Chairs at Princes Risborough

[David Lane]

Just wondering why when I add chairs the sleepers go off from being perpendicular to the straight road.

 

[Martin Wynne]

@David Lane

Hi David,

Equalized timbering is forced on chaired V-crossing angles below 1:7 to ensure the skewed chair sockets do not break out of the side of the timber.

It's prototypically correct -- crossing angles below 1:7 are found only in yards and sidings, where the majority of turnouts have equalized timbering.

cheers,

Martin.

 

[David Lane]

Thanks Martin
the turnouts are part of a loco release loop on a bay platform, I have drawn them as B7 which match the plan I have, the attached photo shows the trackwork and I cant seem to determine equalised timbering.

 

[Martin Wynne]

Thanks Martin
the turnouts are part of a loco release loop on a bay platform, I have drawn them as B7 which match the plan I have, the attached photo shows the trackwork and I cant seem to determine equalised timbering.

View attachment 8031

@David Lane

Hi David,

Looking at the chair placements on the timbers, it is clear that the timbering is equalized:

At 1 and 2, the edges of the skewed X and Y crossing chairs are parallel with the equalized timbers.

At 3 and 4, the edges of the chairs in the main road are clearly at an angle to the equalized timbers.

The most interesting detail in this photo is the use of an S1O bolted half-chair on the wing front rail joint (between 2 and 3). The reason for using that instead of an L1 or S1J isn't clear.

cheers,

Martin.

 

[David Lane]

Many thanks Martin, attached is another photo looking the other way is there anything else I need to look at to get my track right. Princes Risborough being a joint GWR/GC station I was not too sure what type of chairs would be used I think the picture show 3 bolt.

 

[Phil G]

Hi Martin,
I am I right in thinking that's a slab and bracket A chair on the left divergent turnout?
which would then mean there REA chairs?
Or do these chairs pre date REA standards
cheers
Phil

 

[Terry Downes]

Many thanks Martin, attached is another photo looking the other way is there anything else I need to look at to get my track right. Princes Risborough being a joint GWR/GC station I was not too sure what type of chairs would be used I think the picture show 3 bolt.

View attachment 8038

Hi David, great photos, I'm also modelling Princes Risborough in 00-SF. FYI, Martin assisted me with the PR scissor crossing during a zoom meeting which may prove useful. Info and links can be found at the following Share and Show area.

 

[Martin Wynne]

@David Lane

Hi David,

An interesting mix:

@Phil G

Slab & Bracket chairs were used by both the GWR and REA, with slight design differences. Photo is not clear enough to show which. The check rail chairs look to be GWR but not clear.

cheers,

Martin.

 

[David Lane]

Hi Terry
if you email bigcheeseplant@googlemail.com I may have information you might find useful.
David

 

[Hayfield]

Many thanks Martin, attached is another photo looking the other way is there anything else I need to look at to get my track right. Princes Risborough being a joint GWR/GC station I was not too sure what type of chairs would be used I think the picture show 3 bolt.

View attachment 8038

David

Thanks for the photo, its very interesting especially with the kinks in the curved stock rail at the heel end

Looking at the very bottom timber 14" ? with chairs side by side. 2 bolt chairs where most of the others are 3 bolt
The timber above has both 2 & 3 bolt chairs

Someone said trackwork is boring !!!

 

[Phil O]

The check rails cover 4 timbers and means that the chairs are probably 2 bolt GW. The narrow 2 bolt chairs are lettered Z by the GW. See my pictures in the resources file at the top of the page,

see: https://85a.uk/templot/club/index.php?resources/gwr-switch-and-crossing-chairs-photos.13/

 

[David Lane]

Where is the point rodding going there is a bell crank then it goes to the point but its nearer the vee than the blades.

 

[Martin Wynne]

Where is the point rodding going there is a bell crank then it goes to the point but its nearer the vee than the blades.

@David Lane

Hi David,

The rod in the foreground leads to the stretcher bar(s) on the switch. The crank is connected to a rod which runs under all the rails, and connects to a similar crank linked to the rod from the signal box, running alongside the platform.

