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Reverse loops under scenic section


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Hi

I am designing an OO layout which needs 2 (or maybe 3) reverse loops. These will be a lower level than the 'scenic' section at one end of the room in either corner. The main section will be peco finescale 75. I think I can get away with just the loops themselves below the scenic section but have 2 questions as to how to go about it.

1 Would Roco 42424 481 mm radius 2.1 mm profile curves be suitable for the loop section of track and easy to join to the Peco

2 I am not sure as to how to build the 2 levels. The gradient will be more challenging if the loop section has to have clearance below the frames of the top board. Can I have a framework at the lower level with just the loop area area covered over giving access to the top level for wiring , points etc. And then some chipboard (!) supported over it by verticals without much framing

 

The DCC controlled layout will be in a spare room about 16 ft by 13.5 ft. Bournemouth West station is intended to be a peninsula in the middle, feeding into a Y junction going to Bournemouth Central on the right and then the LSWR running round the room to the reverse loop top left. The. Left will repsent the S & D going to Evercreech in the left bottom corner and the continuing to another reverse loop top right

Thanks for any advice

John

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Hi John

 

There are some pictures of layouts with reversing loops and some construction details at the beginning of this Flickr Album.

 

The current layout uses MDF.  There are some further pictures of a layout (with reversing loop) using chipboard. 

 

There are two practical matters to consider.  You will need a difference in level of at least 3 inches (75mm) and with a gradient in the order of 1 in 60 you will need around 15ft of track between high and low levels.  These numbers can be greater or smaller depending on train length and type of locomotive.  It doesn't sound as if you will be running diesels - these can haul greater loads up steeper inclines.

 

You need to think about your minimum radius.  If you want to run close coupled rolling stock you have to decide on your minimum radius and stick to it everywhere - above ground and in the below scenic sections. 

 

Just some thoughts for you to think about

 

Regards

 

Ray

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A common mistake when calculating gradients is forgetting to take into account the thickness of the trackbed itself.  In my case 12mm ply and leaving 75mm clearance actually needs 82mm.  At 1:60 that increases the run from 4.5m to 4.92m.

 

As John has also recognised, any board framing for the upper level will need to be cut away to allow the reverse loop line to go through and point motors and wiring will also be a problem.  I certainly wouldn't recommend pointwork anywhere in an area with a clearance of just 75mm unless parts of the board above any pointwork are removable.  You can guarantee a tie bar will fail in the most inaccessible location.

 

The other thing to consider is track cleaning.  A CMX track cleaner will do the job, but there is additional cost involved.

 

Any curvature on a gradient will also have an impact on haulage capability.  Diesel loco's will fare much better than steam loco's, but it is definitely something to bear in mind.

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Sorry all - I seem to have pasted in the wrong link in post above - now corrected. 

 

I have to take issue with Gordon above - for 00 gauge you only need 65mm clearance  (using Peco Streamline) between the top of the  lower level board and the underside of the upper level board.  If you are using 1/2 inch  (12mm) board then 12 + 65 equals 77mm (call it 75mm or 3 inches).  Obviously if you are working to these minimum measurements you will need to engineer your supports so that that do not interfere with the lower level track runs - as shown in my Flickr links.

 

Regards

 

Ray

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I used the figure of 75mm as that was the figure you quoted, Ray.  It wasn't clear from your post that you had already included the trackbed thickness as it is often overlooked.

 

Don't forget you need to add the thickness of any underlay or cork, typically 3mm and then the sleepers and rail height, which in the case of SMP is another 3.5mm.

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Some thoughts:-

 

Your planned curves are rather tight - but I appreciate that given the space you don't have much option.  However even another 50mm (or thereabouts) on the radius would imho help.

 

Access to the whole of the reverse loop should be provided.  A central hole that you could as a minimum get your arm through to reach the track and lift out any errant derailed train is (again imho) a must.

 

If your carpentry is good, you could go for an open top baseboard.  This uses risers from the frame to support variable level wood track beds.  Alternatively you could use risers off a solid baseboard but c/f access hole mentioned above. 

