Author Topic: Cars not uncoupling at crest of the hump  (Read 3107 times)

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videobruce

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Cars not uncoupling at crest of the hump
« on: July 25, 2022, 09:15:06 AM »
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Most cars are MT truck mounted couplers, the others are Atlas accumate.

Long story short; the 'trip pin' of the lead car doesn't appear to be opening up when coupled to the 2nd car at the crest of the hump. Separately that trip pin does open when not coupled, but together it doesn't appear to be moving. thou it's hard to tell. One does, the other doesn't.

I've move the uncoupling magnet 'up' closer to the crest, but that hasn't changed anything.

Now if I push the string of cars with my hand the cars usually uncouple by the 'jerkiness' of my hand (for lack of a better term).

The uncoupling magnet is 1/2" from the crest. Lastly, I believe I made the crest to 'broad' making matters worse. But that is reaching for a reason this isn't working. See the attachments.

Hope all of that made sense.
« Last Edit: July 25, 2022, 09:22:39 AM by videobruce »

jjb62556

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Re: Cars not uncoupling at crest of the hump
« Reply #1 on: July 25, 2022, 01:51:42 PM »
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If I understand how the couplers work there has to be slack on both couplers in order for them to open...any pressure by any car will not allow the couplers to open. If the car going down hill is trying to roll down  before  it is stop to allow it to open it won't work right. If I am right.

nickelplate759

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Re: Cars not uncoupling at crest of the hump
« Reply #2 on: July 25, 2022, 01:57:37 PM »
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I can't tell if you are already doing this, but in order for the cars to uncouple there must be slack between the two cars.  You need some way of creating that slack in the cars over the uncoupler while you are pushing cars over the hump.
George
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videobruce

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Re: Cars not uncoupling at crest of the hump
« Reply #3 on: July 25, 2022, 02:04:18 PM »
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Would a longer magnet help?

jjb62556

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Re: Cars not uncoupling at crest of the hump
« Reply #4 on: July 25, 2022, 02:15:22 PM »
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I don't think so. Both cars have to be dead stop over the magnet to create the slack in order for the couplers to open..I don't think it will work on a hump..not without letting the couplers open on a magnet on a flat section and pushing over the hill.

thomasjmdavis

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Re: Cars not uncoupling at crest of the hump
« Reply #5 on: July 25, 2022, 02:22:56 PM »
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Is it one car, or a group of cars, or all of your cars? Do you have the same problem with an uncoupler installed on level, flat track? If one or a few cars, I would suggest inspecting and lubing those that don't operate as expected.  A tiny bit of flash or misaligned trip pin could be the issue. Or a spring that is not sitting properly.  On a couple cars where I assembled my own couplers, I discovered I had installed 2 springs instead of one (the springs had sort of interleaved with each other)- they coupled fine, but uncoupling was problematic.

I will admit, I haven't read MTL instructions for coupling/uncoupling in 20+ years, but they seem to work as they always have.  When working on a level track, you would back (to create slack) over the uncoupler, then pull forward a fraction of an inch until the couplers completely disengage, then reverse to position the first car (or, in your case, push it over the hump). The uncoupling magnet holds the couplers on both cars open so the knuckles won't re-engage after pushing past the uncoupler.  This is essentially what you describe when you refer to "jerkiness" from your hand.
Tom D.

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Mike C

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Re: Cars not uncoupling at crest of the hump
« Reply #6 on: July 25, 2022, 04:42:44 PM »
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   Try putting the mag at the bottom of the hump where the track is level ?

wazzou

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Re: Cars not uncoupling at crest of the hump
« Reply #7 on: July 25, 2022, 05:12:28 PM »
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   Try putting the mag at the bottom of the hump where the track is level ?


That could work if it was before the hump.
Bryan

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tehachapifan

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Re: Cars not uncoupling at crest of the hump
« Reply #8 on: July 25, 2022, 07:37:28 PM »
+1

That could work if it was before the hump.

