Typically the base that is bolted into a huge concrete pad provides the crucial support for a tower crane. The base is attached to a mast or a tower and stabilizes the crane that is connected to the inside of the building's structure. Usually, this attachment point is to an elevator shaft or to a concrete lift.
Typically, the mast is a triangulated lattice structure measuring 0.9m2 or 10 feet square. The slewing unit is attached 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. Additionally, two limit switches are used in order to ensure the operator does not overload the crane. There is even another safety feature known 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 will at first have to be brought to the construction site by utilizing a big tractor-trailer rig setup. Next, a mobile crane is used in order to assemble the machinery part of the jib and the crane. After that, these sections are connected to the mast. Next, the mobile crane adds counterweights. Forklifts and crawler cranes could be some of the other industrial equipment that is usually utilized to erect a crane.
When 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 referred to as a climbing frame or a top climber which 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. When 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 operator uses the crane to insert and bolt into position another mast section piece.