Tower Cranes

Posted by Skrud at Friday, August 6th 2004 at 2:05am

Since there is some construction project going on near my domicile, I have noticed that they have erected a giant crane to do the lifting required in the creation of a building. Recently one question popped into my head. How did the crane get to be so high if there’s no crane to lift it up that high to begin with? Since realizing this chicken-and-the-egg type of dilemma, I’ve been asking everyone who happens to be driving me home at the time. Finally I decided I’d check “HowStuffWorks.com”:http://science.howstuffworks.com/tower-crane.htm and I found my answer: They build themselves.

So the crane is made up of a few basic parts. There is the mast which is the height structure of the crane that consists of 20ft. long sections. These can be added to the crane to make it taller. Now the central portion of the crane, called a jib, is where motors, gears, counterweights and operator booth are. This is put together at the construction site by a mobile crane (which is a smaller crane attached to a truck of some kind). The mobile crane also lays down the first two mast portions. The bottom part of the mast is bolted into a 30 ft x 30 ft x 4 ft chunk of concrete that weighs about 182,000 kg. Once the jib is placed on top of the the first two mast pieces, the slewing unit (which is at the base of jib, and is what connects it to the mast) pushes out large hydraulic rams (basically, legs) to lift itself another 20 ft. in the air. Then the crane itself lifts up another mast piece, and fits it into the space created by the hydraulic rams (called a climbing frame). Isn’t that cool?

Tags: random