Generally the base that is bolted into a huge concrete pad provides the crucial support for a tower crane. The base is connected to a tower or a mast and stabilizes the crane that is connected to the inside of the building's structure. Often, this attachment point is to a concrete lift or to an elevator shaft.
The crane's mast is often a triangulated lattice structure which measures 0.9m2 or 10 feet square. Connected to the very top of the mast is the slewing unit. The slewing unit is made of a gear and a motor which enable 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 kilograms or 39,690 lbs. with counter weights of 20 tons. Additionally, two limit switches are utilized in order to make certain that the operator does not overload the crane. There is even another safety feature referred to as a load moment switch to ensure that the operator 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 would at first have to be brought to the construction site by utilizing a large tractor-trailer rig setup. After that, a mobile crane is utilized in order to assemble the equipment portion of the jib and the crane. These parts are then connected to the mast. Then, the mobile crane adds counterweights. Crawler cranes and forklifts could be a few of the other industrial equipment which is typically utilized to erect a crane.
Mast extensions are added to the crane when the building is erected. This is how the height of the crane could match the building's height. The crane crew uses what is called 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 used to adjust the slewing unit up an extra 20 feet or 6.1m. Next, the crane driver utilizes the crane to insert and bolt into place one more mast part piece.