ne or haulage system with the other end attached to a receiving bin that dollies along a frame supported by the room or entry conveyor, tailpiece. Thus, as the machine boom moves, the bridge conveyor keeps it in constant connection with the tailpiece.Brow- A low place in the roof of a mine, giving insufficient headroom.
Brushing- Digging up the bottom or taking down the top to give more headroom in roadways.
Btu�C British thermal unit. A measure of the energy required to raise the temperature of one pound of water one degree Fahrenheit.
Bug dust- The fine particles of coal or other material resulting form the boring or cutting of the coal face by drill or machine.
Bump (or burst)- A violent dislocation of the mine workings which is attributed to severe stresses in the rock surrounding the workings.
Butt cleat- A short, poorly defined vertical cleavage plane in a coal seam, usually at right angles to the long face cleat.
Butt entry- A coal mining term that has different meanings in different locations. It can be synonymous with panel entry, submain entry, or in its older sense it refers to an entry that is "butt" onto the coal cleavage (that is, at right angles to the face).
C
Cage- In a mine shaft, the device, similar to an elevator car, that is used for hoisting personnel and materials.
Calorific value- The quantity of heat that can be liberated from one pound of coal or oil measured in BTU's.
Cannel coal- A massive, non-caking block coal with a fine, even grain and a conchoidal fracture which has a high percentage of hydrogen, burns with a long, yellow flame, and is extremely easy to ignite.
Canopy- A protective covering of a cab on a mining machine.
Cap- A miner's safety helmet. Also, a highly sensitive, encapsulated explosive that is used to detonate larger but less sensitive explosives.
Cap block- A flat piece of wood inserted between the top of the prop and the roof to provide bearing support.
Car- A railway wagon, especially any of the wagons adapted to carrying coal, ore, and waste underground.
Car-dump- The mechanism for unloading a loaded car.
Carbide bit- More correctly, cemented tungsten carbide. A cutting or drilling bit for rock or coal, made by fusing an insert of molded tungsten carbide to the cutting edge of a steel bit shank.
Cast- A directed throw; in strip-mining, the overburden is cast from the coal to the previously mined area.
Certified- Describes a person who has passed an examination to do a required job.
Chain conveyor- A conveyor on which the material is moved along solid pans (troughs) by the action of scraper crossbars attached to powered chains.
Chain pillar
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