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' REVERSAL LOOPS QUESTION II"

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  • Member since
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' REVERSAL LOOPS QUESTION II"
Posted by TrainsRMe1 on Tuesday, March 23, 2021 1:44 PM

Hi All                                                                                                                           I want to thank you guys again for all the info you gave me about the reversal loop problem, I do have another question for you though, I'm using isulated rail joiners to seperate the polarity from the rest of the layout, I'm using a Digitrax AR1, to power the loop, would the polarity be a problem if I ran my yard ladder from WITH IN the loop? the yard will be a go thru yard connecting to the mainline OUTSIDE of the reversal loop. Thanks GUYS.  

 

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Posted by mbinsewi on Tuesday, March 23, 2021 2:10 PM

Inquirring want to know, what was the problem, and the fix, to your first reversing loop problem?

You left that thread, and all participants hanging......Confused

Mike.

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Posted by peahrens on Tuesday, March 23, 2021 3:17 PM

See the following sketch, if I understand your description correctly.  First, consider the basic loop without an attached yard.  You would put gaps at A and B and the loop polarity would be controlled by your reverser.

Add a yard, off the loop at C, which has a through track to the mainline at D.  You can see that this route is a slightly different reversing route, which must also be isolated (somewhere) from the mainline.  You have the choice of putting a 3rd set of gaps at C or D (not both).  If gaps included at C, the yard floats on the mainline.  If gaps put at D, the yard floats on the reversing loop. Your choice.  You might want want to gap at D, for instance, so that a short from a derailment from yard switching would not shut down the mainline.  

Do consider that you do not want two trains crossing reversing section gaps at the same time, not just the locos, but also cars with metal wheels that bridge the gaps.  That will create a problem.  The lengths of the various track sections may influence the preferred choice (least likely conflict) from that standpoint.  Others may be able to elaborate on that.

 20210323_150641 by Paul Ahrens, on Flickr

See the Reversing section on this webpage for a favorite explanation of reversing sections.  Peruse it to glean the concepts.  You will note that there are often options to handling the issues.  Some posts here on the subject are way over my head, but I think I got your situation correct. 

wiringfordcc.com/track.htm

EDIT: I considered gaps and suggested gaps only at D and E (next photo), but that was an error, as Mike points out below. 

 20210323_171706 by Paul Ahrens, on Flickr

 

 

Paul

Modeling HO with a transition era UP bent

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Posted by BigDaddy on Tuesday, March 23, 2021 3:41 PM

mbinsewi
Inquirring want to know, what was the problem, and the fix, to your first reversing loop problem?

You left that thread, and all participants hanging......ConfusedMike.

I'd say go ask the hobby shop that solved your first problem.

Henry

COB Potomac & Northern

Shenandoah Valley

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Posted by peahrens on Tuesday, March 23, 2021 7:25 PM

Mike, thanks for the correction...I needed to check my work some more but get more confused with more looking sometimes.

I can see my idea of gaps only at D & E is wrong, as the A/F/B section is a reversing loop within the D/C/F/A/E larger loop.

To be clear for the OP, and to ensure I've got it, the viable basic options include:

- Gaps at A & F only (if the max train length will fit within)

- Gaps at A & B with an additional gap at C (yard with the mainline) or D (yard with the reversing section)

 20210323_171706 by Paul Ahrens, on Flickr

 

Paul

Modeling HO with a transition era UP bent

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Posted by richhotrain on Tuesday, March 23, 2021 8:22 PM

The gaps at F are not needed and should be removed. Gaps A, B and C are necessary to completely isolate the reverse loop. I don't see any need for gaps at D and E since the tracks between C and D in your drawing can be wired in phase with the mainline. So, there is only one reversing section and that would be the reverse loop inside gaps A, B and C.

Rich 

Alton Junction

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Posted by Texas Zephyr on Wednesday, March 24, 2021 4:56 PM

If this is a functional yard used to switch trains, in my opinion one doesn't want to break the loop at C or F. A locomotive going back and forth working the yard would constantly be going between the two power sections.

