Saturday, August 29, 2009

Crane Structure

Cranes may be thought of as the oldest of heavy-equipment machines, having been invented by the Ancient Greeks for the building of temples. Those cranes, right up until the Industrial Revolution, utilized human or animal power to turn the winch or move the crane, though sometimes they could be connected to a water or wind mill. The first mechanically powered cranes utilized steam engines in the late 18th or early 19th Centuries.These cranes employ a counter balance on the short end of the boom, while the long end does the lifting. Because of their height and their slender base, they must be engineered to withstand forces that would cause them to tip, and are often braced by the very structure they are building. Truck mounted mobile cranes , known as boom trucks, generally employ a telescopic crane mechanism, allowing them to minimize their size for travel to and from job sites. Floating cranes are constructed upon pontoons, and are used mainly in the construction of bridges and ports, though they are sometimes also used to move awkward loads off of ships, and in salvage operations. Some floating cranes have lift capacities of 10,000 tonnes.


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