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So here's an auto-reverse situation to ponder

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So here's an auto-reverse situation to ponder
Posted by rrinker on Wednesday, June 06, 2018 8:01 PM

My planned basement layout is, if drawn schematically, a dogbone with multiple crossovers along the shank. Standard procedure for this sort of thing is to make the loops on the ends reverse sections and just wire the shank part as a double track main so everything is the same phase. But I have added a wrinkle. Since I don;t have room for linear staging tracks to one side of the loop, I am making the loops the staging - instead of just one track looping around and connecting the east and west mains, there will be 3 or 4 nested loops,. joint back to one just before the loop reconnects to the mains. Since this is staging, it's VERY likely that a train may be entering staging from the east main at the same time another is leaving staging on the west main. So the whole thing, all the tracks, cannot be the reversing section.

 SO - where to place the reverseing sections? 

                                    --Randy

 


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PED
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Posted by PED on Wednesday, June 06, 2018 8:27 PM

I have the exact same arrangement except that I don't have nested loops on the end of the dogbone. I have been thinking about your arrangement and do not have a solution other than to make the whole thing a reversing section then restrict arrivals and departures such that you don't have more than one train entering/leaving the loops at the same time.

(edit - deleted proposed solution because it would not work)

Paul

Washita and Santa Fe Railroad
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Posted by rrinker on Wednesday, June 06, 2018 8:49 PM

It’s one of those things that came to me the other night while falling asleep - I’m not doing the trivial “connect both mains with a loop” which is quite easy to wire. And every idea I come up with, I end up determining it won’t work. 

 I’ve gotten to the point of toying with dead end staging tracks insid the loop and making the loop a simple single track one which then can easily be a reverse section. But it depends how far into the laundry area I can go to see if the tracks will be long enough. And even so there may only be room for 3 in each direction. Not really enough. Restaging wouldn’t be too difficult, back out the train, run it through the loop, then back in to the opposite direction staging track with the loco facing out. If I can squeeze in 4 tracks each way, I can probably make it work since many trains will be turns originating in the main yard rather than originating off stage. Might be a case to use Peco radius turnouts instead of #6’s to get more staging tracks in.

 

            —-Randy


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Posted by floridaflyer on Wednesday, June 06, 2018 9:15 PM

Could you make each track of the four track loop  seperate reversing sections? Only restriction would be that trains could not enter or exit the same track at the same time, that's a bunch of reversers but just trying to find a way for it to work. 

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Posted by richhotrain on Wednesday, June 06, 2018 11:42 PM

Randy, we need to know more about what takes place along the shank. If the end loops are nested for staging on each end, then it seems that the shank should be the reversing section. But that raises some questions.

How big is the overall layout and how long is the shank? How many crossovers do you anticipate along the shank? Is the shank just that, a shank? Or is there branching off the shank to points unknown?

My initial thought is to match the polarities of both end loops and treat the shank as the reversing section. Problems could be minimized by limiting the number of crossovers and the number of spurs and sidings running off the shank.

Tell us more about the configuration of the entire layout.

Rich

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Posted by rrinker on Thursday, June 07, 2018 7:02 AM

 The shank runs the entire length of 2 decks and a helix - not practical to make the shank the reverse section. Lots of crossovers.

 Making each track in the loop its own reversing section could work - that's 8 autoreversers, but why not? With some consideration to the sequence of trains, there wouldn;t be one entering and leaving the same track at the same time - with the staging tracks on the loop like that, each track is long enough for 2 trains, so there is some serial staging involved and it would be possible for two trains to be stacked one in front of the other, and the only empty space being the half of the loop behind a train that has yet to start its run, but planning the sequencing can prevent that, with far less interference in operations than having to plan everything so one train can;t be finishing its run while another starts as would be the case if the entire loop was just a single reverse section. 

 Or I have to do the upstairs renovation first, which includes the plan of moving the laundry upstairs, meaning I will have enough space for a pair of plain linear staging yards on each deck with the loop connecting them which could be the reverse section - in that scenario, the loop only would get used for restaging between sessions or for display running. Since I am currently constrained from extending too far into the space, but can go as wide as I want, I was having the loop do double duty since the outside radius can be rather large - I think I have it drawn now as 42", 38", 34", and 30" , no way anything will sideswipe with a 4" spacing, plus it will be easy to reach in to swap cars around. 

                      --Randy

 


Modeling the Reading Railroad in the 1950's

 

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PED
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Posted by PED on Thursday, June 07, 2018 8:12 AM

rrinker

 I’ve gotten to the point of toying with dead end staging tracks insid the loop and making the loop a simple single track one which then can easily be a reverse section. 

