Magic construction cranes?

June 21, 2006 2:29 PM

How are these free standing construction cranes erected?

I've asked construction workers on two occasions, none of them really knew for sure. They seemingly always go up overnight as well. I've also lived near construction sites on several occasions and they just appear out of nowhere.

posted by andywolf to grab bag (8 comments total)

How do construction cranes work???
posted by nathan_teske at 2:31 PM on June 21, 2006

Wikipedia
posted by grouse at 2:57 PM on June 21, 2006

Maybe this one will explain it to you:

How Tower Cranes Work
posted by evercool at 3:00 PM on June 21, 2006

At a former job in downtown Seattle, we got to watch them put one of those cranes together. It's very interesting work, since it basically requires a mobile crane capable of lifting the horizontal span into place. They assemble it on the ground, then raise it up and bolt it onto the tower portion (also built using the mobile crane).
posted by nomisxid at 3:22 PM on June 21, 2006

Some are built horizontally and then lifted as nomisxid said, using a mobile crane to lift it from the ground and put the actual crane housing and boom in place. This works up to a couple hundred feet in the air, but isn't useful above the height of a mobile crane (obviously.)

Still others have the crane housing and boom assembled on the ground, and they're lofted skywards by their own petards, as Nathan_Teske's link explains. This is accomplished by there being a 'lifter' just below the crane housing and turntable that creates a null space in the crane's pillar/stand. Another section of pillar is placed in the section and connected ... and then the turntable is hoisted again on that. Wash, rinse, repeat, and you've got a 400 foot crane.
posted by SpecialK at 3:28 PM on June 21, 2006

These big cantilevers are fun to watch go up, because as SpecialK said, they kinda build themselves. Note that the booms on these things don't go up/down the way we typically think of cranes doing, they swing, and there's a block (with attached thingamabobby) that traverses the length of the boom.

Big cranes abound, but there are discussions about where they biggest is: Malmö? Port of Dubai? Or maybe Odate City? </geek>
posted by Emperor SnooKloze at 4:57 PM on June 21, 2006

Well, obviously they need a bigger construction crane to build the construction crane. But now, how do they build the construction crane crane ? ;)
posted by XiBe at 6:02 AM on June 22, 2006

I have always thought it would be cool to see a war between these cranes, where they all swing stuff around trying to knock each other over.

That is all.
posted by M.C. Lo-Carb! at 12:33 PM on June 22, 2006