There are several commercial and industrial buildings that now surpass 60 stories or more. These buildings all need tall cranes to help move the supplies to the upper floors. There are cranes which have their own vehicle attached or other types that are operated from the back of trucks. Tower cranes are the biggest kinds 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. Wherever new construction like for instance apartment buildings and skyscrapers and commercial facilities such as shopping center are being constructed, 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 which extends from the main section. On a flat tower crane, the jib remains horizontal as it carries things. On a luffing type of tower crane, the jib could ratchet to downward or upward angles. The lifting capacity for both kinds can vary from 30 pounds to 10,000 lbs.
Body
The body of the crane is composed of a mast. This is a vertical steel frame that is a combination of individual sections. In order to increase the overall height of the machine, parts are added. The mast extends upward to where the desired height is, to the control module, which 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
The crane utilizes a braided metal cord to lift materials. This cord extends out from a motor located near the control module to the end of the jib or boom. 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 holds weights. These weights help to prevent the crane from tipping over when heavy materials are carried.