There are some industrial and commercial buildings that now exceed 60 stories or more. These buildings all require tall cranes to help transport the supplies to the upper floors. There are cranes that have their own vehicle attached or other types which are operated from the rear of trucks. Tower cranes are the largest kinds offered 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 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 kinds of cranes could be distinguished by the way in which their boom or jib raises supplies. The jib is the metal frame that extends from the main section. On a flat tower crane, the jib remains horizontal when it carries items. On a luffing type of tower crane, the jib can ratchet to downward or upward angles. The lifting capacity for both kinds can range from 30 pounds to 10,000 lbs.
Body
The crane's body is composed of a mast. This is a vertical steel frame which is a combination of separate parts. In order to increase the overall height of the machine, sections are added. The mast extends upward to where the desired height is, to the control module, which is a small room which 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
The crane uses a braided metal cord to be able to lift materials. This cord extends out from a motor located near the control module to the end of the jib or boom. 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 opposite side of the tower. The counter jib has weights. These weights help to prevent the crane from toppling over when raising heavy materials.