Turnout construction - Question here please.

Discuss the prototype and how to model it.
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grovenor-2685
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Re: Turnout construction - Question here please.

Postby grovenor-2685 » Mon Dec 27, 2021 4:57 pm

BorderCounties wrote:However, there appear to be a couple of errors:

1 - no connection between the loop line and the dock line at the left hand end,
2 - points 9 is double ended with a trap on the loop line

Not easy to see but I believe there are traps in your photo, of the single blade variety located within the turnout. Traps were mandatory, can't just be left out!
John Palmer wrote:I guess that in model form a loose heel switch probably lends itself better to spring working than a flexible switch.

OK side with Martin, I'll believe it when I see it, using flexible switches is very easy as discussed above. :)
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Keith
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Re: Turnout construction - Question here please.

Postby John Palmer » Mon Dec 27, 2021 7:16 pm

grovenor-2685 wrote:Not easy to see but I believe there are traps in your photo, of the single blade variety located within the turnout.
Agreed. https://www.flickr.com/photos/irishswissernie/36234004643/in/album-72157686232283623/ showing the Wansbeck Wanderer is also worth a look, as it shows the connection to these tongues from the main rodding run passing the back of the drop flap signal. I assume there's a detector somewhere in the murk at the base of that signal though it's hard to make it out.

Does anyone have thoughts about polarity switching for sprung points? It seems to me that where there is to be a movement that will push open the sprung switch tongues, there needs to be a mechanism that changes the associated common crossing's polarity to suit the locomotive approaching it, then changes it back once the movement through the sprung switch has been completed. Arranging for that to be accomplished automatically doesn't look at all straightforward to me - hope someone can prove me wrong!

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grovenor-2685
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Re: Turnout construction - Question here please.

Postby grovenor-2685 » Mon Dec 27, 2021 8:12 pm

John Palmer wrote:Does anyone have thoughts about polarity switching for sprung points?
Well, it all depends on the layout configuration and power.
The first ones I did were for the two ends of a passing loop where all trains kept left. So all that was needed was to supply the two crossings and the rails between them by diodes so depending on the direction set on the controller the unwanted track was shorted by a diode.
The current one is the trailing end of a double junction and was DC when built so I used a relay to change the polarity of the crossing. Now its DCC and I haven't changed it but if doing it now for DCC I would just use a 'frog juicer' ie an automatic electronic switch.
The other alternative is just to use an insulated crossing if you can keep the dead section shorter than the minimum pick up length of your locos.
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Keith
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BorderCounties
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Re: Turnout construction - Question here please.

Postby BorderCounties » Mon Dec 27, 2021 8:45 pm

Well I'm pleased I can see it now. I suppose it helps if you know what you are looking for!

The original signal box diagram, now that I've enhanced it a bit more, does show traps, presumably worked by lever 9. I've attached it so you can see what I mean.

As an old colleague of mine used to say, "that's opened a can of wasps".

Bellingham SB diagram A.jpg


It's just as well that I disassembled this turnout.
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Re: Turnout construction - Question here please.

Postby grovenor-2685 » Mon Dec 27, 2021 9:41 pm

The lever pull list there does confirm that the facing points are locked when the lever is normal but the diagram is to faint to see if there is any spring or hand notation against those siding points, but sprung to the loop is a fair assumption, might be the spring that's hidden under the boxing!
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Re: Turnout construction - Question here please.

Postby John Palmer » Mon Dec 27, 2021 10:05 pm

Thanks Keith. My immediate impression is that for an engine release headshunt needing to to be approachable from either of the tracks diverging from the turnout, but held normal for one by the sprung switch, the frog juicer is likely to be the most straightforward solution. That's the situation we have at Burnham, but I'm not sure we'll get round to making such a change on a layout now approaching its 40th birthday!

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Martin Wynne
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Re: Turnout construction - Question here please.

Postby Martin Wynne » Mon Dec 27, 2021 10:31 pm

I will just leave this here. :)

layflat_hand_lever.png

Lay flat lever used in roadways to avoid causing obstruction.

Martin.
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BorderCounties
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Re: Turnout construction - Question here please.

Postby BorderCounties » Sat Jan 08, 2022 11:41 am

Well, I "think" I've sorted out what has happened here, more info in the Bellingham (North Tyne) thread. https://www.scalefour.org/forum/viewtopic.php?f=4&t=7879

I have converted my original plain turnout to one which now includes two single bladed traps. I have only needed to move two sleepers slightly to get a straight point rod in - bear in mind this is a sleepered not timbered turnout and that spaces between adjacent sleepers are at a premium. It's not quite in the same league as the interlaced tandem at the other end of the loop!

IMG_1494.JPG
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