There are some industrial and commercial buildings that now surpass 60 stories or more. These buildings all need tall cranes to help transport the supplies to the higher 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 biggest types on the market.
Tower cranes are stand-alone structures found 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 such as shopping center are being built, chances are a crane would be on site.
Types
The two major types of cranes could be differentiated by the way in which their jib or boom lifts materials. The jib is the metal frame that extends from the main section. On a flat tower crane, the jib remains horizontal as it carries things. On a luffing kind of tower crane, the jib could 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 increase the overall height of the machinery. 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 referred to. The operator of the crane works from inside of the tower.
Lift
The crane utilizes a braided metal cord to lift materials. This cord extends out from a motor located next to the control module to the end of the jib or boom. 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 tower's opposite side. The counter jib holds weights. These weights help to prevent the crane from toppling over when raising heavy supplies.