Several commercial and industrial buildings are capable of reaching heights of more than 60 stories. Obviously, when these buildings are being constructed, they require equally tall cranes to be able to move the materials to the higher floors. There are cranes that are operated from the rear of trucks or other types which have their own vehicle connected. Tower cranes are the largest ones available on the market.
Tower cranes are the stand-alone structures that are often seen on high-rise building projects. Often, they are part of a major city's downtown skyline. Wherever new construction such as skyscrapers or apartment buildings and commercial facilities like shopping center are being built, odds are a crane would be on site.
Types
The two key kinds of cranes can be distinguished by the manner in which their boom or jib lifts supplies. The jib is the metal frame that extends from the main section. On a flat tower crane, the jib remains horizontal as 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 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 equipment, parts are added. The mast extends upward to where the desired height is, to the control module, that is a small room that 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
In order to lift 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 near 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 which 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 supplies are carried.