Typically the base which 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 structure of the building. Often, this attachment point is to a concrete lift or to an elevator shaft.
Typically, 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 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 kg or 39,690 pounds with counter weights of 20 tons. Additionally, two limit switches are utilized to be able to ensure the driver does not overload the crane. There is also one more safety feature referred to as a load moment switch to make certain that the operator does not surpass the ton meter load rating. Last of all, the maximum reach of a tower crane is 230 feet or 70 meters.
Due to their extreme heights, there is a science involved to erecting a crane. The stationary structure will first need to be brought to the construction location by using a big tractor-trailer rig setup. Then, a mobile crane is used so as to assemble the equipment part of the jib and the crane. Afterwards, these sections are attached to the mast. The mobile crane then adds counterweights. Crawler cranes and forklifts may be some of the other industrial equipment that is utilized to erect a crane.
As 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 utilizes 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. Once complete, the slewing unit is able to detach from the top of the mast. In the top climber, hydraulic rams are used to adjust the slewing unit up an additional 6.1m or 20 feet. After that, the crane driver uses the crane to insert and bolt into place one more mast part piece.