Used Self Erect Cranes Nevada - Generally 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 affixed to the inside of the building's structure. Often, this attachment point is to a concrete lift or to an elevator shaft.
Typically, the mast is a triangulated lattice structure measuring 0.9m2 or 10 feet square. The slewing unit is attached to the very top of the mast. The slewing unit consists of a motor and a gear which enable the crane to rotate.
Tower cranes may have a max unsupported height of 80m or two hundred sixty five feet, while the minimum lifting capacity of a tower crane is sixteen thousand six hundred forty two kilograms or thirty nine thousand six hundred ninety pounds with counter weights of twenty tons. In addition, two limit switches are used in order to ensure the operator does not overload the crane. There is also another safety feature called a load moment switch to ensure that the operator does not exceed the ton meter load rating. Finally, the tower crane has a maximum reach of seventy meters or 230 feet.
There is definitely a science involved with erecting a tower crane, particularly due to their extreme heights. At first, the stationary structure needs to be transported to the construction site by using a huge tractor-trailer rig setup. Then, a mobile crane is utilized in order to assemble the machinery part of the crane and the jib. Then, these sections are connected to the mast. Next, the mobile crane adds counterweights. Forklifts and crawler cranes may be some of the other industrial machinery that is typically 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 known 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 used to adjust the slewing unit up an additional 6.1m or 20 feet. Next, the crane driver uses the crane to insert and bolt into position one more mast section piece.
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