Several commercial and industrial buildings are capable of reaching heights of more than 60 stories. Obviously, while these buildings are being built, they require equally tall cranes to transport the materials to the upper floors. There are cranes that are operated from the back of trucks or other types that have their own vehicle connected. Tower cranes are the largest types offered on the market.
Tower cranes are stand-alone structures seen as part of a major city's downtown skyline on high-rise building projects. When new construction such as apartment buildings and skyscrapers and commercial facilities like for example shopping center are being built, chances are a crane would be on site.
Kinds
The two major kinds of cranes can be differentiated by the way in which their jib or boom raises supplies. The jib is the metal frame which extends from the main section. On a flat tower crane, the jib remains horizontal when it lifts items. On a luffing type of tower crane, the jib could ratchet to downward or upward angles. The lifting capacity for both kinds could vary from 30 pounds to 10,000 pounds
Body
The body of the crane is composed of a vertical steel mast that is composed of individual [parts. The parts are added to be able increase the overall height of the equipment. The mast extends upward to wherever the desired height is, to the control module, which is a small room which has glass windows on all four sides or to the tower as it is also referred to. The crane operator works from inside of the tower.
Lift
To lift materials, the crane utilizes a braided metal cord. The cord extends all the way to the end of the jib or boom from a motor located next to the control module. There is a pulley system situated 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 situated on the opposite side of the tower. The counter jib holds weights. These weights help to prevent the crane from tipping over when lifting heavy supplies.