Subject:
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Re: automated train drawbridge
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Newsgroups:
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lugnet.trains
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Date:
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Thu, 29 Jan 2004 22:31:28 GMT
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Viewed:
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1712 times
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>
> How much does it sag when a train crosses the bridge? I'm guessing the magnets
> are to help keep the two sections lined up properly?
Kind of long but here is some more info on the bridge.
> Do you have counter-weights hidden under the piers? And we *need* to see some
> pictures of the lifting mechanism!
I do have counter-weights. They are slung under the table. We can get by this at
ngltc because our water tables are lower than the other tables. Here is a
picture of the counter-weights.
http://www.brickshelf.com/cgi-bin/gallery.cgi?i=641578
The lifting mechanism is very simple. The bridge is string driven. A string is
connected to the bridge around the front of the bridge and back to an axle. the
counter-weight is on the same axle going the same way. Turning the axle lowers
the counter-weight and raises the bridge. It is done through a few worm gears
and one motor. Here is an interior photo.
http://www.brickshelf.com/cgi-bin/gallery.cgi?i=641576
The motor is in the middle under the yellow plate. I have room for wieght to
counter act train weight on either side of the motor.
The bridge actually tilts up when no train is on it, and bends down to straight
when a train comes on it. It can hold my heaviest train.
http://www.brickshelf.com/cgi-bin/gallery.cgi?i=272340
(I don't know if it can carry John Warren's yet.)
It uses eight light sensors. They are wired in series. The only purpose behind
these are to tell the rcx if a train is on the bridge. 4 sensors per track,
close and far from the track. This goes into sensor port 1
The four touch sensors tell the rcx where the bridge is located. 2 per side. 1
ells the rcx if the bridge is in the low position, the other in the raised
position. Two sensors one each section, and they go into one sensor input.
Outputs B and C go to the motors on each track section.
Output A on the rcx, goes into a relay box. (The yellow box next to the rcx)
The relay box has three inputs and two outputs.
Two of the inputs come from the track power. One from lane one, and one from
lane 2. Right now these come from a regulator. but they can come from the track
it self. The two outputs go to the track sections on the bridge and before the
bridge. The third input comes from the rcx input two relays. When the bridge is
up the relays are in the open position which turns off the track on and around
the bridge. This stops the train before it runs into the bridge.
You can see the relays here
http://www.brickshelf.com/cgi-bin/gallery.cgi?i=641520
The magnets are used to hold the two tracks together when a train passes over.
Otherwise if a heavy train were to go from the lower bridge the track would
seperate. The magnets allow both bridges to go up and down together.
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Message is in Reply To:
 | | Re: automated train drawbridge
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| (...) (no pun intended). Do you have counter-weights hidden under the piers? And we *need* to see some pictures of the lifting mechanism! How much does it sag when a train crosses the bridge? I'm guessing the magnets are to help keep the two (...) (20 years ago, 29-Jan-04, to lugnet.trains)
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