There are some commercial and industrial buildings that now surpass 60 stories or more. These buildings all require tall cranes to help move the materials to the higher floors. There are cranes that have their own vehicle attached or other types which are operated from the rear of trucks. Tower cranes are the biggest ones offered on the market.
Tower cranes are the stand-alone structures that are usually found on high-rise building projects. Usually, they are part of a major city's downtown skyline. When new construction such as apartment buildings and skyscrapers and commercial facilities like for instance shopping center are being built, odds are a crane will be on site.
Kinds
The two major types of cranes can be differentiated by the way in which their jib or boom raises materials. The jib is the metal frame which extends from the main section. On a flat tower crane, the jib remains horizontal when it carries items. On a luffing type 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 crane's body is composed of a vertical steel mast which is composed of individual sections. 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 called. The driver of the crane 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 situated 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 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 supplies.