Tuesday, July 20, 2010

Disaster Prevention

A while back, I made a post describing how I built a drop bridge to span the entry door to my layout room.

At the end of that post, I mentioned the need for some type of interlock to prevent running trains into the canyon while the bridge was down. After some searching for the right switch, I finally got around to working on that project. While the solution is rough looking, I'm very happy with how it performs. Here's a short video showing the interlock at work:


The wiring is very simple. What I did was cut a gap in each rail far enough back from the bridge to allow any loco to come to a stop before plunging to destruction when it reaches the unpowered track section. Then I ran a feeder wire from one leg of the powered track section to the switch. It's a normally open switch, so the lip on the bridge has to depress it to allow power to flow to the bridge and each approach section. The switched leg feeds power to both approach sections and the bridge through three separate feeders-all attached to the switched leg. The power reaches the far side of the bridge by way of a wire fastened to the door frame.

I know there are more elegant solutions, especially to powering the far side approach. I may investigate that in the future, but for now, I have made my layout a safer place for the trains that operate there. That's a good thing. And on top of everything else, it was inexpensive-leaving more money for coal gondolas!

Jim

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