Automatic uncoupling

[randgust]

I use them and don't even own a sticker.   

The primary reason for trip-pin derailments is the non-RDA coupler heads displacing vertically under stress and forcing the pins lower to one end.   Fix that and no more snagging pins, and no more pull-aparts, either.  If you watch your train go by at track level under tension, and the knuckles aren't centering with each other under load, and are going 'up and down', there's your problem.  It also is worse with extended and medium box trucks -  it's easier for force the knuckles out of alignment.   A good RDA knuckle (or a modified old one) will pull to the vertical centerline the harder it is pulled, until the knuckle breaks off.   So yeah, considering the length of N-trak trains, that will be a much bigger problem.   You don't see it on shorter trains with less drawbar stress unless the pins are actually set too low.  What's annoying is that you can set the pin depth right, and it will still snag under load, if this knuckle problem exists.   Even on one car in a pair.   

The primary reason for false uncoupling is that the in-the-track, between the rails magnets are just way, way, too long.   Score and snap them far shorter, I use a glass cutter and a vise.   In the 'old days', with poor motors, throttles, and drives, you were lucky to spot a car within an inch.   If you have a throttle precise enough to creep into a car, your magnets can be as short as 3/8" and at least uncouple a knuckle, 1/2" and you can still delay-set.  The shorter the magnet the less likely a false uncoupling is.

Mind you, this only works with MT.   Don't expect Kato, or Atlas, or anybody else's knuckles to work this well.    I'll only use those on cars within dedicated cuts that are rarely if ever uncoupled.

One more point is that if you're attempting to work on any curves at all, body-mounts are not your friends, for either uncoupling or coupling.   I've uncoupled on curves as tight as 8" with truck mounts and short magnets.

I have one big honkin' ex-Kadee electromagnet at my yard throat that will absolutely pull apart anything that the little guys can't.

I've also mixed Z couplers into the mix (particularly on locomotive pilots) and rebent trip pins to reach, and those work well too.

[central.vermont]

I attach a small disposable LED light and battery from a ball point pen to them and this helps significantly find the knuckles.

 Skewers all the way!

md

Mark,

Could you post up some pics of this. Sounds like a neat idea I would like to try on a friends layout.

Thanks, Jon

[garethashenden]

Thanks guys, glad to hear they work that well. The last time I had a layout (10 years ago) I used a skewer but I kept derailing cars while using it. That could very well be my technique, but I thought I'd try something else this time around. I've used magnetic couplers on other people's layouts recently and I like the hands free aspect.

[SD452XR]

I have problems with the couplers on BLMA and Trainworx freight cars. Are these Micro Trains clone couplers? Is there anything that can be done to these to improve uncoupling with out a full out replacement?
Steve

[randgust]

I just got a BLMA beer reefer but hadn't closely examined and tested it.

It sure looks like an MT coupler....but.....

1)  Mine is mounted high with the head of the coupler running about .020 high on center compared to my height gauge.
2)  Trip pin was high on both ends.  Easy to fix.
3)  the real surprise was that neither knuckle was RDA.  Both had the finger 'point' still there on a relatively-new looking brown head, so I'm a bit baffled on that.  I thought that problem was extinct on new production.  Again, easy to fix but if you're getting either pull aparts on banging into trip pins, there's the culprit.
4)  The centering spring is noticeably stiff.   I'm tempted to pull it apart to see if they used a stock spring or doubled-up springs or what, but my coupler will neither throw over all the way to uncouple or properly delay-set either.   Tested it on several magnets.  I think it's stiff.    Normally I'd tear it down but the first casualty will be those cool lift levers.   As I'm not planning on running mine except on through trains, I'll fix the RDA but that's all.

[mark.hinds]

I use the MTL automatic uncoupling / delayed uncoupling feature on my perennially incomplete layout, and they work reliably.  IMHO, reaching over the layout to uncouple manually both destroys the illusion of reality, and risks damage to scenery; thus, MTL is my only acceptable alternative.  However, getting MTL couplers to work reliably has always required a certain amount of effort on my part, e.g.:

 1. I use only MTL couplers, as the other types typically are too stiff.  Trucks and or couplers must be consistently adjusted for all equipment, so that the couplers center between the rails when in the neutral position.  Wheels must be in gauge, to minimize lateral positioning variation. 

