Some commercial and industrial buildings could reach heights of more than 60 stories. Apparently, when these buildings are being built, they need equally tall cranes to transport 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 attached. Tower cranes are the biggest 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. Wherever new construction like apartment buildings and skyscrapers and commercial facilities like for instance shopping center are being constructed, odds are a crane will be on site.
Kinds
The two major kinds of cranes can be differentiated by the manner 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 kind 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 which is a combination of individual 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, that 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 utilizes a braided metal cord to raise supplies. This cord extends out from a motor situated next to 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 situated on the opposite side of the tower. The counter jib holds weights. These weights help to prevent the crane from toppling over when lifting heavy materials.