General knowledge about tower crane
knowledge, tower crane
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. To save space, the vertical part of the crane is often built in a well in the centre of the building, which is then converted into a lift shaft when the crane is dismantled. Assembling of tower crane is usually done by a telescopic crane of smaller lifting capacity but greater height, and in the case of tower cranes that have risen while constructing very tall buildings a smaller crane will sometime be lifted to the roof of the completed tower to dismantle the tower crane afterward.
To know as to how much load is safe for the crane to lift the tower crane uses two switches namely, maximum load and load moment. The maximum load switch monitors the pull on the cable and makes sure that the load does not exceed 18 tons, whereas load moment switch makes sure that the operator does not exceed the ton-meter rating of the crane as the load moves out on the jib.