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 that are operated from the rear of trucks or other kinds which have their own vehicle attached. Tower cranes are the largest ones offered 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 like for example skyscrapers or apartment buildings and commercial facilities like shopping center are being built, chances are a crane would be on site.
Types
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 lifts things. On a luffing type of tower crane, the jib can ratchet to downward or upward angles. The lifting capacity for both kinds could vary from 30 pounds to 10,000 lbs.
Body
The body of the crane is composed of a vertical steel mast which is composed of individual [parts. The sections are added to increase the overall height of the equipment. The mast extends upward to wherever 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
To raise materials, the crane uses a braided metal cord. The cord extends all the way to the end of the jib or boom from a motor located next to 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 that 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 materials are carried.