Passing loops

[peterqd]

Hello everyone, I'm Peter and this is my first post on the forum!

 

I'm just about to start laying the track of a new N gauge layout which it is intended will be operated by youngsters as an introduction to proper model railways.  The layout has two hidden passing loops to be used for train storage plus a platform loop, and I've got a couple of questions for you to answer please.

 

In order to avoid locos crashing into points set against them, is it a sensible idea to put insulated joiners at the appropriate places to isolate the onward track to the points or is there a better way?

 

Also I'd ideally like to have LEDs on a mimic panel indicating the route set by all the points. How should I wire these and what resistors are needed?

 

Very many thanks

Peter

Edited June 29, 2018 by peterqd

[michaelp]

Hello Peter and welcome,

Since you are wanting to use leds for point direction on a panel how about using some train detedtion modules so you can stop your trains at the appropriate place on your layout.

The items I use for both come pre wired so no resistors are required and be operated with DC or DCC.

 

Have a look below.

 

http://www.blocksignalling.co.uk/

 

Michael

[Phil Bullock]

Hello everyone, I'm Peter and this is my first post on the forum!

 

I'm just about to start laying the track of a new N gauge layout which it is intended will be operated by youngsters as an introduction to proper model railways.  The layout has two hidden passing loops to be used for train storage plus a platform loop, and I've got a couple of questions for you to answer please.

 

In order to avoid locos crashing into points set against them, is it a sensible idea to put insulated joiners at the appropriate places to isolate the onward track to the points or is there a better way?

 

Also I'd ideally like to have LEDs on a mimic panel indicating the route set by all the points. How should I wire these and what resistors are needed?

 

Very many thanks

Peter

 

Hi Peter

 

Insulfrog or electrofrog points? if the former would suggest power feeds always from point toe end and insulated breaks in both rails a couple of loco lengths clear of the points. That way a train approaching points on a road that is not set for it will have enough room to stop once on dead track without fouling points

 

Other solutions will be available depending on the degree of electronics you want to go for....

 

Kind regards

 

Phil

Edited June 29, 2018 by Phil Bullock

[peterqd]

Hello Peter and welcome,

Since you are wanting to use leds for point direction on a panel how about using some train detedtion modules so you can stop your trains at the appropriate place on your layout.

The items I use for both come pre wired so no resistors are required and be operated with DC or DCC.

 

Have a look below.

 

http://www.blocksignalling.co.uk/

 

Michael

Thankyou Michael.  I haven't seen that site before and there's a lot there to get me thinking, but probably not for this layout I think.

And thanks Phil, that was what I was hoping to hear.

 

The intention is that this layout will (in the main) be operated and scenically developed by 7-11 year olds, and I'm anxious to make it as simple and error-free to operate as possible, so it will be good old DC with mainly insulfrog pointwork.  It will have CAB 2 control on two levels, with an inner section which can be switched to either controller.  My principal concern is to avoid situations of potential train crashes/derailments as much as possible.  I don't feel it's necessary to detect a train's position in this case, although I can think of lots of ways that could be useful.  It's much more vital here to stop a train automatically it if it's heading for a crash, hence the idea of using insulated joiners to create a short length dead track in front of adversely-set points.

 

I've only used probe and stud to operate point motors in the past, and the problem with that is it doesn't indicate which way the points are set, which makes it more difficult for kids to use - hence the idea of using LEDs.  The need is to indicate which blocks are powered, even though the controllers are set to zero.  I will be using momentary toggle switches this time, which do indicate the route set, but LEDs will be much better if I can work out how to wire them up.  I would like to use the non-controlled 12v DC outlet from the controller, fed through the auxiliary switches on the point motors to each LED, but I'm no electronics expert and the issues of polarity and the resistors with LED's is beyond my ken.

 

Best wishes

Peter

[cliff park]

If you start with 1000 ohm ( 1K ) resistor in series with any LED you won't go far wrong. If it looks too bright try a 1.2 K or a 1.8 K ( 'preferred' values  ), if not bright enough try 820 Ohms or 680. As regards polarity, look carefully at the body of the  LED, most have a flat on one side, and/or one leg (wire) longer than the other. But don't panic. With the resistor in series and a 9-15 volt, dc supply it will light one way round and not the other, but it won't do any harm. It just won't light. Make a note which way is right for your particular LEDs

[peterqd]

If you start with 1000 ohm ( 1K ) resistor in series with any LED you won't go far wrong. If it looks too bright try a 1.2 K or a 1.8 K ( 'preferred' values  ), if not bright enough try 820 Ohms or 680. As regards polarity, look carefully at the body of the  LED, most have a flat on one side, and/or one leg (wire) longer than the other. But don't panic. With the resistor in series and a 9-15 volt, dc supply it will light one way round and not the other, but it won't do any harm. It just won't light. Make a note which way is right for your particular LEDs

Thanks Cliff, that's exactly what I needed.

