With hi-rise buildings being constructed left and right, i was just wondering, how do they raise cranes? this has really been bugging me for a time now..
JIP cranes are used to do so
Tower cranes are usually erected in one of two ways. You could lift the parts into place with a mobile crane with a telescopic boom which is taller than the crane being built. Some people ask why you dont just use the mobile crane all the time, but the tower crane has higher lifting capacity, longer reach and is cheaper. Some tower cranes are assembled at ground level. The long boom, cab and counter weight are assembled and then jacked up off the ground. A small bit of tower is then sliped in beneath the assembly and attached. The crane is the jacked up again and another portion of the tower sliped in. This is repeated until the desired height is reached. The first method is the most common.
I think you mean tower cranes, you will notice on these cranes that there is small size pieces and on larger piece with hydraulic jack, when they want to extend the crane , they insert the smaller size piece into the large piece and push up the upper part to insert the new piece and so on. There is also another type of cranes which is the climbing type, they are almost using the same principle but lifting up the crane it self using the concrete shaft
