There are several industrial and commercial buildings that now exceed 60 stories or more. These buildings all need tall cranes to help transport the supplies to the higher floors. There are cranes which have their own vehicle connected or other types which are operated from the rear of trucks. Tower cranes are the largest types offered on the market.
Tower cranes are the stand-alone structures that are normally seen on high-rise building projects. Often, they are part of a major city's downtown skyline. Wherever new construction like apartment buildings and skyscrapers and commercial facilities like shopping center are being constructed, chances are a crane would be on site.
Kinds
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 items. On a luffing type of tower crane, the jib can ratchet to downward or upward angles. The lifting capacity for both types could 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 sections. In order to increase the overall height of the equipment, parts are added. 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 crane driver works from inside of the tower.
Lift
To lift materials, the crane utilizes a braided metal cord. The cord extends all the way to the end of the boom or jib from a motor situated next to the control module. 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 opposite side of the tower. The counter jib has weights. These weights help to prevent the crane from tipping over when lifting heavy materials.