# Cars not uncoupling at crest of the hump (N Scale)



## videobruce (Jun 15, 2011)

Long story short; the 'trip pin' of the lead car doesn't appear to be opening up when coupled to the 2nd car at the crest of the hump. Separately that trip pin does open when not coupled, but together it doesn't appear to be moving. thou it's hard to tell. One does, the other doesn't.

I've move the uncoupling magnet 'up' closer to the crest, but that hasn't changed anything.

Now if I push the string of cars with my hand the cars usually uncouple by the 'jerkiness' of my hand (for lack of a better term).

The uncoupling magnet is 1/2" from the crest. Lastly, I believe I made the crest to 'broad' making matters worse. But that is reaching for a reason this isn't working. See the attachments.

Hope all of that made sense.


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## DonR (Oct 18, 2012)

I used graphite or white lube powder to lubricate
the couplers. That can help. Also, the orientation
and height of the 'hose' matters. A piece of steel
plating UNDER the magnet functions as an
'amplifier'. Makes the magnet 'stronger'. But,
then, some couplers are just plain 'onery'.

Don


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## videobruce (Jun 15, 2011)

The lube powder would be a non starter, I would have to do that to 500 couplers.


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## OilValleyRy (Oct 3, 2021)

How are you uncoupling exactly? Like a spotting manner?

I’d put the magnet at the bottom of the slope. I’ll try to explain how I’d do it:

Approach magnet. Stop when couplers open. Slightly reverse. Then push forward so couplers cannot recouple once off the magnet unless pressure against them is released. Continue up the hump, which automatically maintains pressure. At the crest, gravity does the rest. 
Rinse. Repeat.

I’m assuming MT couplers will do this like Kadees do in HO. I never did a hump yard in N.

Side note: Did you ever figure out the interference problem with the servo turnouts?


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## videobruce (Jun 15, 2011)

The same as the prototype, a constant forward motion. It worked 25 years ago with my 1st scenic'ed model railroad (same magnet).
i understand your method, but then it would turn the hump into a flat switching yard where they just 'kicked' cars.

I have Neodymium magnets ordered (10x5x2mm).

As to your other question, not really. Some engines are just 'dirty-er' than others. Kato were the best, the older Chinese Atlas were the worst (but not all). Twisting the cable feeds (one twist per inch) was/is just not practical .


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## DonR (Oct 18, 2012)

I agree with Oilvalley's uncoupling method. That's the way
it works best in HO, and I would think the same for N.
It makes sense. Keep in mind when train is in FORWARD
motion when moving over magnet the knuckles are clasped
together under tension. The knuckle design would affect
the resistance to opening. Cars behind the coupling would
add to the resistance, even the car wheel material (plastic
or metal) would matter. In my opinion,
it would take a strong magnet to pull the 'hoses'
in a way that would overcome the knuckle tension friction
when in FORWARD motion.

Don


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## OilValleyRy (Oct 3, 2021)

DonR said:


> I agree with Oilvalley's uncoupling method. That's the way
> it works best in HO, and I would think the same for N.
> It makes sense. Keep in mind when train is in FORWARD
> motion when moving over magnet the knuckles are clasped
> ...


That’s the reason for the short reverse. It lets the couplers fully open. Then when moving forward, either flat or uphill, the knuckle portion is off to the side. If you make a pair of couplers with your hands, like fingers locked, then this results with palm against palm. 
Of course worn out centering springs will create problems. I imagine MT couplers have wear & tear issues as well that could impede this. 
I may have to shim track on my N scale switching layout to tinker with this to see if I can replicate the issue Bruce is encountering. 
If it’s happening with just one or two cars, or only with one loco, I’d say coupler issue.


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## videobruce (Jun 15, 2011)

I moved the magnet (again for the 4th time) to the crest (about 3/4"). Now, some of the cars are now uncoupling as they should (AKA prototype). The others are tightly locked even when stopped over the magnet and me jiggling the two cars. Which I don't get. 

A "short reverse" while I understand that is the way they were designed for flat switching, doesn't work in a hump situation. That turns it into flat switching. 
I'll have to just wait for those magnets from China.


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## Mixed Freight (Aug 31, 2019)

Magnetic uncoupling: Anything OTHER than flat, level, and straight, and you *will* have problems.

Even more so than just flat, level, and straight.


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## OilValleyRy (Oct 3, 2021)

You can do it with a hump. You uncouple at the base of the hump, getting the couplers palm against palm, and push them up the hump in that configuration. When they reach the crest they’ll run down your yard ladder. But they have to be uncoupled flat & level first. Uncoupling on any sort of slope won’t work in any scale other than 1:1.


