Several industrial and commercial buildings can reach heights of over 60 stories. Obviously, while these buildings are being constructed, they require equally tall cranes to move the supplies to the higher floors. There are cranes that have their own vehicle attached or other kinds that are operated from the rear of trucks. Tower cranes are the biggest ones offered on the market.
Tower cranes are the stand-alone structures which are usually seen on high-rise building projects. Often, they are part of a major city's downtown skyline. Wherever new construction such as apartment buildings and skyscrapers and commercial facilities like shopping center are being built, odds are a crane will be on site.
Kinds
The two key kinds of cranes can be distinguished by the manner in which their jib or boom 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 kind of tower crane, the jib can ratchet to upward or downward angles. The lifting capacity for both types can vary from 30,000 lbs. to 10,000 lbs.
Body
The crane's body is composed of a vertical steel mast that is composed of individual [parts. The sections are added to increase the overall height of the equipment. The mast extends upward to wherever 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 crane driver works from inside of the tower.
Lift
The crane uses a braided metal cord to lift materials. This cord extends out from a motor located next to the control module to the end of the jib or boom. 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 situated on the tower's opposite side. The counter jib holds weights. These weights help to prevent the crane from tipping over when heavy supplies are carried.