Generally 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 which is connected to the inside of the structure of the building. Usually, this attachment point is to a concrete lift or to an elevator shaft.
Generally, 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 motor and a gear that allows the crane to rotate.
Tower cranes are able to have a maximum unsupported height of 80m or 265 feet. The maximum lifting capacity of a tower crane is 16,642 kilograms or 39,690 lbs. with counter weights of 20 tons. Furthermore, two limit switches are used in order to make certain that the operator does not overload the crane. There is even one more safety feature called a load moment switch to ensure that the operator does not exceed the ton meter load rating. Last of all, the maximum reach of a tower crane is 230 feet or 70 meters.
There is definitely a science involved with erecting a tower crane, specially due to their extreme heights. 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 used so as to assemble the equipment part of the jib and the crane. These sections are then connected to the mast. Then, the mobile crane adds counterweights. Crawler cranes and forklifts may be a few of the other industrial machinery which is commonly utilized to erect a crane.
When the building is erected, mast extensions are added to the crane. This is how the crane's height could 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 can detach from the top of the mast. In the top climber, hydraulic rams are utilized to adjust the slewing unit up an additional 6.1m or 20 feet. Next, the operator of the crane uses the crane to insert and bolt into position one more mast section piece.