There are some industrial and commercial buildings that now surpass 60 stories or more. These buildings all need tall cranes to be able to help transport the supplies to the higher floors. There are cranes that have their own vehicle attached or other kinds that are operated from the rear of trucks. Tower cranes are the largest types available on the market.
Tower cranes are the stand-alone structures that are often found on high-rise building projects. Normally, they are part of a major city's downtown skyline. Wherever new construction like for example apartment buildings and skyscrapers and commercial facilities like for example shopping center are being constructed, chances are a crane will be on site.
Kinds
The two key kinds of cranes can be distinguished by the manner in which their jib or boom lifts materials. The jib is the metal frame which 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 could ratchet to downward or upward angles. The lifting capacity for both types can range from 30 pounds to 10,000 lbs.
Body
The body of the crane is composed of a vertical steel mast which is composed of individual sections. The sections are added to increase the overall height of the equipment. 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
In order to raise materials, the crane utilizes a braided metal cord. The cord extends all the way to the end of the boom or jib from a motor located next to the control module. 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 located on the tower's opposite side. The counter jib has weights. These weights help to prevent the crane from toppling over when heavy materials are lifted.