Several commercial and industrial buildings could reach heights of over 60 stories. Obviously, when these buildings are being constructed, they need equally tall cranes to be able to transport the supplies to the higher floors. There are cranes that have their own vehicle attached or other types that are operated from the rear of trucks. Tower cranes are the largest types on the market.
Tower cranes are stand-alone structures seen as part of a major city's downtown skyline on high-rise building projects. When new construction like for instance skyscrapers or apartment buildings and commercial facilities such as shopping center are being constructed, chances are a crane will be on site.
Kinds
The two major types of cranes could be differentiated by the way in which their boom or jib raises supplies. The jib is the 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 kinds could vary from 30 pounds to 10,000 pounds
Body
The crane's body is composed of a vertical steel mast which is composed of separate sections. The parts are added to increase the overall height of the machinery. 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 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 jib or boom 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 which holds the cord becomes balanced by a counter jib situated on the tower's opposite side. The counter jib has weights. These weights help to prevent the crane from tipping over when raising heavy supplies.