The tower crane's base is usually bolted to a large concrete pad that provides really necessary support. The base is connected to a mast or a tower and stabilizes the crane which is attached to the inside of the structure of the building. Usually, this attachment point is to a concrete lift or to an elevator shaft.
The mast of the crane is normally a triangulated lattice structure that measures 0.9m2 or 10 feet square. Attached to the very top of the mast is the slewing unit. 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 minimum lifting capacity of a tower crane is 16,642 kilograms or 39,690 lbs. with counter weights of 20 tons. Furthermore, two limit switches are used in order to make certain that the driver does not overload the crane. There is even one more safety feature known as a load moment switch to make sure that the driver does not surpass the ton meter load rating. Last of all, the tower crane has a maximum reach of 70 meters or 230 feet.
There is definitely a science involved with erecting a tower crane, specially due to their extreme heights. First, the stationary structure has to be brought to the construction site by using a big tractor-trailer rig setup. Next, a mobile crane is used in order to assemble the machine portion of the crane and the jib. After that, these parts are attached to the mast. Next, the mobile crane adds counterweights. Crawler cranes and forklifts can be a few of the other industrial machinery which is typically used to erect a crane.
When 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 uses what is called a climbing frame or a top climber that 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. When 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. Next, the operator of the crane utilizes the crane to insert and bolt into position one more mast part piece.