Introduction and function of Tower Crane
Cranes are the commonly used in the construction industry and in the manufacturing of heavy equipments. Construction cranes are either fixed to the ground or mounted on a purpose-built vehicle. On the basis of their structure and functions cranes are divided into a tower or a derrick which is equipped with cables and pulleys that are used to lift or lower materials. Tower cranes are fixed to the ground, which helps to them to attain height and enhance their lifting capacity. These are used in construction of tall buildings. All the tower cranes basically have similar parts, which consist of a base, mast (or tower) and the slewing unit. The base is bolted to a large concrete pad that supports the crane, these are poured several weeks before the crane arrives, large anchor bolts embedded deep into this pad support the crane and hence prevent its falling over. The base is then connected to the mast which gives the tower crane its height. The top of the mast is attached to the slewing unit, which has the gear and the motor which helps the crane to rotate. The slewing unit in turn has three parts all on top of it, namely the long horizontal jib or the working arm, the shorter horizontal machinery arm and the operator's cab. The long horizontal jib is the portion of the crane which carries the load in and out from the cranes center by means of a trolley, which runs along the jib. The shorter horizontal machinery arm contains the crane's motors and electronics as well as the large concrete counter weights. The Operator's cabin is at the top of the tower.A typical tower crane can lift a maximum load of 18 metric tons, which is approximately 39700 pounds; however the crane cannot lift that much of weight if load is at the end of the jib. The closer the load is positioned to the mast, the more weight the crane can lift safely.
1) The long horizontal jib (or working
arm), which is the portion of the
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