I am planning & building a layout (DCC)
It will be a double main line that will eventually go all the way around the room. In the mean time during construction I plan on putting temporary loops at each each end so that I can run continuous trains & check my track work along the way. The end of the loops will connect to the main lines in such away to basically create a "Dogbone" configuration. Since the parallel mains will be wired in the same polarity to each other, I realize that the loops will have to be treated as reverse loops.
Now to the meat of my question: since this configuration does allow for trains that can be longer than the loops themselves I have come up with this idea.
Where the mains meets the loops put in a dead section (neutral zone) on both rails about 1/4" to 1/2" long. The locos would be able to trigger the auto reversers due to the length of their trucks & the all wheel pick-up, but a piece of rolling stock would not effect it since all of my rolling stock trucks are insulated and the metal wheel would not contact the main & loops at the same time
Thus the locos can enter & leave the loop changing polarity with out the rolling stock having effect
Thoughts, suggestions, idas?
This dead zone will work, but unless you are going to have a long train of lighted passenger cars, I don't think that you will need it.
You could try it first without them. If it doesn't work, you can put some tape on the rails where the dead zone would be and try it before actually cutting the track.
The other way would be to wire one of the long straight sections as the reverse loop temporarily.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
Well because the layout will eventally become a complete "circle" I want to keep the mains the same polarity because of other trackage such as crossovers.
dbduck Well because the layout will eventally become a complete "circle" I want to keep the mains the same polarity because of other trackage such as crossovers.
As long as the crossovers from one side to the other are double gaped, it won't matter if the center section is the reversing section or not. And notice that I said "temporarily". But do understand this, the dead zone spacing will not eliminate the need for auto reversers. So you can buy two auto reversers, one for each end, or only one reverser for one of the center tracks.
I do realize that I will need two auto reversers
You can get by with only one auto-reverser if the end loops are so far apart that no train can possibly be in both at the same time. Just wire both of them to the output of one PSX-AR or similar device.
Unless you're going to be running long passenger trains with lighted coaches, there's no need for the "dead zone."
My reasoning for the "dead zones" is that after the lead loco of a consist switches the polarity as it exits the loop the cars would still be entering the loop where the polarity is crossed
..i figured the dead zones would guarentee that a metal car wheel could not re-trigger the reverser while a locomotive is still in the loop
on my starter layout I had a reverse loop with a digitrax reverser and the reversed section was about 5 or 6 cars length long and never had any trouble with the metal wheels setting off the reverser with the train it.. You can even run MU units and not have to worry about it. With DCC you are not changing the polarity but the phase of the current. All I used was the plastic gapper joiners and all was good.
i understand there is no problem..as long as the train is shorter then the reversing loop
but this allows for trains longer than the reversing section
All rolling stock wheels except lighted passenger cars are insulated and will not trigger the auto-reverser.
Even with lighted passenger cars, the lights might trigger the reverser but one side of the wheelsets is insulated.
I have a reversing section on my HO scale home layout that is only two feet long and I have never had a problem running long trains through it. Only the MUd locomotives can trigger it, and I have no more than two units together. I am using the PSX-AR auto-reverser from Tony's Train Exchange.
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What am I missing here?
Your planned layout sounds very much like mine which is a double mainline continuous loop dogbone configuration. If the ends of the loops will connect to the mainlines, and the parallel mains will be wired in the same polarity ot each other, where is the reverse loop?
There may be reversing sections somewhere within the loops or elsewhere in the layout, but a simple continuous loop dogbone configuration should not present a reverse loop problem.
I have included a link illustrating several dogbone configurations including some with and without reversing sections.
http://www.thortrains.net/4holayb.html
Can you provide a diagram of your layout or explain where the reverse loop occurs?
Rich
Alton Junction
the layout will eventually be a continuous running "oval" but while building it & testing trackage I am going to put temporary loops on each ends making the double main on the actual layout a single main dogbone .It is these temporary loops that will have to be wired as reverse sections because the mains on the "real" part of the layout will be wire parallel (same potential)
The obvious question that comes to me is why not just make the reversing portions longer? I think the "desd zone" idea is only going to cause irritation later.
The other option would be to do the wiring to make it easy to switch the polarity on one side of the main when the time comes.
Jeff But it's a dry heat!
I want to wire the permanent part of the layout permanatly & not have to change anything later.(there are crossovers & other trackage that would have to be insulated in the temporary mode, but not in the "normal mode"....so I feel the easiest solution would be reverse loops
BTW the dead zones are temporary as well, & will not exist when the layout is complete
cacole All rolling stock wheels except lighted passenger cars are insulated and will not trigger the auto-reverser. Even with lighted passenger cars, the lights might trigger the reverser but one side of the wheelsets is insulated. I have a reversing section on my HO scale home layout that is only two feet long and I have never had a problem running long trains through it. Only the MUd locomotives can trigger it, and I have no more than two units together. I am using the PSX-AR auto-reverser from Tony's Train Exchange.
The above is incorrect information. The autoreversers - regardless of make or type - are tripped when a metal wheel spans the gap between 2 adjoining rails of opposite polarity. It has nothing to do with resistance across the rails. Any single metal wheel will do to actuate the autoreverser. Which is why the recommendation to stagger the gaps in the 2 rails of the reversing section track by about 1/8". This helps prevent the situation where the autoreverser is tripped by 2 wheels at the same time.
The same potential for autoreverser confusion occurs when the train is longer than the reversing section. If wheels happen to span the gaps at both ends of the reversing section at exactly the same time, the autoreverser gets confused. Hence, the recommendation to make the reversing section longer than the longest train.
