There are several industrial and commercial buildings which now surpass 60 stories or more. These buildings all need tall cranes to be able to help transport the supplies to the upper floors. There are cranes that have their own vehicle connected or other kinds which are operated from the back of trucks. Tower cranes are the biggest ones offered on the market.
Tower cranes are stand-alone structures seen as part of a major city's downtown skyline on high-rise building projects. Wherever new construction like skyscrapers or apartment buildings and commercial facilities like for example shopping center are being built, chances are a crane will be on site.
Kinds
The two key kinds of cranes can be differentiated by the manner in which their boom or jib raises supplies. The jib is the metal frame that extends from the main section. On a flat tower crane, the jib remains horizontal as it carries items. On a luffing type of tower crane, the jib can ratchet to upward or downward angles. The lifting capacity for both kinds could range from 30 pounds to 10,000 pounds
Body
The body of the crane is composed of a mast. This is a vertical steel frame that is a combination of separate parts. In order to increase the overall height of the machinery, 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 crane driver 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 boom or jib. 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 located on the opposite side of the tower. The counter jib holds weights. These weights help to prevent the crane from toppling over when raising heavy materials.