Editing Dragline excavator (section)

==Draglines in mining==
[[File:Curragh Dragline 3.JPG|upright=1.25|thumb|Dragline excavating coal in Australia]]

A large dragline system used in the [[open pit mining]] industry costs approximately [[US dollar|US$]]50–100 million. A typical bucket has a volume ranging from 40 to 80 cubic yards (30 to 60 cubic metres), though extremely large buckets have ranged up to 220 cubic yards (168 cubic meters).<ref>Keith Haddoc, "Extreme Mining Machines – stripping shovels and draglines", pub by MBI, Appendix 4 Tables of capacities page 127 {{ISBN|0-7603-0918-3}}</ref> The length of the boom ranges from {{convert|45|to|100|m|ft}}. In a single cycle, it can move up to 450 tons of material.

Most mining draglines are not diesel-powered like most other mining equipment. Their power consumption on order of several megawatts is so great that they have a direct connection to the [[High voltage|high-voltage]] grid at voltages of between 6.6 and 22&nbsp;kV. A typical dragline weighing 4000 to 6000 tons, with a 55-cubic-metre bucket, can use up to 6&nbsp;megawatts during normal digging operations. Because of this, many (possibly [[apocryphal]]) stories have been told about the blackout-causing effects of mining draglines. For instance, there is a long-lived story that, back in the 1970s, if all seven draglines at [[Peak Downs Mine]] (a very large [[BHP]] coal mine in central [[Queensland]], Australia) turned on simultaneously, they would [[Power outage|black out]] all of [[North Queensland]].{{cn|date=February 2025}} However even in the 2000s if they have been shut down, they are always restarted one at a time due to the immense power requirements of startup.{{citation needed|date=April 2018}}

[[File:Martinson Tractor (reverse).gif|thumb|upright=1.25|"Walking" dragline animation based on Martinson's patent of 1926]]
In all but the smallest of draglines, movement is accomplished by "walking" using feet or [[Pontoon (boat)|pontoon]]s, as [[caterpillar track]]s place too much pressure on the ground, and have great difficulty under the immense weight of the dragline. Maximum speed is only at most a few metres per minute,<ref>[http://dailygleaner.canadaeast.com/cityregion/article/443567 "Maid Marian's journey becomes a 'drag'"] ''The Daily Gleaner'' (10 October 2008) accessed 1 November 2008]</ref> since the feet must be repositioned for each step.<ref>[https://books.google.com/books?id=0N4DAAAAMBAJ&dq=Popular+Science+1930+plane+%22Popular+Mechanics%22&pg=PA153 "Paradise for Sidewalk Superintendents"] ''Popular Mechanics'', October 1947, p. 153-157, detailed drawings and photos of dragline operation</ref> If travelling medium distances (about 30–100&nbsp;km), a special dragline carrier can be brought in to transport the dragline. Above that distance, disassembly is generally required. But mining draglines due to their reach can work a large area from one position and do not need to constantly move along the face like smaller machines.