Turning wye inside R2 loop - can it be done?

[DK123GWR]

Hello everybody. For context, my current layout consists of a loop of R2 track inside a loop of R3 track. The corners are 180 degrees separated by 670mm straights (equivalent to Hornby R603 straights. On the outside of the layout there is a terminus platform, and the layout fills the baseboard (which cannot be made larger). I have a siding layout which allows me to run locomotives around a rake of up to four coaches in the terminus.

 

However, this only works for locos with a coupler on the front, so I am attempting to find a way to fit a turning wye-inspired system into the interior of the layout. I genuinely have no idea whether this is possible, or if it is possible whether it would be practical, but I do know that I can't design it (I've been trying for the past hour).

 

In order to be ideal for my situation, there should be enough room for a 300mm A4 Pacific to negotiate it, and the minimum radius should be R1, or 438mm (I too was supprised when the A4 was able to navigate such tight corners). Even if it can't be made to fit such a large locomotive, it would be a remarkable piece of design even to turn a 0-6-0 tank engine in such a restrictes space. Any ideas for how this could be done?

[Flying Pig]

If you could make the legs of the Y continuous 1st radius (actually 371mm) then they'd still be 742mm apart where they joined the main line so it immediately appears the straights in your circuit are not long enough. In reality, Setrack points are 2nd radius so you'd need a bit more length. 

 

Otherwise and perhaps surprisingly, I think it might just be possible within a 2nd radius loop using the Hornby Y point and 1st radius curves, but you'd need to trim  a couple of curves to get the right angles (the Hornby ones to match the Y are rather large radius and would eat too much room).

 

Wouldn't a turntable be easier though?

[JDW]

What about a reversing loop across the middle instead of a Y? Could that work?

[DK123GWR]

3 hours ago, Flying Pig said:

Wouldn't a turntable be easier though?

It would, but where would the fun be?

 

I've gone back to the puzzle this evening and I've produced this. To cut down on the number of points, it would be possible to remove most of the left section of the loop and replace the bottom set with a 22.5 R2 curve. This would also allow the addition of a short straight onto the upper R1 curve on the left hand side, meaning that larger locos would fit properly (rather than just about squeezing the wheelbase in with large parts overhanging the end). The piece of flexitrack used could probably be subsituted for an R2 given the slight flexibilty of the track in real life, but if not the radius is still large enough for any loco to navigate.

 

If anybody knows the name for this system, please tell me. At the moment I would describe it as either 'an unfolded turning star,' 'a cross between a turning star and a reversing loop,' or 'messy.' Also, feel free to improve on it if I've missed something obvious such as a way to eliminate another set of points.

To clarify, the outer loop using R3 curves is not shown in this diagram.

Edited April 14, 2020 by DK123GWR

[DCB]

You can't get a Y inside a 2nd radius oval with straights less than 40" and even then you need to trim down some set track rail sections to fit.  Its actually easiest with Triang Super 4 track as they had a symmetrical 2nd radius wye point, which current Hornby and Peco set track don't list. However you can substitute a peco streamline short wye if you trim back the 2nd radius curves and lengthen the straights slightly.

[PatB]

As prototype fidelity is going to be of limited importance here, it might help to extend the leg of the Y over the opposite side of the oval, using 90 degree crossings from someone like Atlas. 

[Flying Pig]

14 hours ago, DK123GWR said:

Also, feel free to improve on it if I've missed something obvious such as a way to eliminate another set of points.

 

Never mind eliminating points. If you arrange the gradients right you've got a perpetual motion machine.

[DK123GWR]

1 hour ago, Flying Pig said:

 

Never mind eliminating points. If you arrange the gradients right you've got a perpetual motion machine.

I hope not. Perpetual motion sounds like the recipe for a very nasty accident if another train gets in the way!

[tomparryharry]

The Italian Railways have turning wyes, depending on their location. They are more earthquake proof, I understand. In the UK, you might find triangular junctions are more the norm. Here in South Wales, there is some 4-5 triangular junctions, all within a 15 mile radius of Cardiff. Even with rationalisation, there is still about 4 similar junctions between Severn Tunnel & Carmarthen. 

 

[Harlequin]

[TonyMay]

What about something like Grantham?

 

 

http://www.tracksthroughgrantham.uk/buildings-and-landscape-01/turntables-and-triangles/

[34theletterbetweenB&D]

4 hours ago, Harlequin said:

That looks far more like it.

