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
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.
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.
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.
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.
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.
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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.
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.
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
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.
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.
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.
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.