There are some commercial and industrial buildings which now surpass 60 stories or more. These buildings all require tall cranes to be able to help move the materials to the higher floors. There are cranes which have their own vehicle attached or other kinds which are operated from the rear of trucks. Tower cranes are the biggest ones offered on the market.
Tower cranes are the stand-alone structures that are usually seen on high-rise building projects. Normally, they are part of a major city's downtown skyline. When new construction like for instance skyscrapers or apartment buildings and commercial facilities such as shopping center are being constructed, chances are a crane would be on site.
Types
The two key kinds of cranes could be distinguished by the manner in which their jib or boom lifts supplies. The jib is the metal frame that extends from the main section. On a flat tower crane, the jib remains horizontal when it lifts things. On a luffing type of tower crane, the jib can ratchet to upward or downward angles. The lifting capacity for both types could vary from 30 pounds to 10,000 pounds
Body
The crane's body is composed of a vertical steel mast that is composed of separate [parts. The parts are added to increase the overall height of the machinery. The mast extends upward to wherever the desired height is, to the control module, that is a small room that has glass windows on all four sides or to the tower as it is also called. The crane operator works from inside of the tower.
Lift
In order to raise supplies, the crane uses a braided metal cord. The cord extends all the way to the end of the jib or boom from a motor situated 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 situated on the tower's opposite side. The counter jib holds weights. These weights help to prevent the crane from toppling over when lifting heavy supplies.