There are some industrial and commercial buildings which now surpass 60 stories or more. These buildings all require tall cranes to be able to help transport the materials to the higher floors. There are cranes that have their own vehicle connected or other types that are operated from the back of trucks. Tower cranes are the biggest ones on the market.
Tower cranes are stand-alone structures seen as part of a major city's downtown skyline on high-rise building projects. Wherever new construction like for example apartment buildings and skyscrapers and commercial facilities like for instance shopping center are being built, odds are a crane will be on site.
Kinds
The two major types of cranes could be differentiated by the manner in which their boom or jib raises materials. The jib is the metal frame that extends from the main section. On a flat tower crane, the jib remains horizontal as it lifts items. On a luffing kind of tower crane, the jib can ratchet to downward or upward angles. The lifting capacity for both types could range from 30,000 lbs. to 10,000 lbs.
Body
The crane's body is composed of a vertical steel mast that is composed of separate sections. The sections are added to be able increase the overall height of the machinery. The mast extends upward to wherever the desired height is, to the control module, that is a small room which has glass windows on all four sides or to the tower as it is also called. The crane driver works from inside of the tower.
Lift
The crane utilizes a braided metal cord to be able to lift materials. This cord extends out from a motor situated next to the control module to the end of the boom or jib. 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 has weights. These weights help to prevent the crane from toppling over when heavy materials are lifted.