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Timber Shoving

bordercollie

Member
Location
Australia
Hi
I have attached a file showing how far I have got with timbering a 1:7 crossover.

I am working on GWR Old type curved switches using 9' minumum length sleepers and timbering. On reading the crossing timber section of GWR switching and crossing practice I am assuming that early practise c1900 was in force i.e 14" x 6" was only used for supporting the crossing nose, 12" x 6" for rest except that 10" x 5" sleepers used for first 2 supports at toe end.

I am wondering if it is possible to easiily see the timber spacing between centres rather than working out the difference of the distances from the start off the rail at toe end. I can find out the centre J2 is 12.5' and J1 is 39.5" . Thus J1 to J2 centre to centre is 2'3". However, is it possible to see centre to centre of any two adjacent at a glance?

When extending timber length from one turnout there is what looks like a 3" offset to that of lengthening timbers of the other turnout.The timber lengths are the same.They seem to be displace by about 3'' so there is a slight step when going between the two turnout templates (i.e. when straight stock rails of each turnout are examined). It would be easy to even them up when making the model track work but is this prototypical?
Track work returns to plain track when RF to RF is 3'0". Is there a way to measure this. In my attempt so far I have 17 through timbers. I am not sure if this is too many. I made a rough estimate by lengthening a timber from roughly the from RF of one crossing "V" leg to the RF of the other "V" leg to get the approximate measurement of 3' Is there a more accurate method?

I have a few more queries but I think this enough for one topic,

Regards
Graham
 

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Martin Wynne

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Track work returns to plain track when RF to RF is 3'0". Is there a way to measure this. In my attempt so far I have 17 through timbers. I am not sure if this is too many. I made a rough estimate by lengthening a timber from roughly the from RF of one crossing "V" leg to the RF of the other "V" leg to get the approximate measurement of 3' Is there a more accurate method?

Hi Graham,

I have made you a bit of video showing how to see the timber centres and measure the RF separation:

https://flashbackconnect.com/Default.aspx?id=VMACIToWUKSFyI_BfIAjrw2

The step in the long timber ends is prototypical and depends on the track centres. Long timbers across double track are normally 19ft-6in, or sometimes 20ft. Prototype timbering is seldom as neat as shown in the official diagrams.

cheers,

Martin.
 
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bordercollie

Member
Location
Australia
Thanks Martin. That has cleared up my queries well.
Just a follow up question looking at Fig 44 and accompanying text in GWR Switching and crossing practice. It descibes how the designers had to play around with sleeper spacing. In model railway practise is it feasible to take all the considerations into account e.g the replacement of C6 with an L1 and a CS chair? As this was a flexible switch diagram the L1 wasn't available pre-1933 and thus was not appropriate for curved switch turnout.
I think I am probably tying myself in knots for no observable benefit.

Regards
Graham
 
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Martin Wynne

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In model railway practise is it feasible to take all the considerations into account

Hi Graham,

If you model an exact-scale track gauge and flangeway gap (S4-X in Templot in 4mm scale) you can replicate the prototype designs exactly in model form. With any other gauge/flangeway combination some things are not going to fit. When you get to 00 gauge almost nothing fits, and you can only do 00 designs based on prototype principles, not exact-scale models.

Bolted half-chairs are a common requirement in complex pointwork, on both prototype and model. I'm not too clear what your actual question is? :)

cheers,

Martin.
 
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bordercollie

Member
Location
Australia
Hi Martin
I am having trouble putting what I mean into words. I don't think a diagram would help. Anyway, below, I have tried to explain my query.
I suppose what I am saying is, that it will be quite fiddly transposing the outline of the range of chairs or combination of chairs that may used onto a template and then assessing whether clearances are correct, as explained in Fig 44 of the book. Therefore I am wondering if it worth getting all the dimensions and rail clearances correct and working out the placing of timbers. If it is only the clearances in relation to 4C to 6C that need to be considered it would not be to onerous. At the end of the day I must decide it is worth it for me.
Regards
Graham
 
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bordercollie

Member
Location
Australia
Hi
Please find attached file.

I have been progressing with shoving timbers for a 1:7 GWR old style Switches curved. It has been relatively plain sailing but I would to establish that my sleeper placements are correct. The ends of the first few sleepers after the final timber(T12 on template TL178) i.e. A6 to A10 on template PL181 have been placed in the gaps of the turnout timbers. I am not sure how to space other sleepers i.e. A11 and upwards (A11, A12 and so on). The normal spacing for sleepers on 44'6" with 18 sleepers is usually 30.5" except at the ends. I have kept spacing at 30.5" from from A23 to A12 at the moment with spacing A12 to A11 is 21.5" and A11 to A10 is 23.18. Is this reasonable? I can think of other ways of doing it but what is most prototypical?

