Some industrial and commercial buildings can reach heights of more than 60 stories. Apparently, while these buildings are being built, they need equally tall cranes to be able to move the supplies to the upper floors. There are cranes that are operated from the rear of trucks or other types which have their own vehicle attached. Tower cranes are the largest ones 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 such as skyscrapers or apartment buildings and commercial facilities such as shopping center are being built, chances are a crane would be on site.
Types
There are two different types of cranes: boom crane or the jib crane. The jib is a metal frame that extends from the main section. On a flat tower crane, the jib remains horizontal as it lifts items. On a luffing kind of tower crane, the jib could ratchet to downward or upward angles. The lifting capacity for both types could vary from 30 pounds to 10,000 lbs.
Body
The body of the crane is composed of a mast. This is a vertical steel frame which is a combination of separate parts. In order to increase the overall height of the equipment, sections are added. The mast extends upward to wherever the desired height is, to the control module, which is a small room that 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 utilizes a braided metal cord to lift supplies. 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 that holds the cord becomes balanced by a counter jib located on the opposite side of the tower. The counter jib holds weights. These weights help to prevent the crane from toppling over when heavy supplies are lifted.