Generally the base that is bolted into a huge concrete pad provides the crucial support for a tower crane. The base is connected to a mast or a tower and stabilizes the crane which is attached to the inside of the building's structure. Usually, this attachment point is to an elevator shaft or to a concrete lift.
Usually, 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 is made of a motor and a gear which 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 kilograms or 39,690 pounds with counter weights of 20 tons. Moreover, two limit switches are used to be able to ensure the driver does not overload the crane. There is also one more safety feature called a load moment switch to ensure that the operator does not surpass the ton meter load rating. Finally, the maximum reach of a tower crane is 70 meters or 230 feet.
There is definitely a science involved with erecting a tower crane, especially due to their extreme heights. At first, the stationary structure has to be transported to the construction location by utilizing a huge tractor-trailer rig setup. After that, a mobile crane is utilized in order to assemble the machine part of the crane and the jib. These parts are then attached to the mast. Next, the mobile crane adds counterweights. Forklifts and crawler cranes can be some of the other industrial equipment that is typically used 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 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. Once 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 extra 20 feet or 6.1m. Then, the operator of the crane uses the crane to insert and bolt into position another mast part piece.