 

 

That is what I did. I have a folded dogbone with dead end staging tracks inside the loops then made the single outside loop a reversing section. Since that did not give me as much track as I wanted for a yard, I made a yard in the bottom of the U as a curved yard. This allowed as many parallel tracks as I wanted within the limits of my deck width. That meant that I had two reversing sections (end loops) and then my shank (long) gave me a good size yard, multiple crossovers and multiple industrial sidings.

Paul

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Posted by Lee 1234 on Thursday, June 07, 2018 8:25 AM

If you have space between the last staging turnout and the first crossover you could make it work with two reversing sections.  One for each return loop.  They could be on the entrance or the exit end of the loops and not necessarily the same end.

L

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Posted by carl425 on Thursday, June 07, 2018 8:57 AM

How about making a train length section of only one of the mainlines just before the loop the reversing section on each end?

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Posted by Eric White on Thursday, June 07, 2018 9:33 AM

What if the ladders are the reversing sections?

You'd still need four, but that's half as many as eight, and you could add more staging if you wanted to.

Eric

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Posted by SouthPenn on Thursday, June 07, 2018 10:23 AM

If each staging track is going to have its own switch on and off the main then no reversers are necessary. It would be like sidings. 

If there is only one switch from the mains to multiple sidings, the sidings would need to be isolated from the switches they are connected to. Then each would need to be wired with the proper polarity. Also, each switch would need to be isolated from the other switches and have its own feed to the throat of the switch.

 

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Posted by gregc on Thursday, June 07, 2018 11:29 AM

what if you reversed the polarity of every other track, inner rail of track 1 +, inner rail of track 2 -.

then a train could enter an odd track from the west and leave on an even track to the east w/ the reverser in a stable state

yes, you would have to live with the restriction of using an odd/even track when you need to transit both ends

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Posted by rrinker on Thursday, June 07, 2018 11:34 AM

Eric White

What if the ladders are the reversing sections?

You'd still need four, but that's half as many as eight, and you could add more staging if you wanted to.

Eric

 

 Well, there's two of everything - there is a 4 track ladder/loop for the lower deck, and an identical one for the upper deck - that's where the 8 comes from. Wouldn't be too bad, as I would only need ones for the bottom deck initially, at the slow rate I work, it would be a while before I got around to connecting to the upper loop. Probably just need a 5th AR for a temp loop at the end of however far I've gotten the mains.

                                         --Randy

 


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Posted by rrinker on Thursday, June 07, 2018 11:38 AM

SouthPenn

If each staging track is going to have its own switch on and off the main then no reversers are necessary. It would be like sidings. 

If there is only one switch from the mains to multiple sidings, the sidings would need to be isolated from the switches they are connected to. Then each would need to be wired with the proper polarity. Also, each switch would need to be isolated from the other switches and have its own feed to the throat of the switch.

 

 

 That's why I was thinking simplify with simpel single ended stagng tracks. I stillw ant the loop, for continuous run/display, but if the staging tracks were all simple ladders, then the only gaps would be after those ladders, isolating the single loop track, one reverser (for each level). The key being if I can get enough length nside the loop for sufficient staging (or cheat a little and have the loop climb so the tail end of the staging yard tracks could extend under the loop - hmm, another crazy idea to try)

                                    --Randy


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Posted by rrinker on Thursday, June 07, 2018 11:46 AM

gregc

what if you reversed the polarity of every other track, inner trail of track 1 +, inner rail of track 2 -.

then a train could enter an odd track from the west and leave on an even track to the east w/ the reverser in a stable state

yes, you would have to live with the restriction of using an odd/even track when you need to transit both ends

 

 That could work, except any time a train DID run through and trip the reverser, the tracks to go in and exit without flipping it again would alternate. Say the reverser came up such that the even tracks are the ones an eastbound trainc ould head into without tripping the reverser, this makes the odd tracks the one a train could leave westbound without tripping the reverser. But as soon as a train went all the way around, or an eastbound train then exited to head back west, it woudl trip the reverser. So not the tracks that the next eastbound could enter without flipping the reverser once again would be the odd tracks, and the evens would be for westbounds.

 Maybe not a show stopper, the PSX-AR can easily feed an Arduino circuit to indicate the current state, and I did want to see about possibly automating at least some of the staging operation - especially since engineers won't be able to see the staging areas directly. Plus since I am using Electrofrog turnouts, I'd need gaps for each loop track anyway, so if it didn;t work out, I could just add the extra 3 ARs and be done.

