The tower crane's base is usually bolted to a big concrete pad that provides really crucial support. The base is connected to a tower or a mast and stabilizes the crane that is attached 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 often a triangulated lattice structure that measures 0.9m2 or 10 feet square. Attached 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 minimum lifting capacity of a tower crane is 16,642 kilograms or 39,690 pounds 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 ensure 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.
There is definitely a science involved with erecting a tower crane, specially because of their extreme heights. At first, the stationary structure has to be transported to the construction location by utilizing a large tractor-trailer rig setup. Then, a mobile crane is utilized in order to assemble the machine portion of the jib and the crane. Afterwards, these parts are connected to the mast. After that, the mobile crane adds counterweights. Crawler cranes and forklifts can be a few of the other industrial machinery that is commonly 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 that 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. Once complete, the slewing unit is able to detach from the top of the mast. In the top climber, hydraulic rams are utilized to adjust the slewing unit up an extra 6.1m or 20 feet. After that, the crane operator utilizes the crane to insert and bolt into place another mast section piece.