Some commercial and industrial buildings could reach heights of more than 60 stories. Apparently, while these buildings are being constructed, they require equally tall cranes to transport the supplies to the higher floors. There are cranes that have their own vehicle attached or other types which are operated from the back of trucks. Tower cranes are the biggest types 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 such as apartment buildings and skyscrapers and commercial facilities such as shopping center are being built, odds are a crane would be on site.
Types
The two major kinds of cranes can be distinguished by the manner in which their jib or boom lifts supplies. The jib is the metal frame that 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 types can vary from 30,000 lbs. to 10,000 lbs.
Body
The body of the crane 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 machinery. 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 referred to. The driver of the crane works from inside of the tower.
Lift
The crane utilizes a braided metal cord to raise supplies. This cord extends out from a motor situated near 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 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 heavy materials are carried.