Craig

Craig,

I'm not a wiring expert so please take the following with a grain of salt.

First, the double crossovers will need to be gapped anyway to operate properly, basically isolating the entire center frog section of the crossover. You'll only need to add an additional gap on the end near Loop A (both tracks) to separate the loop into a separate power district, one controlled by an auto reverser.

Loop B doesn't need to be separated from Loop A, but I think I would, in order to avoid having a train in A flop the polarity on your in B. I would think that separating it from A, and wiring it as another block like the rest of the layout should avoid that problem. In this manner, Loop A will correct itself based on the traffic, regardless of where the the trains enter or exit.

This is a case where I would strongly recommend frog juicers for the crossovers; I think a slight investment in this case will pay off in dividends quickly.

I hope that helps!

Reverse Loop

I would run a single reverse loop from about the "P"  in reverse loop to the first switch in the lower double crossover.  Make it a train length long.  It does not need to run from switch to switch. 

If you can't get a train length then use double gaps to prevent individual wheel shorts.  This probably precludes lighted or otherwise powered cars from working properly at these gaps.  The possibility of these cars shorting exists depending on how the power pickup system is designed.  A car with all wheel pickup will short out the system as the pickup length would be longer than the short double gap used to prevent individual wheel shorting.  Testing individual cars would identify any problems before the long train is run with visitors present.

An auto reverser would be the easiest way to power this reverse section.  A different solution would be needed for a DC layout

Linkages can be built to reduce the number of switch machines needed.  Master Comstock posted pictures about a year ago of a single machine design that I did in the '90s.

Note that each switch on each double crossover would need to have it's frog wired according to your standard frog control method regardless of linkage used.  A commercial double crossover like Walthers  has the center crossing gapped and wired correctly. 

Dang, I didn't mean to get this wordy--

Terry

Reversing Section

I concur. I don't know how much track is actually there, or how long your trains are, but ideally, if it's long enough, run the reversing section from just to the left of the crossovers between the two loops, to just to the left of the first switch in the crossover at the bottom. (Exactly what Terry was suggesting). Don't include the switches or the "B" loop in the reversing section.

Right, although that's completely unrelated to the reversing loop. (Not saying it doesn't need to be considered, it does; it's just a completely different issue that's in addition to and completely unrelated to the reversing circuit).

What Chris said

Chris is right.  The frog issue has nothing to do with the reverse loop.  However, I have found that some tend to forget to include the everyday things when solving problems and I tend to mention them in passing as a reminder.  Maybe a belt and suspenders issue on my part.

Terry

The right way

Craig,

You are attacking this the wrong way, just because the loop on the left is your reversing loop it is not actually the problem. Normally you would just do the whole loop from the crossover as a reversing block, but as you have the extra crossover and loop (non reversing) very close there would always be problems especially with coach lighting without some tricky wiring, I can tell you how to do that but the way you have asked the question tells me it could be trouble sometime later if there was a problem and you did not fully understand enough to diagnose the real cause.

The method you need is to isolate the crossings as per my alterations to your plan here

http://noarail.com/members2/v/Tony/Help+Files/Complicated+Revering+loop.jpg.html

The two red lines are isolation on both rails on all tracks. The right hand ones must be at least one train length from the crossover (longer if possible as your trains will grow) Power this section via the reverser.

You will need to isolate the crossovers and power the frogs as usual if they are not done by the manufacturer. I have marked them in for you.

There is one proviso with this that ONLY ONE train may be in the reversing section block at anytime when a reversing move is made, the loops and rest of the layout is no problem as is straight through moves.

The 'A' and 'B' tracks need to be wired in phase so that a train crossing over will not cause a problem, just follow from the inside rail of the 'A' line over the crossing you be on the outside rail of the 'B' line and wire that to the same side of your system then do the same with the other rail. Don't forget the isolators on the crossover.

Tony

On second review

If the trackage on the right side of the drawing forms another loop then I would add a second train length reversing section, preferably in the lower track or somewhere away from complicated trackwork.  This would be in addition to the "reversing loop" section.  While the double crossovers appear to be the point that the reverse loop ends, any part of loop track can be the reverse section so the double crossover can be treated as a regular section of track.

This leaves both double crossovers as well as loop B and the "rest of the layout' as regular track with no special wiring.  Train length tracks, if available in these locations, eliminate the potential design complications caused by lighted or otherwise powered cars. 

Each of the reversing sections can only hold one train at a time so most, if not all, of the "only one train at a time in this area" problems go away.  This does cost an additional reverser.