 

And thanks everyone, now I'm ready to get started.

[DCB]

Hello everyone, I'm Peter and this is my first post on the forum!

 

 

In order to avoid locos crashing into points set against them, is it a sensible idea to put insulated joiners at the appropriate places to isolate the onward track to the points or is there a better way?

 

 

Peter

It is a good idea with Insufrog points but a very bad one with electrofrog as any train approaching the wrongly set point will cause a momentary dead short.  I have fried several sets of pick ups due to using this technique with DC .   

[BR60103]

Peterqd

I would suggest a block of at least a loco length and that before the fouling point.

We are having interesting problems with some of the newer units (DMUs and such) when the power car or pickup is 3 or more cars from the front. 

[BrendanS]

You could just make the points sprung.  I have that on my loop.  Just use piano wire to hold the points for whichever route is normal.  Set the tension so that the lightest wagon you have can push the points over when going against them. You can only enter the loop on the same route every time but if that is not an issue. . . .  No LEDs needed for those points, either.

 

Brendan

[peterqd]

Thanks for all the help so far. Sprung points is an interesting idea Brendan, I've never thought of that. For this layout I'd rather not limit the routes like that.

Here's the layout proposed. The baseboard is now built and trackwork is about to start.  I'd love to hear any ideas you have about it before I start. I don't know a lot about prototype conventions so please forgive any glaring errors and please put me straight.  The rural area shaded blue is at high level and the green area is at baseboard level.  The baseboard will be hinged on a wall (at the top of the plan) and the controllers and mimic panels are along the bottom edge, to each side of the hidden loops.  One controller will be dedicated to the outer track at low level and the other to the branch at high level.  The inner lower track and the gradients will be switchable to either controller.

 

It's not intended to base the layout on any particular place, save that I was born at St. Helens on the Isle of Wight and I well remember the old station and yard on the branch to Bembridge, so I'm hoping the gradients will be OK for a little Terrier and a couple of 4 wheelers.  The bulk of the rolling stock I have is GWR and my trainspotting days were spent at Southall and thereabouts, so the main line station will be of that ilk.  As for the era, I haven't decided yet and it probably won't conform to history, but it will certainly be sometime in the steam age.

 

 

 

 

[Pete the Elaner]

That looks like a very steep incline from the blue section to the hidden section. It is also a reverse loop which needs some careful isolating & switching to operate.

[peterqd]

Thanks, you're right about the gradient and I gave it a lot of thought when I was drawing the plan.  The slope is 1 in 18.  It's only going to be used by small tank engines pulling 2 small coaches or a few trucks at most.  If a loco can't manage it then the gradient can be designated as downwards only.  Other things are possible too, I could move the top point along a little or alter the level of the top section.  One of the difficulties is that the clearance has to be 12mm greater than normal to allow for the under-board point motors.

 

About the reversing loop, each of the gradients will be isolated at both top and bottom and powered by its own supply from the controller.  Whilst the train is in either of these sections, the polarity of the main track will be reversed by a DPDT switch.  I'm thinking about ways to stop the train if the polarity has not been set correctly.

Edited July 13, 2018 by peterqd

[DCB]

1 in 18 is too steep.  Check how much clearance you actually need under the upper section.  I would keep the upper as low as possible and make some detachable covers to get at derailments etc on the points under the upper section.  The upper can be less than 2" higher that the lower in N.

 

The slope up could be lengthened by subtle re routing, see my revised plan.

 

The layout is designed for Right Hand running.  UK is left hand running so flipping the layout horizontally would make more sense.   A second crossover in the station would allow prototypical operation. Trains usually departed from bays, very seldom did they arrive, much more usual to arrive at a through platform, run round and push back into a bay to depart

[RAF96]

You could half your gradients slope by making the under track go down some of the height and the over track go up the rest of the height. It means the baseboards need more work though to achieve both half-gradients.

Rob

[peterqd]

Thanks for the comments so far.  Back to the drawing board!

