There are some industrial and commercial buildings that now exceed 60 stories or more. These buildings all require tall cranes to be able to help transport the materials to the upper floors. There are cranes which are operated from the back of trucks or other types that have their own vehicle attached. Tower cranes are the largest 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 skyscrapers or apartment buildings and commercial facilities like for instance shopping center are being built, 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 lifts things. On a luffing type of tower crane, the jib could ratchet to upward or downward angles. The lifting capacity for both kinds could range from 30 pounds to 10,000 pounds
Body
The crane's body is composed of a mast. This is a vertical steel frame that is a combination of individual sections. In order to increase the overall height of the equipment, parts are added. 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 called. The crane operator works from inside of the tower.
Lift
To lift materials, the crane uses a braided metal cord. The cord extends all the way to the end of the boom or jib from a motor located next to the control module. 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 toppling over when lifting heavy supplies.