strange coupler behavior

John

   Perhaps I used the wrong terminology.  I should have said coil coupler, hence no button tack on the bottom.

Marty

If it opens spuriously and is not connected electrically, then the coupler is bad mechanically.

I have heard of disassembling the coupler and stretching the spring that presses on the pin.

I have also heard something about putting graphite in the coupler, or on the internal pin, but have no idea how that would stop spurious uncoupling.  Maybe you do that after stretching the spring.

I have taken some of these apart and smoothed all the internal mating surfaces.  This prevents the coupler from "walking" open due to vibration.  A number of years ago, Boxcar Bill had posted his fix, opening them and smoothing the mating surfaces.  I tried it, and it has worked well for a number of these.  Obviously, you have to pull the rivet, do the work, and then reassemble with a new rivet.

Stretching the spring is also a suggested fix.  I'd really replace the coil spring, but I've never found a part number for the spring.  This spring is not the wire spring that actually opens the knuckle, that one is readily available.

If you choose to replace the spring, a Lionel TC-112 may work.

What is the intended use of the TC-112?  Have you tried it in this application?

The TC-112 is the generic plunger spring used on many Lionel coil couplers as such.

Oh, that's for the old couplers.  That might work, the design of the new ones is very similar.  I'll have to find a place to get those.

Thanks for all the replies.  I will get on it next week and see what happens

Marty

I have a similar problem will ALL my TMCC locomotives.  Some are worse then others. I won't even run a Berkshire.

Well, all your couplers aren't bad, at least that's MORE than unlikely.  Of course, the first step is to isolate if it's electrical or mechanical by unplugging the coupler.

I just unplugged the worst offender and it ran the last 30 minutes without uncoupling.  So one down.  Glad I found this thread.  I'm going to try the graphite next, sounds easiest.

Beemer posted:

I just unplugged the worst offender and it ran the last 30 minutes without uncoupling.  So one down.  Glad I found this thread.  I'm going to try the graphite next, sounds easiest.

If it holds with the electrical cable disconnected, then there is an electrical problem where the coupler is spuriously be commanded to open. The fix in the old days was to put a capacitor across the power leads to the coupler. I do not remember the value of the capacitor.

Roy is right, you're looking at the wrong end of the horse!   You want a 1uf 50V non-polarized capacitor, usually the best place to put it is soldered on the back of the motherboard where the coupler plugs in.

Do NOT apply this to later Legacy locomotives with the RCMC control board!   They use DC for the couplers and the capacitor is very bad for their health.  Earlier Legacy with the R4LC still use the AC drive for the couplers, this fix is appropriate for those models.

I'm always looking at the wrong end of the horse.

Guys, the part that I do not get is when I disconnect the coil coupler from the board or used another coil coupler which was totally not wired to anything the coupler would still randomly open???

Marty

martind posted:

Guys, the part that I do not get is when I disconnect the coil coupler from the board or used another coil coupler which was totally not wired to anything the coupler would still randomly open???

Marty

Seems a manufacturing defect, the pin is not engaged enough to prevent the knuckle from opening.

That is an indication of a mechanical problem, it's obvious that it's not electrical as there is no connection.