Subject:
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Re: Crane mathematics
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Newsgroups:
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lugnet.technic
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Date:
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Tue, 2 Aug 2005 00:04:52 GMT
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Viewed:
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3600 times
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In lugnet.technic, Nathan Bell wrote:
> Does anyone who makes cranes have some easy math such as geometry for crane
> design? The problem I see is that for a crane to be always balanced the weight
> in the back needs to move according to the load weight.
Hi Nathan, looking good! I wish I could be at Brickfest to see it.
WRT balance, the answer is that cranes are very rarely in total balance. That is
why they need such strong accurately machined turntables - the turntable is
generally taking more weight on one side than the other. The trick is to work
out the load charts so as to make sure the turntable is strong enough to take
the maximum imbalance.
Unfortunately in LEGO there is not much choice for turntables. The best for
technic scale models is the technic turntable, which is quite good, but because
it only clips together, there's a limit to the unbalance it can support. You can
improve it by adding more rollers around it like Jen Clark did in her AC-50, or
adding more support through the centre.
Mobile and crawler cranes can be adjusted for different lifts by simply adding
or removing ballast. But that is all worked out before the lift - the ballast
never changes during a lift. Before the lift it will be very heavy in the rear,
during the lift it will usually be heavy in the front.
But many tower cranes have movable ballast, because it is difficult to add or
remove ballast once it is erected. In fact some have ballast that is geared to
the main boom, and is automatically moved backward as the boom is lowered.
The other thing to consider is raising the boom - like on this CC2800
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=26905 the extra ballast at the
rear was only required to raise the boom, and was disconnected during lifts.
HTH
ROSCO
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Message has 1 Reply:
 | | Re: Crane mathematics/netiquittte?
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| (...) Thanks Ross. Hopefully the outriggers will not give way. I used the diagonal outriggers to minimize the complexity of the crane mechanisms, but they may give way under the wieght. I hope it is as good as your designs! I just realized (...) (19 years ago, 2-Aug-05, to lugnet.technic)
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Message is in Reply To:
| | Crane mathematics
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| Does anyone who makes cranes have some easy math such as geometry for crane design? The problem I see is that for a crane to be always balanced the weight in the back needs to move according to the load weight. The boom on mine bends, but when (...) (19 years ago, 1-Aug-05, to lugnet.technic)
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