Talk:Dragline excavator

Pre-2006 Comments

Scottfisher, can you add the geographical location of Manitowok in the photo caption? Thanks! Badagnani 00:55, 17 August 2005 (UTC)[reply]

Badagnani

Sure, Not a problem, I know the history of "Manny"; It came from the Nevada Test Site, then went to Lawrence Livermore National Laboratory in California, now at to Oakridge, Tennessee, ORNL. All are Department of Energy sites, in the USA. I think Manny is up for sale now. Regards, Scotty

Shovel vs Dragline

I believe Big Brutus is technically a "shovel", not a dragline (one lifts, the other drags). In the article, Big Brutus is referred to as a "dragline shovel". Is there such a thing?

The external link at the bottom of the article is a website that calls Big Brutus a "electric mining shovel", not a dragline.

There is no such thing as a "dragline shovel". Big Brutus is a rope shovel which is completely different from a dragline.

Mark

Caterpillar tracks versus feet

Regarding the statement:

In all but the smallest of draglines, movement is accomplished by "walking" using feet or pontoons, as caterpillar tracks place too much pressure on the ground

What kind of feet are these that they put less pressure on the ground than caterpillar tracks? Is it even true? That GEM thing linked near the bottom of the page is pictured on caterpillar tracks. --ToobMug 12:48, 12 December 2006 (UTC)[reply]

Jargon in 'Limitations' Section

I am no expert on draglines, mining, or similar, so the following text is (a) under the wrong heading (should be 'Usage' or similar), and
(b) almost completely incomprehensible. I have identified (wikified) most of the terms I think need defining. (Note that NONE of these links has been checked for relevance!)

Draglines have different cutting sequences. The first is the side cast method using offset benches; this involves throwing the overburden sideways onto blasted material to make a bench. The second is a key pass. This pass cuts a key at the toe of the new highwall and also shifts the bench further towards the low-wall. This may also require a chop pass if the wall is blocky. A chop pass involves the bucket being dropped down onto an angled highwall to scale the surface. The next sequence is the slowest operation, the blocks pass. However, this pass moves most of the material. It involves using the key to access to bottom of the material to lift it up to spoil or to an elevated bench level. The final cut if required is a pull back, pulling material back further to the low-wall side.

It looks fascinating, and definitely belongs in the article. However, it would benefit from a series of diagrams to explain what was being described. This would avoid the need for 'every other word' to be a wikilinked! A section on 'definition of terms' would be a useful bonus.

EdJogg 10:56, 15 December 2006 (UTC)[reply]

The GEM (Giant Excavating Machine)is a shovel, not a drag line. While the size and application are similar the machines opeation is not. A shovel works best while digging from its tracks up. A dragline does better while working below the level of its base.

I don't know the engineering involved, but nearly all shovels operate on tracks, while drag lines tend to have feet and are usually refered to as "walking draglines". This may have something to do with the method of operation. I have seen a couple of photos of draglines that have slid into the pit that they were digging.

The shovels also have an operational hazard in that the high wall can collapse on them. The GEM was damaged at one point in its career by such a fall. Steve

Removal of GEM

GEM is a 'Rope Shovel', not a dragline excavator. Compare the pictures of GEM [1] with the pictures in Steam Shovel

Well-spotted. Details have been moved to steam shovel, replacing the information about Big Muskie which is a dragline!

EdJogg 00:56, 3 May 2007 (UTC)[reply]

Discussion of efficiency compared to bucket-wheel excavators

As a dragline excavator only moves overburden half of its working time (the other half being used to re-position the empty shovel) and for each working cycle, its enormous mass has to be accelerated and decelerated twice, I think it would be interesting to compare the efficiency of those machines to bucket-wheel excavators which work more steadily. Since draglines are in widespread use in strip mines around the world and really large bucket-wheel excavators only seem to be in use in Germany, is there any real advantage of the draglines? --217.225.66.7 (talk) 23:08, 8 July 2008 (UTC)[reply]

There may be other factors to consider, too: geology of material to be moved, staffing needs, complexity, overall cost, etc. It would be good to find a good reference that discusses these matters, to explain why one should be chosen over the other. EdJogg (talk) 11:56, 9 July 2008 (UTC)[reply]

I have now found an answer using Google's book search, but am unsure whether copyright law would allow to use the text here. In an anthology (Howard L. Hartman, Seeley W. Mudd: "SME Mining Engineering Handbook: Vol.2". Memorial Fund of AIME., Society for Mining, Metallurgy, and Exploration. p. 1403 ff.), M.K. McCarter writes that basically, draglines are more flexible and can cope better with, say, small landslides, while bucket-wheel excavators work better in homogenuous materials. Draglines also seem to be cheaper when bought initially. He points out that BWEs consume power more evenly, but makes no statements whether or not they use more or less power per ton of moved material than draglines. --217.225.59.67 (talk) 22:53, 13 July 2008 (UTC)[reply]