Used Self Erect Cranes Portland - Typically the base that 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 building's structure. Often, this attachment point is to an elevator shaft or to a concrete lift.
The mast of the crane is often a triangulated lattice structure that measures 0.9m2 or 10 feet square. Connected to the very top of the mast is the slewing unit. The slewing unit consists of a gear and a motor which allows the crane to rotate.
Tower cranes may have a max unsupported height of 80m or two hundred sixty five feet, while the tower crane's maximum lifting capacity is sixteen thousand six hundred forty two kg or 39,690 lbs. with counter weights of 20 tons. Additionally, two limit switches are used to be able to ensure the driver does not overload the crane. There is also another safety feature known as 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 230 feet or seventy meters.
There is certainly a science involved with erecting a tower crane, specially due to their extreme heights. At first, the stationary structure needs to be transported to the construction location by utilizing a big tractor-trailer rig setup. After that, a mobile crane is used so as to assemble the machine part of the jib and the crane. Then, these parts are connected to the mast. Afterward, the mobile crane adds counterweights. Crawler cranes and forklifts could be a few of the other industrial equipment which is used to erect a crane.
Mast extensions are added to the crane when the building is erected. This is how the height of the crane is able to match the building's height. The crane crew uses what is called a climbing frame or a top climber 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. 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 twenty feet. Then, the crane operator uses the crane to insert and bolt into place another mast section piece.
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