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Reverse Loop Control with DC Power

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Posted by Dave K on Tuesday, April 6, 2021 3:54 PM

Kevin,  now only concerned about the one reversing loop.  I have insulater joiners at the ebeginning and end of the revers loop.

 

Dave

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Posted by ATLANTIC CENTRAL on Tuesday, April 6, 2021 7:02 PM

richhotrain

 

 
ATLANTIC CENTRAL
 

My steps are:

Push one button to set the wye to allow the west bound diverging route into the wye/staging.

Make sure I am pulling into a staging track that is available, push one button if needed to select a track.

Pull the train in until it clears the wye.

Push one button to align the wye for west bound exit from the staging.

Now, which way is my train going? It is still going west. So I don't change my throttle direction. Start the train, it will now back out of the staging and move west bound in reverse around the wye.

After you are fully on the mainline, reset the the wye turnouts to the main, again done with one button. Which way is your train facing now? East. 

Change your throttle direction to east, and proceed.

You have not pushed one more button, or flipped one more toggle switch (in fact no toggles were flipped), or aligned one more turnout, than you would have with DCC.

 

 

Sheldon, my reply, which follows, is not meant to be argumentative but rather observational.

 

The operation of that part of your layout seems complex. I count four buttons to be pushed in addition to throwing turnouts. I haven't stopped to figure what would be required to conduct that same operation in DCC.

On my DCC layout, it is essentially a dogbone with reverse loops at both ends. But, visually, you would not see any "reverse loops" because the layout is large and the loops at both ends don't appear to be loops because the middle of the layout (which is the bulk of the layout) is a 4-track mainline controlled by four double slips, all wired in phase.  

What I actually have to deal with the loops are what I call four "reversing sections" of straight track that end with gaps leading into and out of the loops. Four auto-reversers controls the four reversing sections. So, I have to do nothing as the mainline trains enter and exit the loops. It is all handled automatically by the four PSX-ARs.

Whenever I want to switch a train from one mainline track to another, I manually throw spring-loaded Peco turnouts and/or double slips. But those movements don't happen often because in that area of my layout it is mostly high speed mainline running of trains.

That is the beauty of DCC.

Rich

 

Rich, first there are several different things being discussed just in my post and your reply. So let me explain and separate them.

Regarding turning a train on my wye, when I say "set" the wye, those buttons I am pushing ARE the turnout controls. This does assume my train has already been given authority to use this section of the mainline, but even that requires only two additional buttons to be pressed and then left alone.

So as my train proceeds west, I push one button that aligns the two turnouts that will divert me from the main and thru the branch of the wye into the staging yard.

You would have to manually throw two turnouts.

Because the wye leads into a staging yard, entering the yard requires a clear track. Only if not already selected, that would require pushing one button that will throw the necessary turnouts, however many it takes in the yard ladder automaticly, and it would direct the power only to the selected track, all automaticly with one button.

I have pushed two buttons, you would have manually thrown a minimum of three turnouts, possibly more.

The train clears the wye and stops.

I push one button, and now the turnouts necessary to let the train out of the other leg of the wye are all properly aligned. And the polarity of the staging yard "branch" of the wye is reversed automaticly.

You would have had to manually throw two turnouts and reversed your throttle direction.

I power up my train, without touching the direction buttons on the throttle, my train now backs up, because even through the train is now backing up, it is still proceeding WEST on the layout.

The train backs out of the wye onto the mainline, now facing the opposite direction from when I entered.

After I clear the wye, I push one button that realigns the wye turnouts to allow thru traffic on the mainline.

My train is now facing east. I push my EAST direction button on my throttle and proceed east back the way I came.

You would have had to align two manual turnouts and reverse your throttle direction again.

Again assuming I already had authority on that section of the main, I would have pushed a maximum of four buttons, possibly only three, and changed throttle direction once.

You would have thrown at least 6 manual turnouts, possibly more for the staging yard, and changed throttle direction twice.

