Used Self Erect Cranes Modesto - The base of the tower crane is typically bolted to a large concrete pad that provides very necessary support. The base is attached to a tower or a mast and stabilizes the crane which is connected to the inside of the building's structure. Often, this attachment point is to an elevator shaft or to a concrete lift.
Typically, 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 gear and a motor that enable the crane to rotate.
Tower cranes may have a max unsupported height of eighty meters or 265 feet, while the minimum lifting capacity of a tower crane is 16,642 kilograms or 39,690 lbs. with counter weights of 20 tons. Moreover, two limit switches are utilized in order to make certain that 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 tower crane has a maximum reach of seventy meters or two hundred thirty feet.
There is certainly a science involved with erecting a tower crane, particularly due to their extreme heights. At first, the stationary structure has to be brought to the construction location by utilizing a huge tractor-trailer rig setup. After that, a mobile crane is utilized in order to assemble the machinery portion of the crane and the jib. These parts are then attached to the mast. The mobile crane next adds counterweights. Crawler cranes and forklifts can be some of the other industrial equipment that is utilized to erect a crane.
Mast extensions are added to the crane as the building is erected. This is how the height of the crane is able to 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 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 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. Then, the operator of the crane uses the crane to insert and bolt into place one more mast section piece.
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