Usually the base which is bolted into a big concrete pad provides the necessary support for a tower crane. The base is connected to a mast or a tower and stabilizes the crane that is attached to the inside of the structure of the building. Normally, this attachment point is to an elevator shaft or to a concrete lift.
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 motor and a gear 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 lbs. with counter weights of 20 tons. Moreover, two limit switches are used to be able to make sure that the driver does not overload the crane. There is also another safety feature called a load moment switch to make certain that the operator does not surpass the ton meter load rating. Finally, the tower crane has a maximum reach of 70 meters or 230 feet.
There is definitely a science involved with erecting a tower crane, especially because of their extreme heights. First, the stationary structure has to be transported 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. These sections are then attached to the mast. The mobile crane then adds counterweights. Crawler cranes and forklifts may be a few of the other industrial machines that is typically utilized 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 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. When complete, the slewing unit can 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 driver utilizes the crane to insert and bolt into position another mast section piece.