Aar !
Some of us go back to the dim and distant days when you used
wooden props (which you cut to size) with wedges and wooden bars to
hold up the face on the longwall panel and then, after cutting and
blasting down the coal, you shovelled it onto the conveyor. As you
started that you dug a path down beside the conveyor to let people
out if something went wrong, and dug in bays to put in additional
props where needed. then in the next shift they broke the conveyor
belt into bits and pulled it forward, and then chopped out the
previous timber set so that the roof would fall in behind them. (The
recommended practice was to use a come-along to pull the props but I
almost never did that nor saw it done)
Dave
>I would support Kelvin's posting. The only timber i have seen used in
>coal mines was pine. It was placed behind steel roadway supports or
>above powered supports on the coal face as packing in areas of 'bad
>ground'. It would support the in-situ strata, to prevent its collapse,
>and to prevent debris falling through. Thus the type of timber was
>unimportant, factors such as strength and consistent size might be
>considered, but the most important was probably cheapness.
> Barry
>Job.
>
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--
David A. Summers
Curators' Professor of Mining Engineering
Adjunct Professor of Nuclear Engineering
Director
Rock Mechanics and Explosives Research Center
University of Missouri-Rolla,
Rolla, MO 65409-0810
"fools talk, wise men listen." (a variant of Prov 12:23)
phone: (573) 341 4314
FAX: (573) 341 4368
related web pages
A growing selection of Dr. Summers' papers are being put on the Web
and can be accessed through the Bibliography
http://www.umr.edu/~rockmech/faculty/biography.html
Rock Mechanics http://campus.umr.edu/rmerc/
Waterjet Lab: http://www.umr.edu/~waterjet/
UMR Stonehenge: http://www.umr.edu/~stonehen/
Personal: http://www.umr.edu/~rockmech/data/Summers.html
Mining Eng. http://www.umr.edu/~mining/
Waterjet Assoc http://www.wjta.org/
International Waterjet Society: http://www.iw.uni-hannover.de/iswjt/
Next American Waterjet conference: http://www.wjta.org/conference.htm
7th Pacific Rim Conference (May 2003) http://www.kojet.org
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