If these were the only options I would opt for D, B, and A.

If this were mine, I would just use two reversers. Move C to the frog side of the turnout and do a DC section. Move F to the frog side of that turnout get rid of E and B and do an FA.

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Posted by richhotrain on Wednesday, March 24, 2021 5:11 PM

I would be interested in hearing back from the OP.

Is Paul's drawing an accurate depiction of the OP's layout?

Rich

Alton Junction

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Posted by peahrens on Wednesday, March 24, 2021 5:29 PM

Texas Zephyr
If this is a functional yard used to switch trains, in my opinion one doesn't want to break the loop at C or F. A locomotive going back and forth working the yard would constantly be going between the two power sections. If these were the only options I would opt for D, B, and A.

I agree, I would choose the D, B, A gaps in the simple case.

Texas Zephyr
If this were mine, I would just use two reversers. Move C to the frog side of the turnout and do a DC section. Move F to the frog side of that turnout get rid of E and B and do an FA.

The idea of two reversing sections (and reversers) did not jump out at me because of how I drew my schematic.  Very interesting.  For instance, if there were a long distance from A to E, I could see how a train might be entering a D/B/A gapped loop via point D while another train could be exiting the loop towards the mainline at point A.  Thus, a 2nd reversing section (as you describe, I presume) would handle that setup nicely.  Train length needs to be considered.

Yes, it would be nice if the OP could (please) post a layout diagram, as the lengths of track involved come into play.  Then someone can volunteer an optimal approach for your configuration.

Paul

Modeling HO with a transition era UP bent

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Posted by mbinsewi on Thursday, March 25, 2021 8:43 AM

richhotrain
Is Paul's drawing an accurate depiction of the OP's layout?

We don't that yet, Rich.  Paul did a rendering going by the OP's description.

He hasn't divulged the cure to his first reversing loop question.

I think we are all waiting.  

Mike.

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Posted by cv_acr on Thursday, March 25, 2021 10:19 AM

richhotrain

The gaps at F are not needed and should be removed. Gaps A, B and C are necessary to completely isolate the reverse loop. I don't see any need for gaps at D and E since the tracks between C and D in your drawing can be wired in phase with the mainline. So, there is only one reversing section and that would be the reverse loop inside gaps A, B and C.

Rich 

Not really..  the whole thing* can be done quite simply with just gaps at A and F and making the loop the reversing section. If you delete the loop between A and F, all the rest of the trackage is parallel. Although it could depend on how far it is exactly between A and F. If you want more length, you could remove F and gap and C and B. Either/or.

*For the given drawing. We still don't really know if that's what the OP's setup looks like.

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Posted by Texas Zephyr on Thursday, March 25, 2021 10:23 AM

cv_acr
*For the given drawing. We still don't really know if that's what the OP's setup looks like.

Yes, it is so much fun guessing at stuff.

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Posted by cv_acr on Thursday, March 25, 2021 10:27 AM

Texas Zephyr

If this is a functional yard used to switch trains, in my opinion one doesn't want to break the loop at C or F. A locomotive going back and forth working the yard would constantly be going between the two power sections.

So? That's not really a particular issue.

Texas Zephyr

If these were the only options I would opt for D, B, and A.

This would work IF D and B are actually as close together as depicted here. If the yard runs parallel to the main for a distance and D is considerably to the "west" I definitely wouldn't do it that way. since trains could enter the yard at D and exit at A at the same time and short.

But even if they are close together, probably a bad idea because a train off the loop at A could wait at the switch by E and be across the gaps at A, which would short out when a train pulls in at D.

Texas Zephyr

If this were mine, I would just use two reversers. Move C to the frog side of the turnout and do a DC section. Move F to the frog side of that turnout get rid of E and B and do an FA

Seems unnecessarily complicated when the only reversing section is the loop between F-A. Not sure what you need a D-C section for.

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