the metal railcar wheels short out the AR gap shutting down the loco(s) as it recognises a short...
Can this not be cured with a bit of plastic in the gap? maybe just a couple thou proud to the inside to hold the wheel flange off? I think the wheels don't have to short the gap...
Cid (Memphis, Tennessee)
chenxueCan this not be cured with a bit of plastic in the gap? maybe just a couple thou proud to the inside to hold the wheel flange off? I think the wheels don't have to short the gap...
it sounds like the train is longer than the reversing section and was causing shorts at either end.
CPbuffI will try to figure how to post the track plan in the next few weeks for those who may be interested!
few weeks? a month?
it would be helpful if CPbuff could confirm that the diagrams I posted are accurate or describe inaccuracies
where is the 3rd gap?
greg - Philadelphia & Reading / Reading
chenxue the metal railcar wheels short out the AR gap shutting down the loco(s) as it recognises a short... Can this not be cured with a bit of plastic in the gap? maybe just a couple thou proud to the inside to hold the wheel flange off? I think the wheels don't have to short the gap...
This can only happen if the train is longer than the reversing section. In the case of a simple loop where the diverging side of the turnout loops back around to the straight route, this would mean the loco is sideswiping its own train, a bigger issue than shorting the gaps.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Hello All,
gregc(I)f there's a DCC bus from a command-station/booster with feeders to track, why wouldn't you connected the AR to the bus and from it to feeders in the rev section?
Absolutely!
rrinkerYes, you normally would connect the input of the AR to the main bus. MRC likes to 'simplify' their instructions, which can lead to consequences.
I concur!!
If the OP is following the printed directions there might be a flaw in the wiring schematic that I have found through my personal experience installing this exact same unit.
If the unit can be attached directly to the bus then to the isolated section that might be the easiest solution.
The caveat would be- -IS the OP using a bus with feeders to the track?
If they are using a single pair of wires from the command-station/booster to the track then powering from the track would be necessary. Unless the OP want's to run the power feed wires from the AR unit to the command-station/booster.
To repeat, ad nauseam: IF the OP can only use track power the feeder wires (Red) to the AR unit should attach to the track BEFORE the turnout, contrary to the printed instructions from MRC. The gaps to isolate the reversing section should be after the turnout on all four rails as diagramed by gregc.
IF the OP can attach the feeder wires directly to a bus then to the isolate reversing section that would be the optimum.
Regarding the size of the loop or train...
rrinker...this would mean the loco is sideswiping its own train, a bigger issue than shorting the gaps.
A valid concern for possibly another thread.
Hope this helps.
"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"
Resurrecting this thread because the OP sent me a pic last month. I was moving the next day so I forgot about his email. He has added another gap and another Autoreverser, which, reading his old post, controls everything to the left of Gap 3.
He thinks it may have solved the problem, but has not fully tested it. I think he needs another gap.
As I understood the problem, he had one reversing loop around the turntable.
From the track plan, from the turnout at Gap 3 left and downward is a second reversing loop. I don't think Garry, the OP realizes that.
Henry
COB Potomac & Northern
Shenandoah Valley
I can understand the complexity of some layouts needing Auto reverse loops.
I'm old school and only have one reverse loop on my layout that is very short. I will have a toggle switch on the fascia that can be flipped the direction the train is going. Even if I had three or four, I like to keep things simple. To me, I think paying attention and flipping a switch is part of the fun of the sport.
If I had a master computer controlling everything on my layout so I didn't have to do anything which I'm sure is very achievable on any layout. Why bother, at that point I would have nothing to do but watch
TF
Agree on the second reversing section. I would move gap 3 to the divergent track of the turnout and put a second gap some distance on the divergent track and have the AR control that section. No gap where gap 3 is currently located
The two gaps above and below the roundhouse are good, if that length of track is longer than the longest train. The second sets of gaps should be all the way down on the lower loop. Starting in the square ont he lower left, 3 squares up and 7 squares to the right, gap both rails. and 1 square up and 10 squares to teh right. If that section is about equal to the length of the top loop. No other reverse sections are needed.
The track plan is a dogbone with a crossover. Isolate the end loops and use 2 autoreversers, and you can have as many crossovers along the shank as you want with no futher autoreversers.