The point is it did not take me any more actions, or any great complexity to turn the train on the wye compared to DCC.

Keep this in mind, turning a train on a wye is a separate idea from your dogbone layout reversing issues.

Leaving my WESTERN MARYLAND branch line out of the conversation for now, my layout does not at any point contain a track arrangement like your dogbone layout.

A train going west NEVER goes around a loop and becomes an EAST bound train on a track parallel to the track is was moving west bound on.

Trains on the ATLANTIC CENTRAL portion of my layout are always EASTBOUND or WESTBOUND unless turned on the wye or rebuilt in the yard where there is a turntable to turn locos.

Next issue - Your dogbone layout - YES, you are correct that your layout would be bothersome to wire for DC.

No judgement here, and no disagreement about the advantage of DCC here, but personally I would not choose a dogbone track plan no matter the control system. It simply does not fit my desired operational scheme.

Important point - when you view my new layout, or any of my recent old layouts, you are inside a large double track squiggly oval. Left is always WEST, right is always EAST. And until you go thru a crossover they are two separate isolated loops.

There are no reverse loops on the ATLANTIC CENTRAL mainline. A west bound train does not disappear into staging and then return from that same tunnel as an east bound train.

If allowed to proceed all the way thru the staging, it reappears at the other visable end of the mainline still as a west bound train.

When a train moves thru a crossover from one mainline track to another on my layout there are no polarity issues, there are no special switches to set, no reverse loop toggles. Again, because there are no reverse loops. 

The wye is the only way to turn a whole train on the ATLANTIC CENTRAL portion of the layout.

The single track WESTERN MARYLAND branch line is a different story, better explained with drawings I don't have handy. But, it is a single track branch line and its operation is different from the ACR mainline.

I hope this makes sense.

Below is the track plan for other readers who may be trying to follow this.

Sheldon

  

    

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Posted by SeeYou190 on Tuesday, April 6, 2021 10:43 PM

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Posted by Dave K on Wednesday, April 7, 2021 6:52 AM

Kevin,

All of the support posts finally made me realize that I needed to add insulated joiners to the main line block to insulate it from the remaining main line track.  This means adding two more sets of insulated joiners.

Dave

 

 

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Posted by KitbashOn30 on Wednesday, April 7, 2021 7:39 AM

There is an extrememly simple and hassle free solution to the reverse loop (and wye) situation but so many modelers just ignore it - all you have to do is model electric traction with the overhead wire as one side of the electricity delivery circuit and the rails paired as the other side, the reverse loop problem does not and can not happen! Big Smile

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Posted by richhotrain on Wednesday, April 7, 2021 7:44 AM

ATLANTIC CENTRAL

The point is it did not take me any more actions, or any great complexity to turn the train on the wye compared to DCC.

Keep this in mind, turning a train on a wye is a separate idea from your dogbone layout reversing issues.

Leaving my WESTERN MARYLAND branch line out of the conversation for now, my layout does not at any point contain a track arrangement like your dogbone layout.

A train going west NEVER goes around a loop and becomes an EAST bound train on a track parallel to the track is was moving west bound on.

Trains on the ATLANTIC CENTRAL portion of my layout are always EASTBOUND or WESTBOUND unless turned on the wye or rebuilt in the yard where there is a turntable to turn locos.

Next issue - Your dogbone layout - YES, you are correct that your layout would be bothersome to wire for DC.

No judgement here, and no disagreement about the advantage of DCC here, but personally I would not choose a dogbone track plan no matter the control system. It simply does not fit my desired operational scheme.

Important point - when you view my new layout, or any of my recent old layouts, you are inside a large double track squiggly oval. Left is always WEST, right is always EAST. And until you go thru a crossover they are two separate isolated loops.

There are no reverse loops on the ATLANTIC CENTRAL mainline. A west bound train does not disappear into staging and then return from that same tunnel as an east bound train.

