Inconvenient Truth About KD Couplers (216) 

When you click on an American railroader's vid and the first thing you see is a T9 (Greyhound) in Southern Railway livery and a C Class loco, you realise this man has taste!

I'm not much into model railroading outside of a couple computer simulations, but I just think it's amazing that you can find detailed videos on virtually any topic like this one.

Many thanks Larry not least for the quick response, the video is just what the doctor ordered to clarify the process with the Kadee parts to complete the job, many thanks - John

The Kadee coupler system works very well if you have no unwanted magnetic problems as we seen demonstrated here. I chose to use the Rix Products HO Scale uncoupling tool which needs to be placed between the cars and has magnets on each side and opens them without the need to pull forward then back up to clear the under the track magnet to re-couple later. You can uncouple cars anywhere so long as you can reach which then under the track magnets are needed.

For putting weights inside a vehicle I use Alloy Wheel Balancing Weights. They come in strips of 5 and 10 grams and are self-adhesive. Martin. (Thailand)

Related to this, it was impressed on me the importance of not using steel floor weights and steel axles or wheel treads. This was forty years ago when joining my local clubs timetable operating sessions using the standard Kadee uncoupling magnets for use with Kadee couplers. These aspects would usually be highlighted in magazine reviews as a caution that an item of rolling stock may cause problems as supplied.

It also helps to file down the mold parting line on the inside of the knuckles.

In my personal experience of 50 years with Kadee and Athearn cars, I have never had uncoupling problems after steel wheels and/or axles were replaced with non-magnetic parts. That being said, however, I do like the idea of a shorter "uncoupling zone" using the small rare earth magnets. Great idea!

Thank you for the great videos, Larry. Just got back to N scale after about 25 years. Things have changed so much snd a lot of new things to learn.

this is a great video !!! love watching your videos and learning from them. thank you for sharing these ideas

Excellent! I love that you have some UK locomotives and cars too. I found myself with several of those private wagons, which I think just drip character!

Thanks for taking the time to make these videos. Not all of them apply to my situation but I watch them all anyway. But when I do need to know something you always produce the goods.

Thanks for sharing this most interesting 'how to' on KD's & magnet uncoupling. This will be part of my next project on 'The AnneliesVille RR'. Most enjoyable and well produced video ! Cheers, Filip ( from France)

Great video and good description. Makes a lot of sense and easy to follow 👍👍👍

Great job, Larry. Always enjoy your videos

What a great Idea, Thanks Larry. KD couplers are so realistic too.

Excellent explanation thanks Larry

Thanks Larry, I will use that method as I develop my new layout

Great vid. This is the first video I’ve seen explaining how Kadees are supposed to work and the first using these magnets. I was aware of the neodinium magnets and have used them for various purposes but had no idea they could be used like this. I will use this method on my layout that is under construction. Thanks! 👍🏻

Thank you for sharing. Enjoyed.

Being new to your channel it's nice to see a couple of British locomotives visiting your Railroad in the background.

Very helpful indeed, thanks!

EXCELLENT presentation! Neodymium cube magnets (2.6mm) allow 9' spacing of ties. 2 pair or 3 pair or 4 pair of these set just inside each rail (or even just outside each rail) will attract the pins and can be very easily hidden by ballast. Steel weights and the plastic floor on Athearn's 40' boxcars can be "flipped" although the plastic center sill now needs to be Tenaxed or Plastic-Welded to the floor (easy) and the floor "door bars" will need to be clipped off and filed flush (also easy). Inexpensive and easy. Intermountain wheels roll far better with pin-point axle tips and also stay much cleaner longer. Kadee wheels' "blackening agent" rubs off with running and eventually ends up on the rail head; combined with dust, this causes conductivity issues later on.

