Subject:
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Re: New Crane...
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Newsgroups:
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lugnet.technic
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Date:
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Fri, 13 Jun 2008 19:56:54 GMT
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Viewed:
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14390 times
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In lugnet.technic, Thomas Avery wrote:
> Impressive supply of Technic beams you have there :-) The completed model is
> going to be a monster. Nice job.
Yeah, check out my brickshelf folder....I still have all the cranes there with
the exception of the 18000...So I have a good bit of beams :D
> I've been checking out the design of the dual CC8800, and it appears to not
> really require that the turntable resists overturning moments. If the wheeled
> ballast carrier in the back is connected, then the main turntable will mostly
> see vertical (compressive) loads. If the crane tips, then the wheeled ballast
> carrier will lift off the ground, and the whole thing will "hinge" about the
> main turntable (I've seen this happen in real life on Manitowoc 2250's with
> wheeled ballast carriers - in fact, crane operators will purposely do this so
> that it's easier to slew). If you carefully control your load (which is how it's
> done in real life), then your rear wheels come off the ground slightly and the
> whole rig is carefully balanced on the main turntable. The main turntable will
> see a very small amount of overturning moment, but it's controlled by the
> careful balance being maintained between the load and the rear ballast.
>
> Hope that makes sense. Here's a shot of the 2250 during a heavy lift. With the
> wheels being off the ground, it's easier for the crane to slew and also move on
> its crawlers (i.e. you don't have to stop and align the wheels to the movement
> of the crane).
>
> http://www.texbrick.com/temp/2250_liftoff.jpg
>
> Of course the first time I saw this, I freaked out and ran over to the yard
> leaderman. He explained that it was the normal way of doing things :-)
Yeah, I have seen the 2250's do the same thing. One thing that I have noticed
about the 8800-Twin is the fact that the side counterweight carriers do not have
wheels on them, so if the crane is not under load and the maximum counterweight
is placed on them, it cannot slew. I thought they would have used a dual
counterweight cart just like the 12600 does?? Makes no sense to me, but I
didn't design it :D
-Alvin.
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Message is in Reply To:
 | | Re: New Crane...
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| Impressive supply of Technic beams you have there :-) The completed model is going to be a monster. Nice job. (...) I've been checking out the design of the dual CC8800, and it appears to not really require that the turntable resists overturning (...) (16 years ago, 12-Jun-08, to lugnet.technic)
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