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## JeffHurl (Apr 22, 2021)

It's also possible that the cars that aren't uncoupling simply aren't the style that can be uncoupled magnetically. For example, if the "air hose" is copper, it won't work no matter how strong of a magnet you use.


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## kilowatt62 (Aug 18, 2019)

I would be looking for stuck, glued, or nonoperative knuckles first. Then whether the trip pin/air hose is magnetic.


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## videobruce (Jun 15, 2011)

Why would they not be magnetic? Why copper, it's more expensive.


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## kilowatt62 (Aug 18, 2019)

videobruce said:


> Why would they not be magnetic? Why copper, it's more expensive.



All Kadee trip pins are in fact magnetic. At least to my experiences.
I wouldn’t be surprised if there are some brands/styles from other manufacturers that are not. 
Copper? Yeah, I agree, not probable but, aluminum or some other pot metal is. 
I’ve come across more than a handful of non Kadee couplers whose trip pins had actually worked themselves loose. Some to the point of no longer operating the knuckle. 
I’ve also seen many a knuckles glued closed, more so from to much of or, the wrong glue at the knuckle springs. 
While I agree in absolution with what others here say about the magnet needing to be just before the beginning of the hump, it doesnt matter where it is if a coupler is faulty. 
All I’m saying is, check knuckles before all else. Then try putting the magnet where suggested by those who've already played the hump track game.


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## JeffHurl (Apr 22, 2021)

I have cars with knuckle couplers that have the little air hose thing, and the knuckles don't even open at all.


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## videobruce (Jun 15, 2011)

The portion that I have 'dug out' is getting way too long as it is. I'm going to wait for these stronger magnets and see how they work before I extend this ditch any longer. 

Maybe I should start a thread about what magnets everyone is using to uncouple their cars.


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## OilValleyRy (Oct 3, 2021)

A comparison topic would probably be very helpful to all, unless there is a sticky topic already? I’ve seen Larry Puckett demonstrate those NeoDim..Dyn…Those lol versus Kadee under track magnets in HO. 
In N I used those Kato uncoupler tracks, with the mag between the rails… and find their reliability less than desirable.

A multi-scale (N, HO, O) topic collaboration between several members would be nice, like an article in a mag.


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## Mixed Freight (Aug 31, 2019)

MTL (Kadee) magnetic uncoupling system was developed before Neodymium (rare earth) magnets came to market. The MTL magnets are the old standard ceramic magnets that have been around forever, and specially polarized to work properly on the coupler trip pins. Unfortunately, the magnets are not that strong, and unless everything is installed, adjusted, and dry-lubricated with pin-point accuracy, do not always work that great. And they're a pain in the posterior to properly install in the track to boot.

20 years ago I did some experimenting with rare earth magnets for my N-scale layout. After trying out a few different sizes and shapes, I settled on some 1/4" dia. x 1/8" thick disc magnets. The 1/8" thick works great for 1/8" thick cork roadbed. For an uncoupling station, you need two magnets, one directly under each rail. Simply punch a pair of 1/4" diameter holes at 3/8" centers in the cork roadbed (far easier SAID than DONE!), install the magnets, then lay the track over it. You can later ballast the track too, no big deal. The magnets operate the trip pins with some REAL authority! They don't take "no" for an answer! Incidentally, you want a snug fit of the magnets in the cork, so they stay put when you push them in the holes.

Some other folks found some nominal 1/8" dia. x 1/8" thick disc (or possibly rod) magnets that also worked good. These could be installed AFTER laying the track, by simply drilling a pair of holes in a tie space. One hole up against each rail. Then push the magnets in the holes. You can even do this method after ballasting. I never tried this size of magnets, but have no doubt that they will also work quite well. One magnet supplier I found offers .100" diameter x 1/8" thick disc magnets that should do the job. I'd drill 3/32" dia. holes in the cork in order to provide a snug fit for these particular magnets.

Neodymium Magnet Discs | Neodymium Disc & Cylinder Magnets

Kadee's (& MTL's) coupler patent ran out some time in the late 90's/early 2000's, and so the opportunity arose for other manufacturers to start making their own, similar couplers. But in my opinion, Kadee/MTL are still the best designed couplers out of everyone else as far as magnetic uncoupling goes.


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## videobruce (Jun 15, 2011)

MT are better than Atlas's system. I even had a CSR from Atlas say so. I would be nervous about drilling holes next to the track.


