Used Self Erect Cranes BC - The base of the tower crane is generally bolted to a large concrete pad that provides really crucial 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. Normally, this attachment point is to an elevator shaft or to a concrete lift.
The crane's mast is normally a triangulated lattice structure that measures 10 feet square or 0.9m2. Connected to the very top of the mast is the slewing unit. The slewing unit is made of a motor and a gear which allows the crane to rotate.
Tower cranes may have a max unsupported height of eighty meters or two hundred sixty five feet, while the tower crane's maximum lifting capacity is sixteen thousand six hundred forty two kilograms or 39,690 lbs. with counter weights of twenty tons. Furthermore, 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 known as a load moment switch to make certain that the operator does not exceed the ton meter load rating. Finally, the tower crane has a maximum reach of two hundred thirty feet or seventy meters.
There is definitely a science involved with erecting a tower crane, especially because of their extreme heights. First, the stationary structure needs to be brought to the construction location by using a huge tractor-trailer rig setup. After that, a mobile crane is utilized in order to assemble the machinery part of the jib and the crane. Then, these sections are connected to the mast. The mobile crane next adds counterweights. Crawler cranes and forklifts could be a few of the other industrial machines which is usually utilized to erect a crane.
As the building is erected, mast extensions are added to the crane. This is how the crane's height is able to match the building's height. The crane crew utilizes what is called 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 so as 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 additional 20 feet or 6.1m. Next, the crane driver uses the crane to insert and bolt into place one more mast section piece.
Self Erect Cranes PDF