It is, in fact, completely opposite with DC compared to DCC. With DC, you keep the loop constant and change the polarity of the main before the train exits the loop. With DCC, you change the polarity (phase to be completely accurate) of the loop before the train exits back tot he main. And with DCC, you change it under the moving train with no effect, since the polarity of the signal on the rails has nothing to do with the direction the train travels.
The DC method can still work fine with DCC, but generally is not used with automatic reversing since that means the autoreverser has to carry the load of the entire layout sans the loops. Most are not designed to switch that kind of current. They expect to switch the current of one train on the reverse section, not the 4 or 5 other trains out on the rest of the layout.
Thanks for the info Especially using the box method to describe where to place them! As this a new layout I have 3 available ARs from my previous layout! I will give it a try first snowy day! Which in Canada won't be too long from now! I will remove the second AR.and I will add the gaps and 1 AR in the box locations you mentioned! And Close gap 3... I will let you know later!
Back again! I added a second AR at the bottom of the layout per previous suggestions in the second loop at the bottom of the layout, but the problem still exists when the loco(s) exits the first loop crossing the gap , the sparks fly and the locos stops... I'm so frustrated after a year I guess I will rework the loop so the complete layout is just a dogbone with no crossover... If I want the trains to return the opposite direction I will manually rotate the cars in the opposite direction, the locos can be turned on the turntable!
I had to go back to the beginning of the thread to catch up.
In the very first post you said it shorted out in one direction (going from gap A to gap B) but not the other direction. The diagram that I posted for you does not clearly show which is gap A which is gap B.
Be that as it may, I recall you've tried 2 or 3 new MRC reversers without luck.
Did we establish that the length of your trains are shorter than the reversing section?
If you isolated the end loop at the bottom as I suggested, and you still get issues, then parhaps the to legs are not wired the same way - the track to the left of the bottom riught loop, both tracks, should have feeders in the same order.
If we take the bottom most track first, if you have a black feeder to the bottom most rail and a red feeder to the upper rail, then for the section of track at the top of the loop, the rail closest to the lower track should be black feeder, and the rail closest to the top would be the red. Both tracks in parallel to each other is how it works.
If the same thing is done with the upper loop - ignore the crossovers, the crossovers should be part of the 'shank' wiring - then you should be good to go. Make sure at no point along the 'shank' you have flipped the feeders, the order should be the same on both tracks all the way around, except for the isolated end loops.
Forgive the crudity of the model, didn;t have time to build it to scale or to paint it - but here is a diagram that mau help
Thick red slashes show where the gaps go (approximately). Thin red and black lines show which polarity the track should be in those various areas. I notice int he upper left there is some A/B labeling - if this is the way the feeders are hooked up, it's backwards. Both tracks need to be the same, as shown by my red and black lines.
If I am understanding the track plan correctly - the track to the left loops around in a helix, the track in front passes over that track there in the middle left, no connections between them?
I think Randy nailed it. I saw the A B B A and it didn't make sense to me, but I didn't think to ask about it either. My bad.
Thanks Randy! I checked the feeds and everything is the way your diagram shows them to be . As a matter of fact I used an ohm meter to ensure the meter shorted at the top loop on both when testing black rail to black rail and red to red... Problem continues! the A and B were to show that when the the rails on the second track (down from the top) returned to the top of the layout the polarity would have been reversed? To check further I gapped the second track from the top (as I have a feed on both top and bottom track ) and problem still exists when the loco crosses the gap at the top... going counterclockwise!
On simple track change - get rid of that short section so signle track at the top, that's where the problem is, there's a wye AND a loop. Have the track on the diverging route of the top turnout that leads to those sidings across the top go to the top of the loop, rather than have the tracks join.
Can I send you an email at rer@lehighgrads.net and you could scan a rough drawing on paper of what you saying I need to do?
Like this:
Then the only reversing sections are the two end loops.
If you have room, you can put a second crossover going the opposite way in there as well. Anywhere along the two mains, you can put a crossover, actually. Changing the track at the top makes it a true dogbone.
Will a locomotive run through the loop without a train?
Jim
Thanks, Again Randy, but I reworked the layout this afternoon per your diagram and now the loco shorts out across the gap in both directions not just one...
And too the others asking, its only one loco at a time I am trying to get around the loop, no consist and numerous locos do the same thing!
CPbuff Thanks, Again Randy, but I reworked the layout this afternoon per your diagram and now the loco shorts out across the gap in both directions not just one... And too the others asking, its only one loco at a time I am trying to get around the loop, no consist and numerous locos do the same thing!
