Building Sn3 and N Worlds

By Stationmaster

Switch motor - making the turnout turn

This is a very boring photo of an electric switch motor. But after showing the details of the turnout or switches and the switchstands, I thought I would show how these things actually work. The layout is built on expanded styrofoam sheets. Very easy to carve into land forms, pretty strong, and stable. But not very strong in tension or the forces a switchmotor would exert. So I mount the motor on a small piece of plywood which is glued to the bottom of the styrofoam under the switch, spreading out the stress. The wire rod you see extends up through a hole and goes through a small hole on the throw rod that holds the turnout or switch blades - the ones that move directing a train to the left or right. Because of the depth of the structure, I had to add an extension to the wire. Actually, because of the length, the stock wire was too flexible so I made a new wire from thicker wire, and then soldered on a thin piece of wire at the top to match the hole in the throw rod.

So this blip shows the motor on its side while final installation will be vertically under the table. I chose this sort of construction so that I could construct all the switches on my desk rather than having to lay under the table and work over my head. Did that before - not fun. Here is the visual - lay on your back, reach up underneath the table and drill and screw in the switch motor. Then solder on the wires having hot solder drop on your chest. You really don't notice that until it burns through your favorite shirt onto your skin. Then you jump and hit your head and start to bleed. Nice. This is why my wife makes me wear a hard hat when working under the table - she got tired of patching me up.

So the wires? Well - the outside red and green wires power the motor. The polarity is switched by an DPDT toggle switch, making the little wire rod go right or left, aligning the switch blades. The other red and green wire powers the frog - the place on the switch where the tracks cross. This has to be electrically isolated and also change polarity so there is no short when the locomotive runs over it.

So why go to all this trouble? This sort of motor moves very slowly and quietly. And the switch blades move very slow - like the real thing. The remote DPDT toggle switch is on the layout fascia so I can remotely change the switch.

Sorry - way too much writing. I need to get back and make the rest of the switch motor mounts. Only 15 to go.

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