There are some industrial and commercial buildings that now surpass 60 stories or more. These buildings all require tall cranes to help move the materials to the upper floors. There are cranes that are operated from the rear of trucks or other kinds which have their own vehicle connected. Tower cranes are the largest ones 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 such as skyscrapers or apartment buildings and commercial facilities such as shopping center are being built, odds 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 that extends from the main section. On a flat tower crane, the jib remains horizontal as 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 can range 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 separate parts. In order to increase the overall height of the equipment, sections are added. The mast extends upward to where 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 operator of the crane works from inside of the tower.
Lift
The crane uses a braided metal cord to lift supplies. This cord extends out from a motor located near the control module to the end of the jib or boom. 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 situated on the tower's opposite side. The counter jib has weights. These weights help to prevent the crane from tipping over when raising heavy supplies.