There are some industrial and commercial buildings which now exceed 60 stories or more. These buildings all need tall cranes to be able to help move the supplies 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 ones 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. When new construction like skyscrapers or apartment buildings and commercial facilities like 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 which 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 upward or downward angles. The lifting capacity for both types could vary from 30 pounds to 10,000 lbs.
Body
The crane's body is composed of a mast. This is a vertical steel frame which is a combination of separate sections. In order to increase the overall height of the machine, parts are added. The mast extends upward to wherever the desired height is, to the control module, that is a small room that has glass windows on all four sides or to the tower as it is also referred to. The operator of the crane works from inside of the tower.
Lift
In order to raise materials, the crane uses a braided metal cord. The cord extends all the way to the end of the jib or boom from a motor located next to 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 that holds the cord becomes balanced by a counter jib situated on the opposite side of the tower. The counter jib has weights. These weights help to prevent the crane from tipping over when raising heavy materials.