Used Self Erect Cranes Alaska - Usually the base that is bolted into a large concrete pad provides the essential support for a tower crane. The base is connected to a mast or a tower and stabilizes the crane that is affixed 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 is made of a motor and a gear 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 kilograms or 39,690 lbs. with counter weights of twenty tons. Moreover, two limit switches are utilized in order to make sure that the driver does not overload the crane. There is also another 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 230 feet or 70 meters.
Due to their extreme heights, there is a science involved to erecting a crane. The stationary structure will at first need to be transported to the construction location by using a large tractor-trailer rig setup. Next, a mobile crane is utilized in order to assemble the equipment portion of the crane and the jib. These sections are then attached to the mast. The mobile crane then adds counterweights. Forklifts and crawler cranes could be some of the other industrial machines that is typically utilized to erect a crane.
Mast extensions are added to the crane when the building is erected. This is how the height of the crane could match the building's height. The crane crew uses what is called a climbing frame or a top climber that fits between the slewing unit and the top of the mast. A weight is hung on the jib by the work crew so as to balance the counterweight. Once 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 extra twenty feet or 6.1m. Then, the crane operator utilizes the crane to insert and bolt into position one more mast part piece.
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