Turnouts Or Points (whichever)

[Old Buffer]

As this is the permanent way Q & A section I do have a question.
Can someone please give a description of the way in which the turnouts are measured, in as much as what are the dimensions/differences between A, B, C etc. and the numbering.
I am aware of the numbering side, (the angle used with the crossing V) and have a basic simple understanding of the lettering (the length of the blades?).
The reason I am asking, is, not everyone (me included to a degree) is knowledgeable regarding this subject and it would help us all if there was a list of the basic dimensions of each type of point.
Alan

 

[Dog Star]

Noted - I have a table of info somewhere and I need to check copyright before posting.

 

[Rob Pulham]

Thanks Alan, that's one you have saved me asking. Although to be fair to Graham, he has explained it verbally to me at least once before.

 

[daifly]

Take a look at:

www.templot.com/martweb/templot_gs.htm

and click the 'Real Track' link on the left hand menu.

Cheers, Dave

 

[Eastsidepilot]

Guys,
A simple way of looking at point work is to think of them as if made in three sections, 1/ switch unit, 2/ closer rails and 3/ crossing unit.
Taking bull head track as an example the switch units are classed by letter, A,B,C,D,E&F, A being the shortest. There were some bigger than F but I don't think we need to bother ourselves with these in modelling terms.

The closer rails, which link the switch and crossing will be of different lengths and radius depending on the lead which is the distance between the toe (end of switch) and the nose ( point of the vee) this is all dependent on the combination of switch size and crossing type.

The common crossings are classed by their angle and range in size from 1-4 to 1-20, the larger the number the more acute the angle.
For each size of switch there are are a limited number of common crossing sizes used, I have listed them below

A .... 1-4 to 1-8, including half angles i.e 1-7.5
B .... 1-6 to 1-11 " " " and quater and three quater angle except for 9,10 & 11's
C .... 1-7 to 1-14
D ....1-8 to 1-16
E .... 1-10 to 1-16
F ....1-16 to 1-20

There are half and quater size angle on some but not all of the C-F range but I have not shown these.
I have a full blown chart giving further details containing the standard leads for the "big four" companys & L.P.T.B.
If any body would like at scan I will email a copy to you, pm me. I also have info on flat bottom rail point and crossing work as well.
As I said this is just a simple explanation and basically the radius increases with the size of the angle.
An example:- An LNER B6 had a radius of 312' with a lead of 57'-1" while a B9 had a radius of 613' with a lead of 65'- 8.5" so in 7mm scale a difference in length of the lead by about 61mm.

This info applies to ordinary points, when it comes to slips and obtuse crossings then they are a different matter.

I hope this made some sense and if your interested in knowing more about track then I can recommend searching for a book by the title of "British Railway Track" Design, Construction and Maintenance published by The Permanent Way Institution. My copy is dated 1964 there were other copys at different years, the later ones being flat bottom track only.

ATB, Col.

 

[Dog Star]

Guys, the S7 Starter Pack has the full table of turnout data for switches and leads... I have asked for permission to publish that data in the WT forum.

regards, Graham