Typically the base which is bolted into a large concrete pad provides the crucial 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 structure of the building. Usually, this attachment point is to a concrete lift or to an elevator shaft.
Usually, 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 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. Moreover, two limit switches are utilized in order to make certain that the operator does not overload the crane. There is also one more safety feature called a load moment switch to ensure that the driver does not exceed the ton meter load rating. Lastly, the maximum reach of a tower crane is 70 meters or 230 feet.
Due to their extreme heights, there is a science involved to erecting a crane. The stationary structure will at first have to be transported to the construction location by using a big tractor-trailer rig setup. Then, a mobile crane is used in order to assemble the machine portion of the crane and the jib. These parts are then attached to the mast. The mobile crane next adds counterweights. Forklifts and crawler cranes could be some of the other industrial equipment that is commonly 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 climbing frame or a top climber that 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 could 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 place one more mast section piece.