Used Self Erect Cranes Kentucky - The base of the tower crane is typically bolted to a large concrete pad that provides very necessary support. The base is connected to a mast or a tower and stabilizes the crane which 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 10 feet square or 0.9m2. The slewing unit is connected to the very top of the mast. The slewing unit is made of a motor and a gear which enable the crane to rotate.
Tower cranes are able to have a maximum unsupported height of eighty meters or 265 feet. The maximum lifting capacity of a tower crane is 16,642 kg or 39,690 lbs. with counter weights of twenty tons. Additionally, two limit switches are used to be able to ensure the operator does not overload the crane. There is even one more safety feature called a load moment switch to make certain that the driver does not exceed the ton meter load rating. Lastly, the maximum reach of a tower crane is 70 meters or two hundred thirty feet.
Because of their extreme heights, there is a science involved to erecting a crane. The stationary structure will at first need to be brought to the construction location by using a large tractor-trailer rig setup. After that, a mobile crane is utilized so as to assemble the machinery part of the jib and the crane. Afterwards, these parts are attached to the mast. Then, the mobile crane adds counterweights. Crawler cranes and forklifts can 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 could match the building's height. The crane crew uses what is referred to as a top climber or a climbing frame 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. When 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 20 feet or 6.1m. After that, the crane driver utilizes the crane to insert and bolt into place one more mast part piece.
Self Erect Cranes PDF
