Several industrial and commercial buildings can reach heights of more than 60 stories. Obviously, while these buildings are being built, they require equally tall cranes to transport the supplies to the upper floors. There are cranes that have their own vehicle connected or other kinds that are operated from the back of trucks. Tower cranes are the biggest ones offered on the market.
Tower cranes are the stand-alone structures which are often found on high-rise building projects. Usually, they are part of a major city's downtown skyline. Wherever new construction like for example apartment buildings and skyscrapers and commercial facilities like shopping center are being built, chances are a crane will be on site.
Kinds
The two key types of cranes can be differentiated by the manner in which their boom or jib lifts supplies. The jib is the metal frame which extends from the main section. On a flat tower crane, the jib remains horizontal as it lifts things. On a luffing type of tower crane, the jib can ratchet to downward or upward angles. The lifting capacity for both kinds can range from 30,000 lbs. to 10,000 pounds
Body
The crane's body is composed of a mast. This is a vertical steel frame which is a combination of individual parts. 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 that has glass windows on all four sides or to the tower as it is also called. The operator of the crane works from inside of the tower.
Lift
In order 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 situated near 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 tower's opposite side. The counter jib has weights. These weights help to prevent the crane from toppling over when lifting heavy materials.