 

Next development, you can have points on the plain track curves that form the reversing arrangement to provide several spurs for loco storage.

 

And then you roof it all over: for the world's first 'wavy turning running shed'.

[F-UnitMad]

On 15/04/2020 at 02:21, PatB said:

As prototype fidelity is going to be of limited no importance whatsoever here, 

Just corrected that for you

 

Re having a turntable being easier:-

On 14/04/2020 at 21:48, DK123GWR said:

It would, but where would the fun be?

Yes, real life railway planners ask that question all the time when devising track routes & yard layouts....  

[DK123GWR]

10 hours ago, Harlequin said:

What is the angle of those R2s?

 

4 hours ago, F-UnitMad said:

Re having a turntable being easier:-

Yes, real life railway planners ask that question all the time when devising track routes & yard layouts....  

A wye would be cheaper in real life and probably in model form if using Harlequin's design, and cost is a question they ask all the time. I also wanted to avoid committing to a turntable without evaluating other options. While a turntable may be easir to design, I imagine that it will be harder to install than anything I've done before, and I'm not neccesarily ready to do that on my current layout (If I'm lucky I could have another six decades 6.2 decades or more to change things around, so I'm sure I'll get around to it at some point).

 

Edit: It's slightly odd (scary?) to think that 6.2 decades into the past there were still ten years of mainline steam left, and the world wide web was still over thirty years away. Who knows what the world and its railways will be like in 2082?

Edited April 16, 2020 by DK123GWR

[Philou]

Whoa there cowboys - nice plans and ideas but is OP running DC or DCC? If the former, be aware of short circuits - just sayin'.................. .

 

Cheers,

 

Philip

 

[F-UnitMad]

22 minutes ago, DK123GWR said:

A wye would be cheaper in real life and probably in model form if using Harlequin's design, and cost is a question they ask all the time.

A wye takes up a lot of space, though - as you are finding out.

As for installing a turntable, you're using set track so I would think a Hornby turntable would do just fine, and is pretty much ready to use, no cutting holes in baseboards or suchlike. I've no idea how much they cost; I've been out of OO for a very long time.

[Steam here!]

A new Hornby turntable R070 on Ebay for £66.95.

 

Hope that helps.

Edited April 16, 2020 by Steam here!
I missed out some detail.

[DK123GWR]

16 minutes ago, Philou said:

Whoa there cowboys - nice plans and ideas but is OP running DC or DCC? If the former, be aware of short circuits - just sayin'.................. .

 

Cheers,

 

Philip

 

 

DCC, which will likely be a problem. For some reason, when I thought about it before I could get around that by switching points the right way and not attatching point clips to any of the points in the 'wye'. Of course, that would mean that the middle section is always isolated. More thought needed.

 

10 minutes ago, F-UnitMad said:

A wye takes up a lot of space, though - as you are finding out.

As for installing a turntable, you're using set track so I would think a Hornby turntable would do just fine, and is pretty much ready to use, no cutting holes in baseboards or suchlike. I've no idea how much they cost; I've been out of OO for a very long time.

£74.99 new, plus upgrading to digital. I don't know whether its worth looking into used turntables, its certainly something I would be very cautious about doing online (by which I mean it isn't going to happen). By contrast, three sets of points and R2 curves linking them should come to less than £60 (I have spare flexitrack to do the rest). Having said that, I wouldn't need to upgrade my turntable to DCC if I just used my now redundant analouge controller to turn it. It would also allow me to keep a newly made station platform where it is without altering the platform itself. And I could avoid the even more daunting prospect of confronting short circuits until another day. Maybe the wye inside R2 will be a useful idea to save for the  future, but a turntable the way to go on this occasion... I need time to consider this now as it's a rout I never thought I'd be going down (I did start out with the backup plan of limiting the A4 to through platforms if a wye was impossible, even though that would make no sense in the context of my layout, so even getting to the stage of wye vs. turntable is a big step from where I was.

[Harlequin]

1 hour ago, DK123GWR said:

What is the angle of those R2s?

 

 

You would need to do a bit of cutting: The angles are roughly 27.5 and 28.75 - the tangent between the R2 curves is at roughly 40 degrees from horizontal.

 

On DCC the simplest solution is probably to just isolate the flexitrack section and feed it through an auto-reverser. But isolating and auto-reversing almost any section of the centre track would do.