 

David, moving the point along is what I meant earlier.  It's a relatively simple alteration but it doesn't gain very much.  Much more useful is reducing the difference in levels.  The 1 in 18 gradient was calculated on 60mm and I could reduce this in one or two ways. I allowed 12mm for the depth of the point motors beneath the top level, which are directly over the lower track.  I could regain that by either rerouting the lower track or, better still, by offsetting the motors.  I'll give that some more thought.

 

I'm intending to lay the track on Trackbed foam, and the height from the baseboard to the top of a loco is around 34mm.  Ignoring the point motors above, if I have 5mm clearance and I use 3mm ply for the top board over the lower track I can reduce the rise from 60 to 42mm, which would give a gradient of  1:26, and it would be even greater if I move the point as well.  How does that sound?  Other options are dispensing with the Trackbed in the hidden area and creating a "hump-back bridge" over the gradient rail.  As I said earlier, the branch line is only for small and slow engines and very short, light trains - the heaviest freight will be a few churns of milk and some beer barrels!

 

I designed the layout for LH running, except that branch line trains have to go against this for a short way, which is unavoidable with a reverse loop.  But I wasn't sure about the direction of the crossovers.  Did I get them wrong?  It seemed logical to have them in the direction of travel, not to have to reverse over them.

 

Rob, I did think about that when I was doing the planning.  Raising the level of the main line station helps a bit, as I can lift the curved point at the foot of the main gradient a little. Sloping the top level down from the country station edge is definitely an option, but I decided against it as the sidings need to be level.  That could be overcome fairly easily though.

Edited July 14, 2018 by peterqd

[DCB]

Thanks for the comments so far.  Back to the drawing board!

 

David, moving the point along is what I meant earlier.  It's a relatively simple alteration but it doesn't gain very much.  Much more useful is reducing the difference in levels.  The 1 in 18 gradient was calculated on 60mm and I could reduce this in one or two ways. I allowed 12mm for the depth of the point motors beneath the top level, which are directly over the lower track.  I could regain that by either rerouting the lower track or, better still, by offsetting the motors.  I'll give that some more thought.

 

I'm intending to lay the track on Trackbed foam, and the height from the baseboard to the top of a loco is around 34mm.  Ignoring the point motors above, if I have 5mm clearance and I use 3mm ply for the top board over the lower track I can reduce the rise from 60 to 42mm, which would give a gradient of  1:26, and it would be even greater if I move the point as well.  How does that sound?  Other options are dispensing with the Trackbed in the hidden area and creating a "hump-back bridge" over the gradient rail.  As I said earlier, the branch line is only for small and slow engines and very short, light trains - the heaviest freight will be a few churns of milk and some beer barrels!

 

I designed the layout for LH running, except that branch line trains have to go against this for a short way, which is unavoidable with a reverse loop.  But I wasn't sure about the direction of the crossovers.  Did I get them wrong?  It seemed logical to have them in the direction of travel, not to have to reverse over them.

 

Rob, I did think about that when I was doing the planning.  Raising the level of the main line station helps a bit, as I can lift the curved point at the foot of the main gradient a little. Sloping the top level down from the country station edge is definitely an option, but I decided against it as the sidings need to be level.  That could be overcome fairly easily though.

UK Practice is to avoid facing points and crossovers as far as possible so it is usual to drive past and then reverse to change tracks.   The Midland railway had about 50 miles of main line from Settle Junction to Appleby without a single facing point.     That included goods lay byes where the train had to run past the stations and reverse in. It sounds a big waste of time and effort but it let the signalman check the train was complete before allowing a following train into the section and actually was quicker than waiting for a guard to wander along to confirm the train was complete.   Models don;t like reversing but if you drive in you still have to reverse out....

 

Any tricks you can use to reduce the gradient will pay dividends. Watch out for the "Hump" at the top, bend a piece of rail to the curve and don't have a rail joiner atbthe crest or something is bound to sit there rocking on its middle wheels which have traction tyres and or on pick ups.    The 3mm ply for the upper level sounds good for N gauge, I would use something thicker for the main baseboard but you can span 3" or 4" quite happily in 3mm ply which will allow you not to need a support where the lower level passes underneath. 

Lifting baseboards are a PITA as you have to remove every bit of stock and anchor or remove every building before lifting. I often forget a wagon or two ...

