There are some commercial and industrial buildings which now surpass 60 stories or more. These buildings all require tall cranes to help move the materials to the upper floors. There are cranes that have their own vehicle attached or other kinds that are operated from the back of trucks. Tower cranes are the largest kinds on the market.
Tower cranes are the stand-alone structures which are often found on high-rise building projects. Normally, they are part of a major city's downtown skyline. When new construction like for example skyscrapers or apartment buildings and commercial facilities such as shopping center are being constructed, odds 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 which extends from the main section. On a flat tower crane, the jib remains horizontal as it lifts items. On a luffing type of tower crane, the jib can ratchet to downward or upward angles. The lifting capacity for both types can range from 30 pounds to 10,000 pounds
Body
The crane's body 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 where the desired height is, to the control module, which 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 uses a braided metal cord to lift supplies. This cord extends out from a motor located 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 opposite side of the tower. The counter jib holds weights. These weights help to prevent the crane from tipping over when heavy supplies are lifted.