The tower crane's base is generally bolted to a large concrete pad that provides very crucial support. The base is connected to a tower or a mast and stabilizes the crane which is affixed to the inside of the structure of the building. Normally, this attachment point is to a concrete lift or to an elevator shaft.
The crane's mast is normally a triangulated lattice structure that measures 0.9m2 or 10 feet square. Connected to the very top of the mast is the slewing unit. The slewing unit consists of a motor and a gear which allows the crane to rotate.
Tower cranes are able to have a maximum unsupported height of 80m or 265 feet. The tower crane's maximum lifting capacity is 16,642 kilograms or 39,690 pounds with counter weights of 20 tons. Furthermore, two limit switches are used to be able to make sure that the operator does not overload the crane. There is even one more safety feature known as a load moment switch to make certain that the operator does not exceed the ton meter load rating. Finally, the tower crane has a maximum reach of 230 feet or 70 meters.
Because of their extreme heights, there is a science involved to erecting a crane. The stationary structure would first need to be transported 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 crane and the jib. Then, these parts are attached to the mast. After that, the mobile crane adds counterweights. Crawler cranes and forklifts may be a few of the other industrial machines that is used 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 utilizes 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 so as to balance the counterweight. When complete, the slewing unit can detach from the top of the mast. In the top climber, hydraulic rams are utilized to adjust the slewing unit up an extra 20 feet or 6.1m. Next, the crane operator utilizes the crane to insert and bolt into position another mast section piece.