Several industrial and commercial buildings are capable of reaching heights of over 60 stories. Obviously, when these buildings are being built, they require equally tall cranes to be able to transport the supplies to the upper floors. There are cranes which are operated from the back of trucks or other kinds which have their own vehicle attached. Tower cranes are the biggest types on the market.
Tower cranes are stand-alone structures found as part of a major city's downtown skyline on high-rise building projects. Wherever new construction like for example skyscrapers or apartment buildings and commercial facilities like for instance shopping center are being built, chances are a crane would be on site.
Types
There are two different types 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 carries things. On a luffing type of tower crane, the jib can ratchet to downward or upward angles. The lifting capacity for both types could range from 30,000 lbs. to 10,000 lbs.
Body
The body of the crane is composed of a vertical steel mast which 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 referred to. The driver of the crane works from inside of the tower.
Lift
The crane uses a braided metal cord to lift supplies. This cord extends out from a motor situated near the control module to the end of the boom or jib. 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 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.