Usually the base that is bolted into a huge concrete pad provides the essential support for a tower crane. The base is connected to a tower or a mast and stabilizes the crane which is connected to the inside of the building's structure. Often, 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 connected to the very top of the mast. The slewing unit is made of a motor and a gear 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 kg or 39,690 pounds with counter weights of 20 tons. Furthermore, two limit switches are used to be able to ensure the driver does not overload the crane. There is also one more safety feature called a load moment switch to make certain that the operator does not exceed the ton meter load rating. Last of all, the maximum reach of a tower crane is 70 meters or 230 feet.
Because of their extreme heights, there is a science involved to erecting a crane. The stationary structure will first have to be transported to the construction location by utilizing a huge tractor-trailer rig setup. Next, a mobile crane is used in order to assemble the machine portion of the jib and the crane. These parts are then connected to the mast. Afterward, the mobile crane adds counterweights. Crawler cranes and forklifts could be a few of the other industrial equipment that 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 uses 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. When 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 driver uses the crane to insert and bolt into position another mast part piece.