Been using 3mm cube neodymium magnets on my exhibition layouts for some time. I put a small block of foam between the wagon floor and one axle to stop the wagon shimmying. Cheap,cheerful and adds no weight. I use bits of old roofing lead as weights to replace steel weights. Wagons here in the U.K. are not really set up for KDs and therefore require a little bit of work. Most now have NEM pockets making the use of KD nos. 18 and 19 easy

That C Class in the background, I've seen and ridden on a train pulled by the only remaining preserved locomotive left a few times at the Bluebell Railway in Sussex. Such a beautiful locomotive. By far one of my favorite locos for sure.

Fishing weights were always my go to lead solution. I always hammered them to shape but I've seen others melt it - beware of fumes.

Great video, thanks for sharing!

Great video Larry

Thanks Larry, Very good to know. 🐾🚂 KY.

VERY USEFUL VIDEO!!! Thanks.

I put 5/16 square super magnets on my scale lead under the scale rails. Works great.

Neat! Conveys 4 minutes of information in only 21 minutes!

I always wondered about this and what happens with the magnets. I might try this now that I know how it works properly. Always learning new ideas with you MRR pros! Thanks!

Great Video... I'm so glad I don't snip the hoses off the Kadee Couplers.🤗🤭

Buck shot works if you can find old led stuff. I use nickles (5 grams) and pennies (3 grams). non magnetic, not harmful and way cheaper than any store bought weights. I have been using little square super duper magnets for a long time :D

I saw, a few years ago, where a guy put a small bent piece of copper strip just barely touching the axle to give just a tiny amount of resistance against free rolling. That was enough to stop unwanted uncoupling.

Great video I’m in uk and the latest on Karee couplers and I am going to give it ago I do have US and UK stock I belong to a uk based club and we do run both we run N scale and HO . Thanks again

What I used for weights were pennies. 12 pennies = 1 ounce. Hiding them in open cars took a bit of trickery, but it was possible.

For a marker, you can also glue down an HO (or OO) scale painted figure there near the magnet; even better if it has a railroad lantern in its hand. 😊

This is interesting - good analysis on what happens when the steel weights/axles engage with the magnets. I suspect that the reason that the shorter magnets work is that they are so short that the axles/weights are never over the magnet at the same time as the couplers are over the magnet and thus when the slackening occurs when the wheels/weights pass over the magnets, the uncouplers are not over a magnet and do not uncouple despite being temporarily slack. An alternative is to use non-permanent magnets. Some use electromagnets, but they are difficult to handle since they take a lot of current and can get extremely (fire-startingly) hot if left on for more than a few seconds and easily burn out switch contacts after a while in use. A better solution is to use very large/strong permanent magnets underneath the baseboards moved up and down by a servo motor. The magnets being under the baseboard, there is no need to cut any holes in the baseboards. Being moved by a servo, they can be as long as necessary to allow easy uncoupling without having to be so precise, but can be retracted when not in use to prevent unwanted uncoupling. They can also be left up for as long as desired to allow people to take as long as they need to do the uncoupling. One can make these DIY, I am sure, but a company called Dingo Servo makes laser cut aluminium/3d printed ones of these that I have found work well.

Great piece of information 🙂 cheer's.

Great demonstration! How do you decide the position of magnets regarding their polarity? Vertically, horizontally? Both the same direction or different direction? Also, could it be they work fine because thet are not under the cars attracting the steal plates or wheel plates? Could we install a row of them to get a longer area working as the decoupler area?

I first remember Kadee couplers back in the 80s when I modeled in N-scale. I chose to stay with Rapido couplers because of the jiggling cars in trains equipped with Kadees. These cars bounced into one another like folks dancing in a Conga line - huge turnoff for me, since any effort at achieving realism went out the window because of the jiggling trains. Don't see that jiggling anymore in model railroad videos I watch, so I imagine Kadee remedied the problem.

