Some commercial and industrial buildings could reach heights of more than 60 stories. Apparently, when these buildings are being constructed, they require equally tall cranes to transport the materials to the upper floors. There are cranes that are operated from the back of trucks or other types which have their own vehicle attached. Tower cranes are the biggest ones on the market.
Tower cranes are the stand-alone structures which are normally seen on high-rise building projects. Often, they are part of a major city's downtown skyline. When new construction like for instance skyscrapers or apartment buildings and commercial facilities such as shopping center are being constructed, chances are a crane would be on site.
Types
There are two different types of cranes: jib crane of the boom crane. The jib is a 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 can ratchet to upward or downward angles. The lifting capacity for both kinds can 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 individual parts. In order to increase the overall height of the machine, parts are added. The mast extends upward to where 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 materials. This cord extends out from a motor located near 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 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 toppling over when lifting heavy materials.