Several commercial and industrial buildings are capable of reaching heights of more than 60 stories. Obviously, when these buildings are being built, they need equally tall cranes to be able to move the supplies to the upper floors. There are cranes which are operated from the back of trucks or other types which have their own vehicle connected. Tower cranes are the largest ones offered on the market.
Tower cranes are the stand-alone structures which are often seen on high-rise building projects. Normally, they are part of a major city's downtown skyline. Wherever new construction like for example skyscrapers or apartment buildings and commercial facilities such as shopping center are being built, odds are a crane will be on site.
Types
The two key types of cranes could be differentiated by the manner in which their boom or jib lifts supplies. The jib is the metal frame which 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 can ratchet to downward or upward 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 which is a combination of individual sections. In order to increase the overall height of the equipment, sections 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 operator of the crane works from inside of the tower.
Lift
To lift supplies, the crane utilizes 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 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 holds weights. These weights help to prevent the crane from tipping over when lifting heavy supplies.