Subject:
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Re: Building Bridges
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Newsgroups:
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lugnet.trains
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Date:
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Tue, 30 Nov 1999 17:28:35 GMT
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Viewed:
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1304 times
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In lugnet.trains, James Powell writes:
>
> >
> > Lift Bridge. I'm actually on my second version; the first was lifted by
> > long chain-link chains and powered from the top of the towers. It only
> > carried a single track, and the deck was quite light, and a little flimsy.
> > I ran into difficulty with the fleixibility - when the centre of the
> > bridge depressed (eg: when the engine got there) the tips of the bridge
> > would rise slightly - enough to derail the car that was passing over,
> > at high speeds.
> >
> > The current edition is very stiff, carries two tracks, and uses a rack and
> > pinion system at each end to crawl up the towers.
>
> I'm using strings, and have problems with them not winding evenly. This then
> causes one side or another to be higher than the other. End to end isn't too
> bad, but I did not leave in any way to ajust a single string save much hassle
> at one end...stupid, but it works for now, and I doubt I will change it until
If you use the chain links, you don't get the offset problem. Drape them
over a driving gear and let the tail ends hang free (ie: don't wind them up)
That version of the bridge was powered from the centre of the connecting truss
at the top, and I had to use a differential (barrel of it rotation-locked) to
reverse the directions of the two drive axles so that both ends climb at
the same time. A side-effect was that I build an adjustment wheel onto the
side of the differential that could adjust the height of one end with
regard to the other by rotating the differential barrel.
Jeff Elliott
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Message has 1 Reply:
 | | Re: Building Bridges
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| (...) Jeff, Thanks for the idea for adjusting the height of one side of the bridge. I have been using crown gears to send power to both sides of my bridge. When the dogs kick it over it is a pain to adjust. You locked the drive axels together using (...) (25 years ago, 30-Nov-99, to lugnet.trains)
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Message is in Reply To:
| | Re: Building Bridges
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| (...) I'm using strings, and have problems with them not winding evenly. This then causes one side or another to be higher than the other. End to end isn't too bad, but I did not leave in any way to ajust a single string save much hassle at one (...) (25 years ago, 29-Nov-99, to lugnet.trains)
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