There are some industrial and commercial buildings that now exceed 60 stories or more. These buildings all need tall cranes to help transport the materials 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 biggest kinds available 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 such as skyscrapers or apartment buildings and commercial facilities like shopping center are being constructed, odds are a crane will be on site.
Types
There are two different kinds of cranes: jib crane of the boom crane. The jib is a metal frame that extends from the main section. On a flat tower crane, the jib remains horizontal when it lifts items. On a luffing type 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 body of the crane is composed of a vertical steel mast that is composed of individual [parts. The sections are added to increase the overall height of the machinery. The mast extends upward to where 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 operator of the crane works from inside of the tower.
Lift
The crane uses a braided metal cord to be able to raise 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 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 located on the tower's opposite side. The counter jib has weights. These weights help to prevent the crane from tipping over when heavy materials are carried.