Some commercial and industrial buildings can reach heights of over 60 stories. Apparently, when these buildings are being constructed, they need equally tall cranes to be able to move the materials to the higher floors. There are cranes that are operated from the back of trucks or other types which have their own vehicle connected. Tower cranes are the largest ones available on the market.
Tower cranes are the stand-alone structures that are often seen on high-rise building projects. Normally, they are part of a major city's downtown skyline. When new construction like apartment buildings and skyscrapers and commercial facilities like for example shopping center are being built, chances are a crane will be on site.
Types
There are two different kinds of cranes: jib crane of the boom crane. The jib is a metal frame which extends from the main section. On a flat tower crane, the jib remains horizontal as it carries things. On a luffing type of tower crane, the jib could ratchet to downward or upward angles. The lifting capacity for both kinds can range from 30,000 lbs. to 10,000 lbs.
Body
The body of the crane 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 machine, sections are added. The mast extends upward to where the desired height is, to the control module, that is a small room that has glass windows on all four sides or to the tower as it is also referred to. The crane operator works from inside of the tower.
Lift
The crane utilizes 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 boom or jib. There is a pulley system situated at the end of the jib, through which the cord is positioned and lowered down. The jib which holds the cord becomes balanced by a counter jib situated on the tower's opposite side. The counter jib has weights. These weights help to prevent the crane from toppling over when heavy supplies are carried.