Great info for anyone installing Kadee couplers for true operation. Wished I'd seen this when I was building HO layouts! When I was in HO, I built elaborate motorized mechanisms that raised and lowered the Kadee magnets into place. I could have avoided all of this if I saw this video on ferrous weights and axles! Today I run all outdoors, G scale live steam, so this info is not applicable. I use G scale Kadee couplers but in the outdoor environment I can't keep the magnetic uncoupling working reliably. , Not a concern because on my G scale live steam layout, the more 'hands-on" the better.

superb mini doc, hav now subscribed :)

Hornby has an uncoupling ramp which works on the kadees as well for uncouple with a spring loaded trigger you roll your coaches or wagons on top of it it springs up pushing both couplings up and apart

Great idea.

Very interesting.

I'm glad I saw this prior to building my layout (researching). Quick question: Does polarity [lay a role? If you have positive on one side, negative on the other, etc?

I've seen many folks use uncoupling markers - though they tend to be in fitting with the scene: a barrel, a switch lever frame, a cat(!), just anything that doesn't look too much out of place, but serves as a marker from a distance. And wheel balance weights in the cars!

Love your stuff! Couplers work better at the same height (:

You can still get the lead sheet as roof flashing and in plumbing supply stores or roofing suppliers for pouring in concrete as water pans.

I recently ran into the same issue with the under the track magnets. Found some metal wheels are also magnetic. Been experimenting with the NDM magnets, but haven't found something totally reliable yet to replace the under the track magnet. I bought some 25mmx3mmx3mm (1"x1/8"x1/8") bars and tried different spacings. I did find that you want them no closer than centered under the rails otherwise they don't offer enough sideways pull. I wanted the bars to increase the uncoupling zone up to 1" in length or so. But even doubling or tripling the magnets on each side, the small bars still didn't have enough pull from under the track to be reliable. Going to buy some larger bars and try them. What did work a lot better was the little 3mmx3mmx3mm cubes placed between the ties on the inside of the rails. They were reliable, but stick up above the ties a little and would be hard to hide.

Excellent informative video 👍😀😀😀🚂🇬🇧

You can buy lead roof flashing used for roof vent pipe...I keep mine double bagged in ziplocs in my work bench.

No one has mentioned the health risk of those Neodymium magnets. They are very brittle. The thinner ones easily break - even just by the sudden force of uncontrolled attraction to another one or a ferrous surface. The thin ones don't just break - they produce many fragments. If any of the magnets or pieces are ingested then they can cause the intestines to cross-couple together - causing a blockage that requires surgery. It's becoming a recognised problem with children's toys that use them. They are safer in use if encapsulated in plastic/resin - but that still leaves the problem of small children putting them in their mouth.

Larry: Can I send you a double-A battery for your SRR clock ? 😂

The gondola can also be underweight or not heavy enough. I have the same jerkiness with light cars even going mainline speeds. I understand the magnet is hitting the weight on the car but could be the combo of factors… also going kind of slow too.

Hi Larry. Excellent video again. Do you keep the delayed uncoupling effect? Or it becomes difficult because the short magnetic field?

NEW SUBSCRIBER near Fort Worth, Texas. Good info. Eaglegards...

Great video. It's working great but not for the reason you think. The way magnetic couplers work is that when a piece of ferris metal (the coupler pin) enters a magnetic field it becomes magnetic itself and takes on the polarity of the field it is in. When two pins enter one field they both become magnetized and with the same polarity. What happens when you bring the same pole of two magnets together? They repel each other. So the coupler pins are repeling each other, not being attracted by two magnets. So you should be able to make it work with one small magnet (one of the rods inserted vertically) in the center of the roadbed. Of course it will be really finicky getting the right distance from the pins. That's a problem Kadee had but if you can get it just right, you'll have a very percise uncoupler. Please post results when you do. Bill I had a thought... You could attach the magnet to an actuator like a servo, a solenoid, switch motor or even a lever or a cable to raise and lower it. Up to uncouple, down to not. Attach your marker to tell if it's active or not.

Those rare earth magnets are cool. Small and easily hidden in scenery. What are your thoughts on small electro-magnets for this purpose?

Copper makes great weight replacement as it is has a higher density than steel without be magnetic.

