There are some commercial and industrial buildings which now surpass 60 stories or more. These buildings all need tall cranes to be able to help transport the materials to the higher floors. There are cranes which are operated from the back of trucks or other kinds which have their own vehicle attached. Tower cranes are the largest kinds on the market.
Tower cranes are stand-alone structures found 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 shopping center are being constructed, odds are a crane would be on site.
Types
The two major types of cranes can be distinguished by the manner in which their jib or boom raises supplies. The jib is the metal frame which extends from the main section. On a flat tower crane, the jib remains horizontal when it carries things. On a luffing kind of tower crane, the jib could ratchet to upward or downward angles. The lifting capacity for both types could vary from 30 pounds to 10,000 lbs.
Body
The body of the crane 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 equipment, parts are added. The mast extends upward to wherever the desired height is, to the control module, which is a small room that has glass windows on all four sides or to the tower as it is also called. The driver of the crane works from inside of the tower.
Lift
The crane uses a braided metal cord to be able to lift materials. This cord extends out from a motor situated next to the control module to the end of the boom or jib. 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 opposite side of the tower. The counter jib has weights. These weights help to prevent the crane from toppling over when heavy materials are carried.