Some industrial and commercial buildings could reach heights of more than 60 stories. Apparently, while these buildings are being constructed, they require equally tall cranes to transport the materials to the upper floors. There are cranes which have their own vehicle attached or other kinds which are operated from the rear of trucks. Tower cranes are the largest kinds 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 apartment buildings and skyscrapers and commercial facilities like shopping center are being built, chances are a crane will be on site.
Types
There are two different kinds 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 when it carries items. On a luffing type of tower crane, the jib can ratchet to downward or upward angles. The lifting capacity for both types can vary from 30 pounds to 10,000 lbs.
Body
The crane's body is composed of a mast. This is a vertical steel frame that is a combination of separate sections. In order to increase the overall height of the machinery, sections are added. 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 driver of the crane works from inside of the tower.
Lift
The crane uses a braided metal cord to be able to raise materials. This cord extends out from a motor located next to the control module to the end of the jib or boom. 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 opposite side of the tower. The counter jib has weights. These weights help to prevent the crane from tipping over when heavy supplies are lifted.