A crane is a type of machine, generally equipped with a hoist rope, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It is mainly used for lifting heavy objects and transporting them to other places. The device uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of a human. Cranes are commonly employed in transportation for the loading and unloading of freight, in construction for the movement of materials, and in manufacturing for the assembling of heavy equipment. A telescopic crane has a boom that consists of a number of tubes fitted one inside the other. A hydraulic cylinder or other powered mechanism extends or retracts the tubes to increase or decrease the total length of the boom. These types of booms are often used for short term construction projects, rescue jobs, lifting boats in and out of the water, etc. The relative compactness of telescopic booms makes them adaptable for many mobile applications.Though not all telescopic cranes are mobile cranes, many of them are truck-mounted. A telescopic tower crane has a telescopic mast and often a superstructure on top so that it functions as a tower crane. Some telescopic tower cranes also have a telescopic jib.

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