Atlas uncoupling track (magnet)

What voltage are you using.  The higher the voltage the more "pull" you'll get.  If you have a voltmeter (or multimeter) you need to check your power supply.  You should use a 18 volt fixed power supply or a dedicated variable power supply set to 18 volts.

You don't run them off track power.

Jan

Hi Jan.

I am running the un-coupler off the 14 volt fixed tap on my MTH Z4000.  Magnet seems to have plenty of pull on other couplers, and when I order new coupler "tacks" from MTH they work well. 

Try 18 volts.  You should get better performance.  Then you can decide what you need/want to do.

Jan

Thanks Jan.

I tried 18 volts.  Makes no difference.

By new coupler tacks do you mean the entire coupler assembly as below or are you somehow replacing just the "tack" disc?

So going to 18V made no difference - a ~30% increase in magnetic field strength.  I was going to suggest loosening the screw on the right to relax the spring force.  This would make it easier for the track magnet to pull down the tack.  But since spring force is proportional to spring length, it's impractical to loosen more than 30%.

I assume you examined the stock part with the replacement part and fiddled with manually closing and opening them. Anything obvious?  If you're the curious type, remove the screw on the right and examine the good/bad springs to see if there was a run of unduly strong or long springs - or swap springs. 

As to whether there was a bad run of steel used in make the tack discs is going off the deep end...but makes for a good play on words if you can measure its ferocity (ferrous-ity) .

Problem solved!  It appears that the metal MTH uses in some of their "thumb tack" parts to uncouple do not respond well to the Atlas magnetic uncoupler track.  As mentioned in a prior post, when the "tack" is replaced, the magnet will pull the tack down, and activate the coupler.  I haven't seen anyone else with this issue, so perhaps it has to do with the Atlas uncoupler tracks on my layout not having enough strength to pull down the mth tack. (I tried using 18 volts, with no change in results) This issue has not happened on all of my mth trains with "thumb tacks" though.  It seems to be consistent however with like type train cars.

So here is the solution I used.  My Amtrak fleet cars all had issues with the thumb tack uncoupler not working.  I took a common washer, the same size as the thumb tack and glued it to the thumb tack!  And not only is this a cheap fix....it works perfectly!  The details:  Took my dremel and completely removed the finish on the bottom of the tack, plus a little extra.  Took the washer and "roughed up" the surface with some sand paper.  Used some "Sinbad Glue" to bond the washer to the tack.  I found this glue at a train show a few years ago.  Works very well and dries in a few minutes, very strong!  After the glue was dry, I then took some "gun blue" and put it on the now in place washer to blacken it.  Took a little flat black paint to touch up the sides of the washers just for cosmetics.  You can't see the washer in place.  I ran the entire train around the layout a few times to make sure there is good clearance and there is plenty of clearance, even over the Atlas switches.  If I ever needed more clearance for whatever reason, the dremel can take care of that.  The washers respond perfectly to the Atlas magnetic uncoupler.  Problem solved!  I will try to post pictures if I can figure out how to do it.  On some of the mth cars it requires taking the body off to change out the coupler.  This can result in some of the little springs flying away.  (how do I know this?)  Using the washer method works, is cheap, and is easy to do.  Hope this information will be of value to someone.

Nice fix.  G