Unwanted Caboose Uncoupling


E

ethiesen

New Member
I have one permanent uncoupler magnet on my main line that loves to uncouple my cabooses. The trains expand and contract like an accordion when in motion so I suspect slack is causing the problem as the last car travels across the magnet. I've added an additional 0.25 oz weight to the car giving me 0.97 oz total which is slightly above NMRA recommendations (at least as far as I can tell). Even with the added weight, I still have problems losing the caboose as it travels across the magnet. I don't seem to have the same problem with any other cars. Coupler heights appear to be close but then again I don't have a gauge to double check for accuracy. Any thoughts?

Eldon
 
I'm assuming you're using Microtrains couplers, they have a spring pushing the coupler forward I believe?
I'd look at changing the cabeese couplers to a non sprung type, I forget the number as it's been years since I worked in that scale.
Oh another fix might be the small spring that goes on the axle end to create drag?
 
I'm not sure which couplers are on the caboose. It's an Atlas Trainman product. I know it's not a horn-hook but outside of that I'm not familiar with the n scale options or what they look like. Another thing I can see is that the couplers are mounted to the body and not the trucks.

I've experimented a bit more. If I add a trailing car or two behind the caboose, it will not decouple (nor do the other cars). If I run the caboose only behind the engine, it does not decouple. I going to start adding cars between the engine and the caboose to see if there is a magic number when the decoupling begins.
 
Does the caboose have metal axle wheels that are attracted to the uncoupler magnet? This could be the cause of the uncoupling when pulled as the last car in the train. When the metal axles are pulled backwards the are creating the slack.

Keep us posted.

Greg
 
Yes to the metal axle/wheels. I recently replaced the plastic wheels with Fox Valley metal wheels and axles on all my empire (about 20 cars!). I also misspoke in my other post. I hooked up my caboose only to an engine and left it running. I returned an hour later to find the engine pushing the caboose. Also some further research indicates that Atlas cars might use Accumate couplers instead of Micro-Trains couplers. As I look at my other cars in more detail, they all seem to have Micro-Trains trucks with couplers as one unit while the caboose coupler is attached to the body. That may be where the issue lies.
 
Just thought of one other item to check and that's if the caboose's coupler is at the proper height.

Greg
 
I don't have a gauge yet but by eyeballing them they seem relatively even although not perfect. What is the "trip pin" you are referring to? Is that the metal air hose used to open the knuckles?
 
Yes, the trip pin is disguised as an air hose. I have some Atlas cars in HO, which use their Accumate coupler. I have had instances of them staying open after reversing or when going down a grade with other cars behind and then not closing once the weight comes off, causing a decoupling.
 
This is a picture of the Accumate coupler. It is in 2 pieces, a top and a bottom with both pivoting about a peg in the gearbox. One piece has the hook of the jaw, the other the guide and lock that holds the opposite coupler in place when they close together. Each piece has a curved integral plastic spring that not only centers the coupler but also closes the jaw, no metal spring to lose.



It should be compatible with your other couplers but just check to see how well they holding together.
 
Eldon:

I believe that I read somewhere that KD discourages having uncoupling magnet(s) on a mainline just for the problem that you maybe be having. Perhaps try removing it and run the trains and see what happens.

Just a thought.

Greg
 
All good suggestions. I also found this solution on YouTube but it's a bit (or two) above my current pay grade: https://www.youtube.com/watch?v=akdnhLfPJb4&list=LL8_5FilDu7-x03jx8aEaW1Q&t=6s&index=5 . He uses a servo attached to an Arduino to raise and lower the magnet.

I was able to pull apart the coupler and can confirm it is an Accumate. But yikes, trying to put it back together was fun.

Before going too far, I think I'll buy a coupler gauge to check both the height of the coupler and the pin. And I can use that to attack my next problem: why some cars won't uncouple at all.
 
I mounted magnets under the track in some sidings and also on a passing siding in a town where I do a lot of switching and did have the caboose problem a couple of times when a train through the passing siding. One was a caboose that came with metal wheels with steel axles. The magnet was so strong that the caboose was just about held over the magnet. The wheels were replaced with metal wheels with plastic axles and the problem was solved. Another thing you might consider is to use a piece of spring metal on the axle to cause just a little bit of drag on the wheels. This solved the problem on another caboose that would unintentionally uncouple. Most of my cabooses are wood kits and the trucks are sprung Kadee trucks and there is just enough drag that they do not uncouple.
 
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After reading and pondering all the great advice here, I had the "brilliant" idea to replace the metal wheels and axles with the original plastic wheels and axles that came with cabooses. Although it's not a perfect solution since there is still an occasional decoupling, the plastic wheels seem to provide just enough drag to keep everything together.
 
Micro trains offers a restraining spring to put on the axles of cabooses, to help prevent them from uncoupling. It will also help the in-and-out movement from the coupler springs as the train moves along.
 
Thank you. I found them on their website. The description doesn't say how many springs come in a package or in fact how many are necessary but I'll give them a call today and get some more information.
 
ethiesen said:
Thank you. I found them on their website. The description doesn't say how many springs come in a package or in fact how many are necessary but I'll give them a call today and get some more information.
Click to expand...

One per axle, probably only a couple of axles would be needed.
 
Thank you. Good to know. I've got them on order already along with an N scale coupler gauge. It'd be good to be able to use metal wheels and axles. I was hoping down the line to install some lights in the caboose. That is whenever my skill level gets that far. A long way to go.
 
If all else fails, you can actually remove the trip pin from Accumate couplers. They're not a structurally necessary part of the coupler. That would mean you couldn't automatically uncouple the caboose, but it also wouldn't keep uncoupling as you run the train.

BTW, you cannot remove the trip pin from MTL couplers, as they are part of what actually holds the coupler together and are structurally necessary.
 
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