I mean... how can the construction cranes get taller, and taller, and taller, going up together with the building? Unless there are TWO construction cranes in the site (one lifts the cabin of the other so construction workers can add some meters of steel structure, then the cabin is replaced at a higher level, and the taller crane then does the same with the other crane)... then I see no way to increase the height of cranes...

please, enlight my mind!

I also want to add a question about cranse. When the building is under construction, some cranes will be located inside the building as it builds up. How does the crane come out when the tower finishes?

If a building only has one crane, it is probably jacked up hydraulically from the base.

A documentary on building the Twin Towers in New York City. It should answer your question.

http://www.pbs.org/wgbh/amex/newyork/sfeature/sf_building_pop_02_rm.html

At OzScrapers we have a few cranedrivers and a dedicated thread for discussion of cranes which is filled with complicated tech-talk on these amazing beasts. You can have a look here (http://www.skyscrapercity.com/showthread.php?t=242154). A new thread has just been started so the old thread is here (http://www.skyscrapercity.com/showthread.php?t=112288)

Here's a item on jacking up a crane from forumer FAVELLE. Not sure if this is the usual way of doing it.
http://img.photobucket.com/albums/v54/favelle/linkbelt_06.jpg

The climbing tower crane works in a simple concept.
The attached frame (green colored) on the main tower frame, can be moved vertically along the main frame. When you need to heighten up the crane, a powerful hydraulic pump will jack up the green colored frame. This will leave a hollow gap in between the last section of the main frame and the outrigger on the top of the green colored frame. So, a new section of main frame will be inserted into the gap, and bolten up. The steps keep on repeating until the crane climbs to its desire height.

For the tower crane in the building case, usually it can be dismantle out and taken out by smaller moving hoisting machines from the inside of the floor. The gap leaves by the crane will be patched up to make way as a floor panel.

If you see how workers are put up to unlock and tighten the bolts of the frame, you ll learned that they are the sky warriors in the construction sites. To fix the bolts, they have to stand out of the frame, and use the heavy hammer to punch the bolts tightly as they can.

If you want to know how a Favco tower crane gets higher, go to www.lcrgroup.com.au and follow the link about climbing tower cranes. It explains it in an easy way.

James Foong has given a pretty good interpretation of it all. The crane gets higher by hydraulically rising on a special frame called a climbing frame. Towers are added one at a time by sliding them into the gap of the climbing frame along a monorail attached to the underside of the crane. The bolts are done up at the bottom of the new tower, the climbing rams attached to the climbing frame are reset and the process is repeated. Vice Versa on the way down.

This is a diagram that appeared in Melbourne's Herald Sun a while ago the explains how Eureka's cranes will come down. Thanks to Favco750.

http://img353.imageshack.us/img353/6122/eurekacranes7lf.jpg (http://imageshack.us)

Perfect place to ask the perfect question that is essential to the construction of all the towers we all admire so dearly! I learned something new today.

Excellent thread!

does tower crane can stand up firmly against hurricane?

Great thread -- something that I always wanted to know but never really had a chance to ask

I would love to get to know the biggest tower crane in the world. Could anyone can show up to the world, the pictures of probably the biggest crane ever seen?

Indeed, great thread. I always wanted to know how they assembled, increased the height and dismantled cranes.

does tower crane can stand up firmly against hurricane?
i am pretty sure they can. There are not much cross-area at the crane (just steel frames) to generate force from wind.

Thanks Vincent!

What's the maxium height and floors a kangaroo crane floor can reach from the ground?

Originally Posted by TalB
What's the maxium height and floors a kangaroo crane floor can reach from the ground?

kangaroo cranes were used in the construction of the New York's World Trade Center. so, its probably can reach to 110 storey highs. thats above 400m mark.

On WTC they had internal lifts that took stuff up to the cranes. It starts to get a little difficult when you try and put half a klm of non rotating wire rope on the drum on the back of the crane. It gets tighter and starts to crush it's self.