Used Self Erect Cranes Richmond - The base of the tower crane is usually bolted to a large concrete pad that provides very necessary support. The base is attached to a mast or a tower and stabilizes the crane that is affixed to the inside of the structure of the building. Often, this attachment point is to a concrete lift or to an elevator shaft.
The crane's mast is usually a triangulated lattice structure which measures 10 feet square or 0.9m2. Attached to the very top of the mast is the slewing unit. 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 minimum lifting capacity of a tower crane is sixteen thousand six hundred forty two kg or 39,690 pounds with counter weights of twenty tons. In addition, two limit switches are utilized to be able to make sure that the driver does not overload the crane. There is also another safety feature called a load moment switch to make certain that the driver does not surpass the ton meter load rating. Finally, the tower crane has a maximum reach of two hundred thirty feet or seventy meters.
Because of their extreme heights, there is a science involved to erecting a crane. The stationary structure would first need to be transported to the construction site by utilizing a big tractor-trailer rig setup. After that, a mobile crane is utilized in order to assemble the machinery portion of the crane and the jib. After that, these sections are attached to the mast. The mobile crane next adds counterweights. Crawler cranes and forklifts may be a few of the other industrial machinery which is used to erect a crane.
Mast extensions are added to the crane as the building is erected. This is how the height of the crane can match the building's height. The crane crew utilizes what is referred to as 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 in order to balance the counterweight. Once complete, the slewing unit is able to detach from the top of the mast. In the top climber, hydraulic rams are utilized to adjust the slewing unit up an extra 6.1m or twenty feet. After that, the crane driver utilizes the crane to insert and bolt into position another mast section piece.
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