From where I can get complete information about DSL (Down Shop Lead), i.e. power source for EOT cranes.
2 Answers
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Well, that is an interesting question, while the NEC (commonly used in the US) article 610 covers “cranes and hoists” the copy I have (a bit old, 1990) says nothing about the Down Shop Lead of a Electric Overhead Traveling (Crane) by name. Exception 3 in section 610-13 does say: “Flexible conductors shall be permitted to be used to conduct current and, where practicable, cable reels or take-up devices shall be used”.
In small installations I have seen the cable festooned from a travel system on rings or special carriers supported on a steel (not current carrying) cable or track.
And NEC article 610 part C covers “Contact Conductors” which may be what you are asking about
By the way, the first answer is an copy and paste from http://en.wikipedia.org/wiki/Crane_(machine) while not citing the source is bad form to start with, the fact that it doesn’t even begin to address the specific question makes it even worse.
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A crane is a mechanical lifting device equipped with a winder, wire ropes and sheaves that can be used both to lift and lower materials and to move them horizontally. It 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 the transport industry for the loading and unloading of freight; in the construction industry for the movement of materials; and in the manufacturing industry for the assembling of heavy equipment.
The first cranes were invented by the Ancient Greeks and were powered by men or beasts-of-burden, such as donkeys. These cranes were used for the construction of tall buildings. Larger cranes were later developed, employing the use of human treadwheels, permitting the lifting of heavier weights. 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. The earliest cranes were constructed from wood, but cast iron and steel took over with the coming of the Industrial Revolution.
For 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. 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. 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 utilised where the provision of power would be uneconomic.
Cranes exist in an enormous variety of forms – each tailored to a specific use. Sizes range from the smallest jib cranes, used inside workshops, to the tallest tower cranes, used for constructing high buildings, and the largest floating cranes, used to build oil rigs and salvage sunken ships.