Terry

No Terry, you are mistaken

No Terry, you are mistaken as that would not work at all. The loops on each end, while they form part of a reversing loop are not the problem, it is the fact that there are actually four reversing loops (two loops with two different possibilities each and they are all overlapped. Multiple reversers would spend all day fighting with each other as they would be controlling the same track work. Reversers have to be on the part of the track that is causing the short. The only way for this to work is as I described.

Tony

Thanks and another question for Tony

Thanks to all who replied.

Tony, I like your approach and I think I'll go in that direction. Let's see if I'm understanding you correctly; the loop won't actually be the reversing section, rather the section in the middle will be. I'll wire up the green loop in phase with the black one.

I'm using all DCC-friendly Peco turnouts so does that mean I can omit the isolators at the crossovers?

And assuming that, can my 'train-length' be between your two red lines? I won't have room for a train-length between the black crossover and the right-hand red line.

Thanks....Craig

4 reversing loops

Tony,

Take out the track that is labled reversing loop and the straight section above "insulating joiners' and please tell me where the other reversing loops are.  I don't see them on the sketch.

As drawn, loop b is an oval and the section containing both double crossovers form a short section of double track that is connected to the rest of the layout via a single track when deleting both of the tracks I have described as reversing sections.

Thanks,

Terry

possible point of confusion

Tony,

Thinking more after I pushed the button, the possible point of confusion is where I gapped my reverse sections.

Both are single track with no turnouts or crossings contained within the reversing sections.  No part of either double crossover is included in either reverse section.

Not enough coffee yet this morning,

Terry

more confusion?

I don't know if this will help or just create more problems but my layout is identical to your A line and I had considerable trouble figuring out the wiring.  This is what helped me in the end.

For your A line only - no opinion on the B line

Confusion

This works, I used it in a previous layout, but it only has one double crossover.  The drawing shows two  and some other tracks not connected in what one normally (nothing wrong with that) sees so I feel some other method is necessary.  I chose to divide the loops into two separate single track sections with a double track section for operational convenience rather than a single reverse section incorporating both double crossovers and some additional track where the possibility of multiple trains crossing into the reverse section at the same time will possibly confuse the reverser.

Terry

1 reverse loop?

It looks to me as though

• The passenger loop is not a reverse section as no configuration of the double crossover between it the the section labeled "reverse loop" can result in a train reversing its direction.
• Either the section labeled "reverse loop" (and the passenger loop attached to it) or the section labeled "rest of layout" needs to be reversing.

If I were wiring this I would

• make the double crossover between the "reverse loop" and rest of layout operate as an all or nothing configuration. Either turnouts are aligned for both crossing tracks or aligned for straight through operation. It makes little sense to allow completely independent control of the 4 turnouts since operation in the wrong direction would result in a derailment.
• power either the "rest of the layout" or the "reverse loop" and "passenger loop" from a relay with a robust (10A) set of at least DPDT contacts. I would drive the relay from the position of the double crossover -- straight through configured as normal power, crossover position configured as reversed power polarity for which ever piece is deemed the reverse section

Of course I could be wrong -- considerations:

• How much track and how many trains would be in each section? What booster current capacity is needed?
• How many booster districts are needed in each section? If multiple power boosters are needed for a section, then multiple relays, one per booster that needs reversing, would be required to keep the booster outputs separate. Instead of multiple relays, a single relay with increased contacts, a 4PDT for 2 boosters or a 8PDT for 4 boosters, would suffice.
• I found that running my 5 track staging yard built on a reverse loop on my previous  layout through a relay worked well. The relay switched fast enough so that even soundtrax locos didn't glitch when the polarity changed.

Using a DCC autoreverser is possible, but it would mean limiting the max current to the reversing section to the capacity of the autoreverse unit. Auto reverse units also allow very brief short circuits to occur each time a loco bridges a mis-polarized track junction and the shorts produce small arcs which over time lead to pitted wheels and tracks.

FWIW

Charlie Comstock

Nope, Two reverse loops

Charlie.

As drawn, the right side is also a reverse loop.  Took me a while to figure it out...  Both can be controlled by a single reverse section although track complexity in the area may lead to electrical issues.  I can't tell from the not-to-scale drawing.  Not knowing the actual track layout led me to designating two reverse sections in locations that would minimize or eliminate any potential electrical issues during operation.

I couldn't figure out a  way to auto reverse polarity with a relay for either of the sections I designated as reversing so I went with the auto reversers.

Each of the sections I selected are single track with no turnouts so only one train can be be in either section at a time in normal operation thus limiting the current necessary to that of a single train for each rather than the full current requirement of the booster.

