The base of the tower crane is generally bolted to a big concrete pad that provides really crucial support. The base is attached to a tower or a mast and stabilizes the crane that is attached to the inside of the structure of the building. Normally, this attachment point is to a concrete lift or to an elevator shaft.
Typically, 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 is made of a gear and a motor that allows 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 kilograms or 39,690 pounds with counter weights of 20 tons. Furthermore, two limit switches are used to be able to make certain that the driver does not overload the crane. There is also one more safety feature called a load moment switch to ensure that the operator does not surpass the ton meter load rating. Lastly, the tower crane has a maximum reach of 70 meters or 230 feet.
There is certainly a science involved with erecting a tower crane, particularly because of their extreme heights. At first, the stationary structure has to be brought to the construction site by using a large tractor-trailer rig setup. After that, a mobile crane is used in order to assemble the machine portion of the crane and the jib. Afterwards, these sections are attached to the mast. Then, the mobile crane adds counterweights. Forklifts and crawler cranes could be some of the other industrial machinery that is commonly used to erect a crane.
Mast extensions are added to the crane when the building is erected. This is how the height of the crane is able to match the building's height. The crane crew uses what is known as a top climber or a climbing frame which fits between the top of the mast and the slewing unit. A weight is hung on the jib by the work crew in order to balance the counterweight. Once complete, the slewing unit could detach from the top of the mast. In the top climber, hydraulic rams are used to adjust the slewing unit up an extra 6.1m or 20 feet. Then, the crane driver uses the crane to insert and bolt into place another mast section piece.