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> Manual Points operating system, Bowden tubes
post 31 May 2010, 10:34
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Hello all,
Has anybody any experience with Bowden Tube type of points operation.
What I would like to know is-
1. The relative expense compared with electric operation,
2 How reliable they are, and,
3 Whether they look authentic. (I intend to model GWR steam in the 1940's and BR WR to the mid 1960's). I personally think the tubes will give the look and feel of the points operation of that time. How does anybody else feel?
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John Webb
post 31 May 2010, 12:32
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1. Over short distances the tube system will be cheaper, but I have never calculated what the 'break-point' between tube and motor is.
2. Very reliable if properly installed.
3. Grossly over-scale for 4mm/ft (the outer tube is some 2mm dia = 6inch; the actual point rods were around 1.5 inches or less across. Still overscale for 7mm/ft and almost right for 10mm/ft.

John Webb
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post 1 Jun 2010, 12:34
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Footplate Inspector

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Personally i like the feel of mechanical point operation but I think I would only use it on a small layout such as a branch line terminus. I have never used cable but have used dowels. But that was before I took to switching the current on the frogs, this is something cables do not do unless you add some cunning device to throw the dpdt switch.

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post 1 Jun 2010, 15:50
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Regional Controller

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this is something cables do not do unless you add some cunning device to throw the dpdt switch.

or..use the DPDT switch to throw the cables?...ie, mount switch at board side, drill hole through plastic slider [remove finger first]....pass wire through hole [make Z-shape in wire first?]....

or..if reet posh and using a lever frame.....why not use something like a Peco [screeeekkkk]...sliding switch, under the trackbed, linked directly to the tie =bar..or the operating cable, via a rigid dropper?
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post 2 Jun 2010, 11:56
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Passed Fireman

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I have this systen in operation on my layout, and its been reasonably reliable, as my layout is on sundele board, I could easily sink the tubes just below the surface then cover them with scienic materials, were i made a big mistake was, once all the trackwork and point were working correctly, i started to put down the balast etc, using diluted pva, what i did not realise at the time was, that via capillary action, some of the dilluted pva got sucked into the tube and rusted the steel wire inside it, hence jamming it up, on subsequent installs, I put a small amount of greese on the end of the tubes to prevent it happening again, had not trouble since, using the tube and steel wire, along with the levers and cranks is probrably more expensive than solanoids, but personaly find it more satisfying pulling the lever and seeing the points move over slowly. On a side issue why are turnout (points) so called? i cant even think why thet are called points. question.gif
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post 2 Jun 2010, 16:57
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Although for O gauge I have used 0.7mm nickle silver wire running in holes through 10mm brass angle with upto four holes 1.5mm apart and the longest run is approx 4.5m long and this has two angle cranks on it to turn 90 from the leverframe and then another at the point. the angle cranks are soldered to 1.5mm dia rod that runs in a brass tube through the 10mm thick baseboard and has an arm under the baseboard working a micro switch to change the frog polarity.

The lever frame is homemade from steel flats and sheet with brass spacers on a rod that the levers work on. I have an 18 lever frame for the main terminus and a 5 lever one for the fiddle yard. The only down side I have had is that the soldered joints on the rods, a piece of tube 6mm long can break, I think this has been due to leaving the points pulled off and the cold/heat in the loft has caused the rods to shrink and the tension has been to much for the joint if not fully soldered.

The tiebar on the points are sprung one way and the rods only pull off the spring doing the return when the lever is let off.

I hope the above is clear, the system has been in use for about 5 years and I have only had to replace one micro switch that jammed in one direction, it took ages to find what was causing the short when the point was pulled of and a train entered the rail section beyond the point.


mike g
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post 2 Jun 2010, 20:37
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QUOTE (alastairq @ 1 Jun 2010, 16:50) *
or..use the DPDT switch to throw the cables?...ie, mount switch at board side, drill hole through plastic slider [remove finger first]....pass wire through hole [make Z-shape in wire first?]....

The use of slide switches in this way works exceedingly well, although used with rigid push rods rather than bowden cables in my case. Definitely put a spring in the mechanism to take up the excess movement from the slide switch.

There is a further potential benefit in the form of wiring simplification. The switched output can be connected to the push rod or wire by a short flexible lead. At the point a further small lead takes the power to the crossing. (Obviously a non conductive tie bar is required if the push rod engages this directly.) This is especially neat with DCC, as just the two connections from the bus wires are necessary to a bank of point control switches. None of the usual mass of knitting beneath the layout.

The only caveat I would have with bowden cables is ensuring that a replacement wire can be installed, and that there is enough working space to crimp on or otherwise attach a new termination.
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post 4 Jun 2010, 07:13
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Bog Snorkeller

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I've used wire in tube (not Bowden cable) on a previous layout operated through a bank of sliding dpdt switches built into small plastic boxes around the layout which gave me control of frog switching and panel lights.

The secret is to accurately measure the throw of your point at the tie bar, then go find sliders to match.

Cost wise I would suggest it worked out about the same as installing cheap solenoids (which I hate) and once you get the installation method firmly in your mind are easy to lay - start at the point and work back to the switch box.

All in all I think they are about as 100% reliable as you can get.




'Marriage is a relationship where one person is always right and the other is the husband'
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