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Signalling a model railway

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Signalling a model railway

Unread postby South Western John » Tue Jul 28, 2015 9:57 am

Having now installed three semaphores on my layout plus a crossover, I am having trouble with backlash in the linkage to the crossover. The two parts of the crossover are working completely in unison but it is the linkage out to what will be the interlocking frame that is causing me problems. There are three elements here. The points themselves have a 3 mm travel, the slider switches are 3.5mm travel and the interlocking frame and push-pull operating levers that include the "notches" into which the locking bars engage, have a travel of 15mm.

So therefore I cannot afford any backlash whatsoever,in order that the synchronising of input, switch and lock is not compromised.

Can anybody please help with elimination of backlash.

I understand that Peter Jordan, owner of the layout "Egloshayle" has mastered this problem and I wonder if it is possible to contact him.
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Re: Signalling a model railway

Unread postby Bob Davies » Tue Jul 28, 2015 8:16 pm

Peter Jordan no longer subscribes to the group but I can tell you that Egloshayle was modelled as an experimental electro-pneumatic installation, which meant that it could use normal solenoid point motors (mounted under the base board, and there was no mechanical connection between the 'lever frame' and the points.

There are model layouts which use (or attempt to use) direct mechanical linkage between a lever frame and points and signals but I am afraid that I cannot recall the details. Other members of the group may be able to assist, otherwise I suggest a web search.
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Re: Signalling a model railway

Unread postby South Western John » Tue Jul 28, 2015 9:39 pm

Thank you for your thoughts, Bob, I have actually solved my backlash problem already. I had drilled the fulcrums of intermediate levers too large a size so that there was lateral movement at the screw. By soldering on a plate and re-drilling the hole to a suitably smaller size the problem is solved - no more backlash!!!

I have found that by using 1/32" bore brass tube and 0.6mm nickel-silver wire for signals and 0.5 mm piano wire for points also running in 1/32" tube, a very satisfactory and backlash free result is obtained.

The hard part is introducing the slider switch for switching the frogs of live frog points. I have used live frog points throughout the layout with the exception of crossings, single and double slips.

I have a matrix of single and double slips at the "London Terminus" platform end. These will be electrically switched with colour light signalling with routeing through the points.

However the country through station is all semaphore signals with mechanically operated points. So far it all seems to work OK, but mechanical interlocking COULD become a bit of a headache!!!
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Re: Signalling a model railway

Unread postby South Western John » Tue Jul 28, 2015 9:51 pm

I should add that I use Eileen's Emporium brass sections, tubes and wire with the exception of the piano wire that came from a model shop in London. If I require a very long run then I join two or more 10" lengths of tubing by fitting the ends with 1/16" bore brass tube into which the 10" lengths of 1/32" tubing fit precisely and solder up with no difficulty.

I hope that this will encourage other 4mm scale modellers to have a go. The result using signals constructed from Model Signal Engineering kits is so pleasing to the eye. It makes a model look like a real railway of the period I model i.e. 1940s/50s. Brackets and gantries with handrails and ladders make for total realism.
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Re: Signalling a model railway

Unread postby Fast Line Floyd » Wed Jul 29, 2015 1:40 pm

Bob Davies wrote:Peter Jordan no longer subscribes to the group but I can tell you that Egloshayle was modelled as an experimental electro-pneumatic installation, which meant that it could use normal solenoid point motors (mounted under the base board, and there was no mechanical connection between the 'lever frame' and the points.

There are model layouts which use (or attempt to use) direct mechanical linkage between a lever frame and points and signals but I am afraid that I cannot recall the details. Other members of the group may be able to assist, otherwise I suggest a web search.

The normal way is to interpose an omega loop in the wire run so that any over throw by the lever is lost in the omega loop.

The Egloshayle layout has (I believe) been scrapped as I now own that frame and have relocked it for a totally different purpose.
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