Replace steel weights with lead or brass . Use electro controlled uncoupled, not fixed magnets. Thus steel axles are no longer a problem I started with KDs back in 1975, on Riva Rossi American line cars( HO). Plastic coupler box covers, no steel wts ( they get rusty as well.) Now that I prototype 1:48 scale, On42, I use Hook and adjustable Shackles. ( original). And a Hand Incoupling Hook.

Spot on, Larry. Problem just as you describe with small, light UK trucks such as Dapol 00 gauge, which have steel axles. It is well worth experimenting with Neodymium magnets, the positioning is quite critical. I find 5mm dia x 12mm works well under Peco 100 track. Also worth adding some lead weights into those light trucks. Thanks.

Luckily I've not had serious enough issues with the Kadee to want to replace it. My tiny sidings are only long enough for 2 or 3 old time cars, so avoiding highly magnetic ones to park is not too hard. If I had a lot of space it'd be all different though! I put up a video of working the uncoupler and switch with an E-L gp7.

I am pretty new to trains and such. I don't really even have space for a layout. However, why doesn't the company just include an electro magnet with a switch. It's not a track switch but a switch switch, lol. When you want to disconnect cars, just flip it on and connect the circuit. It could probably power it through the track electrical system. It would also allow you to disconnect groups of cars together so they are already ready to go for whoever picks them up? Anyway what do I know. Never even seen a train layout in person.

HO couples are the bane of my existence..They fall off so easily and they are hard to get back on , unless you got three hands. Seems like they could have been designed better

You could use a figure of a switchman as a marker. Modern prototypes use an orange traffic cone to mark the clearance point. If you’re modeling modern stuff, and orange cone would be perfect. Is it possible to kick cars on a layout?

I have a decent collection of older trains and rolling stock. They have different types of couplers. What is the best method, if it's possible, to convert them to all one type of coupler so they function well together? Then engines have couplers that are attached to the body through a slot and the rolling stock vary as to where they are attached... most commonly the trucks.

I asked in a different thread, will the rectangular ones fit between the H O scale ties? Or is the orientation important for that shape?

I replaced all the magnets on my open frame (Pittman) motors with rare earth magnets and it made a HUGE difference in current draw and now they "creep" around the tracks. I didn't know that you could use 'em for uncoupling cars. I was wondering about the trip pins on the Kaydee couplers. I've seen one modeler cut 'em all off. Guess I'll have to install a couple of magnets on a siding for uncoupling. Yep, if you can find typeset you can use those for weights as they are the perfect size of HO gauge cars. Cheers from eastern TN

Larry: What brand of wheels did you say you used to replace the originals on the old Athearn tank cars? Did you say Intermountain? Much obliged for another great video.

I was wondering if you had worked with braking on the Piedmont.... specifically, on a main line, when you want to run one train after the other but the following train stops if the block ahead is not open

Well this was CERTAINLY INTERESTING AND helpful, I jus don't know what the hell happened here in Denver, Colo USA, they use to have 2 big train hobby stores, Minzel Trains in Westminster a suburburb of Denver and CABOOSE Hobbies in Denver, needless to say their BOTH SHUT DOWN, I CANT FIND A TRAIN STORE ANYWHERE here😭😭😭, HOW SAD IS THAT, Caboose had jus about (EVERYTHING I NEEDED IN STOCK), OF ALL GAUGES, WHICH I LOVE SEEING IN PERSON of WHAT I WANT & NEEDED. Including MANY DIFFERENT (KADEE COUPLERS I DIDN'T EVEN KNOW EXISTED) I don't do online. That's so sad, 😭😭 NOW I've bascilly given on this hobby😭

Neodymium magnets are also dangerous when they interact with electronics the Locomotive/Engines Youre running so be careful when running your engines near them unless they are too small to do anything

Liked and subscribed ,, thanks heaps for the awesome advice on how these kaydees work and how they uncouple as i knew it was possible but never knew how they worked ,, i was wondering if you could set up like an elctro magnet type of setup and run it off of either a transformer be it dc or ac to uncoupler the cars in switch yard or where ever you need them or is this already a done thing. Sort of how a points motor works to push the rod that changes the points direction. Thanks again. Cheers from John in Australia

Now that All Electronics has ceased operation I’m looking for a substitute for the Mag 74 you seem to prefer. Is the last dimension provided the thickness? Would you happen to know the pull rating?

