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to gap or not to gap ?

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  • Member since
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  • From: Chateau-Richer, QC (CANADA)
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to gap or not to gap ?
Posted by chateauricher on Thursday, July 17, 2008 4:54 PM

I have a cross-over situation on my N-scale layout.  I am wondering if I should gap the rails or not.

I am using Atlas' #7 code 55 turn-outs with insulated metal frogs with Atlas' N-scale code 55 under-table switch machines which include a switch to change the polarity of the frogs.  The 2 turn-outs are wired to be thrown at the same time to allign for either straight-through or for cross-over travel.  My plans are to use DCC (haven't chosen a system yet).

Before installing the cross-over, I was of the understanding that with insulated frogs (wired to have the correct polarity depending on which way the turn-out is thrown) that I did not need to cut a gap in the rails joining the two turn-outs.

Now, I am told that I should have a gap.

Since the tracks have been installed without a gap, I'll have to go back and cut the gaps.  But before I do so, do I really need to ?  If so, why ?

Below is a diagram of the track configuration...

From what I can tell, at no time is a short-circuit possible.  The insulated frog would prevent any short-circuits.  And, even if the frog is powered, its polarity is determined by the direction the turn-outs are thrown.

So, given the situation, should I cut gaps ?  If so, why ?

Thanks in advance for your help.

 

 

Timothy The gods must love stupid people; they sure made a lot. The only insanity I suffer from is yours. Some people are so stupid, only surgery can get an idea in their heads.
IslandView Railroads On our trains, the service is surpassed only by the view !
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Posted by CSX Robert on Thursday, July 17, 2008 9:25 PM
You are right, there is no need for gaps.
  • Member since
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  • From: Poconos, PA
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Posted by TomDiehl on Friday, July 18, 2008 3:02 PM

To really answer this question, I need to ask for a bit more info: you said you "haven't chosen a DCC system yet," so I'm assuming you're running standard DC block control until that time.

The main question is about the two tracks connected by the crossover, do you plan to run these as separate blocks (ie. run two trains from different power packs on each of the two tracks)? If so, I'd recommend that you insulate the joints between the switches. This whole thing about figuring out if you have power routing switches or not is unnecessary if you isolate the rail joints, at least off the frog. Plus, if the isolation fails, you can have a short.

As a standard practice, I put insulated rail joints on both rail where I intend to break a section into blocks, and definately both rail through a crossover.

An added advantage, after you convert to DCC is to leave these insulators in place. When you experience a short in the system (notice that I didn't say "if"), you can isolate the track in the original sections for easier troubleshooting.

Smile, it makes people wonder what you're up to. Chief of Sanitation; Clowntown
  • Member since
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  • From: Chateau-Richer, QC (CANADA)
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Posted by chateauricher on Friday, July 18, 2008 4:09 PM
 TomDiehl wrote:

To really answer this question, I need to ask for a bit more info: you said you "haven't chosen a DCC system yet," so I'm assuming you're running standard DC block control until that time.

My layout is still under construction.  I have not connected any power to the tracks -- DC or DCC.  I plan to use DCC (most likely MRC Prodigy Advance) right from the beginning.  I don't plan to use DC at all. 

 

The main question is about the two tracks connected by the crossover, do you plan to run these as separate blocks (ie. run two trains from different power packs on each of the two tracks)? If so, I'd recommend that you insulate the joints between the switches. This whole thing about figuring out if you have power routing switches or not is unnecessary if you isolate the rail joints, at least off the frog. Plus, if the isolation fails, you can have a short.

As a standard practice, I put insulated rail joints on both rail where I intend to break a section into blocks, and definately both rail through a crossover.

The cross-over in question is on the upper level of my 2-level layout.  It is on a section of benchwork that is physically separate from the rest of the upper level (a bridge over a gorge at one end, and a swing-gate (for a walk-through) at the other).  All the wiring for this section -- including the double tracks, turn-out motors, signals and structure lighting -- is also physically separate from the rest of the layout, connected at either end by terminal blocks.  The tracks crossing the bridge will eventually be gapped to create a short-circuit management block (the tracks crossing the swing-gate already being gapped).

 

An added advantage, after you convert to DCC is to leave these insulators in place. When you experience a short in the system (notice that I didn't say "if"), you can isolate the track in the original sections for easier troubleshooting.

My layout is designed and will be built in sections.  Each section's wiring -- track power bus, turn-outs, accessories, structure lighting, signals, etc. -- will be connected to neighbouring sections using terminal blocks so that I can easily disconnect different sections of the layout.  Its not really a true "block" system as it includes more than just track power buses.  At the moment, I have not gapped any rails; but I plan to go back later and cut gaps (more for short-circuit management than for DC block control).

I designed and am building my layout this way as it is the simplest I could think of; and it allows me to work on individual sections to near 100% completion.  Also, I can power each section separately for testing, and for running trains.

I can understand using gaps to create power blocks.  But what I am wondering :  in this cross-over situation with insulated frogs, are gaps absolutely necessary to prevent shorts ?  From what I've learned so far, it would seem I do not absolutely need the gaps.  However, if that proves to not be the case, I can always go back and gap the rails.

Thanks for your input so far.

 

 

Timothy The gods must love stupid people; they sure made a lot. The only insanity I suffer from is yours. Some people are so stupid, only surgery can get an idea in their heads.
IslandView Railroads On our trains, the service is surpassed only by the view !
  • Member since
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Posted by TomDiehl on Friday, July 18, 2008 10:06 PM
 chateauricher wrote:

I can understand using gaps to create power blocks.  But what I am wondering :  in this cross-over situation with insulated frogs, are gaps absolutely necessary to prevent shorts ?  From what I've learned so far, it would seem I do not absolutely need the gaps.  However, if that proves to not be the case, I can always go back and gap the rails.

Thanks for your input so far.

Absolutely necessary? No, but a wise precaution. It's been my experience that Murphy's Law is strictly enforced on layouts.

If it would be easy lift the track at this point to insert the insulators, I'd probably do it, but if it's not, don't worry about it and hope for the best.

Smile, it makes people wonder what you're up to. Chief of Sanitation; Clowntown

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