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 Technic / 10216
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Subject: 
Re: drawbridge
Newsgroups: 
lugnet.technic, lugnet.trains
Date: 
Tue, 29 Apr 2003 14:36:00 GMT
Viewed: 
2965 times
  
In lugnet.technic, Christopher Masi writes:
<snip>
Has anyone tried using a single motor, and putting the motor in the
span? I know it isn't prototypical, but if the motor was in the span,
and the string/chain was drawn into the span by a single motor, then the
span would pull itself up evenly. This was just a thought, I haven't
tried it.

My lift bridge used a single motor, and I put a drive shaft across the
top to provide power to both sides of the lifting mechanism. I never got
around to trying an alternate design.

http://users.rcn.com/cjmasi/lego/bridges/bridge.htm


The GMLTC tried that on our previous layout.  We had a motor mounted in the
span, geared down to technic 8-tooth gears on each corner.  The gears would
engage this piece:
http://guide.lugnet.com/partsref/search.cgi?q=2428  (1x20 gear rack)
to lift/lower the span.  Problem was, since we couldn't keep the bridge
towers perfectly in line, one end would invariably slip, throwing the span
off level.

One other thing we talked about trying but never did, would be to have the
gears engage a length of chain hanging from the top of the towers.  That
would give us more flexability with alignment.

We're pretty happy with our pivoting bascule bridges on our current layout,
so I doubt we'll try the vertical lift bridge again anytime soon...  :-)

JohnG, GMLTC



Message has 1 Reply:
  Re: drawbridge
 
Chain: been there done that, it wasn't a pretty sight... Lego chain is not strong enough for the weight and forces a lifting mechnism will put on it. I tried chain on my lift bridge before eventually moving on the string. I bought over $120 worth of (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)

Message is in Reply To:
  Re: drawbridge
 
(...) That is a nice bridge, but I was chiming in to comment on syncronization... Has anyone tried using a single motor, and putting the motor in the span? I know it isn't prototypical, but if the motor was in the span, and the string/chain was (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)

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