I think this is the idea with MT couplers, which is to uncouple over a magnet on a straight and level area, then push the car(s) to the desired destination (with the couplers uncoupled) and then drop the car(s). I also think the uncoupling would have to happen before the hump on straight and level track, then push the uncoupled car(s) to the top of the hump.
« Last Edit: July 25, 2022, 07:39:25 PM by tehachapifan »

Maletrain

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Re: Cars not uncoupling at crest of the hump
« Reply #9 on: July 25, 2022, 09:18:37 PM »
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You definitely need slack to make the couplers disengage, due to the lips on the knuckles.  The usual technique is to push the cars over the magnet to disengage the couplers, reverse the loco a short distance to allow the couplers to swing wide to each side so that they will not recouple when pushed back together, then push the uncoupled car off the magnet and to the location where you want to spot it.  You then should be able to back away from the uncoupled car.

But, my experience with the slinky effect with some MTL couplers (some have springs that slinky in forward, and some in reverse) has been spotty at best - too often the cars recouple when being pushed if there is the slightest bit of jerkiness.

One think I have found is that those between-the-tracks magnets are too narrow to be 100% reliable in uncoupling.  But, the wider and more powerful under-the-track magnets that Bachmann provides are really reliable at getting slack cars uncoupled.  Those magnets work fine when placed in the plastic roadbed part of Bachmann and Kato sectional track, as well as putting them in pockets cut out of cork roadbed under flex track.

I am not sure what effect you are trying to achieve for our hump operation, but I am suspecting that you want to be able to push a car over a magnet and have it roll away once it is uncoupled by the magnet, without the stop, back-up, then push process.  I think that might be possible with a long enough magnet located at exactly the right place with respect to the beginning of the down-grade.  You need to make sure that the cars uncouple before there is any tendency of the lead car to start down-grade, and then keep pushing while still over a magnet until the car does roll away.  If I was going to try to do that, I would get several of the Bachmann magnets to be able to make a long-enough uncoupling section by placing them in series.  I would test position those magnet by moving them along the track until I saw the lead car just roll away cleanly.  Not sure how many it will take to do that.

One thing that will completely kill your ability to do that is steel axles or steel weights in the car that needs to roll away by force of gravity.  The problem is that the steel will be so strongly attracted to the uncoupling magnet that gravity will not make it roll away until it is so far past the uncoupling magnet that it has recoupled.  The only way to deal with that is the original push-stop-reverse-push off the magnet with the couplers not engaged because the magnet has them pulled far to the sides.  The Bachmann magnets will do that reliably with steel in the cars.

Too often, the Bachmann magnets have actually pulled a car with steel in it in a manner that causes uncoupling when I do not want it.  What happens is that  the loco is pulling the cars with no slack, and the magnet pulls the car with steel in it toward the magnet faster than the loco is pulling the car string, and that creates slack over the magnet and the cars uncouple, allowing the car with steel to stay at the magnet while the loco pulls the more forward cars in the string away.  That is why I don't use those magnets on my layout, and use a pick to uncouple. 

But, that should not be a problem in a hump yard unless you intend to pull the cars out of the yard back over the hump after they are classified.  If you do want to pull over the hump, then maybe use an electomagnet uncoupler that is as long as what you find you need using the Bachmann magnets for trial and error testing. 




Day One

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Re: Cars not uncoupling at crest of the hump
« Reply #10 on: July 25, 2022, 09:41:44 PM »
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step 2: Back train slightly, allowing slack so that the couplers can disengage.



Also, you may need to align the magnet between the rails better if one side is working better than the other.
« Last Edit: July 25, 2022, 09:43:44 PM by Day One »

Maletrain

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Re: Cars not uncoupling at crest of the hump
« Reply #11 on: July 25, 2022, 10:00:35 PM »
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You definitely need slack to make the couplers disengage, due to the lips on the knuckles.  The usual technique is to push the cars over the magnet to disengage the couplers, reverse the loco a short distance to allow the couplers to swing wide to each side so that they will not recouple when pushed back together, then push the uncoupled car off the magnet and to the location where you want to spot it.  You then should be able to back away from the uncoupled car.