 

[Philou]

@DK123GWR Oh no, quite the contrary with DCC, you will need a switching unit that automatically senses the polarity and changes it - you CAN do wyes and the such where reverse-polarity is created. It's with DC that things are a little more complicated where you need to put breaks in the circuit and DPDT switches and the rest.

 

By the way, welcome to the RMweb collective.

 

Philip

 

Edit: Phil answered as I typed .........

Edited April 16, 2020 by Philou

[DK123GWR]

21 minutes ago, Philou said:

@DK123GWR Oh no, quite the contrary with DCC, you will need a switching unit that automatically senses the polarity and changes it - you CAN do wyes and the such where reverse-polarity is created. It's with DC that things are a little more complicated where you need to put breaks in the circuit and DPDT switches and the rest.

 

By the way, welcome to the RMweb collective.

 

Philip

 

Edit: Phil answered as I typed .........

If it was DC I could just isolate the central flexitrack from the rest of the track and use my spare controller (I used to have a three loop DC layout, so if I were using one controller each on the main loops I would have a spare) to control it, changing the direction of the R2 loop's controller before the loco reached the end of the flexitrack (in practise, bringing the loco to a stop in the middle may be neccesary, but even so that wouldn't be too much of a problem. By contrast, using an autoreverser would mean:

1) A completely new piece of kit that I don't really understand (I've only heard of them very recently, and whereas I understand the physics behind turntable motors and isolating sections of track to avoid short circuits, I would have to start from the beginning on what an auto reverser actually is and how to wire it.

2) Losing the cost advantage a wye would otherwise have against a turntable, as I would have what I need to resolve short circuit issues in DC but an autoreverser (around £25-30, as far as I can tell from brief research) added to the cost of track would make a wye as expensive as the turntable, even if I could save around £10 on the RRP. For a roughly equal price, I would get a turntable to preserve the buildings that I have produced so far.

49 minutes ago, Harlequin said:

You would need to do a bit of cutting: The angles are roughly 27.5 and 28.75 - the tangent between the R2 curves is at roughly 40 degrees from horizontal.

Thank you. I'll definitely preserve this idea in case I have a yard area of a similarly restricted size in the future, but for the variety of reasons set out above I think I've been swayed towards trying a turntable on this occasion.

[Mike Buckner]

Here is a Wye within a loop of Code 100 track with loop radius of R2, using some standard Setrack pieces, and 5 pieces of shortened straight track, cut from Hornby R601 (335mm) straights:

 

 

 

 

 

The loco would need to be able to traverse R1 curves.

You would need to cut a small bit off the bottom curve of the Wye.
You would need to isolate the section at the bottom of the Wye and feed it by a double-pole double-throw switch, or on DCC you have the option of feeding it with an auto-reverser.
The 3 terminal curves in the Wye would accomodate a loco + tender length of about 285mm. If you could extend the width and height of the layout by 3 or 4", even the longest locos could fit.

 

Inventory:

 

8   Hornby     R607 (R2)
5   Hornby     R605 (R1)
2   Hornby     R604 (R1)
4   Hornby     R600
1   Hornby     R8072
1   Hornby     R8073
1   Hornby     R8076
1   Peco       SL-91
1   Peco       SL-92
1   Peco       SL-93
2   Straight    93 mm
1   Straight   263 mm
1   Straight   264 mm
1   Straight   299 mm

 

 

Below is the SCARM layout (in the plain text format of the older versions of SCARM):

 

# SCARM Project File

 

V=0.9.23 beta

 

TStraightArrowRail|R8072|R8072|2|167.5|438|22.5|0|0|1
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|1579.32179735349|542.977334323592|192|0

 

TCurvedRail|R604 (R1)|R604|371|22.5|0
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|1023.40510599452|695.599102429919|55.5|0

 

TStraightArrowRail|R8073|R8073|2|167.5|438|22.5|0|0|0
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|614.379189229595|543.18524601441|348|0

 

TCurvedArrowRail|R8076|R8076|2|852|11.25|1|852|11.25|0|0|0|0
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|1099.09230115584|994.589004185589|269.25|0

 

TCrossRail|SL-93|SL-93|124.5|124.5|24|1
  RM|16.5|76|1|2.5|28|2|2.75|0|Peco|OO|0|0
  SP|1036.44987894623|427.586345919736|12|0

