In crystallography, an element of symmetry such that, for each and every
lattice point, asymmetric unit, or crystal plane, there is another
equidistant in the opposite direction. It is represented by i or by 1.
Adj. centric or centrosymmetric. Syn:inversion
See:torsional center
See:torsional center
Eng. A prop set temporarily under the center of a plank to support it
before props are set at the ends of the plank. Syn:middle prop
SMRB
a. Framed supports, usually arch shaped, upon which are placed the lagging
boards used, in building an arch, for supporting the roof of a tunnel.
See also:center
b. Linear distance between coal-mine entries or crosscuts.
A shot in the center of the face of a room or entry. Also called center
cut. Fay
A method of casting molten metal, in which the molds are spun and
centrifugal force helps to fill them. Pryor, 3
One of two approaches used in plotting seismic reflection data on time
cross sections. Center-trace times are the times picked on the two traces
from the respective detector groups nearest the shot and on opposite
sides. The average of the two times for each reflection is plotted at the
shot-point position. The points thus plotted for adjacent shot points are
connected by straight lines. CF:trace-by-trace plotting
See:Celsius
The one-hundredth part of a poise, an absolute unit of fluid viscosity.
Viscosity of drill-mud fluid is sometimes expressed in centipoise or
millipascal-second units. See also:poise
A breaker where the coal from a number of mines in a district is prepared.
Central breakers, representing the last word in mining technology, make it
economical for operators to abandon many local breakers. Korson
A device that lines up a drill steel or string between the mast and the
hole. Nichols, 1
A safety device on a mine hoist drum that applies a brake if the drum
speed exceeds the set limit. Pryor, 3
Casting molten metals in a rapidly revolving mold.
Consists of a driving hub having one or more weighted sections fitted with
friction lining on the outer radial surfaces that contact a driven hub
having a flange covering that portion of the driving hub containing the
radial elements. Upon starting, the radial elements of the driving hub
have no appreciable drag, but upon accelerating to the operating speed the
force produced by the centrifugal action increases rapidly as the square
of the speed and the elements grip the driven element, thereby causing it
to speed up to the required speed of the driving hub.
Pit and Quarry
centrifugal discharge bucket elevator
A type of bucket elevator using centrifugal discharge elevator buckets
suitably spaced to permit the free discharge of bulk materials.
See also:bucket elevator; centrifugal discharge elevator bucket.
centrifugal discharge elevator bucket
A bucket designed to scoop material from the boot of an elevator and
discharge by reason of the combined effect of centrifugal force and
gravity.
a. A type of fan often used in mines and ventilation activities in which
an impeller, generally consisting of numerous blades, discharges the air
radially into an expanding scroll casing while imparting an increase in
pressure to the air. Hartman, 2
b. See:radial-flow fan
See:filter
a. A form of pump in which water is drawn through the eye of a rotating
impeller and discharged from its periphery into a chamber containing a
series of passages of gradually increasing cross section. The kinetic
energy given to the water by its centrifugal discharge is thus largely
converted to pressure energy. CF:duplex pump
b. See:turbine pump
Mineral replacement in which the host mineral is replaced from its center
outward. CF:centripetal replacement