There are some industrial and commercial buildings that now surpass 60 stories or more. These buildings all need tall cranes to be able to help transport the materials to the upper floors. There are cranes which have their own vehicle attached or other kinds that are operated from the back of trucks. Tower cranes are the biggest ones 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 such as shopping center are being constructed, chances are a crane would be on site.
Kinds
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 as it lifts things. On a luffing kind of tower crane, the jib could ratchet to downward or upward angles. The lifting capacity for both types could range from 30 pounds to 10,000 pounds
Body
The body of the crane is composed of a vertical steel mast which is composed of separate [parts. The sections are added to increase the overall height of the machinery. The mast extends upward to where 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 crane driver works from inside of the tower.
Lift
The crane utilizes a braided metal cord to be able to lift supplies. This cord extends out from a motor situated next to 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 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.