Regards
Graham
 

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20210403_134818.jpg

Graham, yes this is a nasty one, i will give you some of my thoughts, i am also not easy satisfied when it comes to this.

For prototypical i would suggest (yellow marked) you want to make those sleepers longer, as one whole sleeper, like the two with the red marker.

I would also suggest for prototypical appearance that the two in red are at the right distance apart from each other.
Due to the stresses and pounding on prototypical railroad the spacing between the sleepers is smaller in turnouts than on a main line.
I would be for prototypical begin my sleepers at the middle of a frog and some more than you have under your frogs
Sleepers have different spacing when it comes to curtain lines, main line freight or passenger or fiddle yards side yards ect.
If there is still some existing from your desired period try google maps in that region? I was surprised what was hidden from public eye for my railroad and still in existence...I can give you a good idea.

I think you will find some satisfying photo's in the above mentioned link.
On the old site where some very good close ups of turnouts incl frogs safety rail ect, incl timber.
For me that was a good inspiration.
I hope Martin will chime in for that one.

My two cents, i hope this was helping a bit,
With best regards Igor
 
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This is a approximation of the idea/thought of what i think will come close to prototypical within your case.
Except for two missing timbers.
 

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Martin Wynne

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Hi Igor,

Thanks for posting the file, but you have made a fundamental error in the timber shoving. :(

For UK bullhead track (and most other tracks), there are some special chairs (rail fixings) which will fit on the rails only in certain specified positions. Which means that there must be some timber under those positions.

This can have some surprising results. For example here it would be OK to shove the timber quite dramatically and still have the nose of the V-Crossing correctly supported in its chair. But not to shove a timber along the rails a short way, because that would leave the knuckle chair hanging in fresh air:

timbers_under_chairs.png


Here is a photo of the real thing -- you can see that the chairs can fit the rails only in the designed position, and can't be moved along the rails:

bullhead_crossing_detail2.jpg


Here is a photo part of a switch, and again the special block chairs will fit the rails only in one designated position:

switch_anchor.jpg


A a general rule, any chair which supports two rails at an angle to each other will fit the rails in only one position, and must have a timber under it at that position.

cheers,

Martin.
 
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bordercollie

Member
Location
Australia
Hi
Is my attempt so far, acceptable? I think that I have spaced the timbers as per the David Smith book. Do you agree? I am using the the old curved switches GWR practice.

My next question is in relation to the distance between RF and end of the timber (RFET). DS says that this distance on turnout side was between 18 and 24 inch. He was talking about the time after 8'6" sleeper had become standard. In the 9' sleeper period this distance would have been 27" (I think). So, during this earlier time the first timbers and sleepers at toe end would have been 9' and thus the RFET would have been 27" (I think). After the initial 9' sleepers and timbers, i.e. 9'6" and up was the RFET 18" to 24", or 21” to 27” in sympathy with the 9’ sleeper plain track practise?

My templates show that the RFET varies from approx 30’ using the spacing ring i.e. S4 to S9. S10 increases to 10’ before the minimum of 18” is reached (see TL180). Therefore I wish to ask is this there a reason for timber lengths being as depicted on template or is it something that needs to be manipulated using the shove timber function to reflect the company practises of the prototype chosen.

Best wishes
Graham
 
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David Higgs

Member
Location
Bletchley
Is my attempt so far, acceptable? I think that I have spaced the timbers as per the David Smith book. Do you agree? I am using the the old curved switches GWR practice.

Hello Graham,

It may be worth checking David Smith's Book for the number of Chairs used on the Check Rails. During my research for my Moretonhampstead Project, I found reference that suggests that from 1910, Guard Rails on Crossings up to 1 in 7 ½ were 11' 6" in Length with 4 Check Chairs.

Regards

David
 
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Martin Wynne

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Therefore I wish to ask is this there a reason for timber lengths being as depicted on template or is it something that needs to be manipulated using the shove timber function to reflect the company practises of the prototype chosen.

Hi Graham,

Templot has several options for the timbering style, including the option to have the timber ends in a neat line, or centralized under the rails:

timbering_styles.png


The default settings in Templot show the typical layout for REA bullhead turnouts. GWR turnouts are different, as you know, and need to be fully customized.

"Typical" has an engineering meaning. It means what is shown on the drawing indicates the principles of the design. It doesn't mean that any given turnout on the ground will follow the drawing exactly. The only way to know for sure the distance from the gauge-face to the end of a specific timber on a specific turnout is to go on site and measure it. It might follow the drawing exactly, but it is just as likely to vary from it, and from other timbers, especially if the timber has been renewed at some stage or the turnout has been re-used as serviceable material from elsewhere.

For historic turnouts that means studying photographs, or making an educated guess from other turnouts nearby. Generally in a fast main-line running line the turnouts will follow the drawing quite closely, unless some local factor intervenes. For example on soft ground or on a viaduct or over culverts. On branch lines and secondary lines there is likely to be more variation. In yards and sidings the official drawings are only a rough guide to what you might find on the ground.

