Kadee uncoupler
#1
In the new north yard hidden behind tables resulting in limited access Kadee uncouplers have been installed the first time. They work fine and I had to learn that not all couplers have been installed and adjusted as carefully as it should be. That has been corrected and switching without "the big hand" works fine now.

One track is sometimes used as a through track when I sit in my chair and watch a train running around. That track has two uncouplers needed when switching. Some cars have a tendency to uncouple when the train passes over the uncoupler with constant speed. A train of five cars will have one false uncoupling in about five rounds. That is an error rate of 1 in 25 or 4%.

I did not understand what kind of adjustment should be checked in that case. What is out of alignment when a coupler uncouples when run over the magnet at constant speed?
Reinhard
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#2
Reinhard, it most likely isn't the coupler adjustment. Small changes in the speed of the loco as it moves along the track combined with variations in the "free-rolling-ness" of your rollingstock causes slack between couplers on occasion, and if the slack couplers happen to be above a magnet, then you get the unwanted uncoupling. Honestly, free rolling cars are the bane of magnetic coupling. You are better off having cars with a touch of drag in the wheels and trucks. I have never tried this, but have read that friction can be added by cutting a kadee coupler spring in half, removing an axle from the truck, place the half spring on the axle end and then put it into the truck. Another solution would be a piece of small diameter spring wire under one axle, then up over the truck, then back down under the other axle. Point is, the friction helps keep the slack out of the couplers as the train rolls along.

YOu can experiment with this... take a car that doesn't roll very well and put it on the very back of a train. Then run the train over the magnet as much as you want. It is almost guaranteed that you'll have no unwanted uncouplings because the non-free-rolling car on the back will keep all the slack out of all the couplers.

My solution was to use the permanent magnets only on spurs, and electromagnets on the "main" where trains routinely travel. I also weighted my cars at about 1.4 times the NMRA recommendation, which causes more friction in the trucks.
Three Foot Rule In Effect At All Times
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#3
Another problem can be steel axles on the cars. The trailing car gets pulled onto the magnet and catches up with the car ahead and the couplers open. That is why they make electromagnets. You could try adding the drag to your cabooses. Kadee used to sell springs to add to N gauge cars.
Also: watch out where you put magnets in sidings. If you put one a whole number of cars from the bumper, you will never get them coupled.
David
Moderato ma non troppo
Perth & Exeter Railway Company
Esquesing & Chinguacousy Radial Railway
In model railroading, there are between six and two hundred ways of performing a given task.
Most modellers can get two of them to work.
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#4
Good thoughts... lots of intricacies involved with the magnets. And you're right, steel weights and screws in the cars can also pose a problem. All my cars have lead weights, brass screws, and non-magnetic wheelsets.
Three Foot Rule In Effect At All Times
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#5
Thanks for the feedback. I did read in my books that the fixed magnets are not the best choice for through tracks. It is not a big deal because my layout is mostly a switching layout only. I do run a train on rare occasions around the room only. So it is acceptable for me but the recommendation not to place the fixed magnets in trough tracks is a good one!
Reinhard
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#6
For the times you want to just sait back and let the trains run around in circles, I like BR60103's idea of adding some drag to the cabooses, well, assuming you are using cabooses. If not, maybe make a special freight car with drag in the trucks and use that as the last car.
Three Foot Rule In Effect At All Times
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#7
Gary, unfortunately LAJ and PHL both run without cabs. But I think about a wire under the trucks of the cars pressing on the axis like some pickups do. That might be an easy soft break. That would also improve coupling of single cars. They have a tendency to roll away when they are softly hit for coupling.
The additional engine power should be no problem with a max train length of five cars (2 * (engine + 5 cars) is the length of the pier warehouse).

btw. I will use under the track uncouplers in stub tracks and electric uncouplers in other tracks when I do the next rebuild of the southyard (old part). I really get used to uncouplers in the north yard (new part under construction) after I adjusted some misaligned couplers.
Reinhard
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#8
faraway Wrote:Gary, unfortunately LAJ and PHL both run without cabs. But I think about a wire under the trucks of the cars pressing on the axis like some pickups do. That might be an easy soft break. That would also improve coupling of single cars. They have a tendency to roll away when they are softly hit for coupling.
The additional engine power should be no problem with a max train length of five cars (2 * (engine + 5 cars) is the length of the pier warehouse).

btw. I will use under the track uncouplers in stub tracks and electric uncouplers in other tracks when I do the next rebuild of the southyard (old part). I really get used to uncouplers in the north yard (new part under construction) after I adjusted some misaligned couplers.

A couple of techniques I use instead of electromagnets:

1) Mount the under-the-ties uncoupler on a hinge or a push-pull slide. This allows the magnet to be moved enough where it won't uncouple until I am ready to move it into place. It doesn't really take much movement sideways, and a 45 degree drop is also plenty to prevent unwanted uncouplings.

2) Use cylindrical rare earth magnets (I use 1/8" diameter x 3/8" long) mounted in opposite pairs vertically flush with the top of the ties. These have a fairly limited gathering range along the rails unless you install several pairs down the rails. And with nothing under the track center, steel axles and weights are not affected much. The downside of a single pair of rare earth magnets is that fairly accurate spotting (within an inch) is required for uncoupling. The upside is the easy installation (two 1/8" holes), out of sight unless you mark the position, and much cheaper than Kadee magnets.

The rare earth magnets won't totally prevent unwanted uncouplings - depending on the situation where they are mounted - but the slack has to occur within plus/minus 1/2" of the magnet location for uncoupling to occur. If mounted on a downgrade or similar situation, you are likely to have slack regardless.

my thoughts, your choices
Fred W
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