Turnout gauge widening

Discuss the prototype and how to model it.
Derek
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Turnout gauge widening

Postby Derek » Tue Oct 20, 2015 2:21 pm

At the risk of asking stupid questions (even by my standards) and not wanting to re-invent the wheel, am I right in thinking that turnout gauge widening follows the same rules as normal track- ie 10-7ch, 7-5.5ch and <5.5 ch?

I am assuming that gauge widening has to come AFTER the set to avoid introducing gauge widening to the straight road and/or an iffy angle for the set; I am also assuming that it is better to remove gauge widening before the check rails (even though I know I can move the check rail to keep the correct check gauge). How quickly does the gauge go from standard to wide?

All the turnouts on this shed were A6, which were recorded by the NER as being too tight for several of its classes anyway, but I know B1's and 4MT's used to manage them OK.

(with apologies for more questions. I don't mean to monopolise the forum. I hope this will be my last question before laying the foundations).

Derek

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Mark Tatlow
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Re: Turnout gauge widening

Postby Mark Tatlow » Tue Oct 20, 2015 10:05 pm

You definitely do need to gauge widen through a turnout on the curved road. The widening will depend on the severity of the curve but I think you will find that the curve on an A6 is quite fierce. If you really need to know it I can look it up via Templot easy enough.

However, my view is that you should do this through the entirety of the switch and also slightly over do it through this.

My answer starts from the presumption that a little bit outside of gauge is not a problem but any under gauge is; so always err on the wide side not the tight side. Thereafter I have found that where the switch blades are not restrained by fixed chairs there is a tendency for them to flex outwards slightly no matter how carefully you seek to measure gauge so a deliberate over gauging compensates for this.
Mark Tatlow

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grovenor-2685
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Re: Turnout gauge widening

Postby grovenor-2685 » Wed Oct 21, 2015 6:10 am

Derek,
I was unsure whether you were asking about the prototype or the model, so i held off to see if Martin Wynne came up with one of his detailed answers.
I have never seen any specific reference to gauge widening in turnouts apart from the normal references about curved track as you mention.
So far as building a model is concerned i have always used the 3 point gauges to install the curved closure rail as shown here. It has worked for me.
Regards

Derek
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Re: Turnout gauge widening

Postby Derek » Wed Oct 21, 2015 12:07 pm

Hello Mark, Keith,

I think after reading your posts that I am looking to solve a problem that doesn't exist. I was worried about doing anything that would damage the neat stock/ blade interface, but of course the curving doesn't start until after the end of the planing. I think that I will just stick the 3pt gauges on and leave the maths behind it to someone else- if that system has worked for you for 50 years then I can't see any reason it is going to stop working now.

I am of course most familiar with www.norgrove.me.uk and find it essential reading for anyone learning track construction- even if we are using different systems to do it. In fact, I am reviewing your "how to re-wheel a 25" page as my baby Sulzer is going to be my first victim.

Mark, thanks for the suggestion of widening it right through and I think in terms of getting better running you are right. However, I have read of the 'dangers' of doing that if the turnout is going to be connected to another turnout. Thanks for the reminder about the feature in Templot for working this out; I am not familiar with it but I have read an article on it so will re-read it.

As for the prototype, I am assured by a NYMR worker that their 4MT and B1 (the main post war classes used in my location) really don't like short turnouts at all, and so I suspect without gauge widening they would not manage it.

Thanks again for the help. I will now try to stop asking questions and find out the hard way...

Derek

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Martin Wynne
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Re: Turnout gauge widening

Postby Martin Wynne » Wed Oct 21, 2015 6:28 pm

grovenor-2685 wrote:I have never seen any specific reference to gauge widening in turnouts apart from the normal references about curved track as you mention.

Hi Derek, Keith,

David Smith has several pages and diagrams about check lumps, continuous check rails, gauge-widening through turnouts, and special gauge-widened switches, in his GWR book (essential reading for all track modellers), pages 40-46:

Image

I don't want to infringe copyright, but maybe one page would count as fair dealing for review. If you choose to read this, please be sure to order a copy from: http://gwsg.org.uk/GWSG_Publications.html Image

Image

That's for the GWR and BR(W) of course, but in the absence of similar information for other companies, it probably represents typical practice.

p.s. "lead" is GWR-speak for a turnout. "elbow" is GWR-speak for a K-crossing.

Martin.
40 years developing Templot. And counting ...

Derek
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Re: Turnout gauge widening

Postby Derek » Wed Oct 21, 2015 7:42 pm

Thanks Martin

That was what I concluded above, so it's reassuring to know that I have that right now. I know that you and others have recommended that publication, even when dealing with non GWR, such as the Nicest Ever Railway. I shall add it to my growing library.

I assume for 9ft switch, I can substitute 'A' switch.

Derek

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Martin Wynne
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Re: Turnout gauge widening

Postby Martin Wynne » Wed Oct 21, 2015 8:01 pm

Derek wrote:I assume for 9ft switch, I can substitute 'A' switch.

Yes and no. An 'A' switch is a flexible swich (i.e. a "spring" switch in NER-speak). A 9ft switch is a loose-heel switch (i.e. a "standard" switch in NER-speak). In the case of the GWR it is a curved switch (and joggled). A full list of the GWR switches is available as pre-sets in Templot.

The NERA book shows NER standard switches in 9ft and 10ft lengths (and longer). I suspect your 1:6 turnout has one of those. It also shows their spring switches in 12ft-6in and 15ft sizes (and longer). The NER didn't use the 'A' designation.

regards,

Martin.
40 years developing Templot. And counting ...

