There are several commercial and industrial buildings that now exceed 60 stories or more. These buildings all require tall cranes to be able to help transport the materials to the upper floors. There are cranes which are operated from the rear of trucks or other kinds that have their own vehicle connected. Tower cranes are the largest 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. Wherever new construction like apartment buildings and skyscrapers and commercial facilities like for example shopping center are being constructed, chances are a crane will be on site.
Kinds
The two key types of cranes could be differentiated by the manner in which their boom or jib raises materials. The jib is the metal frame that extends from the main section. On a flat tower crane, the jib remains horizontal when 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 could vary 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 individual parts. 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, that 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 lift materials. 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 which holds the cord becomes balanced by a counter jib situated on the tower's opposite side. The counter jib has weights. These weights help to prevent the crane from tipping over when lifting heavy supplies.