.
There shouldn't be any need for insulating pins with an 1121, unless you want to isolate a block starting at the turnout. The 1122 uses them to implement its non-derailing feature, which the 1121 lacks. You can create separate insulated control rails leading to the 1121 and make your own non-derailing function if you want.
If you bought a turnout that had insulating pins in it, perhaps a previous owner used it in one or another of these optional ways.
Maybe I am not making myself clear. How does the electrical wiring connect the power to the track going into the 1121 switch, through the switch,out the switch,into track that loops back around and goes into the other track side of switch, then back into the track which it started from without throwing breakers or shorting out? Man I hope I'm making sense here.
The circuit breaker will not trip unless there is (an excessive) current flowing between the center rail and the outside rails. Connecting the center rail to itself does nothing to allow current to flow to the outside rails; so it doesn't trip the breaker. In fact, there are some good reasons to connect the center rail to the transformer through multiple paths.
Do you perhaps have a two-rail background? Loops are a problem with two rails because the loop connects the two rails together. In a two-rail setup, that does allow excessive current to flow. With three rails, the loop also connects the outside rails together. But, in a three-rail setup, the outside rails are intentionally connected together anyway; so no harm is done.
Saq,
You are making perfect sense in the world of two-rail, as lionelsoni has observed. There are reasons for the popularity of three-rail, however, and you have stumbled onto one of them.
At any point on a three rail layout the "difference in potential" (voltage) that drives the locomotive is between the center rail and at least one of the outside rails. (Usually both of them, except in special circumstances.)
Assume that the current is DC for a moment, and trace a loop, keeping in mind that as long as the center rail is positive and the outside rails are negative, the loco can pick up power from the center rail, route it through the motor, and return it through the wheels to an outside rail. Once you understand this, the fact that alternating current (AC) is commonly used makes no difference.
The switches (or "turnouts" as some call them) maintain the same logic, with small gaps and/or insulating sections keeping things from shorting out where they cross; and dual (or more) pickup rollers providing "bridging" of potentially troublesome sections by allowing at least one pickup always to be in contact with a "live" portion of the center rail.
Hey!! I understand it now . The main power source is the center rail insulated from the two outside rails. I can only get a spark or short if the center rail makes a "ground" to any one of the two outside rails. Thanks for clearing me on this!!
That is why it was so easy for Lionel and others to provide you a figure eight layout with a crossover track that was easy to set up and by golly it worked great! The dang train would around as soon as you turned it on, just as they planned.
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