 

Peco (code) 75 rail is 75 thou (thousandths of an inch) high.  With approx 25.4mm to the inch, this gives a nominal rail height of 1.9mm.  Curiously code 83 gives a nominal rail height of 2.1mm.  This would imply a .2mm (8 thou) step between the Peco Code 75 and Roco 2.1mm.  Code 75 fishplates would need to be widened to fit the 2.1mm high rail; Code 83 fishplates would be somewhat loose and would need judicious tightening with pliers to ensure good contact.  Also I would suggest that you file down the rail ends of the Roco track to match the height of the Peco code 75.  Of course, if you haven't bought the track yet - you could get Peco code 83 instead?

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Hello

Thanks for the advice. Certainly looking at your great layouts has given me some ideas. If one just has the curve of plywood (?) where the reverse loop runs it would give access from underneath both to the loop track itself and to the top layer which would also contain track. If one arranges so there is no conflict between the reverse loop and any points on the upper layer then presumably ~80 mm clearance between the top of the lower board and the bottom of the upper bard would be OK. So perhaps 100 mm overall. I think I have enough room to have a gradient of no more than 1 in 60.

The layout is intended to be in the 50's to recall the gleaming (at least some) steam engines of my childhood near Bournemouth West station - so all steam.

I already have a quantity of Peco code 75 track, points etc. I ask about the reverse loop track as I have read that it is difficult to achieve smoothly with flexitrack. I understand a radius of 530 mm or so would be better than the 480 mm I quoted. Is this difficult to achieve with flexitrack - if so any other suggestions.

John

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I am building something similar right now, with a reverse curve under the the visible track.  Still early days but you may get some ideas on the construction front.  I use open frame trackwork so access is easy from underneath.  I will add 25mm 'safety rails' to any hidden trackwork as the last thing I want is a derailment and stock falling 3-4' to the floor...

 

http://www.rmweb.co.uk/community/index.php?/topic/3422-eastwood-town-ecml-in-00-sf/page-96

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...I understand a radius of 530 mm or so would be better than the 480 mm I quoted. Is this difficult to achieve with flexitrack - if so any other suggestions...

 No one can answer that question except you. Because what the running quality depends on, is how well you are able to build the track support, and then lay the track; whether set track curves or flexible track is used. Over the years I have seen appallingly unreliable layouts built from both systems, some were mine until I got the hang of it!

 

Don't 'cheap out on yourself' is my top suggestion. Arrive at the design you need for the space available, and then build it as a test piece; which you can then trial thoroughly with the trains you intend to run and 'debug' as required before going any further. Nothing kills interest in a layout faster than the trains not running reliably in my opinion. It may need a couple of attempts to get it working: better to get this sorted before anything goes on top making it a near impossible task to modify.

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Did a quick Google - Peco do a 21 inch radius 00 Tracksetter which is near enough 530mm.  This allows you to lay accurate curved track.  They also do other radii and also n/009 gauge Tracksetters.  Obviously you will need to cut the inner rail to length and fettle the rail ends at each joint.

 

Using metal fishplates will avoid any kinks at the joints; plastic insulating fishplates will in my experience bend giving the unwanted kink.  If laying in the cold (i.e. winter ~ 20C) allow a gap for expansion (e.g. in mid summer 30C) between each yard length of flexible track; I would estimate around 1mm. 

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Hi John

 

If you have a few minutes to spare there is a YouTube video here with a Camtruck trip around my reversing loop.  Food for thought.

 

Regards

 

Ray

 

Thanks for posting that Ray.  That's one huge layout and some very good carpentry.  It will certainly keep you occupied for years to come.

 

How big is the room you have?

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There's some excellent advice in the preceding posts that is well worth taking.

 

As a builder of a multi-level layout, I can confirm that it is a much less simple effort than a "flat earth" variant, but far more interesting to watch and operate when it works.

 

The point about testing in #12 actually applies to any layout but is particularly pertinent to one where some track is hidden. In my case the lower part, which includes storage sidings and points that are under other track, was operated for a year or so to make sure it was ok, nothing derailed or was tight on the curves etc. It can be accessed if necessary, but its a bit of a pain to do so. To quote the last post "nothing kills interest in a layout faster than the trains not running reliably..."  which should probably be in bold capitals at the start of any book on layout construction!

 

Further down the path when you do get stuff running its worth mentioning that you would be wise pay particular attention to cleanliness and restrained lubrication. I've found that track that is covered becomes less dirty over time anyway, presumably it gets less dusty, and you can really help this by not having greasy wheels and oil seeping from every part of the underframe.

