Some industrial and commercial buildings could reach heights of over 60 stories. Apparently, when these buildings are being built, they need equally tall cranes to move the supplies to the upper 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 kinds 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 like for instance apartment buildings and skyscrapers and commercial facilities such as shopping center are being constructed, odds are a crane will be on site.
Kinds
The two major types of cranes can be differentiated by the way in which their jib or boom raises 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 items. On a luffing type of tower crane, the jib could ratchet to downward or upward angles. The lifting capacity for both types can vary from 30,000 lbs. to 10,000 pounds
Body
The body of the crane is composed of a mast. This is a vertical steel frame which is a combination of separate sections. In order to increase the overall height of the machine, sections are added. The mast extends upward to wherever the desired height is, to the control module, which is a small room which has glass windows on all four sides or to the tower as it is also called. The crane operator works from inside of the tower.
Lift
The crane uses a braided metal cord to be able to raise supplies. This cord extends out from a motor situated 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 which holds the cord becomes balanced by a counter jib located on the tower's opposite side. The counter jib holds weights. These weights help to prevent the crane from tipping over when lifting heavy supplies.