                             --Randy

 


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Posted by Cymrych79 on Thursday, June 07, 2018 11:51 AM

rrinker

 The key being if I can get enough length nside the loop for sufficient staging (or cheat a little and have the loop climb so the tail end of the staging yard tracks could extend under the loop - hmm, another crazy idea to try)

                                    --Randy

That should be easily doable with even a short space if you also drop the ends of stub yard tracks while the loop track climbs. Granted, it might make fiddle work interesting if cars keep wanting to roll away on you, but it could work if you really needed to minimize your loop size/maximize your stubs.

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Posted by rrinker on Thursday, June 07, 2018 11:51 AM

Lee 1234

If you have space between the last staging turnout and the first crossover you could make it work with two reversing sections.  One for each return loop.  They could be on the entrance or the exit end of the loops and not necessarily the same end.

 

Possible - although there will be a crossover and junction right near where the main goes through the wall to staging to support a short branch (or maybe just a single large industry, haven't decided). Might still work though.

                              --Randy


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Posted by gregc on Thursday, June 07, 2018 11:57 AM

rrinker
But as soon as a train went all the way around, or an eastbound train then exited to head back west, it woudl trip the reverser.

i don't understand.

rrinker
Since this is staging, it's VERY likely that a train may be entering staging from the east main at the same time another is leaving staging on the west main. So the whole thing, all the tracks, cannot be the reversing section.

i thought you wanted a possible solution for the above.

when a train enters staging, the AR may or may not reverse.  But once it's stable it's now possile enter/exit from odd/even tracks at each end of the section.

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Posted by rrinker on Thursday, June 07, 2018 12:18 PM

 Wait, where are you saying to connect the AR? Simplyfy to a double track loop. One is wired +/-, the other is wired -/+. If the mains are wired +/-, then a train from the one main could enter track 1 with no polarity issue. A train could leave track 2 on the opposite main, also with no polarity issue.

 Now a train goes all the way through track 1 and back out to the main. This causes a short where track 1 and the main meet, so the AR flips. Now track 1 is -/+ and track 2 is +/-, if both are connected to the AR. A train on the one main can now enter track 2 without a polarity mismatch, or leave track 1 without a mismatch. How would you keep it so that east main and even tracks were always the same, and west main and odd tracks were always the same? WHen the loop section changes polarity, that would reverse every track.

                        --Randy

 


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Posted by gregc on Thursday, June 07, 2018 1:06 PM

maybe i misunderstand you problem.

normal situation is one end of a reversing section (RS) matches polarity on the main when the other end doesn't.   train enters from one end and the AR may or may not reverse.   when that same train exists RS, the AR switches.

i thought in your case, you want to be able to enter the RS/staging and stop in staging while a 2nd train is exiting the RS/staging.   By alternating the wired polarity of the RS/staging tracks at either end of the RS, there is always one track (not the same track) at either end of the RS that matches the polarity of the main.    This allows two trains, one at either end of the RS/staging to be spanning the RS and main; one on an odd track and one on an even track.

in one AR state the even tracks at the east end of the RS match the polarity of the main AND the odd tracks match at the west end.   The reverse is true for the opposite AR state.

is this what you're looking for?

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Posted by richhotrain on Thursday, June 07, 2018 3:55 PM

rrinker

Making each track in the loop its own reversing section could work - that's 8 autoreversers, but why not? 

I thought that I was nuts with four auto-reversers. Unless you plan to have sessions with multiple operators, as a lone wolf, how many trains can you operate at once. Instead of 8 auto-reversers, just use DPDT switches to manually control the reversing sections.

Rich

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Posted by rrinker on Thursday, June 07, 2018 6:59 PM

I nay have an even better idea. Remember a few posts ago I mentioned having a branch off the main, right before it goes through the wall to staging?

Well, since the only purpose of the loop is for display running, why not have the loop come off the branch? The staging tracks off the main could be simple stub end tracks, no reverser needed. And I can probably get more of them in there. Foor continuous run, the train would take the branch, where a turnout on the branch's main would lead into the loop, which would have a lone autoreverser. The loop could then also serve as staging for the branch, since the loop wouldn;t be needed during regular ops.

 Only problem is an east-bound train would have to cross over to the west main and then onto the branch, and when the train comes back out of the loop, the branch turnout has to be lined back to the main and the crossover has to be lined for straight. Or I have to switch my modeling focus to the CNW, which ran left hand.

 That would take care of the lower level, but the upper level, if it had the same arrangemtn (would would be way too contrived) would have that detour into the loop run right across the stairs (lower level would be UNDER the stairs) and that's not even remotely practical. 

