There are several industrial and commercial buildings which now surpass 60 stories or more. These buildings all need tall cranes to be able to help transport the supplies to the upper floors. There are cranes that have their own vehicle attached or other kinds that are operated from the rear of trucks. Tower cranes are the biggest kinds on the market.
Tower cranes are the stand-alone structures which are normally found on high-rise building projects. Normally, they are part of a major city's downtown skyline. Wherever new construction like skyscrapers or apartment buildings and commercial facilities like shopping center are being constructed, odds are a crane will be on site.
Types
There are two different kinds 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 type of tower crane, the jib could ratchet to upward or downward angles. The lifting capacity for both kinds could range from 30,000 lbs. 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 parts. In order to increase the overall height of the machine, parts are added. 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 crane driver works from inside of the tower.
Lift
In order to raise materials, the crane uses a braided metal cord. The cord extends all the way to the end of the boom or jib from a motor located 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 toppling over when heavy materials are lifted.