If the reverse loop arrangement was a simple loop or a simple loop with storage tracks then I would go with the relay controlled by the switch machine at the entrance/exit of the loop as the least expensive method of control at the possible high current levels.

I agree that a single normal/reverse selection for the double crossover is the best way to go.  It's easier and prevents a lot of possible mistakes.

Coffee's beginning to kick in--finally,

Terry

inside - outside

When the crossover is set to straight routes (no crossing over) the outside track of the left loop is connected to the outside track of the right loop and the inside track is connected to the inside.

When the crossover is set to both routes crossing over the outside of the left is connected to the inside of the right and the inside of the left is connected to the outside of the right. To avoid a short when passing through the crossover, either the left or the right side need to be polarity flipped (reversed).

The polarity flipping (reversing) can be slaved to the state of the crossover. The key seems to be insulated gaps in the crossover more or less as shown (but the frogs in the crossing may need a little polarity assistance and that's where an auto-reverser, if used, should go).

I'm just not seeing a big problem. Or is it because I'm blind?

Cheers,

Charlie

what reverse loop?

Charlie,

You're making me think--shame on you...

If one throws all of the turnouts in the right hand double crossover on the diagram at one time then the track configuration changes from an oval to a figure eight or vice versa.  No reverse loop.  Yet, when changing configurations between oval and figure eight, one of the end loops will have to change polarity.

How to gap and wire it so it works?  Using the 20 year old Walthers code 83 double crossover I have available, the only gaps I would have to cut are to the straight through stock rails on each side.  Note, this particular double crossover had factory gaps through all the rest of the rails at the center, including the crossing.

 One of the end loops will have to reverse polarity when switching between oval and figure eight so it cannot be wired as a normal block.  I believe that the two frogs on one end would drive the loop at the far end.  Use high current contacts for these frogs as significant current can be drawn depending on the number of locomotives and other things being powered--a spot for Charlie's high current contacts.  The other two frogs would be connected as usual.  I think this will work using a quick drawing and a sample of a double crossover, but I have not wired it up.

This will only work on DCC as the track polarity on one loop will change as the double crossover is thrown. 

In the crossing mode only one train can be routed through the double crossover at a time thus eliminating the potential for electrical interaction between cars and locomotives.  Yes, two trains can pass through the straight route at one time, but the crossing route cannot be selected while either train is on the double crossover so no interaction in that mode either.

Okay, where did I mess it up?

Terry

Answers in the order of postings

Sorry I had to work so getting back took a while, answers in the order of postings.

Craig,

There are two loops with two possible places of reverse polarity each.

A train can go anticlockwise around the left loop and exit at the top.

A train can go clockwise around the left loop and exit at the bottom.

A train can go clockwise around the right loop and exit at the top.

A train can go anticlockwise around the right loop and exit at the bottom.

What you call the reversing loop is irrelevant; the problems are where two tracks of opposite polarity meet.

Yes the green loop must be in phase with the “reversing loop”

All turnouts and crossovers will need some isolation, most times this is built in but you usually still need to isolate the frogs from the rest of the track, Work out what is needed then look at the points to see which bits are there and what needs to be added.

It sounds like the layout is quite small so we may need to modify the approach somewhat. See Artarms answers.

Terry,

I think you need much more coffee; you cannot take out sections of track just to make it easy. The track is there and a solution is required. Here, I have done as you said, look closely and tell me you cannot see two possible reverse polarity positions

http://noarail.com/members2/v/Tony/Help+Files/Complicated+reversing+loop+2.jpg.html

Then go here and you will see two more

http://noarail.com/members2/v/Tony/Help+Files/Complicated+reversing+loop+3.jpg.html

Artarms,

What you have drawn is good, the only problem I see with it is if a train triggers the reverser and then enters the passenger loop which would try to trigger it back but the tail of the train would still be triggering it the other way. This could be got around by flipping your plan over and reversing the other side of the layout or by the not as good option of powering the passenger line via the reverser

Charlie,

Your observations are correct re the passenger loop that is why it was not included in the reverser. And the all or nothing crossover is good as you say no point in making it independent.

I am dubious that a relay could switch fast enough to beat the short circuit shutdown of the booster but then I would have to guess that either you are using a below par DCC system or there are those horrible globes stopping the system from seeing the short and so circumnavigating the protection that you paid big dollars for.

From reading between the lines the layout is quite small so there would not be much current draw.

Terry,

Looks like the coffee beans are starting to work.

Craig,

After consideration of all the information so far in your case I would go with the Artarms set up but flip it and reverse the “rest of the layout” unless you are going to have lots of locos in that section and the total current draw exceeds the reverser rating. Or you could reverse the whole of the left end and passenger loop, which one will have the lower draw?