While I will run trains myself much of the time, I figure there are easily jobs for 4-5 crews, maybe more, plus a dispatcher. I'm sure I can get that many locally to come over for an ops session once a month or so, once i actually get this built.

                                      --Randy

 


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Posted by Cymrych79 on Thursday, June 07, 2018 7:23 PM

Just had a thought based on the info Randy provided...

The plan is for two good sized loops, enough for 2 trains in each of 4 staging tracks per loop. And the loops are at each end of a double main, such that only eastbound trains enter and westbounds exit for one loop, and vice versa for the other.

With that in mind, I'd run a single reversing section in each loop, starting at the mid point of the loop and including all staging tracks to just after the exiting ladder condenses it all to the main.

Then you'd just need an operations rule stating that all arriving trains must stop in the arrival half of their staging track. Which makes sense, if there's a future outbound waiting for it's turn on the other half of that staging track. As nothing should be rolling across the end of the reversing section at the mid point of the loop, the outbound side of the loop would effectively stay in phase with the main most of the time.

Of course, active staging during sessions would/could bring back your original problem, if you have to cycle an arrival into an outbound on the fly. But food for thought, anyhow.

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Posted by rrinker on Friday, June 08, 2018 9:45 PM

 That;s probably doable - again, I need some sort of monitoring to tell people when to stop anyway because staging isn;t directly viewable from the operating area. Unless I go for closed circuit tv cameras.

 Thinking about it in the pool (I do a lot of thinking while relaxing in the pool), I'm probably overthinking this. The chances of someone leaving the staging loop while someone else is entering is rather unlikely - how many people can cram into one area? If two operators are runnign in the corner where staging goes through the wall and under the stairs, it's far more likely that one will be entering/leaving the lower level while the other is entering/leaving the upper leve, and since those are two distinct reverse loops with their own controllers, it's not a problem.

 I'm still going to draw out the idea of having the looop connection be on the branch, at least for the lower level. I don't know why I was thinking everything has to cross over, an eastbound train can just roll under the stairs into the loop and then it reappears on the branch heading back to the westbound main. No croossing over of the mains necessary. And again, that's just for solo/demonstration running. Upper level, I can just go on the premise that it is very unlikely that one train would be entering while another exits. Or sicne it won;t have a branch off the main at the same point, on the upper level I may indeed be able to make a train length section of the main the reversing section.

                                          --Randy

 


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Posted by richhotrain on Sunday, June 10, 2018 4:18 AM

Randy, in thinking more about this multiple reverse loop issue, it seems to me that you would ideally want all of the nested loops in phase so that none of them would be reversing loops. Somehow, some way, the shank, or part of the shank, should provide the reversing function. That would eliminate concerns over locomotives simultaneously entering and exiting reverse loops along with the need for as many as 8 auto-reversers.

Rich

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Posted by gregc on Sunday, June 10, 2018 5:00 AM

diagram?

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Posted by richhotrain on Sunday, June 10, 2018 5:23 AM

gregc

diagram? 

I do agree that a drawing of the proposed layout would be extremely helpful.

Rich

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Posted by rrinker on Sunday, June 10, 2018 10:09 AM

 I've posted it before.

Although this version left off the staging layer, it's just concentric loops under the stairs and intoot he laundry area. Although I have an even better idea - It wouldn't be too hard to make half circles that drop down or are removable - by doing so the loops, which would not be needed for normal operation, could extend into the "no fly zone" and the staging tracks could be simple single ended stubs, with the removable loop connecting then end of one on the east side to one on the west side. The loop section alone would be the reversing section and there would be no chance of one train entering while another was leaving. If I make the loop removable and attached with bolts and wing nuts, I could simply have a plain block that attaches to the same bolt to provide a solid fence to prevent any trains running off the end of the staging track.

                               --Randy

 


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Posted by rrinker on Sunday, June 10, 2018 12:38 PM

 This is what I was pondering. By using a compound ladder arrangemetn and starting it slightly on the visible side of things, I can get what amounts to 9 usable single-ended tracks and then the removable loop, The crossover betweeb mains is a #8, to reduce S curve issues, rest are #6. Simple enough reversing - there's just one loop track.


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Posted by grinnell on Monday, June 11, 2018 12:32 AM

You may be overthinking this into an unrealistic problem. It all depends on how active your operations sessions really are. My layout has been operating for a couple of years with similar nested staging reversing loops protected by a single AR without any problems: we just have a local rule that you don't enter staging if a train is leaving. It isn't a failsafe, idiot proof system, but the consequences of failure should not be disasterous. If it turns out to be a "real" problem then buy more ARs.

Grinnell

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