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Gauge 3 track standards and large radius turnuts

Started by MikeWilliams, Dec 16 2015 19:19

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Just planning a garden line and thinking of a trailing crossover using Mr.Barker's largest turnouts - 20ft radius.

Some have said that our track standards mean wheels can drop into the crossing V on large radius turnouts, so has anyone experience please of 20ft radius?

Also, the track on which this will be cited will be not quite straight but on a curve of maybe 200ft radius.  Cliff only supplies ready made points on straight track, so any thoughts on whether that straight length in the centre will be noticeable?  If so I can build my own, but ready made would be so much easier.



John Candy


The short answer is, yes, wheels do drop and non-compensated four-wheeled vehicles can tilt quite dramatically if they happen to stop on or pass extremely slowly over the crossings!
You will recall, that because of the very small wheel diameter and short wheelbase of the Sentinel, I ordered the wheels to have wider than normal treads, to bridge the gap. Cliff recommends filling the base of the crossings with Isopon or similar filler. I have not done this but may have to if it proves necessary.

Regarding turnouts on curves, the larger the radius, the longer the turnout.
If you try a 200ft radius with a straight turnout road, at a guess the overall turnout length could be 20 or 30 feet.
If it were a "Y" with a small radius turnout road, the length could be shortened significantly.

I used Templot to build a 3-way on a curve with a 20ft running road and two larger radius turnout roads and the overall length of that is around 5 feet.

My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.


Thanks John, I suspected that would be the case.

Just to clarify, it was not a 200ft radius point, but a 20ft radius coming off a 200ft radius!



Even the GRS points have the metal plate in the frog of the point for the flanges to run on as per the 8' radius points on blackgang. It does work and makes a real difference.



This was also the case in gauge 1.  All of Cliff Barker's large radius points needed the frog filling to stop wheels falling down the gap.  The old Society wheel standards would help, the narrower the wheel the worse the problem becomes.  Have a look at a Hornby Dublo point and you will see the same filling in of the frog - nothing is new.




Thanks chaps.

So, if you fill the V so that wheels conforming to the latest standards are supported by their flange, does that, in practice, cause a problem with older standards, especially pre-War and vintage stock.  i.e. will my Carson and Basset Lowke locos (those most likely to be travelling at speed) bounce up on the in-fill?  Or, in practice, does it actually work OK?

One of the delights of a garden line is that one's friends can bring all of their Gauge 3 locos and stock to run and I am concerned that I may be creating a track which will not do that?


John Candy

When I was last at Trevor's line, his circuit had been relaid with GRS track and GRS-built turnouts, with the cast brass crossings ("frogs") with "infills".

A few items of a visitor's older rolling stock, with coarse wheels, "jumped" as they took the crossings but none actually derailed.

Does Alan Marsden have his infilled? I didn't think so but may be wrong.
He doesn't seem to have any such problems but perhaps his very old turnouts and slips were built to tighter standards?

My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

David S

Mike, why not make a shim that can be removed if required?  I would imagine that older stock and locomotives would have coarser wheel profiles but the shim could be removed when running these.  I've had the wheel drop problem on my line as well, although my gauge 3 stock seems to run well through unmodified GRS points (there is a very slight drop with slaters wheels), 16mm and gauge 1 wheels can be a bit of a problem because the flanges aren't as deep and tread not as wide as gauge 3, a removable shim solved this :)