Several industrial and commercial buildings could reach heights of more than 60 stories. Apparently, while these buildings are being constructed, they need equally tall cranes to be able to move the materials to the upper floors. There are cranes that are operated from the back of trucks or other types which have their own vehicle attached. Tower cranes are the biggest types on the market.
Tower cranes are stand-alone structures seen as part of a major city's downtown skyline on high-rise building projects. Wherever new construction such as skyscrapers or apartment buildings and commercial facilities like shopping center are being built, odds are a crane would be on site.
Types
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 kind of tower crane, the jib can ratchet to downward or upward angles. The lifting capacity for both kinds can vary from 30,000 lbs. to 10,000 pounds
Body
The crane's body is composed of a vertical steel mast which is composed of separate [parts. The parts are added to be able increase the overall height of the machinery. The mast extends upward to wherever 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 called. The driver of the crane works from inside of the tower.
Lift
In order to raise supplies, the crane uses a braided metal cord. The cord extends all the way to the end of the jib or boom 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 that holds the cord becomes balanced by a counter jib located on the opposite side of the tower. The counter jib has weights. These weights help to prevent the crane from tipping over when heavy supplies are carried.