Great video. I didn't catch which magnet you used on your layout of the four you showed. Was it the MAG-80? TY

Hi Larry, I hope you see this question as it had been a while since you posted the video. When installing the small neo magnets, do you need to be precise about the poles on the magnets, i.e have a north pole up on one side and a south pole up on the opposite side? Thanks, Andrew

You can get lead at pluming supply store it use in black pipe

These look perfect for uncoupling cars before backing them into buildings. Easy to retrofit and not as unsightly as the magnets that go above the ties.

Larry, will the MAG-74 work as well as I could cut space for them in the cork roadbed without having to move the track?

Hi Larry, good info on the kadee couplers. I’ve just started converting some of my Hornby rolling stock from Nem tension look couplers to kadee. Having seen your video I’ll be ready for that issue as I haven’t yet installed the uncoupling magnet yet. Many thanks.

Hi Larry - try using an electromagnet. With some finagling you can set it up with a rotary switch (or something more modern) and have multiple locations for uncoupling.

Hi Larry! where do I find your recent video on converting UK couplers to Kadee, I've seen it once but can't find it again to make sure I order the correct parts to convert my UK rolling stock with Kadee couplers. Thanks John Boyle

My passenger cars un-couple at my MRR club so the magnet solution is not possible. Any other reasons for un-coupling? I'm at my wits end and thinking seriously of installing draw bars on my problematic passenger rolling stock.

nice

HELLO LARRY ITS IS RANDY AND I LIKE U VIDEO IS COOL THANKS LARRY FRIENDS RANDY

Also where did The springs go in all my couplers...

I use rare earth magnets myself, and they're fine. But can anything be done to make Kadees work better on curved track? That is what annoys me most about them. Of course a lot of people disdain magnets totally, and use bamboo skewers instead, but I'd prefer not to reach into the scene.

How do you shove more than one car across the magnet without uncoupling each car as it crosses? I like James' electromagnet idea. I have a hump yard in my head that would benefit from an electromagnet versus a constant magnet.

Larry Great video and good idea. I use the Electronic Kadee magnet in my main yard. But this looks good for my sidings. I have another kadee question tho I have a MTA train has one engine and three cars came as a kit from Trainworld. Very nice looking but one of the cars continues uncouple any ideas Thanks Tom

I have never been satisfied with magnets under the track to uncouple. I’d solve this problem by eliminating the magnets.

Thats why i never use magnets with NEM pocket kadees

Do you know the strength of the magnets you tested, as I'm trying the same idea using 20mm x 10mm x 2mm rectangular magnets don't seem strong enough, supposed to be N50 the ones I have, or am I doing something wrong?

Apologies if this has been asked and answered already (please point to it if so). Can you describe the procedure for removing the Kadee magnets? Did you have to pull up the track? I have six of the Kadee delayed-action magnet uncouplers in my HO Code 70 yard ladders.

KD's Hate short British outline short wagons. Most have magnetic axles which gives you the magnetic creep as shown at the beginning. Even worse are Alan Gibson wheels that have steel tyres on plastic wheel centres. these need special wagon brakes to provide sufficient drag to keep coupled. I use small shreds of a harder packing foam that will slide against an axle without pulling the foam out of place. This drag limits the number of wagons small locomotives can haul. I'd NEVER use KD's on my big exhibition layout where I haul up to 60-70 wagons and require to separate the train at any random location. Like all products they have their place for best use. Wouldn't use anything else on my shunting (Switching) layouts.

Hi Larry. Do you have opposite polarities on each magnet so that one pulls and the other pushes or are the polarities the same for both?

Flat lead strips are available on eBay $6.99 per package of 50 pieces.