Western region K crossing vs double slips.

[mightbe]

My mistake. I had assumed the tem "K crossings" applied only to the fixed type.

 

Quentin

[The Stationmaster]

Hi Mike,

 

The GWR and BR(W) term for switch-diamonds was "Movable Elbows".

 

The limit for "Standard Diamonds" with fixed elbows (Fixed K-Crossings) was 1:8 in straight track, and shorter in curved track:

 

In radius down to:   the flattest angle for a fixed K-crossing is:

60 chains ( 3960ft )........1:8

30 chains ( 1980ft )........1:7.75

20 chains ( 1320ft )........1:7.5

15 chains ( 990ft ).........1:7.25

12 chains ( 792ft ).........1:7

10 chains ( 660ft ).........1:6.5

below 10 chains.............1:6

 

The above information is dated 1943 for the GWR.

 

Quentin wrote:

 

Switch-diamonds have "Movable K-Crossings", so described by several companies (and in Templot).

 

regards,

 

Martin.

Most of the time us operating folk just called them 'elbows' Martin although many in the the S&T seemed to like the term 'Movable Elbows' while it varied between the two terms depending on who you spoke to in the Pway Dept or their Drawing Office (I'm speaking as a member of WR staff, largely Operations side/local & Regional management, for the final 28 years of the Region). 

[micknich2003]

Following the recent discussion on K Crossings the attached may be of interest. Thanks to Michael Raising.

[NorthHighlander]

Help folks....!

I have spent a couple of days installing stretcher bars (rectangular flexible bar type) on a double slip on the Penhafod Upper layout. By chance, I came across Mike Bryant's document at:

https://www.scalefour.org/members/stores/info-sources/DN143OU.pdf

which says that the GWR only employed loose heel switches on double slips ('compounds') and that all loose heel switches have round stretcher bars installed in the web of the rail. I have two choices:

1. find a photograph of a GWR double slip that has B or C switches (and would have been in place in the late 1950s) that proves the exception

2. remove the rectangular stretcher bars and the Ambis brackets and replace with round bars (and careful and tedious drilling of the rail webs) :<

What should I do?

 

Tony

[martin_wynne]

https://www.scalefour.org/members/stores/info-sources/DN143OU.pdf

 

Hi Tony,

 

That document contains an error in the very first line. The GWR flexible switches introduced in 1930 were fully curved switches, not semi-curved switches.

 

When they were introduced a new stretcher bar design was introduced to replace the old round stretcher bars. The new bars were retro-fitted to many old-type loose-heel switches during maintenance, although it is true that a great many old round stretcher bars remained in use.

 

More info on pages 23-27 of David Smith's GWSG book.

 

regards,

 

Martin.

[hayfield]

Somehow I accidently answered in this thread what I thought was an answer on another forum. My daughter and son-in-law keep telling me I should not be let near new technology

 

Simon

 

There is here a case in building a model to perhaps not follow the prototype exactly (as the special chairs required are not available) and use a method which works in model form, and given that C&L now do J1 & L1 chairs on their 2 bolt chairs and Modelu sell 2 bolt slide chairs A model of  GWR turnouts and crossings can be far better now

 

You must decide the optimum length of slide rail which is allowed to move, making the switch rail flexible enough for the operating system you are using. The plan shown by Mick shows a hinged switch blade. Looking carefully the plan there are 5 slide chairs, (a double followed by a normal slide chair, then 3 special chairs (where the stock rail is held in place and the switch rail slides))

 

If I were making this crossing I would have 6 or 7 slide type chairs on a flexible switch rail, but I would look to support the stock rail as soon as possible.

 

The center timber is a 16" timber made from 2 sleepers joined side by side and I would make double slide chairs by splicing standard ones together side by side

The next timber to the center one I would use a standard slide chair 

The following slide chairs I would try and make a special slide chairs by using a standard slide chair suitably trimmed on the inside and a slide chair slide plate (outside part cut off) trimmed if necessary. I think this would be needed for the next 3 positions

The next 2 timbers I would try and use standard slide chairs on the switch rails and standard chairs on the stock rails

 

Whilst not fully prototypical I think it would give me the correct balance between following prototypical practice verses packability in model form 

Edited August 9, 2020 by hayfield

[Stephen Freeman]

If you want to see how the GWR actually did it, please see David Smiths book page 53. You would need a special timber 17inches wide and two special sole plates for the central timber.