For GWR information beyond what is in the book you would need to refer to historic drawings or other sources. You could perhaps contact David Smith direct c/o the Great Western Study Group, or other members of GWSG, or GWR online forums.

cheers,

Martin.
 
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David Higgs

Member
Location
Bletchley
Is my attempt so far, acceptable? I think that I have spaced the timbers as per the David Smith book. Do you agree? I am using the the old curved switches GWR practice.

The number of "through Timbers" could possibly be reduced when the extended rails of the vee are more than 3'-0" apart, plain line timbers can commence on the "Main", in which case the first sleeper should not be more than 2'-6" from the last timber, centre to centre.

Please see Page 87 (1st new paragraph on right hand side) of David Smith's Book.
and Page 115 (v)
 
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bordercollie

Member
Location
Australia
Hi David
I have used p87 to postion the first plain track sleeper (A4) closer to last through timber (T12) so that it doesn't interfere with the 11'6" timber (T11). The 11'6" timber is the first non-through timber past the point where the divergence is over 3' RF to RF. However by moving sleeper (A4) towards the last timber (T12) it means that on average timber spacings on plain track panel has been increased. On the attached screenshots I have made the best attempt I can to keep the CtoC distances as small as possible. However, there are CtoCs of 33.5 and 32.5 between A7/A6 and A7/A8 respectively. Therefore if these distances were to be not acceptable then I would need to add another sleeper. Adding a sleeper would result in an average sleeper spacing of something less than the standard 30.5", in the plain track panel. Although this would not present any problems engineering wise I was wondering if this was prototypical. As Martin pointed out, in another post, in engineering there something called "typical" which I suppose was to take care of any slight differences to those specified and that are not critical. However, I don't know if increase from 30.5" to 32.5" and 33.5" would have been within the bounds of "typical".
Also, in either of the above scenarios, were any adjusted sleeper spacings averaged over the whole panel length or for example only the last few sleepers were closed up eg A4 to A8. I am beggining to believe that this sort of detail has been lost in the mists of time.
Regards
Graham
NB The trackwork in the top and bottom of each screenshots are copies. I needed to do this to highlight the timber numbers.
 

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Martin Wynne

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Hi Graham, @bordercollie

An important detail missing from your post is the traffic which will be using this crossover. Trackwork is designed to carry rail traffic safely, and any rules about sleeper spacings, etc., apply mostly to running lines, especially main running lines. They don't apply with the same force, or at all, to goods loops, yards and sidings, or even to lightly used branch lines.

Generally for running lines, no spacing should be more than 31" centres, or 25" centres at a rail joint, and if necessary additional sleepers are inserted to achieve that. The cost of one extra sleeper is fairly small in relation to the potential cost and consequence of a broken rail. But you haven't said whether this track is in fact a running line, so it is difficult to say whether it is right or wrong.

Note also that timbers T2 to T11 are not adjacent to a rail joint or carrying special chairs. They can therefore be moved along a bit, or twisted (skewed) a bit if it makes it easier to lay out the sleepering for the adjacent plain track. Within the same 31" limit. That's more likely for older pointwork originally laid in situ than for prefabricated renewal pointwork, for which the adjusted chair drilling would make it a special order. So again it comes down to whether this is a modern running line or an old siding.

Likewise the long timbers could be skewed a bit either way (but not moved along) if it makes the timbering layout easier, with the same considerations about on-site chair drilling.

Finally it's permissible for a sleeper to be shortened by a few inches if that's the only way to clear the pointwork timbers. Having timbers closely end-to-end or side-by-side is not ideal for packing and maintenance, but sometimes needs must.

As always, all the above needs to have the words "generally", "mostly", "usually", "normally", etc. added, so that folks can post a photo showing the exact opposite. :)

cheers,

Martin.
 
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bordercollie

Member
Location
Australia
Thanks Martin
It did occur to me when walking the dog after sending my last post that the crossover was for loco release (if that is correct teminology) at the end of the line. The plain track, I suppose, was technically on the running line, but I expect that the rules may been loosened somewhat in this situation. After reading what you have said I will play around with Templot to see what I come up with. Hopefully I can make things work without having sleeper spacings more than 31".
Best wishes
Graham
 
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bordercollie

Member
Location
Australia
Hi
I have played around with the plain and turnout templates. I have skewed T10 and 11. I also reduced the RF to timber end distance to the minimum of 18". The sleeper spacings are now a maximum of 31" from A9 to A4.
I have moved the check rails forward so that there are supported by four sleepers only.
I did have a go at adding the extra sleeper but I would be happy with the template setup that I have come with (see attached), if it is a feasible/plausable solution.
Can you see any mistakes?
Regards
Graham
 

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