 

TStraightRail|93|93|93
  RM|16.5|87|1|2.5|29|2|2.5|0|Special|HO|0|0
  SP|944.803017894165|408.250558673684|12|0

 

TStraightRail|93|93|93
  RM|16.5|87|1|2.5|29|2|2.5|0|Special|HO|0|0
  SP|1249.19698210583|408.250558673684|168|0

 

TCurvedRail|R604 (R1)|R604|371|22.5|0
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|1113.1539366951|828.392667344826|282|0

 

TStraightRail|R600|R600|167.5
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|762|1259|0|0

 

TStraightRail|R600|R600|167.5
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|929.5|1259|0|0

 

TStraightRail|R600|R600|167.5
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|1097|1259|0|0

 

TStraightRail|R600|R600|167.5
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|1264.5|1259|0|0

 

TCurvedRail|R607 (R2)|R607|438|45|0
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|762|1259|180|0

 

TCurvedRail|R607 (R2)|R607|438|45|0
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|452.287229840292|1130.71277015971|225|0

 

TCurvedRail|R607 (R2)|R607|438|45|0
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|324|821|270|0

 

TCurvedRail|R607 (R2)|R607|438|45|0
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|452.287229840292|511.287229840292|315|0

 

TCurvedRail|R607 (R2)|R607|438|45|1
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|1432|1259|0|0

 

TCurvedRail|R607 (R2)|R607|438|45|1
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|1741.71277015971|1130.71277015971|315|0

 

TCurvedRail|R607 (R2)|R607|438|45|1
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|1870|821|270|0

 

TCurvedRail|R607 (R2)|R607|438|45|1
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|1741.71277015971|511.287229840292|225|0

 

TStraightRail|299|299|299
  RM|16.5|87|1|2.5|29|2|2.5|0|Special|HO|0|0
  SP|947.5|383|0|0

 

TStraightRail|264|264|264
  RM|16.5|87|1|2.5|29|2|2.5|0|Special|HO|0|0
  SP|1036.44987894623|453.471351426547|168|0

 

TStraightRail|263|263|263
  RM|16.5|87|1|2.5|29|2|2.5|0|Special|HO|0|0
  SP|1158.22925523759|453.471351426547|12|0

 

TStraightArrowRail|SL-91 (S)|SL-91|2|185.5|609|12|0|57.44|0
  RM|16.5|76|1|2.5|28|2|2.75|0|Peco|OO|0|0
  SP|762|383|0|0

 

TStraightArrowRail|SL-92 (S)|SL-92|2|185.5|609|12|0|57.44|1
  RM|16.5|76|1|2.5|28|2|2.75|0|Peco|OO|0|0
  SP|1432|383|180|0

 

TCurvedRail|R605 (R1)|R605|371|45|1
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|614.379189229595|543.18524601441|168|0

 

TCurvedRail|R605 (R1)|R605|371|45|0
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|1579.32179735349|542.977334323592|12|0

 

TCurvedRail|R605 (R1)|R605|371|45|1
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|1099.09230115584|994.589004185589|89.2499999999999|0

 

TCurvedRail|R605 (R1)|R605|371|45|0
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|785.263669973334|540.948245622805|10.5|0

 

TCurvedRail|R605 (R1)|R605|371|45|1
  RM|16.5|76|1|2.5|28|2|2.5|0|Hornby|OO|0|0
  SP|1408.43731660975|540.740333931987|169.5|0

 

 

Edited April 17, 2020 by Mike Buckner
spelling

[Mike Buckner]

For added fun, if you use DCC, the terminal curves and segments of track between turnouts contain up to 7 spaces for stabling locos.
If you keep up to 6 locos occupying some of these spaces, then you can play a shuffling game, making room for an incoming loco and choosing which of the 7 locos exits, and whether you shuffle clockwise or anti-clockwise so as to choose the orientation of the exiting loco.

[Flying Pig]

On 16/04/2020 at 09:52, Harlequin said:

 

Phil, can you try a solution with the Streamline small Y please (24" radius against 33" of the Hornby unit)?

[Mike Buckner]

Here is an improved version of the embedded Wye, which properly respects the 12-degree/24-degree Peco geometry and obviates the need to cut the bottom curve.
The changes are two slightly shorter compensation straights of 260mm each, and the use of the Streamline small Y instead of the Hornby Y.