The tower crane's base is generally bolted to a huge concrete pad that provides really crucial support. The base is attached to a mast or a tower and stabilizes the crane which is affixed 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 connected to the very top of the mast. The slewing unit consists of a gear and a motor which allows 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. In addition, two limit switches are used in order to make sure that the operator does not overload the crane. There is even one more safety feature referred to as a load moment switch to make sure 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 would at first need to be transported to the construction location by using a big 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. The mobile crane next adds counterweights. Forklifts and crawler cranes could be a few of the other industrial machines that is typically utilized to erect a crane.
As the building is erected, mast extensions are added to the crane. This is how the crane's height is able to match the building's height. The crane crew utilizes what is referred to as a top climber or a climbing frame which 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. When complete, the slewing unit could 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 driver of the crane uses the crane to insert and bolt into place one more mast section piece.