The tower crane's base is typically bolted to a big concrete pad that provides really necessary support. The base is connected to a tower or a mast and stabilizes the crane which is affixed to the inside of the building's structure. Normally, this attachment point is to an elevator shaft or to a concrete lift.
Generally, 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 consists of a gear and a motor which allows 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 lbs. with counter weights of 20 tons. Furthermore, two limit switches are used to be able to ensure the operator does not overload the crane. There is also another safety feature called a load moment switch to make certain that the driver does not surpass the ton meter load rating. Lastly, 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 would first need to be brought to the construction site by using a big tractor-trailer rig setup. Then, a mobile crane is utilized in order to assemble the machinery portion of the jib and the crane. Afterwards, these parts are attached to the mast. Afterward, the mobile crane adds counterweights. Crawler cranes and forklifts could be a few of the other industrial machinery which is typically 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 can match the building's height. The crane crew utilizes what is called a climbing frame or a top climber which 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 can detach from the top of the mast. In the top climber, hydraulic rams are used to adjust the slewing unit up an extra 20 feet or 6.1m. After that, the crane operator utilizes the crane to insert and bolt into place one more mast section piece.