In mine subsidence, the break that occurs over the seam at an angle from
the vertical equal to half the dip. Lewis
Eng. See:gate
The crosscut that traverses the entire mining field and penetrates all
deposits. There is such a crosscut at each level, and it is the main one
for the level in question. It serves the same purpose as the shaft and
thus must have correct cross section, and be particularly well
constructed, as repairs to its support would hold up the transport of the
entire level. Stoces
A main tunnel driven in the rock underlying a lead and about 50 ft (15.2
m) below the wash dirt. It is used as a drainage tunnel for carrying the
water from the drainage holes to the shaft sump and also for the transport
of cars from the raises. Eng. Min. J., 1
Pairs of narrow coal headings with crosscuts at intervals, driven to form
large pillars of coal in panel working. See also:narrow work
Nelson
N. of Eng. The surface pumping engine, usually of the Cornish type.
Fay
a. The principal entry or set of entries driven through the mine from
which cross entries, room entries, or rooms are turned.
Federal Mine Safety
b. A term used in the United States for the principal horizontal gallery
giving access to an underground mine and used for haulage, ventilation,
etc. Where two entries are driven in parallel, the term "double entry" is
used. With three parallel entries, the term "triple entry" is used.
Nelson
c. An entry driven at right angles with the face slips of the coal.
See also:entry
d. A main haulage road. See also:main road
A drive-type, split-tube soil-sampling device, usually equipped with a
flap or clack valve near the cutting shoe. Usually produced in sizes
having outside diameters ranging from 4 to 6-5/8 in (10 to 17 cm).
Long
A soil-sampling device that works essentially on the same principle as a
Maine sampler. Long
a. The bezel and pavilion facets.
b. Any facet extending from the girdle to the table or from the girdle to
the cutlet.
Main fans produce the general ventilating current of the mine, and are
generally of large capacity and permanently installed. They are assisted
by natural ventilation, if present, and, if necessary, by booster fans.
They are installed to perform a certain duty, and great attention is paid
to their efficiency since this governs the cost of performing the duty.
Roberts, 1
The firing of a round of shots by means of current supplied by a
transformer fed from a main power supply. BS, 12
The principal or central heading along which the coal is conveyed from two
or more conveyor panels. Normally, the main gate is also the intake airway
to the face. See also:double-unit conveyor; bottom gate; mother gate.
Nelson
a. That portion of the haulage system that moves the coal from the
secondary haulage system to the shaft or mine opening. The method employed
is the same for either longwall or room-and-pillar mining. Any one of four
methods may be used: (1) mine cars and battery or trolley locomotives, (2)
mine cars and a direct rope haulage, (3) a combination of methods 1 and 2,
or (4) belt conveyors. Wheeler, R.R.
b. The system by which coal is transported in trains in or out of a slope
or drift entry or from the bottom of a shaft. BCI
Generally 500 to 3,000 ft (approx. 150 to 1,000 m) in length. It is used
to transport material between the intermediate haulage conveyor and a
car-loading point or the outside. NEMA, 2
The principal transportation road, drift, tunnel, etc. BCI
The first or primary borehole from which secondary or branch holes are
drilled. Also called original hole; parent hole. CF:branch
Long
The trunk or principal intake airway of a mine. The main intake air
current is usually split into two or more air currents before reaching the
workings. Nelson
The first and leading excavations in mines that are made for the purpose
of opening out or winning the material being mined, and that are intended
to be the principal roadways of the mine. Peel
A large, high-powered locomotive that hauls trains of cars over the main
haulage system. BCI