If allowed to proceed all the way thru the staging, it reappears at the other visable end of the mainline still as a west bound train.

When a train moves thru a crossover from one mainline track to another on my layout there are no polarity issues, there are no special switches to set, no reverse loop toggles. Again, because there are no reverse loops. 

I don't want to take this thread off topic by comparing our two layouts.

But on the subject of trains always going in one direction, it is inevitable except on point-to-point layouts. But, what I imagine as I operate my trains is that I am viewing a linear layout in which trains are always running East or always running West. The track just happens to connect over a long oval which the viewer does not perceive.

As for this thread, it is all about reverse loops and trains move West through the loop and return East. Reverse loops in DC require several gaps and switches to be thrown. On layouts like mine, operating in DCC, the auto-reverser(s) do it all automatically, not  manually. That is my only point in expressing a strong preference for DCC over DC.

Rich

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Posted by ATLANTIC CENTRAL on Wednesday, April 7, 2021 8:04 AM

Agreed, I just wanted to show that DC reverse loop and reverse polarity issues can be dealt with in a number of ways that do not involve flipping switches while the trains are running.

Yes, DCC allows the trains to just run anywhere, without regard for polarity or block boundries. And for some track plans, and some layout concepts that is an important benefit.

For other track plans and concepts, not as much.

My other point is this, I don't need or want reverse loops as part of my mainline to accomplish my goals, so toggle switches or expensive auto reversing equipment is not a factor for me either way.

The one reverse loop I will have will be hidden from view and still be easy to operate, only used to stage trains on the branch line.

It is all about what your priorities are.

Sheldon

    

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Posted by SeeYou190 on Wednesday, April 7, 2021 8:11 AM

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Posted by Dave K on Wednesday, April 7, 2021 10:05 AM

The Atlas Wiring Book, Page 31,  explainss how to fix my problem, I believe.  Need to add more gaps.

 

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Posted by SeeYou190 on Wednesday, April 7, 2021 11:45 AM

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Posted by Dave K on Thursday, April 8, 2021 8:45 AM

I am now aware of the need to block off the adjoining and turnback blocks.  I'll let all know what happens.

 

Regards,

Dave K.

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Posted by Dave K on Thursday, April 15, 2021 9:55 AM

I gave up n the two DPDT switches to control the turnback and have gone back to one.  Still having difficulty synchronizing the DPDT switch when the train leaves the block and enters the main line.  

 

Dave

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Posted by SeeYou190 on Thursday, April 15, 2021 10:05 AM

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Posted by Dave K on Thursday, April 15, 2021 10:47 AM
I figured it out.  Run train into post reverse loop block.  Stop train and flip DPDT switch and power pack direction and go.  I cannot figure out why I am getting a short with DPDT switches but I will eventually solve.  I will also add a rectifier to the DPDT switches as you recommend.

Dave

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Posted by ATLANTIC CENTRAL on Thursday, April 15, 2021 7:57 PM

When Dave, or anyone, posts a reasonable drawing of the layout in question, I will offer my serious opinion on how to wire it.

Without such information, myself and others have already offered plenty of "theory" on the subject.

Base on the pictures posted of this layout in the other thread, I have my doubts that there is any really good solution.

And yes, I have some set rigid ideas about good layout design and DC control - based on 50 years of experiance and some very good teachers, who in their day helped put men on the moon and designed top secret radar.

Lastspikemike - I understand your theory on this, but feel as though you are not explaining yourself well for those who don't already understand the topic fully.

And I doubt that your approach would be very effective on what appears to be a very small layout. Of course your theory/method works, but it fails several basic operational requirements in my view.

Just my opinion, but reverse loops on small layouts are not practical.

As Dave seems to be finding out, they are cumbersome and complex.

I am a DC user, but I have long said that small layouts actually benefit from DCC in ways that do not matter as much on larger layouts.

So, here I am, waiting to see an actual track plan to offer a complete system wiring diagram that will work.

