There are some industrial and commercial buildings which now exceed 60 stories or more. These buildings all require tall cranes to help move the supplies to the upper floors. There are cranes which are operated from the rear of trucks or other kinds that have their own vehicle connected. Tower cranes are the biggest kinds on the market.
Tower cranes are the stand-alone structures that are usually found on high-rise building projects. Usually, they are part of a major city's downtown skyline. Wherever new construction like apartment buildings and skyscrapers and commercial facilities such as shopping center are being constructed, 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 that extends from the main section. On a flat tower crane, the jib remains horizontal as it carries items. On a luffing type of tower crane, the jib can ratchet to downward or upward angles. The lifting capacity for both kinds can vary from 30 pounds to 10,000 lbs.
Body
The crane's body is composed of a vertical steel mast that is composed of separate sections. The parts are added to be able increase the overall height of the machinery. The mast extends upward to where the desired height is, to the control module, which is a small room that has glass windows on all four sides or to the tower as it is also called. The crane driver works from inside of the tower.
Lift
In order to lift materials, the crane uses a braided metal cord. The cord extends all the way to the end of the boom or jib from a motor located 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 tower's opposite side. The counter jib has weights. These weights help to prevent the crane from toppling over when heavy materials are lifted.