Several commercial and industrial buildings are capable of reaching heights of over 60 stories. Apparently, while these buildings are being built, they require equally tall cranes to transport the supplies to the upper floors. There are cranes which are operated from the back of trucks or other kinds that have their own vehicle connected. Tower cranes are the largest types offered 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 apartment buildings and skyscrapers and commercial facilities like shopping center are being constructed, odds are a crane would be on site.
Types
The two key types of cranes could be distinguished by the way in which their boom or jib lifts materials. The jib is the metal frame which extends from the main section. On a flat tower crane, the jib remains horizontal when it lifts items. On a luffing type of tower crane, the jib could ratchet to downward or upward angles. The lifting capacity for both types could vary from 30 pounds to 10,000 lbs.
Body
The body of the crane is composed of a vertical steel mast that is composed of separate [parts. The parts are added to increase the overall height of the equipment. The mast extends upward to where 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 crane driver works from inside of the tower.
Lift
The crane uses a braided metal cord to raise materials. This cord extends out from a motor located next to the control module to the end of the boom or jib. 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 located on the opposite side of the tower. The counter jib holds weights. These weights help to prevent the crane from toppling over when lifting heavy supplies.