 

John.

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Thanks Gordon

....  It will certainly keep you occupied for years to come.

 

How big is the room you have?

The layout is 'L' shaped.  There is 12 x 9 ft area at one end with three levels and a below ground reversing loop.  Then there is a a thirty foot 'leg' along one wall which finishes with abother reversing loop 'on the level'.  There are more details on my Blog.  There are perhaps onetwo or three posts that are particularly relevant.

 

Regards

 

Ray

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I can speak with over 35 years of experience of operating a reversing loop on my DCC 00 gauge three level interconnected exhibition layout ‘Crewlisle’ & all in a space of 2.6M x 2.3M.  Last weekend it appeared at the NEC Warley show, not because it is super detailed but because it entertains with a minimum of two & sometimes as many as four trains running simultaneously.  I was continuously answering questions of how I managed to squeeze a quart into a pint pot!  The high level is the terminus, loco sheds & marshalling yard; the mid level is a double track continuous run representing the WCML with OLE; the lower level is the reversing loop which leaves the ‘down’ side of the WCML, runs down the inside of the central operating well where I have a cartridge exchange system in lieu of a fiddle yard, under the end baseboard then rising up on the other side to rejoin the WCML on the ‘up’ side.  Enter ‘Crewlisle’ in Google & a track plan should appear on the first page.

 

All baseboards are solid & built to 1970s ‘standard’, that is 50 x 25 framing @ 300mm centres topped with 15mm Sundaela soft board.  The high level is of 6mm plywood with minimum headroom clearances, ie 65mm to 70mm.  To reduce the severe gradients, the reverse loop was built as follows using Peco Code 100 Set Track second radius curves & Streamline for the straight sections.   Make up the required number of 12mm ply ‘U’ shaped sections to support the track on the bottom of the ‘U’ where they will pass through the stiffeners of the lower baseboard, decide where your reverse loop should go under the lower baseboard then screw & glue in position.  Then you cut out the lower baseboard stiffeners in way of the ‘U’ sections to give clearance for the locos & retain the strength of the stiffeners on the lower baseboard.   Do not cut the stiffeners until the glue has dried.  The straight gradient sections can be of 10mm plywood to reduce the number of supports required.

 

Gradients:  With a combination of removing weights from coaches &/or adding extra weight to steam locos, my pacific locos can comfortably haul six Bachmann MK 1s on the gradients.  Diesels have no problems.  Main line up to terminus is 1:38; reversing loop from ‘down’ WCML through cartridge in central operating well is 1:28 (normally only one way);  reversing loop to ‘up’ WCML under coal shed is 1:33.  I have fitted DCC Concepts 'Powerbase' to reversing loop to improve hauling power.  Next job is actual trials with locos.

 

Peter

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If you look at Dent, in the S&C section, starting at the start, it goes through some growing pains...involving rebuilding the spirals to make the grade much less substantial.  I know of one of our club members layouts here that had a major revision to remove the underside of it, because of the grades involved and the difficulty of accessing the track. 

 

My own layout, Long Marton, has a LOT of "hidden" trackage, and care in laying it is required.  Some parts of it are currently getting re-worked (as in, right after I finish a cuppa I am going back at it).  There are areas which don't work reliably in both directions, which need attention.  (in spite of being basically designed for single direction operation over a lot of the track, sometimes I want to just run a train on the small circuit).  Think through your access plan, and consider how you will get to the most difficult piece of track to replace it after the layout is finished.  Murphy says that one is the one that will need work.  Note, underengineering support structures is a bad idea- that's why I have had the problem I am currently having- as it involves the segment of OO that crosses through the middle of the spiral of Lego trains.  The track base is 8mm ply at this point, and is too thin to not bend on a 33" span.  

 

11426695745_e484175622_c.jpg

 

7118903745_4544b878b4_c.jpg

 

 

The section that I put on a old piece of 1 1/2" (30mm thick) wood in behind the chimney wall is still OK.  Which is good, as access to repair that bit is dubious at best.  (I forget how I slid it into place, but I suspect there was some bad language involved)  This is a 6' long length between the wall and the chimney brick.  Somewhere down there, there is a wagon that fell off the track...

 

James

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