The base of the tower crane is typically bolted to a big concrete pad which provides really crucial support. The base is connected to a mast or a tower and stabilizes the crane that is connected to the inside of the building's structure. Usually, this attachment point is to a concrete lift or to an elevator shaft.
Typically, the mast is a triangulated lattice structure measuring 0.9m2 or 10 feet square. The slewing unit is connected to the very top of the mast. The slewing unit is made of a gear and a motor that enable the crane to rotate.
Tower cranes may have a max unsupported height of 80m or 265 feet, while the tower crane's maximum lifting capacity is 16,642 kilograms or 39,690 pounds with counter weights of 20 tons. Furthermore, two limit switches are used to be able to make sure that the driver does not overload the crane. There is even another safety feature called a load moment switch to ensure that the operator does not exceed the ton meter load rating. Last of all, the tower crane has a maximum reach of 230 feet or 70 meters.
Due to their extreme heights, there is a science involved to erecting a crane. The stationary structure will first need to be transported to the construction site by using a big tractor-trailer rig setup. Then, a mobile crane is used in order to assemble the machine portion of the jib and the crane. Afterwards, these sections are attached to the mast. Then, the mobile crane adds counterweights. Crawler cranes and forklifts can be a few of the other industrial equipment that is typically used to erect a crane.
As the building is erected, mast extensions are added to the crane. This is how the crane's height could match the building's height. The crane crew utilizes what is called a top climber or a climbing frame that fits between the slewing unit and the top of the mast. A weight is hung on the jib by the work crew so as to balance the counterweight. When complete, the slewing unit is able to detach from the top of the mast. In the top climber, hydraulic rams are utilized to adjust the slewing unit up an additional 20 feet or 6.1m. After that, the crane driver uses the crane to insert and bolt into place one more mast section piece.