prop-free front
Mining
noun
An area in front of a coalface where no props are placed, so as to leave access for a mechanical conveyor, the roof being supported by cantilever bars; the system of supporting a roof in this way.
Origin
1950s.
| 单词 | prop-free front |
| 释义 | prop-free frontMining noun An area in front of a coalface where no props are placed, so as to leave access for a mechanical conveyor, the roof being supported by cantilever bars; the system of supporting a roof in this way. Origin |
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