Some commercial and industrial buildings are capable of reaching heights of more than 60 stories. Obviously, when these buildings are being constructed, they need equally tall cranes to be able to move the materials to the higher floors. There are cranes which are operated from the back of trucks or other types which have their own vehicle connected. Tower cranes are the biggest kinds on the market.
Tower cranes are stand-alone structures found as part of a major city's downtown skyline on high-rise building projects. When new construction like for example apartment buildings and skyscrapers and commercial facilities such as shopping center are being built, chances are a crane would be on site.
There are two different kinds of cranes: boom crane or the jib crane. The jib is a metal frame that extends from the main section. On a flat tower crane, the jib remains horizontal when it lifts things. On a luffing kind of tower crane, the jib can ratchet to downward or upward angles. The lifting capacity for both kinds can range from 30,000 lbs. to 10,000 pounds
The crane's body 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 machine. The mast extends upward to wherever the desired height is, to the control module, that is a small room which 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.
The crane utilizes a braided metal cord to be able to lift materials. This cord extends out from a motor located near the control module to the end of the jib or boom. There is a pulley system situated at the end of the jib, through which the cord is positioned and lowered down. The jib that 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 tipping over when heavy materials are lifted.