 

I would suggest full cab control with 3 controllers any of which can be connected to any and all sections.  You have a capability to run 3 trains simultaneously so exploit it

Proper N gauge controllers are good, 

Edited July 17, 2018 by DavidCBroad

[Harlequin]

Hi Peter,

 

3mm ply will need support at very close spacing to prevent it from sagging so you will need to factor that support structure into your spacing calculations.

 

It might pay to use thicker ply, allowing wider support spacing and thus giving you a bit more leeway to thread the lower level tracks between the supports.

 

Some difficult questions for you:

1. Why is the design on two levels?
   1. It creates a lot of technical challenges to overcome such as the spacing of levels and the gradients.
   2. The hidden trackwork will be difficult to access, especially if the spacing is very tight. So difficult to: rescue derailed trains, get at accidental uncouplings, clean the track, fix failing pointwork...
   3. The high level station and scenery immediately in front of the viewer will hide the lower level main line station to some degree, which could become frustrating.
2. Why is the layout hinged at the back?
   1. You will need to make a rigid frame, deep enough to prevent the fixed scenery being crushed when the layout is hinged up, and strong enough to prevent flexing and cracking.
   2. The hinges must be at the top of that frame, not fixed to the lower baseboard, requiring some strong diagonal bracing.
   3. You will need to remove all the rolling stock and non-fixed scenic items before hinging it up. This will be a faff so how often will you do it, realistically?
   4. It will be quite heavy.

Edited July 17, 2018 by Harlequin

[Joseph_Pestell]

Easiest option for passing loops is to have some locos/mu's that always go clockwise and another set that always go anti-clockwise. The +terminal on one group will need to be changed on the motor.

[peterqd]

UK Practice is to avoid facing points and crossovers as far as possible so it is usual to drive past and then reverse to change tracks.   The Midland railway had about 50 miles of main line from Settle Junction to Appleby without a single facing point.     That included goods lay byes where the train had to run past the stations and reverse in. It sounds a big waste of time and effort but it let the signalman check the train was complete before allowing a following train into the section and actually was quicker than waiting for a guard to wander along to confirm the train was complete.   Models don;t like reversing but if you drive in you still have to reverse out....

 

Any tricks you can use to reduce the gradient will pay dividends. Watch out for the "Hump" at the top, bend a piece of rail to the curve and don't have a rail joiner atbthe crest or something is bound to sit there rocking on its middle wheels which have traction tyres and or on pick ups.    The 3mm ply for the upper level sounds good for N gauge, I would use something thicker for the main baseboard but you can span 3" or 4" quite happily in 3mm ply which will allow you not to need a support where the lower level passes underneath. 

Lifting baseboards are a PITA as you have to remove every bit of stock and anchor or remove every building before lifting. I often forget a wagon or two ...

 

I would suggest full cab control with 3 controllers any of which can be connected to any and all sections.  You have a capability to run 3 trains simultaneously so exploit it

Proper N gauge controllers are good, 

David, many thanks for that.  Since my last message I've read that in the early railway days there were many derailments involving trains tackling facing points.  For this layout the main point is that the kids get enjoyment from operating the trains and constructing buildings and scenery.  Reversing a whole train over a crossover, especially in the hidden section, would likely be more of a nightmare than worrying about operational conventions.

 

Please see my answer to Phil below regarding the ply thickness and the need to hinge the baseboard.

 

Good idea about a third controller!   I do have another one they can use, an old H&M Clipper, dating from around 1984.  It seems perfectly OK with modern locos, except that trains stall and jerk more often at slow speeds.  So I think this is probably best used on the outer main line, leaving the dual controller in charge of the inner (suburban) track and the branch line, and this would be switchable.  This is almost what I was planning anyway, but I'll need to give a bit more thought to the electrics - maybe I'll need another mimic panel.

 

Edit:  I've read on the forum that it's possible to bend the pin of a Seep motor into a crank, which offsets the motor about 20mm.  I'm going to try it.

Edited July 17, 2018 by peterqd

[peterqd]

 

Hi Peter,

 

3mm ply will need support at very close spacing to prevent it from sagging so you will need to factor that support structure into your spacing calculations.

 

It might pay to use thicker ply, allowing wider support spacing and thus giving you a bit more leeway to thread the lower level tracks between the supports.