But, my experience with the slinky effect with some MTL couplers (some have springs that slinky in forward, and some in reverse) has been spotty at best - too often the cars recouple when being pushed if there is the slightest bit of jerkiness.

One thing I have found is that those between-the-tracks magnets are too narrow to be 100% reliable in uncoupling.  But, the wider and more powerful under-the-track magnets that Bachmann provides are really reliable at getting slack cars uncoupled.  Those magnets work fine when placed in the plastic roadbed part of Bachmann and Kato sectional track, as well as putting them in pockets cut out of cork roadbed under flex track.

I am not sure what effect you are trying to achieve for our hump operation, but I am suspecting that you want to be able to push a car over a magnet and have it roll away once it is uncoupled by the magnet, without the stop, back-up, then push process.  I think that might be possible with a long enough magnet located at exactly the right place with respect to the beginning of the down-grade.  You need to make sure that the cars uncouple before there is any tendency of the lead car to start down-grade, and then keep pushing while still over a magnet until the car does roll away.  If I was going to try to do that, I would get several of the Bachmann magnets to be able to make a long-enough uncoupling section by placing them in series.  I would test position those magnet by moving them along the track until I saw the lead car just roll away cleanly.  Not sure how many it will take to do that.

One thing that will completely kill your ability to do that is steel axles or steel weights in the car that needs to roll away by force of gravity.  The problem is that the steel will be so strongly attracted to the uncoupling magnet that gravity will not make it roll away until it is so far past the uncoupling magnet that it has recoupled.  The only way to deal with that is the original push-stop-reverse-push off the magnet with the couplers not engaged because the magnet has them pulled far to the sides.  The Bachmann magnets will do that reliably with steel in the cars.

Too often, the Bachmann magnets have actually pulled a car with steel in it in a manner that causes uncoupling when I do not want it.  What happens is that  the loco is pulling the cars with no slack, and the magnet pulls the car with steel in it toward the magnet faster than the loco is pulling the car string, and that creates slack over the magnet and the cars uncouple, allowing the car with steel to stay at the magnet while the loco pulls the more forward cars in the string away.  That is why I don't use those magnets on my layout, and use a pick to uncouple. 

But, that should not be a problem in a hump yard unless you intend to pull the cars out of the yard back over the hump after they are classified.  If you do want to pull over the hump, then maybe use an electomagnet uncoupler that is as long as what you find you need using the Bachmann magnets for trial and error testing.

nkalanaga

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Re: Cars not uncoupling at crest of the hump
« Reply #12 on: July 26, 2022, 02:18:29 AM »
+1
I'm with Maletrain.  What you need is a long magnet, so that the couplers will open while pushing up the grade, when you have the slack bunched, then stay open until the released car has rolled away.  With a short magnet, there either isn't enough time for the couplers to open before the slack is stretched by the downgrade, or the couplers recouple before the car clears the crest.

N Kalanaga
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videobruce

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Re: Cars not uncoupling at crest of the hump
« Reply #13 on: July 26, 2022, 03:10:58 AM »
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I have some Neodymium magnets ordered (10x5x2mm).
25 years ago with my 1st 'scenic'ed' layout that had a hump, it worked with little issue. I'm using the same magnet as I then. Doing so at the bottom of the hump turns it into a flat switching yard defeating the purpose (and effect). Same with starting, stopping, then reversing.  :(

Pulling the track back over the hump wasn't a problem before either. The other problem I also have are the difference in rolling ability of the different cars. Some shoot (literally) down to the end, others just make it 'in the clear'.
« Last Edit: July 26, 2022, 03:22:13 AM by videobruce »

Ed Kapuscinski

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Re: Cars not uncoupling at crest of the hump
« Reply #14 on: July 26, 2022, 09:25:14 AM »
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I have seen this done (20? years ago), so I know it's possible.

I believe the magnets were on the uphill part of the hump, right before the crest.

Also, you're making a working hump yard. That's frigging cool! It was my favorite job on my friends layout back in the day.

@BuddyBorders , Do you happen to have contact info for Mongo? I'd love to hear what that maniac's up to these days.