A crane is a lifting machine that is often fitted with a wire rope drum, which is sometimes referred to as chains and sheaves, which functions by either lifting and lowering material or side to side shifting. It employs one or multiple simple machines to obtain mechanical advantages and allow oversized loads to be moved beyond human capacity.
Cranes are generally used in the transport industry to load and unload freight and in the construction industry to move material and finally in the manufacturing industry to assemble heavy machines.
Cranes exist in a vast variety of styles – each specifically designed to fit a particular use. Sizes range from the tallest tower cranes, used for constructing high buildings, to the smallest jib cranes, used inside workshops.
Mini-cranes are even used to help construct skyscrapers and buildings. The mini crane can fit into small spaces where the larger mobile cranes cannot in order to facilitate the construction site needs. There are also floating cranes which are used to build offshore oil rigs and salvage sunken ships. There are lastly lifting machines that are not technically cranes but are referred to as cranes such as loader cranes and stacker cranes.