The vast majority of the time, you will never run into the situation where 2 gaps are spanned at once. Especially if you have mostly plastic wheels on your cars. But it can happen.
Fred W
that is why I came up with the idea of dead zones so that a rolling stock wheel will not be able to bridge the gap between the main & the reversing loop because of the short piece of dead rail between them
The wheel will bridge the main / dead gap then roll over the dead rail & then bridge the dead / rev loop gap, thus never being able to be in contact with the main rail & rev loop at the same time
Oh boy, I wish that I could visualize what you are trying to do with these temporary loops. From what you seem to be saying, I just don't see where you have a reverse polarity problem. Seems to me that there is no reversing section.
A picture is worth a thousand words. Can you post even a crude drawing or a photo?
Your concerns about reverse polarity may be much ado about nothing.
richhotrain Oh boy, I wish that I could visualize what you are trying to do with these temporary loops. From what you seem to be saying, I just don't see where you have a reverse polarity problem. Seems to me that there is no reversing section. A picture is worth a thousand words. Can you post even a crude drawing or a photo? Your concerns about reverse polarity may be much ado about nothing. Rich
If you have a dogbone layout with just ordinary industry sidings, you do not have a reverse loop. Picture an oval with the long side squished together so the top and bottom tracks are now next to each other as if it were double track.
However - as soon as you add a crossover from one of those lines to the other, you have created a reverse loop (2 actually, one on each end). It's quite obvious if these crossovers are located near the loop on either end, slightly harder to see if the crossover is in the middle, far away from the loops. If you follow it around and say the tran ont eh bottom line is goign to the right, it goes around the loop and comes out on the top track goign to the left. No reverse loop. But then it hits the crossover and switches to the bottom track - now it's going to the left but ont he bottom track - so there is a reverse loop involved.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
if I wasn't at work I would make a drawing, scan & post it
If i have time when i get home later I will try
dbduck if I wasn't at work I would make a drawing, scan & post it If i have time when i get home later I will try
Cool, please do it. I would love to join in and make a positive contribution to this discussion. But, I must be brain dead because I don't see the reverse polarity in your layout description.
Meanwhile let me read Randy's recent comment more closely. Maybe that will help.
the two tracks that are next to each other are the parallel mains & will be as such when the layout is finished,... so their "polarity" (if you will) are the same & crossovers pose no problem
The loops at the ends are single tracks & loops from Main#1 back to Main #2 which make them require a reversing circuit.
I think what most of you are not getting is that the layout will eventually be a double main "oval" type layout and it will not need any type of special wiring..but because adding TEMPORARILY loops at each end it turns it into a single main dogbone..the loops will need to be treated as reversing loops
Why not temporarily reverse the polarity on one of the mains? Couldn't that be done by flipping a single pair of bus wires?
if I reverse the polariity on one of the mains..I will have to go back & put in gaps in areas (such as crossovers) that will not need to be gapped when the layout is finished
That part is already working fine..don't want to temporarily change something that will end having to be put back to permanent...the temporary reversing loops are the easiest solution
I think we have gotten of the main topic...
The original question was regarding the "dead zones" between the reversing loops & the main lines
I definitely know the loops need to be treated as reversing loops
That is the easiest solution without having to change existing wiring or having to go back & add temporary gaps where they will not be needed when the layout is finished
Well, you wouldn't have to remove the gaps when you go permanent. They wouldn't hurt anything.
I understand what you are trying to do. In my opinion, you are trading more work now for less work later, but that's a choice for you to make.
If you do what you are thinking of, I would be tempted to make the dead zones very small, such that the reverser will trip as a single powered truck goes over it. It's not what I would do, but it should work.
A pusher loco or a lighted passenger car could, of course, mess up everything.
If you reverse the bus hookup to one main, now you have the situation I described at any crossover between the mains. It will still create a reverse loop situation.
ANotehr idea, hook all the feeders from one main to an autoreverser and make the entire main the reversing section. When construction is complete and there are no more loops, remove the autoreverser and repalce with jumpers connecting that main's sub bus to the main power bus. Such as, use a 4 position terminal strip. Two go to the one main's feeders, two to the main DCC bus. Autoreverse connects here. When done, move the two wires from the main bus to the same terminals as the ones going to the bus for the main line, and remove the reverser.
I do not plan on reversing any of the wires to either main...here is what I am talking about
dbduck I do not plan on reversing any of the wires to either main...here is what I am talking about
Hmmm, that is a whole lot simpler than what I imagined you were first talking about.
Just out of curiosity, once this around-the-room double mainline oval is complete, how many running feet will that be?
Another question. Since you plan to contruct another temporary loop "at the other end", how long of a mainline run will initially exist between the two loops? I ask this because won't you need to continually tear down and rebuid one of the loops as you move along with permanent construction of the double mainline?
In any event, as to your initial question, sure the dead zone will work. But, as one responder asked, why not just make each loop big enough to accomodate the longest possible train. Since the reversing loops are temporary, why do they have to be so small that you create other problems?
Nuts, it is nearly midnight here in Chicago and I cannot go to bed thinking about this d*** post.
I went back and re-read the entire thread, and I guess that your main question is essentially: what is wrong with your idea of dead zones leading into and out of a short reversing loop.
Answer: Nothing as long as there is no trailing car that can trip the auto-reverser once the consist begins to exit the reversing section without completing its exit.
So, the only remaining question is: do you intend to run any train long enough with a trailining car such as a lighted passenger car, or lighted caboose, that could trip the auto-reverser while a portion of the consist is still exiting the reversing section. If not, no problemo.