Sheldon

    

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Posted by SeeYou190 on Thursday, April 15, 2021 10:07 PM

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Posted by ATLANTIC CENTRAL on Thursday, April 15, 2021 10:18 PM

SeeYou190

 

 
ATLANTIC CENTRAL
When Dave, or anyone, posts a reasonable drawing of the layout in question, I will offer my serious opinion on how to wire it.

 

Sheldon,

Dave has been communicating directly with me via email about the issues he has been having and working towards the best solution.

He has a good handle on the problem, and is learning the realities of DC reverse loops in a very hands-on manner.

The responses in the thread don't quite tell the whole story.

-Kevin

 

That's fine, glad you are trying to help. I have felt from the very beginning that there was not enough information. 

And if the layout is anything like how it appears in the photos, than it will be difficult at best to create an easy operational senerio.

Sheldon

    

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Posted by SeeYou190 on Friday, April 16, 2021 8:37 AM

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Posted by SeeYou190 on Friday, April 16, 2021 8:45 AM

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Posted by Dave K on Friday, April 16, 2021 9:25 AM

I wired the turnback loop DPDT switch as required.  Did the same for the main loop switch.   The main loop is fine but the turnback switch is shorting somewhere?  I am getting a reading when the switch is in the middle and a short in one of the up positions.  I tried to reveres wires in many combinations and chenger switches, all to no avail.

 

Dave

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Posted by ATLANTIC CENTRAL on Friday, April 16, 2021 2:44 PM

Still waiting for a track plan.

Sheldon

    

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Posted by SeeYou190 on Tuesday, April 20, 2021 9:54 AM

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Posted by ATLANTIC CENTRAL on Tuesday, April 20, 2021 10:11 AM

Kevin is so right. Sloppy wiring is an invitation to problems.

My wring looks a lot like Kevins.

Sheldon

    

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Posted by Dave K on Tuesday, April 20, 2021 10:41 AM

I appreciate the housekeeping comments but first I would like to operate my trains.  Then, I intend to perform a cleanup.

 

Thanks,

Dave

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Posted by ATLANTIC CENTRAL on Tuesday, April 20, 2021 2:56 PM

Lastspikemike

 

 
ATLANTIC CENTRAL

Still waiting for a track plan.

Sheldon

 

 

 

You can see the problems on the latest photos.

 

Sure can. 

Biggest problem is that in todays world of metal wheelsets it is only going to work if the whole train is short enough to fit in the reverse cutoffs thru the middle.

Are we dealing with just one throttle/power pack?

I would:

Make the inner loop the mainline and make it one block.

Make each of the outer passing tracks blocks

Make each cutoff thru the middle a block.

Wire each block with a double pole, double throw, center off switch to control the polarity of each block separately.

Label the block toggles based on clockwise and counter clockwise.

Label the cutoff block toggles based on clockwise or counter clockwise entry/exit from the main.

Label the power pack direction switch forward and reverse such that forward and clockwise result in clockwise motion around the main.

Train enters cutoff, once train is in cutoff (it may need to stop simply based on length) mainline block is switched to counter clockwise. Sidings must match mainline for entry. 

Off positions allow parking locos/other trains.

 

But if it was me, and I only had 4x8 to work with, I would ditch the reverse cutoff track completely and just add some sidings in the middle.

Sheldon 

    

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Posted by ATLANTIC CENTRAL on Tuesday, April 20, 2021 10:07 PM

Lastspikemike

Well that's why I suggested making those short straights into the "reversing sections". Once the train is headed out of the crossing tracks making up the figure 8 you should be able to set the polarity correctly with one DPDT controlling all three straights together, 

Atlas wiring book figures 5-8 and 5-9 plus the text description in the chapter 5 explains how and why this would work.  

 

If the whole train is not in a single block for reversing the polarity of the rest of the layout, there will be a short as soon as a metal wheel bridges a plastic rail joiner.