Tony

Reverse loops

Tony,

In your two drawings, there are 4 possible paths to reverse.  However, there is no reversing function contained within the double corossover itself.  The reversing function is the result of connecting the top track to the bottom track with other track.  This track forms the reverse function and some portion of this track needs to be gapped as a reversing section.  None of the double crossover needs to be included.

If the double crossover is treated as a short section of standard double track and none of the turnouts are included in the reversing function(s) then only some portion of the two loops need to be treated as reverse sections for electrical issues if the turnouts are thrown individually. 

If all 4 turnouts are thrown simultaneously then only one section has to have the track polarity reversed as discussed by Charlie and I.  This is theoretically possible.  I believe it is practically possible by using a 8 pole double throw to throw the frog polarity.  The frog polarity(s) on one end controls the track polarity on the other.  I am a little concerned that the relay throw time may disrupt power long enough that sound systems will reset.  I don't know the reset time of sound systems nor the relay throw time from one side to the other.

I had a similar circuit on a much earlier layout, but I don't remember the details.  I still have the double crossover, a Walthers code 83 #6.  I only had to add two gaps, one to each of the straight stock rails.  Walthers had gapped the crossing in the middle.  I also modified the crossover to be DCC friendly so all of the frogs were isolated from the closure rails thus power was routed to the frogs by the relays only--no multiple paths through the closure rails.

I know that toggle switch throw times are in the 10mS range.  I believe relay trow time is similar, but have not checked the specifications

Note this only works for DCC--DC locomotives are east/west direction while DCC locomotives are forward/reverse

Diagrams

Finally figured out how to draw and paste stuff into a response.

Here's how I do the gaps to get one and two reverse sections in this situation.  Hope this clears some of this up.

Terry

Two reverse sections

All gaps shown are related to reverse sections.  Turnout and crossing gaps not shown.

Get another cup of coffee Terry

Get another cup of coffee Terry.

That second diagram is total rubbish, Here I have drawn in the tracks as per your plan

http://noarail.com/members2/v/Tony/Help+Files/Complicated+reversing+loop+4.jpg.html

Red is right rail Green for left rail, tell me how your reversers will do anything except introduce a short and how your train will pass over the crossover without also causing one.

Tony

double track wiring

Tony,

The shorts will go away when you match the polarity of the rails in the double track section.  Make all of the top rails either red or green for both tracks.  It doesn't matter which. 

Terry

5 points for effort

Yes, that would work in a fashion but you have to draw it right, you have the red and green transposed on one leg of the crossover.

It is a very 'out of the norm' way to wire a layout (even for me, and I'm known for doing things a little different when needed) and it wastes one reverser. A more normal approach and saving the cost of one reverser would be much smarter, especially in this case as it is not a large layout so one of your reversing sections would be in the middle of the "rest of the layout" and so prone to having more than one train with lighting partly in the section at once. Remember, there is not enough clear room for a train length from the crossover on that side.

Graig, the more I think about it the more I like Artarms solution and to avoid the 'rest of the layout' go with both the left loop and the passenger line (wired in phase) as the reversing section. It will be the easiest to do and to problem solve if something went wrong later.

Tony

wiring

Tony,

Yep, the crossover is drawn a little wrong.  Sorry

Yep, this is not normal wiring for an oval.  However I submit this is normal for single track to double track, double track point to point, passing sidings and variations on these themes. 

I agree the single reverse section is good for a small low current demand layout with some cautions.

The single reverser is good for small DCC layouts where the maximum current draw in the reversing section is less than the reverser can handle.  It does not work for DC with more than one operator as the direction of locomotives will change when the polarity of the track is changed to match the entrance/exit of the reverse section.

I don't know of a way to get this to work with 2 or more operators in DC.

The two reverse section works for large (read high current) layouts with more than one booster in DCC  and any DC layout with more than one operator.  In DCC the single track reverse section only has to switch the current to the train entering or exiting the reverse section, not all of the current used in that larger part of the layout.  In DC the only trackage where polarity is switched is related to the train entering/exiting the reverse section.  The rest of the layout polarity stays the same.

Layout size, complexity and operating scheme, to me, determine the method to be used.

An off the wall question--does a DCC reverser work for a reverse loop switch in DC?  I think it depends on how the internal circuitry is powered. 

Terry

I don't know of a way to get

It does not matter as the OP is running DCC

I have never tried it, and don't intend to, but not as far as I know as it is sensing an out of phase square wave verses a DC voltage

Tony