 

Some difficult questions for you:

1. Why is the design on two levels?
   1. It creates a lot of technical challenges to overcome such as the spacing of levels and the gradients.
   2. The hidden trackwork will be difficult to access, especially if the spacing is very tight. So difficult to: rescue derailed trains, get at accidental uncouplings, clean the track, fix failing pointwork...
   3. The high level station and scenery immediately in front of the viewer will hide the lower level main line station to some degree, which could become frustrating.
2. Why is the layout hinged at the back?
   1. You will need to make a rigid frame, deep enough to prevent the fixed scenery being crushed when the layout is hinged up, and strong enough to prevent flexing and cracking.
   2. The hinges must be at the top of that frame, not fixed to the lower baseboard, requiring some strong diagonal bracing.
   3. You will need to remove all the rolling stock and non-fixed scenic items before hinging it up. This will be a faff so how often will you do it, realistically?
   4. It will be quite heavy.

 

Hi Phil, thanks for giving me some things to consider.

 

Firstly, the ply thickness.  The basic baseboard is already finished, using 9mm birch ply on 22 x 47 PAR perimeter framing.  The upper level hasn't been built yet, but the plan is to use 6mm birch ply on PAR spacer blocks.  This will be cantilevered over the lower tracks and the blocks positioned to suit the layout (not the other way around).  In order to maximise the headroom over the gradient track I can use 3mm or 4mm ply (or maybe even cardboard come to that) for a narrow area over the lower track only.

 

Now to your questions:

A Two levels:

1   The layout is on two levels in order to increase the number of separate tracks (and therefore operators) from 2 to 3.  Also it gives a more definite break between urban and rural scenery.

 

2   Very good point about the hidden trackwork, it made me think carefully.  The furthest hidden track is only about 100mm from the baseboard edge, so it shouldn't be too difficult to rescue any derailed trains.  The loop nearest the edge is intended to be the re-railing point for all stock on the complete layout.  However, I'm going to see whether it's feasible to make the country station a removable section for lower track cleaning and access.

 

3   Originally the layout was designed to be controlled from the main line station side.  This was before it was decided where the layout would go in the school, and when it transpired there is very little space, and that the layout needed to be either portable or hinged against a wall, I had to reverse it round in order to retain access to the hidden loops.  You're right it will hide the main line station area to an extent, but the difference in levels is only 45mm so I don't think it's a major problem.  I envisaged the main line station on a bridge over the tracks so it will be more visible, but the kids will decide that.

 

B:  Wall mounted and hinged:

1   There is going to be a 6mm ply surround about 175mm high fixed to the edge of the baseboard on all four sides (with an opening to access the hidden loops).  The ply will be flush with the underside of the PAR framing and project above the layout about 125mm, so it forms an open box.  This will be deep enough to protect all the scenery, and also prevent anything falling on the floor.  The surround stiffens the baseboard and stops it twisting and flexing, and I envisage it will be painted to form a backdrop.

 

2   The surround will be sufficiently tough to support strap hinges bolted through it.  I think 4 hinges will be OK.  It might need stiffening along the top edge and I have some aluminium angle to screw on if necessary.  When it's hinged up it will be secured to the wall, probably with a padlock and chain!

 

3   Yes it's going to be a PITA to take down and set up.  If only there was sufficient space for a permanent layout.  Hinging it is better than completely portable though.

 

4   There will always be at least 2 adults on hand to help raise and lower the board. The bare baseboard as it stands is surprisingly light - around 15kg.

[Harlequin]

Hi Peter,

 

Good answers! Thanks for explaining. (I especially like the chain and padlock detail...)

 

Where the country station sits above the storage loops you might need to support the 6mm ply along its outer edge but you're probably already on top of that.

 

To pick up David's point about crossovers: Trailing crossovers make head on collisions a bit less likely, which may be a worthwhile advantage. [Edit: Removed wrong-headed thinking about DC operation of double track circuits... Duh!] 

 

One final thought: If the layout were DCC controlled I'm sure the kids would embrace it very quickly. Driving using their tablets or phones would be second nature to them and you wouldn't need to hardwire the layout for cab control - any number of people could drive anywhere at the same time. Much more playful!

Edited July 18, 2018 by Harlequin

[Chimer]

One final thought: If the layout was DCC controlled, I'm sure the kids would embrace it very quickly. Driving using their tablets or phones would be second nature to them and you wouldn't need to hardwire the layout for cab control - any number of people could drive anywhere at the same time. Much more playful!

 

Ever since I learned about DCC I've been intrigued by the feature (not necessarily a benefit) that it enables head-on collisions ……. 

[peterqd]

deleted

Edited September 12, 2018 by peterqd

[peterqd]

deleted

Edited September 12, 2018 by peterqd