To build high-rise buildings, it is necessary to use tower cranes to lift building materials. Tower cranes are not complete lifting equipment, but are assembled together from metal brackets, including standard sections, climbing sections, and hydraulic jacks. Hydraulic jacks are the driving equipment that drives the climbing sections to increase in height.

The hydraulic jack is installed inside the climbing section and can temporarily perform support work instead of the standard section. When the building is covered layer by layer, the height of the tower crane also needs to be raised accordingly, and the jack will come into use. At this time, the tower crane engineer will loosen the screws that fix the tower crane and operate the jack. After the tower crane rises about one meter, the tower column is fixed to the structure of the building, and then the jack is retracted and the bottom is fixed to the structure of the building. Then, the upper screws are loosened, the jack is supported, and it rises another meter. In this way, the tower crane will rise section by section by reversing the operation.

The main tower of the tower crane is raised by stacking standard sections, and the hydraulic jack is the supporting power below the standard sections.