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## videobruce (Jun 15, 2011)

I moved the magnet up again another 1/2 to 3/4 inch just past the crest and it improved uncoupling. Up from around 25% uncoupling to around 75% of the cars.
With the MT magnet 50x7x3mm (measured) cars now separate at the very end of the magnet meaning to move it up further will require a longer or just more short magnets.


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## wvgca (Jan 21, 2013)

it may be that the crescent is too sharp to allow clearance in the couplers to disconnect ... simply put the grade is in too small of a distance, the couplers jam, and then don't unhook .... the only real fix is to redo the track allowing for a longer grade distance ..


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## videobruce (Jun 15, 2011)

Understood, but I'm reasonable sure that isn't it. The longest cars I have are a dozen or so 60 footers. The others are 40's & 50's and some less. I have a long wait for those magnets from China.


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## Old_Hobo (Feb 20, 2014)

Mixed Freight said:


> Kadee's (& MTL's) coupler patent ran out some time in the late 90's/early 2000's, and so the opportunity arose for other manufacturers to start making their own, similar couplers. But in my opinion, Kadee/MTL are still the best designed couplers out of everyone else as far as magnetic uncoupling goes.


THIS!


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## videobruce (Jun 15, 2011)

I agree Atlas are not that great, but at least they aren't Rapido.


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## videobruce (Jun 15, 2011)

I received my 1st set (of 2 sizes) of Neo magnets I ordered from China (a week earlier than the earliest estimate no less).
I tried these Neo magnets and they pull the couplers together no matter which way I placed the magnets. Instead of uncoupling they do the opposite. I tried taking some pics but it doesn't show up as well as I would of liked.
Compare those w/ the 3rd attachment. MT's magnet works, these super magnets do not. I even stacked two and other then it was stronger (probably because of height) the 'trip pin' still gets pulled inward, not outward on both cars. (Those magnets were not secured down. When the trip pin came close enough the magnet lifted up to the pin.)


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## JeffHurl (Apr 22, 2021)

I have a theory, but it's just an educated guess.

I believe the MT magnets are designed such that the north and south poles are perpendicular to the tracks. I say this because a metalic object is attracted to either pole, but not the center.

If your new magnets have the poles oriented parallel to the tracks, or even oriented up and down, they wouldn't work correctly. I believe you need a pole close to each rail.

Try putting one of your new magnets directly beneath each track, rather than one or two magnets in the middle.

The leading coupler of the trailing car gets pulled one direction, while the trailing coupler of the leading car gets pulled the other.

OR... maybe orient one of the new magnets perpendicular to the tracks instead of being parallel.


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## JeffHurl (Apr 22, 2021)

To test this theory, lay the MT magnet on a table. Drop a straight pin onto the magnet. If I'm right, the pin will align itself perpendicular to the length of the magnet.

Then do the same thing with one of the neo magnets. I'm guessing the pin will come to rest parallel with the neo magnet.


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## videobruce (Jun 15, 2011)

I'll try those tests and report back.

In my situation, magnets can only be between the rails as they are now with a MT magnet, or outside the rails which I did try, but since they weren't glued down the test was meaningless. There is no under the table access since this (the crest) is up on a raised portion probably four inches above the table level which consists of 3/8" ply and 1/2" rigid foamboard.


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## OilValleyRy (Oct 3, 2021)

I believe the neo magnets need to be under the rails, opposite each other, not center line. Centerline they’ll pull the pins toward center. You want them pulling pins rail direction of course. At least that’s how I’ve seen them used by Larry Puckett.


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## videobruce (Jun 15, 2011)

Not practical to do so in my situation & configuration. I should of stuck with MT own designed magnet. I do have 2 half's of the 2nd magnet I will dif out of storage and see if a longer magnet structure works any better with the 25% of the cars that appear to be 'stubborn.


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## videobruce (Jun 15, 2011)

I got the suggestion elsewhere (and link) to those way too small magnets. 

Anyway, I temp placed two stacked magnets against the rail to see what happens. Nothing!


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## JeffHurl (Apr 22, 2021)

Another twist... The following "old versus new" is based on HO, but the concepts are universal.

The older (horn hook) couplers used magnets differently than the way newer couplers use magnets.

