Templot Club Archive 2007-2020                             

topic: 145Track Clearances - slewing
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posted: 29 Aug 2007 07:13

from:

Tim Morrow
 
Melbourne - Australia

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The June 2007 edition of Railway Modeller contains an article "NBR point and signal operation".

A comment is made regarding clearances between structures, such as 'signal stanchions', point rodding, etc. and track location.

As I construct operating point rodding, does Templot have the means of adjusting the track separation at those appropriate areas following setting the 'adjacent track centre to centre spacing' located under "Geometry" for the overall plan.

With a particular project I am working on, which includes a double slip, point rodding is required to run to all the points. In one group, containing five rods, It would be good to be able to increase the track spacing to accommodate this width along this length.

posted: 29 Aug 2007 12:34

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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Tim Morrow wrote:
As I construct operating point rodding, does Templot have the means of adjusting the track separation at those appropriate areas following setting the 'adjacent track centre to centre spacing' located under "Geometry" for the overall plan.

With a particular project I am working on, which includes a double slip, point rodding is required to run to all the points. In one group, containing five rods, It would be good to be able to increase the track spacing to accommodate this width along this length.
Hi Tim,

The geometry > adjacent track centres... setting can be changed for each individual template. But you need to change it while it is the control (current) template and before creating double track or a crossover from it.

Obviously you can't change the spacing between the tracks without some transitional arrangements. For this purpose you can use the slewing function on the adjoining template(s). You need to set the slew amount to match the difference in the track spacings.

Here is a screenshot showing that, with the slewing zone (in the purple template) severely shortened to make the effect clear:

slewed_approach.pngslewed_approach.png

This is EM gauge (4mm/ft), with the tracks on the left at standard 6ft way giving 44.67mm track centre spacings. On the right the spacing is increased to 10ft way, i.e. an increase of 4ft or 16mm to 60.67mm centre spacings.

For the red template, I increased the spacing to 60.67mm and then created the crossover (tools > make simple crossover). For the yellow template, I left the spacing at the pre-set 44.67mm and created double track. For the purple template so created, I then applied geometry > slew (nudge) and in new slew settings I set the slew amount to 16mm.

Now the slewing zone length and position needs adjusting (by mouse action is easiest) to produce a more gradual change. In curved track such as this, for the greatest accuracy at the join the slewing zone should end at the template boundary. It may be worth moving the boundary or splitting templates to achieve this (not necessary in straight track).

If the length of the template is appropriate the slewing zone can be quickly set to match the full length, using geometry > slew (nudge) > change slewing zone length > match length to template menu item. Here's the result of that on this example:

slewed_approach_long.pngslewed_approach_long.png

(You might think that you could use a transition curve instead, but in this case that wouldn't work. The reason is that in this example the 1st and 2nd radii would be concentric -- a condition which produces an infinitely long transition zone.)

Instead of slewing one track by the full amount, you can split the required amount of slew between both tracks, either equally or in any desired proportion. This usually results in smoother curves. Here I have slewed the purple and yellow templates by 8mm each, increasing the space between them by 16mm in total:

slewed_approach_both_long.pngslewed_approach_both_long.png

The full notes about using the slewing functions are at:

 http://www.templot.com/martweb/gs_geometry.htm#slewing

regards,

Martin.

posted: 1 Sep 2007 16:30

from:

Tim Morrow
 
Melbourne - Australia

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Thanks Martin



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