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A power shovel (also stripping shovel or front shovel or electric mining shovel or electric rope shovel) is a bucket-equipped machine, usually electrically powered, used for digging and loading earth or fragmented rock and for mineral extraction. Power shovels are a type of rope/cable excavator, where the digging arm is controlled and powered by winches and steel ropes, rather than hydraulics like in the more common hydraulic
excavator Excavators are heavy construction equipment consisting of a boom, dipper (or stick), bucket and cab on a rotating platform known as the "house". The house sits atop an undercarriage with tracks or wheels. They are a natural progression fr ...
s. Basic parts of a power shovel include the track system, cabin, cables, rack, stick, boom foot-pin, saddle block, boom, boom point sheaves and bucket. The size of bucket varies from 0.73 to 53 cubic meters.


Design

Power shovels normally consist of a revolving deck with a power plant, drive and control mechanisms, usually a
counterweight A counterweight is a weight that, by applying an opposite force, provides balance and stability of a mechanical system. The purpose of a counterweight is to make lifting the load faster and more efficient, which saves energy and causes less we ...
, and a front attachment, such as a crane ("boom") which supports a handle ("dipper" or "dipper stick") with a digger ("
bucket A bucket is typically a watertight, vertical cylinder or truncated cone or square, with an open top and a flat bottom, attached to a semicircular carrying handle called the ''bail''. A bucket is usually an open-top container. In contrast, a ...
") at the end. The term "dipper" is also sometimes used to refer to the handle and digger combined. The machinery is mounted on a base platform with tracks or wheels. Modern bucket capacities range from 8m3 to nearly 80m3.


Use

Power shovels are used principally for
excavation Excavation may refer to: * Excavation (archaeology) * Excavation (medicine) * ''Excavation'' (The Haxan Cloak album), 2013 * ''Excavation'' (Ben Monder album), 2000 * ''Excavation'' (novel), a 2000 novel by James Rollins * '' Excavation: A Mem ...
and removal of
overburden In mining, overburden (also called waste or spoil) is the material that lies above an area that lends itself to economical exploitation, such as the rock, soil, and ecosystem that lies above a coal seam or ore body. Overburden is distinct from tai ...
in open-cut mining operations; they may also be used for the loading of minerals, such as
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when ...
. They are the modern equivalent of
steam shovel A steam shovel is a large steam-powered excavating machine designed for lifting and moving material such as rock and soil. It is the earliest type of power shovel or excavator. Steam shovels played a major role in public works in the 19th a ...
s, and operate in a similar fashion. Other uses of the power shovel include: # Close range work. # Digging very hard materials. # Removing large boulders. # Excavating material and loading trucks. # Various other types of jobs such as digging in gravel banks, in clay pits, cuts in support of road work, road-side berms, etc.


Operation

The shovel operates using several main motions including: * Hoisting - Pulling the bucket up through the bank of material being dug. * Crowding - Moving the dipper handle in or out in order to control the depth of cut or to position for dumping. * Swinging - Rotating the shovel between the dig site and dumping location. * Propelling - Moving the shovel unit to different locations or dig positions. A shovel's work cycle, or digging cycle, consists of four phases: *1 Digging *2 Swinging *3 Dumping *4 Returning The digging phase consists of crowding the dipper into the bank, hoisting the dipper to fill it, then retracting the full dipper from the bank. The swinging phase occurs once the dipper is clear of the bank both vertically and horizontally. The operator controls the dipper through a planned swing path and dump height until it is suitably positioned over the haul unit (e.g. truck). Dumping involves opening the dipper door to dump the load, while maintaining the correct dump height. Returning is when the dipper swings back to the bank, and involves lowering the dipper into the track position to close the dipper door.


Giant stripping shovels

In the 1950s with the demand for coal at a peak high and more coal companies turning to the cheaper method of
strip mining Surface mining, including strip mining, open-pit mining and mountaintop removal mining, is a broad category of mining in which soil and rock overlying the mineral deposit (the overburden) are removed, in contrast to underground mining, in which ...
, excavator manufacturers started offering a new super class of power shovels, commonly called giant stripping shovels. Most were built between the 1950s and the 1970s. The world's first giant stripping shovel for the coal fields was the Marion 5760. Unofficially known to its crew and eastern Ohio residents alike as The Mountaineer,"16 Tone Mobile Shovel Take 90 Ton Bite of Earth"
''Popular Mechanics'', April 1956, p. 95. it was erected in 1955/56 near
Cadiz, Ohio Cadiz ( ) is a village in Cadiz Township, Harrison County, Ohio, United States located about 20 miles from Steubenville. The population was 3,353 at the 2010 census. It is the county seat of Harrison County. History Cadiz was founded in 18 ...
off of Interstate I-70. Larger models followed the successful 5760, culminating in the mid 60s with the gigantic 12,700 ton
Marion 6360 Marion 6360, also known as ''The Captain'', was a giant power shovel built by the Marion Power Shovel company. Completed in 1965, it was one of the largest land vehicles ever built, exceeded only by some dragline and bucket-wheel excavators. Th ...
, nicknamed ''The Captain''. One stripping shovel, The Bucyrus-Erie 1850-B known as " Big Brutus" has been preserved as a national landmark and a museum with tours and camping. Another stripping shovel, The Bucyrus-Erie 3850-B known as "Big Hog" was eventually cut down in 1985 and buried on the Peabody Sinclair Surface Mining site near the Paradise Mining Plant where it was operated. It remains there on non-public, government-owned land.


Notable examples


See also

* P&H Mining *
Bucyrus International Bucyrus-Erie was an American surface and underground mining equipment company. It was founded as Bucyrus Foundry and Manufacturing Company in Bucyrus, Ohio, in 1880. Bucyrus moved its headquarters to South Milwaukee, Wisconsin in 1893. In 1927, B ...
*
Dragline A dragline excavator is a piece of heavy equipment used in civil engineering and surface mining. Draglines fall into two broad categories: those that are based on standard, lifting cranes, and the heavy units which have to be built on-site. ...
*
Excavator Excavators are heavy construction equipment consisting of a boom, dipper (or stick), bucket and cab on a rotating platform known as the "house". The house sits atop an undercarriage with tracks or wheels. They are a natural progression fr ...
*
Marion Power Shovel Marion Power Shovel Company was an American firm that designed, manufactured and sold steam shovels, power shovels, blast hole drills, excavators, and dragline excavators for use in the construction and mining industries. The company was a m ...
*
Steam shovel A steam shovel is a large steam-powered excavating machine designed for lifting and moving material such as rock and soil. It is the earliest type of power shovel or excavator. Steam shovels played a major role in public works in the 19th a ...
* Hulett


Further reading

Extreme Mining Machines - Stripping shovels and walking draglines, by Keith Haddock, pub by MBI,


References

{{Mining technology Stripping shovels Engineering vehicles Excavators