Used Self Erect Cranes California - The base of the tower crane is generally bolted to a large concrete pad that provides very necessary support. The base is connected to a tower or a mast and stabilizes the crane which 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.
Usually, the mast is a triangulated lattice structure measuring 0.9m2 or 10 feet square. The slewing unit is connected to the very top of the mast. The slewing unit is made of a gear and a motor that allows 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 sixteen thousand six hundred forty two kg or thirty nine thousand six hundred ninety pounds with counter weights of 20 tons. Moreover, two limit switches are used in order to make sure that the operator does not overload the crane. There is also another safety feature known as 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 two hundred thirty feet or 70 meters.
Due to their extreme heights, there is a science involved to erecting a crane. The stationary structure would first have to be brought to the construction location by using a huge tractor-trailer rig setup. Next, a mobile crane is utilized so as to assemble the equipment portion of the jib and the crane. These parts are then connected to the mast. The mobile crane next adds counterweights. Forklifts and crawler cranes may be some of the other industrial machinery which 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 which fits between the top of the mast and the slewing unit. A weight is hung on the jib by the work crew so as to balance the counterweight. When complete, the slewing unit is able to detach from the top of the mast. In the top climber, hydraulic rams are used to adjust the slewing unit up an extra 6.1m or 20 feet. Next, the driver of the crane utilizes the crane to insert and bolt into position one more mast part piece.
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