HO scale switch machine

Dean’s been in touch and shows us how he installed his HO scale switch machine:

“Al, cheers from Dean in New Mexico!

Today I want to show how I installed and wired the Atlas HO scale /N Under-Table Switch Machine, which is available from Amazon and others.

This is a very versatile machine which is easy to install and wire.

Since it is an under the table mount, it is not visible and gives a more realistic looking layout.

I used #6 switches throughout this layout and the ones I used didn’t come with machines.

I used the Atlas switch machines in two places on my N-Scale Conejos Valley Railroad, in a usual under-table installation and in a hidden above-table installation with a linkage.

The linkage and switch machine will be hidden with scenery later.

turnout points installation

In the photo below I show a mockup showing how you wire this machine to its controller (on the right). You use three wires.

The center one is the common connector and I usually use a green wire for this.

For the other two wires, I use whatever colors I have at hand.

There are two solenoids inside the machine and the controller makes a momentary connection to one or the other to drive the mechanism in one direction or the other.

If the switch operates in the wrong direction, reverse these two leads.

I’ll talk about the power supply, which connects to the screw terminals on either side of the switch controller, below.

wiring turnout switch controller

The photo below shows how I twist the three wires together using a drill machine. This gives a neat, sturdy, bundle.

wiring swtich turnout controller

First, I’ll show how I mounted the below table switch machine to the upper track. This was a normal type mounting.

Before I mounted the switch to the track, I had cut a short slot in the baseboard directly under the throw bar of the switch.

I screwed the machine on a 3/8” thick board using the screws that came with it. To make the mechanism accessible, I cut a hole in the two layers of Styrofoam that supports this section of track.

placing turnout motor on track

After the assembly was centered in the correct position, I held the machine and its board to the upper baseboard with a C-clamp.

placing HO scale switch machine on track

Then I drilled two screw holes through everything and put in two counter-sunk screws to hold the machine in place. These two screws will be covered with ballast so they won’t be seen. If I ever have to service the machine, I can find these screws and remove them.

turnout switch motor on HO scale track

I don’t like scrabbling around under the train table installing switch machines, so whenever possible I put the machine in an accessible spot.

You can see the second machine on the left of the photo below. It is mounted on two 3/8” boards that are then glued to the table.

When I put in scenery, I will cover the machine and the linkage with scenery. The throw bar of the switch is connected to the tongue of the machine with a thin, rigid wire which has a hook on one end (going to the throw bar) and a circle on the other.

The circle fits over the tongue and is held with a small nut which happens to just fit the tongue. The wire slides inside a styrene cylinder. I glued the end of the cylinder near the switch with hot glue after everything was adjusted.

HO scale switch machine

Below is a photo of the two controllers. These are connected to their respective machines with the three wire bundles and to the power leads to the power supply with the two wires off to the right.

power leads for turnout switch motor

More information on the installation of these two switch machines:

Hope that this has been instructive and that you give this machine a try in the future.


A big thanks to Dean for sharing his HO scale switch machine install.

That’s all for today folks.

Please do keep ’em coming.

And if today is the day you get started on your layout, with or without switches, the Beginner’s Guide is here.



PS Latest ebay cheat sheet is here.

PPS HO scale train layouts here if that’s your thing.

8 Responses to HO scale switch machine

  1. Brian Moretti says:

    The switch machines are nice
    I have 10 or so for sale

  2. Michael Ilkenhons says:

    Dean… Good post on your technique. I have 8 Atlas turnouts and one Peco. The Peco uses a CDU to supply the necessary to give the turnout a positive throw. It also makes the Atlas more trustworthy. I use mini DPDT toggle switches in place if the Atlas switch throws, which break and stop working. Just a thought for you.

  3. Mike says:

    Very good. Thanks for making it look like I could actually do this on my lay out

  4. Terry Miller says:

    Great idea attaching the machine to a piece of wood before installing under the table. I’ve spent a lot of fruitless time trying to screw the screws directly to the table. 9 out of 10 times, a screw will fall out before it’s in the wood and I must then spend time figuring out whether it fell into my shirt pocket or is laying around somewhere on the floor.
    Very good idea!

    Terry/Idaho USA

  5. Rick Shoop says:

    I would suggest that “using any available color wire with the green wire being common’ is going to make any troubleshooting more difficult. I suggest that for any given layout, you establish a color code, write it down in your layout notebook, and stick to it.

  6. William Swan says:

    Thanks for some insight, I am using Atlas switch machines and am going to tie the switch machines to relays controlled by an Arduino. I am always open to ideas on implementing this, Rick Shoop’s comment about color codes is very important, even my small layout would be a wiring nightmare if “any color” was ok. Thanks everyone!

  7. Rocco Maley from Haskell NJ says:

    That is a great Idea. I am using Atlas Deluxe under the table switch machines, but I have a bunch of left over original under the table switch machines which i think I’ll will give a try for some of my switches. I’m 78 yrs. old and my back cannot take any more bending and getting under the table like it use to. You sure helped us old folks out with this Idea. Also a great thank’s to Al for this great website. I find it better than books. Thank’s again. Rocco from NJ.

  8. william janmes palmer says:

    nicely done

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