In the older "horn hook" magnetic uncoupling, magnets were used to push up on one car's coupler, while pulling down on the other coupler. To do this, a tiny magnet was inside every coupler, with one pole on the top side and the other pole on the bottom. I don't know which way they were oriented, but for the sake of this discussion, I'll arbitrarily say they were situated such that north was on top and south was on bottom. Then, the uncoupler magnet, that sat between the rails, actually had 2 magnets, each one in the dead center of the track. One was "North pole up" and one was "south pole up." Since the magnets in the couplers were all "south pole down," when a car passed over, one coupler would be pushed up while the other was pulled down, uncoupling the cars.

The newer knuckle couplers are different... They uncouple by imparting sideways pressure on the couplers... one gets pulled toward one side of the tracks, while the other coupler gets pulled the opposite direction. The little metallic "air hose" on the bottom of each couple is pointed slightly in one direction. There is no magnet in the air hose, so each coupler will be attracted to either pole of a magnet. By having the poles of the uncoupler magnet near each rail, the couplers will get pulled to whichever side their air hose is pointing toward, as there is more metallic mass whichever direction the hose is pointing.

So if someone is telling you to put all the magnets dead center, they are probably doing so based on how the older "horn hook" system worked. The older horn hook decoupling system was quickly antiquated due to the complexity of manufacturing (having to insert a magnet into the coupler shaft).

The older style is more reliable, but very expensive to produce. The newer style is cheaper to produce and more prototypical, but also more finicky and delicate to get working reliably.


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## JeffHurl (Apr 22, 2021)

Another idea... Try to use 1 magnet, but lay it between the tracks rotated 90 degrees (shortways). You may need to cut off a small section to make the magnet shorter. Doing that won't ruin the magnet. Give that a try just to see if the couplers start behaving better than when the magnet is longways.


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## videobruce (Jun 15, 2011)

When I held the magnet sideways and moved it to the coupler, the same thing happened, it drew the coupler to it vs repelling it.


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## JeffHurl (Apr 22, 2021)

Yes, that is what you want, assuming you have knuckle style couplers. The trick is having a magnet on either side that is far enough away from center, that it only pulls one coupler in that direction... but close enough to center that it actually DOES pull it.

If you look straight down, you will notice that the air hose points slightly toward one side. When coupled, one air hose points starboard, and one points port. The port side magnet pulls the coupler with the air hose pointing port. The magnet on the other side pulls the other coupler in its direction.

Here is a really good video describing the process. You can skip to about the 9:00 minute mark for a very good demonstration. It's HO scale, but it's the exact same mechanical process for N scale.


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## videobruce (Jun 15, 2011)

I would have to try it.
I ordered another pair of MT magnets since that seems to be the best solution. Most of the cars uncouple fine. These micro magnets don't seem to be the answer in spite of others liking them.

I received the MT magnet set (2) and discovered that the N & S poles are centered around the *sides* of the magnets which makes sense based on the direction the 'trip pin' is facing.
On these small silver bar magnets the poles are on the* top & bottom* making them semi useless unless one positions them standing up om their side which isn't practical in my situation. The cost difference in nil.

The solution was to cut one in half and extend the length which seems to solve most of the problems. It needed a longer reach past the crest which was the last problem. I still have a few exceptions which I'm dealing with the specific cars.


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## Old_Hobo (Feb 20, 2014)

JeffHurl said:


> The older (horn hook) couplers used magnets differently than the way newer couplers use magnets.
> 
> In the older "horn hook" magnetic uncoupling, magnets were used to push up on one car's coupler, while pulling down on the other coupler. To do this, a tiny magnet was inside every coupler, with one pole on the top side and the other pole on the bottom. I don't know which way they were oriented, but for the sake of this discussion, I'll arbitrarily say they were situated such that north was on top and south was on bottom. Then, the uncoupler magnet, that sat between the rails, actually had 2 magnets, each one in the dead center of the track. One was "North pole up" and one was "south pole up." Since the magnets in the couplers were all "south pole down," when a car passed over, one coupler would be pushed up while the other was pulled down, uncoupling the cars


I had never heard of magnetic horn hook couplers before, and I have been into H.O. model trains since 1986….I guess old dogs can learn something new…. 😁

I always though the pins on the bottom of horn hook couplers ran in a special uncoupling section of track that pushed them apart to un-couple…..


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## videobruce (Jun 15, 2011)

The other problem was Atlas want-to-be magnetic couplers that didn't work. I had to change out 17 pair of truck mounted Accumate couplers because they weren't separating.


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## Old_Hobo (Feb 20, 2014)

Yeah, Atlas uses Accumate couplers on all their rolling stock and locomotives now…..I change them out to Kadees as soon as they are out of the box….


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