There are several commercial and industrial buildings that now exceed 60 stories or more. These buildings all require tall cranes to help transport the materials 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 largest kinds on the market.
Tower cranes are the stand-alone structures that are often seen on high-rise building projects. Usually, they are part of a major city's downtown skyline. Wherever new construction like for instance apartment buildings and skyscrapers and commercial facilities like for example shopping center are being constructed, chances are a crane would be on site.
Kinds
The two key types of cranes could be distinguished by the way in which their jib or boom raises supplies. The jib is the metal frame that extends from the main section. On a flat tower crane, the jib remains horizontal as it lifts things. On a luffing kind of tower crane, the jib could ratchet to downward or upward angles. The lifting capacity for both types could vary from 30,000 lbs. to 10,000 lbs.
Body
The body of the crane 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 driver of the crane works from inside of the tower.
Lift
In order 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 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 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 toppling over when heavy supplies are carried.