The base of the tower crane is usually bolted to a big concrete pad which provides really crucial support. 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. Normally, 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 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 tower crane's maximum lifting capacity is 16,642 kg or 39,690 lbs. with counter weights of 20 tons. Additionally, two limit switches are used to be able to make sure that the operator does not overload the crane. There is also one more safety feature called a load moment switch to make sure that the driver does not exceed the ton meter load rating. Lastly, the tower crane has a maximum reach of 70 meters or 230 feet.
Because of their extreme heights, there is a science involved to erecting a crane. The stationary structure will at first have to be transported to the construction site by utilizing a large tractor-trailer rig setup. Next, a mobile crane is used so as to assemble the machine part of the jib and the crane. These parts are then attached to the mast. Next, the mobile crane adds counterweights. Crawler cranes and forklifts may be a few of the other industrial machines which is used to erect a crane.
When the building is erected, mast extensions are added to the crane. This is how the crane's height can match the building's height. The crane crew utilizes what is known 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 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 operator uses the crane to insert and bolt into place one more mast section piece.