The base of the tower crane is typically bolted to a big concrete pad that provides really crucial support. The base is connected to a mast or a tower 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.
The crane's mast is often a triangulated lattice structure that measures 10 feet square or 0.9m2. Attached to the very top of the mast is the slewing unit. The slewing unit is made 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. Additionally, two limit switches are used in order to make certain that the operator does not overload the crane. There is even another safety feature called a load moment switch to make sure that the operator does not surpass the ton meter load rating. Finally, the maximum reach of a tower crane is 70 meters or 230 feet.
There is definitely a science involved with erecting a tower crane, especially due to their extreme heights. At first, the stationary structure needs to be transported to the construction site by utilizing a large tractor-trailer rig setup. Then, a mobile crane is used in order to assemble the equipment portion of the jib and the crane. Afterwards, these sections are attached to the mast. After that, the mobile crane adds counterweights. Crawler cranes and forklifts could be a few of the other industrial machinery which is usually utilized to erect a crane.
Mast extensions are added to the crane as the building is erected. This is how the height of the crane could match the building's height. The crane crew utilizes what is referred to as a top climber or a climbing frame that fits between the top of the mast and the slewing unit. A weight is hung on the jib by the work crew so as 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 extra 6.1m or 20 feet. After that, the crane driver utilizes the crane to insert and bolt into place one more mast part piece.