Using cranks and rods like this allows a pull to be converted to a push. This compensates for thermal expansion/contraction without needing a separate compensator.

With rodding on this side of the switch there is more space for detector slides, possibly linked to a ground disc signal.

cheers,

Martin.

 

[Phil O]

To add to Martin's reply, the total point rodding run, should have equal lengths of push and pull, there are compensating cranks for runs where there not enough right angle cranks in the run, a place where they often appear is in a crossover between where the first switch and the second switch goes cross track. I would knock up a sketch, if I was at home on my laptop, but I'm on my tablet and not home until Monday evening.

 

[Phil G]

Hi Martin,
Thanks for the info very interesting

Slab & Bracket chairs were used by both the GWR and REA, with slight design differences.

Are saying The GWR were the first to use Slab and bracket chairs?
Or simply being the GWR they saw the benefit, but had to do it there way?

Which leads to a question I often mused over which is, were the GWR ahead of the curve? Or were they a railway that made like a salon, and just had to go against the flow?
Hope I don't open that pro/con GWR debate I am just a curious chap
cheers
Phil.

 

[Martin Wynne]

Hi Martin,
Thanks for the info very interesting

Are saying The GWR were the first to use Slab and bracket chairs?
Or simply being the GWR they saw the benefit, but had to do it there way?

Which leads to a question I often mused over which is, were the GWR ahead of the curve? Or were they a railway that made like a salon, and just had to go against the flow?
Hope I don't open that pro/con GWR debate I am just a curious chap
cheers
Phil.

@Phil G

Hi Phil,

At the grouping in 1923 the GWR were by far the dominant member of their new group, simply absorbing several much smaller companies. They saw no reason to change their existing designs, and carried on using them until nationalisation in 1948 and beyond. And also creating new flexible switches again to their own design.

The other railways in the Big Four were amalgamations of the larger pre-group companies, with a many different p.w. designs in use. The REA designs of 1925 were an attempt to create order out of chaos with a standard set of common bullhead designs which could be used by all. They were so successful that the REA designs are still in use today, largely unchanged after 100 years.

Currently only the REA designs are supported in Templot plug track. Hopefully the GWR designs will follow eventually.

cheers,

Martin.

 

[Phil G]

Hi Martin,
Thank you, a very informative explanation of both why the REA came into existence, and why the GWR did not feel the need to bother.
The LMS issues with the 1923 amalgamation, of both loco and running ideas are well documented. I had not really thought about that in PW terms until you mentioned it.

I read into your post that your implying the GWR were the first with the slab and bracket design, which the REA then later took on board. Is that right?

I was also going to comment to @David.Lane last night my time, but it got a bit late.
If he wants to start trackwork using plug track now or in the near future, although he has photographic proof both REA and GWR chairs where used, he will have to stick with REA if going only plug track I mean.

Nothing to stop a bit of Plug track and commercial GWR Chair mixing I guess, but that's a steep plug track learning curve for anybody.
cheers
Phil,

 

[Martin Wynne]

I read into your post that your implying the GWR were the first with the slab and bracket design, which the REA then later took on board. Is that right?

@Phil G

Hi Phil,

Sorry I can't answer which came first. I will do a bit of digging. Generally new ideas are quickly spread through an industry, and railway permanent way is no different. It's interesting that the REA designs include both cast chairs and slab & bracket designs, suggesting that around 1925 it was a hot topic in p.w. design.

cheers,

Martin.

 

[Phil G]

At the grouping in 1923 the GWR were by far the dominant member of their new group, simply absorbing several much smaller companies. They saw no reason to change their existing designs, and carried on using them until nationalisation in 1948 and beyond.

Hi Martin,
No problem I may have put 2 and 2 together and got 5
In my mind your comment referenced the 1923 grouping of the GWR and not changing existing designs, where as the REA which I believe was first published in 1928, with as I understand it, a cast A chair design coming first and a slab and bracket design coming a few years latter.
So I assumed, possibly wrongly the GWR had a slab and bracket design circa 1923, thus before the REA version circa 1928.

Your comments about PW interest in 1925 are very likely spot on. I guess it makes little real difference, just another curiosity to ponder.
cheers
Phil,