Several industrial and commercial buildings could reach heights of over 60 stories. Obviously, when these buildings are being constructed, they need equally tall cranes to be able to transport the supplies to the upper floors. There are cranes that are operated from the back of trucks or other types that have their own vehicle attached. Tower cranes are the largest kinds on the market.
Tower cranes are the stand-alone structures which are usually found on high-rise building projects. Normally, 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 built, odds are a crane would be on site.
Kinds
There are two different types of cranes: boom crane or the jib crane. The jib is a metal frame which extends from the main section. On a flat tower crane, the jib remains horizontal as it carries things. On a luffing type of tower crane, the jib could ratchet to upward or downward angles. The lifting capacity for both types can vary from 30,000 lbs. to 10,000 pounds
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 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 referred to. The crane driver works from inside of the tower.
Lift
In order to lift 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 located 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 that holds the cord becomes balanced by a counter jib located on the opposite side of the tower. The counter jib holds weights. These weights help to prevent the crane from toppling over when raising heavy materials.