There are some commercial and industrial buildings that now surpass 60 stories or more. These buildings all require tall cranes to be able to help transport the materials to the higher floors. There are cranes that are operated from the rear of trucks or other types which have their own vehicle connected. Tower cranes are the biggest 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 built, odds are a crane will be on site.
Types
There are two different kinds of cranes: jib crane of the boom crane. The jib is a metal frame that extends from the main section. On a flat tower crane, the jib remains horizontal when it carries things. On a luffing type of tower crane, the jib can ratchet to downward or upward angles. The lifting capacity for both kinds can range from 30 pounds to 10,000 lbs.
Body
The body of the crane is composed of a vertical steel mast that is composed of separate [parts. The sections are added to be able increase the overall height of the machine. The mast extends upward to where 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 referred to. The driver of the crane works from inside of the tower.
Lift
To raise supplies, the crane utilizes a braided metal cord. The cord extends all the way to the end of the jib or boom from a motor situated near the control module. 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 located on the opposite side of the tower. The counter jib has weights. These weights help to prevent the crane from toppling over when raising heavy materials.