Several commercial and industrial buildings are capable of reaching heights of more than 60 stories. Obviously, while these buildings are being constructed, they require equally tall cranes to move the supplies to the higher floors. There are cranes that are operated from the rear of trucks or other types which have their own vehicle connected. Tower cranes are the biggest types available 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 such as skyscrapers or apartment buildings and commercial facilities like for instance shopping center are being constructed, chances are a crane would 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 as 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 can range from 30,000 lbs. to 10,000 lbs.
Body
The body of the crane is composed of a mast. This is a vertical steel frame that is a combination of separate parts. In order to increase the overall height of the equipment, sections are added. 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 referred to. The operator of the crane works from inside of the tower.
Lift
The crane uses a braided metal cord to be able to raise 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 located 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 holds weights. These weights help to prevent the crane from tipping over when lifting heavy materials.