There are several industrial and commercial buildings which now exceed 60 stories or more. These buildings all need tall cranes to be able to help move the supplies to the upper floors. There are cranes that are operated from the rear of trucks or other kinds that have their own vehicle connected. Tower cranes are the largest 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. When new construction such as apartment buildings and skyscrapers and commercial facilities like for instance shopping center are being built, odds are a crane will 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 when it lifts things. On a luffing kind of tower crane, the jib could ratchet to upward or downward angles. The lifting capacity for both types can vary from 30 pounds to 10,000 pounds
Body
The body of the crane is composed of a mast. This is a vertical steel frame that is a combination of separate parts. In order to increase the overall height of the equipment, sections are added. The mast extends upward to where 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 crane operator 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 boom or jib 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 situated on the tower's opposite side. The counter jib holds weights. These weights help to prevent the crane from tipping over when raising heavy supplies.