There are several commercial and industrial buildings that now exceed 60 stories or more. These buildings all require tall cranes to be able to help move the supplies to the higher floors. There are cranes which have their own vehicle connected or other kinds that are operated from the rear of trucks. Tower cranes are the biggest ones 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. When new construction like for example apartment buildings and skyscrapers and commercial facilities like for example shopping center are being constructed, chances 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 items. On a luffing kind of tower crane, the jib could ratchet to downward or upward angles. The lifting capacity for both types can range from 30 pounds to 10,000 lbs.
Body
The body of the crane is composed of a vertical steel mast which is composed of individual sections. The parts 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 called. The crane operator works from inside of the tower.
Lift
To raise materials, the crane utilizes a braided metal cord. The cord extends all the way to the end of the boom or jib from a motor situated near the control module. 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 tower's opposite side. The counter jib has weights. These weights help to prevent the crane from tipping over when lifting heavy materials.