Now, with plastic trucks that might not happed with EVERY wheelset, every tme, but it is bound to happen at some point.

On my layout it would never work, I use mostly metal trucks with metal wheelsets, and all my cabooses are lighted for rear of train detection by the detection circuit.

So as soon as one axle is in one block and the other axle of that truck is in a block with opposite polarity - boom, short circuit.

Believe me Mike, I understand all your (and other peoples) reverse loop schemes. I would never use most of them in any case.

I still say, there is more fun to be had without the reverse loops.......

Because operation will be simple.......

No reverse loops on the 420' of double track mainline of the ATLANTIC CENTRAL.

I will turn trains on a dead end wye, no issues, very simple.

Sheldon

    

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Posted by ATLANTIC CENTRAL on Wednesday, April 21, 2021 10:17 PM

Lastspikemike

I've thought about this a bit. The Atlas Twin switch illustrates an illusion about "reversing loops" and that is they aren't loops at all. If they are built as loops they are permanently shirt circuited.  

All that is required to accommodate separate blocks of track that need to be polarity matched is that the block section where the train is needs to be long enough to accommodate the whole train while the polarity is corrected (matched) in the adjoining block. It is not necessary for both blocks to be that long.

The oval loop with connecting crossing tracks that reverse train direction are a special case of "reversing loop" that aren't loops. All that is required is to choose which section is "main" and which section is where the train is when the "main " has its polarity reversed. 

The trouble starts if you think the "main line" has to be the longer line or "the rest of the layout". That's why I suggest people stop thinking of reversing loops as a special problem. A reversing loop is just an isolated section of isolated block no different to any other. The fact that it loops back on itself is not relevant to the required wiring. As long as an entire train can be contained in that block while polarity is matched in an adjacent block it does not matter how long that adjacent block is. All that matters is that a reversing loop needs its own DPDT whereas a block not needing separate polarity control can use a SPDT for block control. If all your blocks used DPDT then reversing loops would present no issues.

Finally, I understand reversing loops, polarity conflicts, common rail and double isolated blocks because I've wired them all incorrectly at one time or another. And in the space of less than a year of layout building.

That qualifies me as an expert....

 

Mike,

Apparently most people don't think like you. Again, I understand what you are saying.

And that is largely the solution I layed out above.

BUT, it assumes a set of conditions not always in play. Call the loop the mainline, call it the loop, call it block #456, it does not matter.

I labeled things the way I did as part of making it easy to learn and understand, and to make the direction of movement of the trains correspond consistently to the position of the block toggles, a feature I found helps most people understand what they need to do.

Sheldon 

    

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Posted by York1 on Thursday, April 22, 2021 9:01 AM

Lastspikemike
Finally, I understand reversing loops, polarity conflicts, common rail and double isolated blocks because I've wired them all incorrectly at one time or another. And in the space of less than a year of layout building. That qualifies me as an expert....

Some of the best learning comes through mistakes we've made.

My layout has many things I've done wrong, and each one will be fixed in the next layout.

York1 John       

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Posted by ATLANTIC CENTRAL on Thursday, April 22, 2021 9:36 AM

Mike, the two passing sidings serve no purpose if you cannot isolate a loco there. So my solution builds that into the system with less toggle switched to wire, and less toggle switches to understand and operate. 

Another solution would be to eliminate the toggles for the sidings, and control them as X sections, only giving them power, always of the correct polarity, only when the turnouts are aligned to them.

But that still requires the operational convention of setting the two reverse switches based on "system direction" and using the power pack reverse switch to "back up".

Sheldon

    

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Posted by ATLANTIC CENTRAL on Thursday, April 22, 2021 11:31 AM

Well Mike, again I understand, but I'm not much for doing stuff over, so my instinct is to design the best comprehensive solution and do it once.

And I see ease of use as an important goal. My solution was by no means complex yet it might well be a complete and comprehensive solution for the op.

"Temporary" is just not in my vocabulary.

Sheldon

    

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