Hey - it works! Permanent magnet uncouplers.

[thor]

A while ago I asked if anyone had tried using permanent magnets as uncouplers but got no replies.

So I went and invented a plastic snap in track fitting that would uncouple mechanically. Took a bit of fiddling to get it to work but eventually it did work with K-Line and Lionel uncoupling studs.

I always liked the idea of something that could be quickly positioned and repositioned to wherever you felt like doing some shunting, something cheap to buy, easy to make like the Triang Hornby 00 spring loaded ramps.

Anyway I was playing around with my invention debugging it and my wife came in to ask me to help her with a necklace and I put it down and 'SNAP!' the test truck coupling promptly uncoupled. Oh ho! The wifes problem was the magnetic fastener is so strong the chain links keep pulling apart. These tiny little magnets are about the diameter of a pencil eraser and 1/8" thick. They will easily pull down the uncoupler every time. I gotta find a source for these because its a much simpler solution than my mechanical one.

One less current drawing fixture to worry about.

[SPFan]

Thor, Do a web search on neodymium magnets. Here is one source http://www.kjmagnetics.com/categories.asp?PARTNER=Google.

These are things that let the Beep run upside down. Very stong for their size. How do you plan to control the uncoupling? In other words how do you turn them off?

Pete

[thor]

QUOTE: Originally posted by SPFan

Thor, Do a web search on neodymium magnets. Here is one source http://www.kjmagnetics.com/categories.asp?PARTNER=Google.

These are things that let the Beep run upside down. Very stong for their size. How do you plan to control the uncoupling? In other words how do you turn them off?

Pete

Pete they dont uncouple at speed, only if you park over them, the field is very tight and if you experiment with the magnet height you can get it so they'll just do the trick if the coupling is gently positioned directly overhead.

[Anonymous]

Hello Thor Interesting topic.You state you found a way using a plastic snap in the track fitting that would uncouple mechanically. Where will you place the magnet? Will you have to modify the track? The third rail would have to have a gap so that you can place the magnet. If your using it as siding to uncouple it probably would'nt matter. The idea is great because the thought of using all those uncoupling tracks would not be necessary. Placing the magnet below the table would be neater but you would still have to remove part of the third rail. I have used the magnets that were mentioned on my HO layout but for a different purpose. I had relays below my table and had the magnets stuck under my cars to activate them. I was using homasote as a table top. [^][:)]........Let us know how you make out with this project............Felix.

[Anonymous]

Sounds great. I use the older Lionel mag couplers that use a flat plate to control the pin freeing the couplers. Have you tried the mags on those type or just the newer ones with a disc on the pin arm?
B TW = does the mag attach itself to the underside of the middle rail? They have some superpower mags at kjm.

[thor]

QUOTE: Originally posted by felixg

Hello Thor Interesting topic.You state you found a way using a plastic snap in the track fitting that would uncouple mechanically. Where will you place the magnet? Will you have to modify the track? The third rail would have to have a gap so that you can place the magnet. If your using it as siding to uncouple it probably would'nt matter. The idea is great because the thought of using all those uncoupling tracks would not be necessary. Placing the magnet below the table would be neater but you would still have to remove part of the third rail. I have used the magnets that were mentioned on my HO layout but for a different purpose. I had relays below my table and had the magnets stuck under my cars to activate them. I was using homasote as a table top. [^][:)]........Let us know how you make out with this project............Felix.

Whoa Felix - one thing at a time!

The plastic snap in was a mechanical uncoupler I built. That was BEFORE I built the permanent magnet one. Seperate devices.

However neither of them involved cutting the rails in any way. Both of them just fit between the middle and outer rail. I simply put the magnet close to the middle rail, it was all it needed.

The mechanical coupler was an inverted L that is pivoted at one end and weighted or sprung at the other. As the uncoupler stud comes along it picks up that rail the weight of which then causes the pin to get pulled down. I also mounted the pivot such that the pickup roller arm would deflect it out of the way.

However given the probable variety and operating height and pressure of various uncoupler pin mechanisms, the magnetic solution is far simpler and better. I'd never have bothered with the other had I realised permanent magnets are so strong.

[thor]

QUOTE: Originally posted by SPFan

Thor, Do a web search on neodymium magnets. Here is one source http://www.kjmagnetics.com/categories.asp?PARTNER=Google.

These are things that let the Beep run upside down. Very stong for their size. How do you plan to control the uncoupling? In other words how do you turn them off?

Pete

Brilliant link Pete, thanks a lot! I didnt know the name of the substance those magnets are made from. Good prices too.

Now to answer your question after a week of experiments. My original over confident reply needs modification!

I had hoped that the uncoupling action would only occur if the coupler wasn't under load, in other words if the trucks were gently pushed over the magnet the pin would come down but if they passed over at speed with the weight of the train putting pressure on the pins they'd stay locked. I'd thought that any pulling would have locked the pins but it doesn't. Probably should but I'm not about to re-design the coupling!

Then I tried repositioning the magnet at differing heights to see if there was a point where the field was just strong enough to do the job if the truck was only nudged into place but not passed over at any speed and it DID work BUT there's too much variation between different brands and cars for that to work. Coupler 'thumbtacks' vary in height from rail by 1/8" (or more) and Lionel's plastic couplers operate with much less field strength than K-Line's which take quite a bit to drop.

Therefore I should mount the magnet so it can be adjusted in height to vary field strength and also to disable it. That's the next design problem to solve.

I had hoped that my design would be a 'one size fits all' but there's too much variation between tubular and fast track to make that possible, so whatever I come up with will probably have to be made to fit a specific rail type. Pity.

Thanks to you though I will soon have a whole bunch of magnets to play with instead of only two!

[thor]

QUOTE: Originally posted by grumpy4

Sounds great. I use the older Lionel mag couplers that use a flat plate to control the pin freeing the couplers. Have you tried the mags on those type or just the newer ones with a disc on the pin arm?
B TW = does the mag attach itself to the underside of the middle rail? They have some superpower mags at kjm.

Grumpy4
All I have to experiment with is 1 K-Line wagon, 1 MTH wagon and some Lionel carriages and locos but they all operate so I'm hopeful that other types of knuckle couplers will.

The magnet is mounted to the side of the middle rail, so its offset but it still does the job though it makes the coupler arms swing to one side a bit. Doesnt stop them disconnecting.

BTW FastTrack is hollow so I just found out I can actually insert a thin permanent magnet into that gap - you can see it by looking on the underside where the electrical hookup pins are.

I should probably concentrate on making my system fit FastTrack as thats what I'll probably end up with the most of. Also thats probably the trackage of the future so a simple removable uncoupler would be the most use for that.

FastTrack lends itself to the addition of stuff like a mechanical way of raising and lowering an uncoupler magnet. I already modified some of mine to take Lego plates so trackside operating mechanisms can be attached easily.