Large floating cranes are generally used to build oil rigs and salvage sunken ships. Mini-cranes are also used for constructing high buildings, to facilitate constructions by reaching tight spaces. Sizes range from the smallest jib cranes, used inside workshops, to the tallest tower cranes, used for constructing high buildings. There are many different types of cranes, each tailored to a specific use. Modern cranes usually use internal combustion engines or electric motors and hydraulic systems to provide a much greater lifting capability than was previously possible, although manual cranes are still utilized where the provision of power would be uneconomic. The first mechanical power was provided by steam engines, the earliest steam crane being introduced in the 18th or 19th century, with many remaining in use well into the late 20th century. The earliest cranes were constructed from wood, but cast iron, iron and steel took over with the coming of the Industrial Revolution.įor many centuries, power was supplied by the physical exertion of men or animals, although hoists in watermills and windmills could be driven by the harnessed natural power. In the High Middle Ages, harbour cranes were introduced to load and unload ships and assist with their construction-some were built into stone towers for extra strength and stability. Larger cranes were later developed in the Roman Empire, employing the use of human treadwheels, permitting the lifting of heavier weights. Construction cranes later appeared in ancient Greece, where they were powered by men or animals (such as donkeys), and used for the construction of buildings. The first known crane machine was the shaduf, a water-lifting device that was invented in ancient Mesopotamia (modern Iraq) and then appeared in ancient Egyptian technology. 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. The device uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of a human. It is mainly used for lifting heavy objects and transporting them to other places. Manual crane from the late 19th century used for unloading small loads (bales, crates, etc.) from ships at the Port of Barcelona, SpainĪ 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. JSTOR ( November 2011) ( Learn how and when to remove this template message)ĭiagram of a modern crawler crane with outriggers.Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources.

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