There are some commercial and industrial buildings that now exceed 60 stories or more. These buildings all need tall cranes to be able to help transport the materials to the upper floors. There are cranes that are operated from the back of trucks or other kinds which have their own vehicle connected. Tower cranes are the largest ones on the market.
Tower cranes are the stand-alone structures that are normally found on high-rise building projects. Normally, they are part of a major city's downtown skyline. Wherever new construction such as apartment buildings and skyscrapers and commercial facilities like for example shopping center are being constructed, odds are a crane would be on site.
Types
The two key types of cranes could be differentiated by the manner in which their jib or boom raises supplies. The jib is the metal frame that extends from the main section. On a flat tower crane, the jib remains horizontal as it carries items. On a luffing type of tower crane, the jib can ratchet to upward or downward angles. The lifting capacity for both kinds can range from 30,000 lbs. to 10,000 pounds
Body
The crane's body is composed of a mast. This is a vertical steel frame that is a combination of separate parts. In order to increase the overall height of the machinery, sections are added. The mast extends upward to wherever 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 referred to. The crane driver works from inside of the tower.
Lift
The crane uses a braided metal cord to raise supplies. This cord extends out from a motor located next to 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 that holds the cord becomes balanced by a counter jib located on the tower's opposite side. The counter jib holds weights. These weights help to prevent the crane from tipping over when heavy materials are lifted.