Generally the base that is bolted into a huge concrete pad provides the crucial support for a tower crane. The base is connected to a mast or a tower and stabilizes the crane that is affixed to the inside of the structure of the building. Normally, this attachment point is to a concrete lift or to an elevator shaft.
Generally, the mast is a triangulated lattice structure measuring 10 feet square or 0.9m2. The slewing unit is attached to the very top of the mast. The slewing unit consists of a motor and a gear that enable the crane to rotate.
Tower cranes may have a max unsupported height of 80m or 265 feet, while the minimum lifting capacity of a tower crane is 16,642 kg or 39,690 lbs. with counter weights of 20 tons. Furthermore, two limit switches are utilized in order to make certain that the driver does not overload the crane. There is even another safety feature known as a load moment switch to make sure that the driver does not surpass the ton meter load rating. Finally, the tower crane has a maximum reach of 230 feet or 70 meters.
There is definitely a science involved with erecting a tower crane, especially because of their extreme heights. At first, the stationary structure needs to be transported to the construction site by using a huge tractor-trailer rig setup. Then, a mobile crane is utilized in order to assemble the machine portion of the crane and the jib. After that, these sections are connected to the mast. The mobile crane then adds counterweights. Forklifts and crawler cranes could be some of the other industrial machines which is utilized 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 in order to balance the counterweight. Once 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. Then, the crane operator utilizes the crane to insert and bolt into place another mast part piece.