Some industrial and commercial buildings could reach heights of over 60 stories. Apparently, while these buildings are being built, they need equally tall cranes to move the materials to the upper floors. There are cranes which have their own vehicle attached or other kinds which are operated from the rear of trucks. Tower cranes are the biggest ones on the market.
Tower cranes are stand-alone structures seen as part of a major city's downtown skyline on high-rise building projects. Wherever new construction such as skyscrapers or apartment buildings and commercial facilities like for example shopping center are being constructed, chances are a crane will be on site.
Kinds
The two key kinds of cranes could be differentiated by the manner in which their boom or jib lifts materials. The jib is the metal frame which extends from the main section. On a flat tower crane, the jib remains horizontal as it carries items. On a luffing kind of tower crane, the jib can ratchet to upward or downward angles. The lifting capacity for both kinds can vary from 30 pounds to 10,000 lbs.
Body
The body of the crane is composed of a vertical steel mast which is composed of individual sections. The parts are added to be able increase the overall height of the machinery. The mast extends upward to wherever the desired height is, to the control module, that is a small room that has glass windows on all four sides or to the tower as it is also called. The crane driver works from inside of the tower.
Lift
In order to lift materials, the crane uses a braided metal cord. The cord extends all the way to the end of the boom or jib from a motor situated next to the control module. There is a pulley system located at the end of the jib, through which the cord is positioned and lowered down. The jib which holds the cord becomes balanced by a counter jib located on the opposite side of the tower. The counter jib has weights. These weights help to prevent the crane from toppling over when heavy materials are carried.