 2. I use MTL #308 under-track magnets, which must be precisely positioned between the rails so that test cars couple and uncouple reliably from both directions.  Centering “by eye” isn't always good enough; you have to test each magnet installation, as well.  Other more powerful, non-MTL magnets might also work, but I haven't tried them. 

 3. Both MTL RDA and non-RDA couplers must have the tips adjusted, per details described below.  Last time I checked (about 3 years ago), and contrary to claims made by some fellow modelers, not all MTL couplers are RDA.  They are easy to distinguish from each other, though, per the second image below. 

 4. I have positioned uncoupling magnets to allow for reasonably prototypical operation, even with non-DCC block control.  For example, I can attach and detach helpers, because the points where this occurs have a block boundary over the magnet.  I haven't experienced random uncoupling, as my layout is small, and maximum train length is equivalent to about 25 40-foot boxcars. However, as insurance against this, I have mounted my mainline magnets on hinged flaps, which drop down away from the sub-roadbed when released. 

NON-RDA MTL:  Traditionally, MTL couplers have had an issue with undesired uncoupling under load with very long trains.  I myself have never seen this issue, as my trains are no longer than about 25 40-foot cars at most.  IN any case, to avoid this on the non-RDA MTL couplers, (per Jim Fitzgerald?) you replace the convex mold release angle with a concave reverse notch in the mating “finger tip” portion of the coupler, made with a sharp hobby knife. 

RDA MTL:  Over 10 years ago, MTL attempted to fix this issue with RDA (Reverse Draft Angle) couplers, which already come with such a  notch.  However (as of last time I checked, which was about 3 years ago), this created a new problem by thickening the coupler tips, so that coupling or particularly uncoupling at scale slow speeds becomes unreliable.  What happens is that the wider tips sometimes catch on each other, when you try to move the cars apart over the magnet; see image below.  This is particularly irritating if you are trying to unobtrusively put the cars into "delayed uncoupling" mode with a short back-and-forth movement.  (Since it is unprototypical, you want it to be unobtrusive).  For what it's worth, the issues I have IDed with RDA occur using the standard #308 MT under-track magnets placed directly under the plastic ties.  Perhaps if you use stronger magnets, the issue may go away (or perhaps not ...). 
 

In any case, I modify my RDA couplers individually to fix this problem.  Details on this modification have been posted in various threads, but the essence of it is shown in the following image: 


Mark H. 

[mark dance]

Mark,

Could you post up some pics of this. Sounds like a neat idea I would like to try on a friends layout.

Thanks, Jon

Here you go...components ripped out of inexpensive pen/flashlight combinations and held to BBQ skewers with heat shrink and a tie wrap.



That's my 9 year old son's hand uncoupling cars in Nelson yard (thanks Isaac!)





md

[peteski]

I have problems with the couplers on BLMA and Trainworx freight cars. Are these Micro Trains clone couplers? Is there anything that can be done to these to improve uncoupling with out a full out replacement?
Steve

Usually if some manufacturers uses real MT couplers, they proudly state that fact on the box. Either in print or by a having "genuine MT couplers" gold metallic sticker somewhere on the box.

I don't have any BLMA or Trainworx cars handy so I can't comment on those. But I do have some Exactrail cars and those have real MT couplers in draft gear boxes molded onto the underframes.  There is also a logo on the box insert which states that they are equipped with genuine MT couplers.

Bus sometimes things aren't as the seem. A good example is the IM AC-12 steam loco.  The paperwork included with the loco states that they are equipped with genuine MT couplers but under close examination the couplers used on that model are actually clone MT couplers. Very close to, but not quite MT.

[central.vermont]

Here you go...components ripped out of inexpensive pen/flashlight combinations and held to BBQ skewers with heat shrink and a tie wrap.

That's my 9 year old son's hand uncoupling cars in Nelson yard (thanks Isaac!)

md

Thanks for the pics Mark. Guess I'll be heading off to the dollar store.

Jon

[Wolf N Works]

I wish this gentleman would get this version to market. I be in for quit a few pairs