There are several industrial and commercial buildings which now exceed 60 stories or more. These buildings all require tall cranes to help move the materials to the upper floors. There are cranes that are operated from the back of trucks or other kinds which have their own vehicle attached. 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. Wherever new construction like apartment buildings and skyscrapers and commercial facilities like for example shopping center are being constructed, odds are a crane will be on site.
Kinds
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 kind of tower crane, the jib can ratchet to upward or downward angles. The lifting capacity for both kinds could range from 30 pounds to 10,000 pounds
Body
The body of the crane is composed of a vertical steel mast that is composed of separate [parts. The parts are added to be able 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 that has glass windows on all four sides or to the tower as it is also called. The crane operator works from inside of the tower.
Lift
The crane uses a braided metal cord to raise 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 that holds the cord becomes balanced by a counter jib situated on the tower's opposite side. The counter jib has weights. These weights help to prevent the crane from tipping over when raising heavy supplies.