Some industrial and commercial buildings can reach heights of more than 60 stories. Apparently, when these buildings are being built, they require equally tall cranes to transport the materials to the upper floors. There are cranes that have their own vehicle connected or other types that are operated from the back of trucks. Tower cranes are the biggest kinds available on the market.
Tower cranes are stand-alone structures seen as part of a major city's downtown skyline on high-rise building projects. When new construction like for instance skyscrapers or apartment buildings and commercial facilities like for example shopping center are being constructed, chances are a crane would be on site.
Types
The two major kinds of cranes could be distinguished by the manner in which their boom or jib lifts materials. The jib is the metal frame that 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 kinds can vary from 30,000 lbs. 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 individual parts. In order to increase the overall height of the machinery, sections are added. The mast extends upward to wherever 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 operator of the crane works from inside of the tower.
Lift
To raise supplies, the crane utilizes a braided metal cord. The cord extends all the way to the end of the jib or boom 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 located on the tower's opposite side. The counter jib has weights. These weights help to prevent the crane from toppling over when raising heavy materials.