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Mechanically Operated Uncoupling Magnets.

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  • Member since
    April 2013
  • 917 posts
Mechanically Operated Uncoupling Magnets.
Posted by Southgate on Friday, April 6, 2018 7:06 PM

I posted a how-to thread years ago, but even if it's still here somewhere, the Photobucket pictures won't be.

I used these 3/8x 7/8x 2 inch magnets. I broke them in half, but you can use them whole. I'd recommend that.

 

Heres a simple picture of some of the components.

Pretty simple really, I used 3/8 Evergreen Styrene tube, glued it to a strip of flat styrene as wide as the magnet and as long. You can contact cement that to the magnet. THE MAGNET MOUNTS ON IT'S EDGE, NOT FLAT! They are polarized over the EDGES.  Fill the magnet end of the styrene tube about 1/2 inch deep, and put a length of piano wire in it.  I coiled that end of the wire, optional. You can see on this one I had to lengthen the piano wire. You want this wire to be flexible.

I use plywood blocks to mount this gizmo to the subroadbed with a sheetrock screw. Drill the screw holes so the screw can turn inside the block.these holes work best near a corner of the block, but far enough from it that the block mounts flat up unser the subroadbed. Don't tighten real hard art first. Once placed under the track, pivot the block to and fro until the magnet raises and drops freely.

A 7/16 hole is drilled in the center of the block and 7/16 K&S brass tube inserted into it. The magnet-tube is simply dropped into the brass tube.

NOTE! My roadbed and subroadbed add up to 1 1/4 thick; 3/4 thick subroadbed, 1/2 thick homasote roadbed. However thick your roadbed and subroadbed is you have to allow the magnet to drop at least 3/8 below the lifted position.

In resting position:

Raised. This would come up and contact the underside of your railroad ties.

I use a 15/32 drill bit to drill 2 holes in my layout where I want the uncoupler, at each end of where the magnet will go. (With the track in place, mark with a pen the inside edges of the rails as guide lines. then remove section of rail and proceed.) Then I use a jigsaw to cut out the gap between the holes for the magnet. You have to make sure this hole is CENTERED under your track.* The magnet runs parallel to the track. Test the fit of the magnet in the gap to be sure it has room to raise and lower freely. I cover the hole with a piece of index card glued in place, and replace rail. Once ballasted and all, the whole thing is invisible under the ties. So MARK where it is somehow!

In the control panel, 1/8 holes are drilled to allow a piece of 3/32 gas welding rod to pass through it, and whatever bench work framing there is, to actuate the magnet by lifting it up. I tried 1/16 for the whole actuating rod, it's too flexy. Aim your drill bit to point at approx 1 inch to one side or the other of the piano wire hanging down from the uncoupler. This is actually fairly forgiving since the welding rod can flex some or be bent a little to suite angles. I bend the control panel end to suggest an uncoupling lever on a car. I angle the end of the lever in toward the panel so it doesn't catch sleeves. 

 

Under the layout: Note the collets on the piano wire just above and below a loop under this one: (It's made of different sliding components but works the same)

In resting position:

Up to uncouple:

I solder a piece of 1/16 gas welding rod to the 3/32 actuator rod, since it's thinner and easier to form a loop on the end. Place a collet on the piano wire...place the loop over the wire, put another collet below the loop, giving it room to jiggle freely. Also note the 1/16 rod coming down from the benchwork to support the actuator rod where it pivots for up and down action.

Something I didn't get pictures of, on the actuating rod, You also need to put collets at some points to keep it from sliding in and out of the control panel. They could even be on the outside of the face of the panel, and one elsewhere undernieth the layout, but you need them to limit in and out motion.

Some notes;

 If I pull a car up and uncouple it, and the knuckles didn't open far enough to use "Delayed uncoupling",I simply give the magnet a tap or two, the vibration usually opens them.

These uncouplers work best in straight track, so the 2 cars are not at any angle to each other.

Steel axles may probably be attracted to the magnets. I don't know, I dont have any.

These devices work best with genuine Kadee couplers, #5s work pretty well, #148 Whiskers work best.

Any number of variations could be applied to the design here, but this is how I do mine and once you get it in place and working, it's just super reliable. I personally really don't like "hand uncoulpling", skewers, any unnecessary reachin in.

 

 

*If you use the magnet uncut, at 2 inches long, you can slightly angle the magnet to the track, be sure the magnet slightly crosses under the track evenly. Then try a few uncouplings until you find the best spot for optimum uncoupling action, and mark it somehow. 

Hope this works for you or gives you some ideas. I know one member mounted the magnets to solenoids to lift them, but I like it as simple as it can be and still work well. Dan

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