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Reverse "loop" unexpected problem

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Reverse "loop" unexpected problem
Posted by DAVID SMITH1234 on Wednesday, January 18, 2017 12:28 AM

Was finishing up the last bit of track on my layout.  A 3 and a half foot section that forms a reversing section.  My layout is DCC so I wired up the reverse module and ran my first locos through.  No problem, was impressed at how seamless it switches over.  I figured this length was more than longer than any consist of locos I run.  Then I ran my first passenger train through.  I'm sure some of you pros know where this is going.  Train enters the "loop" and as soon as the lead loco leaves the "loop".......short circuit.  Hmmmm, not going to let 33 years as an electrican go to waste now, so I look at the situation.  I had totally forgot about my Rapido stainless cars, you know the ones that take power from the track.  Problem is that when lead loco leaves "loop" there will be a passenger car with one truck in the "loop" and one truck on the main.  Lights are shorting out the system.   Guess this is a freight train only reverse loop now.   

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Posted by Steven Otte on Wednesday, January 18, 2017 8:58 AM

I'd suggest moving the gaps that separate your loop from the lead-in track as close to the turnout as possible. That way, there's no way a train could span both entrances to the loop without physically crashing into its own tail end.

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Steven Otte, Model Railroader senior associate editor
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Posted by G Paine on Wednesday, January 18, 2017 10:18 AM

DAVID SMITH1234
Guess this is a freight train only reverse loop now

It can still mess up if you have a freight car that takes power for a sound module or a FRED or a lighted caboose

George In Midcoast Maine, 'bout halfway up the Rockland branch 

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Posted by selector on Wednesday, January 18, 2017 11:05 AM

Digital Specialties, the guyz who make the PSX series, suggest that you don't actually need to make the reversing section fully and consistently capable of taking an entire train between its gaps.  In fact, the gapped length that is being controlled by the reverser only needs to be as long as the longest wheelbase on any item that picks up power...technically.  What counts is how any one axle with metal tires that might bridge two tranversely situated gaps makes contact, or bridges, the two metal rail ends that currently have disparate phases or polarities.

What they say in their literature (I caution it has been five years since I last read it) is that if you cut two (2) sets of gaps set apart by the distance of your longest car truck (NOT on the locomotive, but on a passenger car or other long car with metal tires)...AND stagger the pairs of gaps across from each other by a few mm, you should avoid any conflicts caused by trains longer than the reversing section entering it and metal tires making contact with opposite gaps at the same time while bridging the rails on either side of the gap.

Whew, that's a long and complicated statement...sorry...but...the simplest correction for your situation is to cut new gaps that are staggered.  It lengthens the gap and dead track unfortunately, but only by the 1/2" or so added until the new gap.

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Posted by richhotrain on Wednesday, January 18, 2017 11:43 AM

The solution is relatively simple.  To avoid a short circuit, make the reversing section longer than the longest train. So, in this instance, the OP needs to place the entry/exit gaps further apart.

Rich

Alton Junction

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Posted by Onewolf on Wednesday, January 18, 2017 2:52 PM

Steven Otte

I'd suggest moving the gaps that separate your loop from the lead-in track as close to the turnout as possible. That way, there's no way a train could span both entrances to the loop without physically crashing into its own tail end.

It's funny you mention that. I just finished building and then rebuilding the entrance to my upper return loop. When I first built it I double gapped adjacent to the turnout exits. But then I realized I was planning to use the PSX-AR to auto control the turnout and there needed to be enough distance between the double gaps and the turnout to allow time for the turnout points to throw the correct direction before the train got to the turnout.  :)

Modeling an HO gauge freelance version of the Union Pacific Oregon Short Line and the Utah Railway around 1957 in a world where Pirates from the Great Salt Lake founded Ogden, UT.

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Posted by MisterBeasley on Wednesday, January 18, 2017 8:09 PM

DAVID SMITH1234
A 3 and a half foot section that forms a reversing section.

I'm guessing this is N scale, and also that this is NOT a loop but rather a diagonal crossover between opposite sides of an oval.  Is that correct?

One option is to move the gaps OUTSIDE of the diagonal section, out to the main line on the straight-through path of the turnout.  You will need two gaps, not one, but you will gain at least the length of the turnout for your reversing section.  You need to be careful when running trains on the diagonal, but you will be able to run the longer passenger trains if you do this.

It takes an iron man to play with a toy iron horse. 

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Posted by DAVID SMITH1234 on Wednesday, January 18, 2017 8:53 PM

It is HO scale but you are correct that it isn't a loop, thats why i put loop in parenthese.  It is bascially like you said connecting two sides of an oval, even though at the joining part they are physically less that a foot apart.  Sort of the dogbone thing.  

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Posted by DAVID SMITH1234 on Wednesday, January 18, 2017 9:00 PM

Does anyone know what the shortest you could make a reverse section? Would the length of your longest truck work, I don't have any steam locos yet but i do have one of the planned Rapido Royal Hudsons reserved so I guess that idea wouldn't work anyways.  The reverse module would be working overtime if the section was that short as it would have to flip for every truck.  Just going to make the reverse section longer I guess.

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Posted by richhotrain on Thursday, January 19, 2017 3:19 AM

MisterBeasley

 

 
DAVID SMITH1234
A 3 and a half foot section that forms a reversing section.

 

I'm guessing this is N scale, and also that this is NOT a loop but rather a diagonal crossover between opposite sides of an oval.  Is that correct?

One option is to move the gaps OUTSIDE of the diagonal section, out to the main line on the straight-through path of the turnout.  You will need two gaps, not one, but you will gain at least the length of the turnout for your reversing section.  You need to be careful when running trains on the diagonal, but you will be able to run the longer passenger trains if you do this.

 

As always, a track diagram would help.

Rich

Alton Junction

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Posted by DigitalGriffin on Thursday, January 19, 2017 11:42 AM

What Rich said.  Track plan a big plus here.

Don - Specializing in layout DC->DCC conversions

Modeling C&O transition era and steel industries There's Nothing Like Big Steam!

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