Wherever you are in a city, there are lots of things that always keep visible for you. Among them, tower crane is the most common one. Whenever we raise our eyes on the street, we would see many tower cranes swinging in the sky above the city. They are so high and seemingly so dangerous that you cannot ignore them. They are usually used in the construction of tall buildings. What’s more, their height can grow as the building grows taller. As such a heavy equipment, how are the tower cranes able to grow with the growth of the building? For once a while, this question had bothered me. And if you dear readers were confused with the same question, then reading the post will dispel all your suspicions.
Tower cranes arrive at the construction site on 10 to 12 tractor-trailer rigs. The crew uses a mobile crane to assemble the jib and the machinery section, and places these horizontal members on a 40-foot (12-m) mast that consists of two mast sections. The mobile crane then adds the counterweights.
The mast rises from this firm foundation. The mast is a large, triangulated lattice structure, typically 10 feet (3.2 meters) square. The triangulated structure gives the mast the strength to remain upright.
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To rise to its maximum height, the crane grows itself one mast section at a time! The crew uses a top climber or climbing frame that fits between the slewing unit and the top of the mast. Here’s the process:
- The crew hangs a weight on the jib to balance the counterweight.
- The crew detaches the slewing unit from the top of the mast. Large hydraulic arms in the top climber push the slewing unit up 20 feet (6 m).
- The crane operator uses the crane to lift another 20-foot mast section into the gap opened by the climbing frame. Once bolted in place, the crane is 20 feet taller!
You dear readers may be also wandering how the tower crane comes down when a building is finished. As long as you have understood the above steps, the question is naturally solved, because the process is reversed — the crane disassembles its own mast and then smaller cranes disassemble the rest. As we can see, the whole process are actually not confusing at all, although a little bit complicated indeed.
Tags: grow, tower crane
July 3rd, 2010 at 11:23 am
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July 18th, 2010 at 11:50 am
Fantastic site. I am so looking forward to reading more
July 19th, 2010 at 11:58 pm
It’s weird how many sites there are about this topic. I don’t know if I’ll need to be back, but it’s good to know I found the one that offers some valuable stuff if this comes up for me again