My main question is, why is there a change in the position of the rail joints?
You have opened a can of worms which I have been trying to keep the lid on for years.
Just trying to explain it is going to create a page full of ifs and buts below.
The prototype rail lengths and timbering for K-crossings varies a lot, and for movable K-crossings (switch-diamonds) prototype info is almost impossible to find for angles shorter than about 1:9. There are also significant differences between bullhead and flat-bottom designs.
For Templot I tried to simplify it by providing:
1. some default settings which look about right in most cases, and
2. the option to set custom rail lengths if you know what you want.
But some of this is still a work-in-progress on my to-do list. My excuse is that I'm still waiting to find some definitive prototype information.
The rail joints change because for movable K-crossings, Templot sets a single default wing rail length of 36ft (total). This differs from the defaults for fixed K-crossings, which vary according to the K-crossing angle.
You can move the rail joint by going to
real > K-crossing options > customize K-crossings > K-crossing wing rails...
Click the ? info
button on the dialog for full details.
Note that you are entering the full length
of the rail, across both half-diamonds. i.e. double the length on each half-diamond template.
1. For a fixed K-crossing Templot will adjust the timbering to suit (as far as possible), with closed up timbers adjacent to the rail joint.
for fixed K-crossings the above applies only if you have set the real > timbering > half-diamond timbering > fixed K-crossing : timber-spacing as prototype
If you choose the as model
option (recommended for all except P4, S7, etc.), Templot will adjust the timber spacing to suit the flangeway gaps so that the point rail tips are properly supported on a timber, and ignore the prototype rail joint positions and timber spacings.
2. For a movable K-crossing Templot leaves the timbering unchanged. This is because for the movable point rails the timber-spacing must be specified to suit the special K-crossing switch chairs, and I don't (yet) have the prototype info for that for every K-crossing angle. You are on your own to shove the timbers to match your required prototype.
for movable K-crossings the above applies only if you have set the real > timbering > half-diamond timbering > movable K-crossing : timber-spacing normal
If you choose the as turnout switch
option, Templot will adjust the timber spacing to match the currently set switch for this template. This is primarily intended for use when using an irregular half-diamond to represent a symmetrical Y-turnout.
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