Used Self Erect Cranes Sunnyvale - The tower crane's base is typically bolted to a huge concrete pad which provides really necessary support. The base is attached to a tower or a mast and stabilizes the crane that is affixed to the inside of the building's structure. 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 attached to the very top of the mast. The slewing unit is made of a motor and a gear that 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 kilograms or thirty nine thousand six hundred ninety pounds with counter weights of twenty tons. Moreover, two limit switches are used in order to make certain that the operator does not overload the crane. There is also one more safety feature known as a load moment switch to make sure that the driver does not surpass the ton meter load rating. Finally, the maximum reach of a tower crane is 230 feet or seventy meters.
Due to their extreme heights, there is a science involved to erecting a crane. The stationary structure would first need to be brought to the construction site by using a huge tractor-trailer rig setup. Then, a mobile crane is utilized in order to assemble the equipment part of the crane and the jib. These sections are then connected to the mast. The mobile crane next adds counterweights. Forklifts and crawler cranes could be some of the other industrial equipment which is utilized to erect a crane.
As the building is erected, mast extensions are added to the crane. This is how the crane's height can match the building's height. The crane crew uses what is known as 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 in order to balance the counterweight. Once complete, the slewing unit could 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 operator of the crane uses the crane to insert and bolt into position another mast section piece.
Self Erect Cranes PDF