Rich
Alton Junction
That would seem to indicate you have the shank part wired backwards somewhere. It's stillt he same as I previously posted with the red and black lines indicating polarity. Unless any of those turnouts making the crossover is an electrofrog type.
You have the 2 gaps in the upper right loop, correct? and that track is fed through the autoreverser? And the lower loop,. same thing, 2 sets of gaps, and all track within the loop, inside the gaps, must be powered ONLY through the second autoreverser.
Yes, polarity is correct... Yes, 2 gaps in the upper loop and 2 gaps in the lower loop!and no feeds inside the loop, only powered by the AR... The diagram you saw, each square is 1' square! so distance apart should not be and issue!
I will investigate further into a possible bad frog before reaching the AR? as I just noticed that the headlight of my steam loco flashes briefly (sitting in the engine house just to the right of the roundhouse) as a normal car passes over the turnout (two turnouts left of the upper AR) which suggests a quick short!
Thnks Rich! Your diagram (all be it crude) does match the the wiring I have in place, per my previous diagram the squares are 1' square and the total layout is 11'W by 12'6"Long...
Another update! To isolate the problem, I have removed all feeds from the layout (as I use terminal blocks under the layout for trouble shooting) except for one located on the top track where the "A" is on the diagram, I reversed polarity too and the problem continues, I moved the feed to where the "B" is on the top of the diagram and tried both polarities and the problem continues, so I am going back to thinking somethings wrong with the AR, although all AR's bench tested fine... ( using a process that MRC supplied to me a while back)...
Easy to test. Bypass the AR. Connect the loop tracks with the feeders matching one of the two tracks, for example, on the top loop, if you have the rail to the top of the digram as A, and the rail towars the bottom as B like where the A abd B are in the top left, then wire the loop the same way so that on the loops ide of the upper right gap, the top rail is A and the bottom rail B.
Now a train should smoothly run into the loop at the top right, crossing those gaps with no problem. Main to loop, loop to main. There WILL be a short if you attempt to cross the gaps at the bottom of the upper loop though, because now the polarity is backwards across the gaps.
If this works, and there's no reason it shouldn;t, put the AR back in place. If the train will no longer enter/leave the loop at the upper gaps, there is something wrong with the AR. If it goes in, but shorts coming out, reverse the feeds to the AR with the train in the loop. If it now comes out of the loop fine, that points to the AR not reversing. If the AR is not working, then the train should now cause a short at the upper gap, because the loop polarity no longer matches the track on the other side of that gap.
ANd if you get a short as soon as you turn on the power - that means you don't have both rails gapped at each end of the loop. Or a feeder from outside the gap connects to a rail inside the gap, or vice-versa.
Lastspikemike An object lesson here is to wire the reversing loop for fully manual operation and get it to work. Only then fit the auto reverser.
An object lesson here is to wire the reversing loop for fully manual operation and get it to work. Only then fit the auto reverser.
rrinker Easy to test. Bypass the AR. Connect the loop tracks with the feeders matching one of the two tracks, for example, on the top loop, if you have the rail to the top of the digram as A, and the rail towars the bottom as B like where the A abd B are in the top left, then wire the loop the same way so that on the loops ide of the upper right gap, the top rail is A and the bottom rail B. Now a train should smoothly run into the loop at the top right, crossing those gaps with no problem. Main to loop, loop to main. There WILL be a short if you attempt to cross the gaps at the bottom of the upper loop though, because now the polarity is backwards across the gaps. If this works, and there's no reason it shouldn;t, put the AR back in place. If the train will no longer enter/leave the loop at the upper gaps, there is something wrong with the AR. If it goes in, but shorts coming out, reverse the feeds to the AR with the train in the loop. If it now comes out of the loop fine, that points to the AR not reversing. If the AR is not working, then the train should now cause a short at the upper gap, because the loop polarity no longer matches the track on the other side of that gap. ANd if you get a short as soon as you turn on the power - that means you don't have both rails gapped at each end of the loop. Or a feeder from outside the gap connects to a rail inside the gap, or vice-versa. --Randy
CPbuff Another update! To isolate the problem, I have removed all feeds from the layout (as I use terminal blocks under the layout for trouble shooting) except for one located on the top track where the "A" is on the diagram
Another update! To isolate the problem, I have removed all feeds from the layout (as I use terminal blocks under the layout for trouble shooting) except for one located on the top track where the "A" is on the diagram