Derek
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Re: Turnout gauge widening

Postby Derek » Wed Oct 21, 2015 9:50 pm

Thanks again Martin

Comparing an A6 and a 9ft straight switched 1:6 in Templot to a photo of the location and the A6 is closer (I can't see the fishplates between blade and closure but there is at least two special chairs between the end of the blade and the fishplate and it is sufficiently far away from the tips not to match up with the 9ft version.

I know the location was modified quite a bit in 1922 so perhaps it was one of the first areas to be built to later standards- especially as it was around grouping time.

SENTENCE REMOVED. IT IS WRONG (SEE BELOW)

I know there was an interlaced design of approximately the same size as an A6 which lasted until post WW2, so I will go back and see if that photo is clear enough.

Again many thanks for being such a font of knowledge.
Derek
Last edited by Derek on Wed Oct 21, 2015 10:52 pm, edited 1 time in total.

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Martin Wynne
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Re: Turnout gauge widening

Postby Martin Wynne » Wed Oct 21, 2015 10:19 pm

Derek wrote:I know the location was modified quite a bit in 1922 so perhaps it was one of the first areas to be built to later standards- especially as it was around grouping time. If I recall correctly, you said that REA designs were an evolution primarily of LNER

Hi Derek,

The REA designs were introduced in 1926 after the grouping. Any renewals in 1922 would most likely have been in original NER designs.

I don't recall suggesting the LNER as the primary source of the REA "Standard Railway Equipment" designs, or if I did I can't remember where the idea came from. Can you provide a link? I do know that the SR were very active in permanent-way developments between the wars.

regards,

Martin.
40 years developing Templot. And counting ...

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Martin Wynne
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Re: Turnout gauge widening

Postby Martin Wynne » Wed Oct 21, 2015 10:36 pm

Derek wrote:Comparing an A6 and a 9ft straight switched 1:6 in Templot to a photo of the location and the A6 is closer

p.s. Derek, when comparing with Templot designs, always remember to check with both regular and generic type crossings, and for the shorter angles try CLM instead of RAM angles.

Note also that the pre-set 9ft straight switch in Templot is not an NER design. You need to create custom switches from the drawings in the NERA 1912 book in order to compare with NER photographs.

Generally to match prototype designs accurately in Templot you need to change to generic-type crossings (except where an entry straight is shown in the REA lead tables, column A), and to CLM unit angles. Also of course to be using exact-scale track gauge. 18.83mm.

The majority of Templot users are not using exact-scale track gauge, e.g. for 00, EM, so it is impossible to create an exact match to the prototype. Templot therefore defaults to the other settings which are more convenient for modellers.

Martin.
40 years developing Templot. And counting ...

Derek
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Re: Turnout gauge widening

Postby Derek » Wed Oct 21, 2015 10:59 pm

Hi Martin

Thanks for the further information. I think I will have to wait until my NER book arrives and I can study drawings before your post will make full sense.

I must be mistaken about the relationship between LNER and REA. I have deleted that sentence completely as I wouldn't want google to cache it and/or someone see part of it and not necessarily your reply.

All the photos I can see so far are of regular crossings. There are a couple of odd ones, such as an A6 sized turnout with a 7 chair check rail (appears after 1933) but that again is a straight main road with a regular crossing. (I assume on that one there's some rotten timber so they put a larger check rail in to ensure it was secured well enough).

Derek

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Martin Wynne
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Re: Turnout gauge widening

Postby Martin Wynne » Wed Oct 21, 2015 11:06 pm

Derek wrote:All the photos I can see so far are of regular crossings.

Hi Derek,

I'm impressed that you can see the difference between regular and generic crossings in a photograph. I don't think I could do that. Did you mean not curviform crossings?

regards,

Martin.
40 years developing Templot. And counting ...

Derek
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Re: Turnout gauge widening

Postby Derek » Wed Oct 21, 2015 11:20 pm

Hi Martin

Using this as one example, you can see the curve in the stockrail changing to straight BEFORE it goes onto the check rail, and as it's a 7 chair rail (in a shed) the straight section is longer than normal. Of course, this doesn't mean that all turnouts on shed were like this.

http://railphotoprints.zenfolio.com/p86 ... #h3c7e7b26

BTW this photo has had me and a chap from Canada working for dozens of hours trying to work out what that spaghetti like track work is on the far right side of the photo. If it hadn't been for Templot I don't think I'd ever have done it; certainly pen and paper would have been 'a challenge'.

Derek

EDIT: I have just read through the help guide for custom switches. Now to go back through my photos armed with my new knowledge.

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Martin Wynne
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Re: Turnout gauge widening

Postby Martin Wynne » Thu Oct 22, 2015 12:01 am

Derek wrote:http://railphotoprints.zenfolio.com/p86258800/h3c7e7b26#h3c7e7b26

Hi Derek,

That's not much to guess the size of the turnout from Image, but the plain angled flare on the check rail indicates that it is not an NER design with curly ends, so probably an LNER renewal. For an A-6 turnout the LNER is the only one showing a regular-type crossing in the list, with a short entry-straight of 12.5". LMS, SR and LPTB have generic crossings for an A-6 (no entry straight). The GWR didn't have any A switches.

regards,

Martin.
40 years developing Templot. And counting ...

Julian Roberts
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Re: Turnout gauge widening

Postby Julian Roberts » Sun Mar 06, 2016 6:55 am

Mark Tatlow wrote:You definitely do need to gauge widen through a turnout on the curved road. The widening will depend on the severity of the curve but I think you will find that the curve on an A6 is quite fierce. If you really need to know it I can look it up via Templot easy enough.
.


Derek, did you or Mark come to a conclusion how much gauge widening was needed through your A6?

I hope you don't mind my briefly revisiting this thread...


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