Used Self Erect Cranes Maine - Generally the base that is bolted into a big concrete pad provides the crucial support for a tower crane. The base is attached to a mast or a tower and stabilizes the crane that is connected to the inside of the building's structure. Often, this attachment point is to a concrete lift or to an elevator shaft.
The crane's mast is usually a triangulated lattice structure that measures 0.9m2 or 10 feet square. Connected to the very top of the mast is the slewing unit. The slewing unit consists of a motor and a gear which enable the crane to rotate.
Tower cranes are able to have a maximum unsupported height of 80m or two hundred sixty five feet. The maximum lifting capacity of a tower crane is sixteen thousand six hundred forty two kg or thirty nine thousand six hundred ninety lbs. with counter weights of 20 tons. In addition, two limit switches are utilized in order to make sure that the driver does not overload the crane. There is also another safety feature called a load moment switch to ensure that the driver does not surpass the ton meter load rating. Last of all, the maximum reach of a tower crane is two hundred thirty feet or seventy meters.
There is certainly a science involved with erecting a tower crane, specially because of their extreme heights. First, the stationary structure has to be brought to the construction location by using a big tractor-trailer rig setup. Next, a mobile crane is used so as to assemble the machine portion of the jib and the crane. These parts are then attached to the mast. The mobile crane then adds counterweights. Forklifts and crawler cranes could be some of the other industrial machines that 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 could match the building's height. The crane crew utilizes what is called 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 so as to balance the counterweight. Once complete, the slewing unit can detach from the top of the mast. In the top climber, hydraulic rams are utilized to adjust the slewing unit up an additional 6.1m or 20 feet. Then, the driver of the crane uses the crane to insert and bolt into position another mast part piece.
Self Erect Cranes PDF
