On a wagon drill, a guide to hold the starting steel in proper alignment.
Nichols, 2
A skilled member of a team specially trained to erect steel framed
buildings, bridges, and other steel structures. Hammond
Steel rails, rods, or bars fixed in a vertical shaft to guide the cage and
prevent it from swinging. See also:fixed guides
a. A screw jack esp. suitable in mechanical mining. Under headers at or
near the face, steel jacks or posts are used for upright timbers to be
replaced as equipment advances. Also called steel post. Kentucky
b. See:sphalerite
The process of making steel from solid or molten pig iron, with or without
admixture with steel scrap. The processes used are the Bessemer,
open-hearth, crucible, electric arc, high-frequency induction, and duplex.
CTD
A mill where steel is made, processed, and shaped. Webster 3rd
An instrument used in preparing blasting holes; used before the safety
fuse was invented. Fay
A name given to various iron ores and esp. to siderite, because it was
supposed to be esp. adapted for making steel by the earlier and direct
process. Fay
See:plate conveyor
A machine for compressing molten steel in casting to improve the quality
of the product. Standard, 2
A steel upright or post used to support the nether roof at a longwall or
other face. It usually incorporates a yielding device.
See also:hydraulic prop; mechanical yielding prop;
self-advancing supports. Nelson
A hinged clamp on the bottom of a hand drill. Nichols, 1
steel rectangular shaft supports
A shaft support consisting of H-beams, I-beams, angles, and sheeting. The
design is somewhat similar to that used for timber. Bolts, rivets, and
fastening angles are used to connect and secure the steel members. The
fastening angles are riveted to the beams. The addition of galvanized-iron
corrugated wall sheets (or laggings) form a secure and fireproof shaft.
See also:permanent shaft support; barring; bunton; wallplate; lagging.
Nelson
Ring- or horseshoe-shaped support for underground traveling way. Also
called arch ring. See also:steel arch
Miscellaneous pieces of steel, old and new, used in the bath for steel
making, esp. in the open-hearth furnace. Mersereau, 2
A steel door specially erected for the purpose of being closed only in an
emergency, such as a fire or an explosion. Steel is necessary for strength
and to avoid destruction by fire. Steel doors may also be used as
separation doors in the vicinity of the pit bottom or fan drift. Also
called safety door; emergency door. See also:separation door
Nelson
Used in main entries of coal mines and in shafts of metal mines in the
United States. The sections have I-beams for caps and H-beams for posts or
wall plates, the H-section giving equal stiffness in two directions at
right angles to each other. Steel sets of various shapes are coming into
wide use in deep European coal mines where pressures are so great that
timber would not be satisfactory. See also:steel tunnel support
Lewis
Piling composed of interlocking rolled steel sections driven vertically
into the ground with guide walings in place before excavation starts.
Hammond
Chilled cast iron drops. Syn:chilled shot
A straight or curved length of steel, usually of H or channel section,
used for support purposes in mine roadways, faces, or shafts. A steel
support (1) possesses a high degree of permanency or long service; (2)
ensures a minimum area of excavation for given dimensions in the clear;
and (3) is fireproof. In return airways and shafts, a chrome-nickel-copper
steel is sometimes used to counteract the corrosive air. For high-strength
roof bars best results are obtained by the use of heat-treated low-alloy
steels of the carbon manganese type. See also:arch girder; steel arch;
straight girder support; support; Usspurwies arch;
Toussaint-Heintzmann arch. Nelson
Tunnel-support systems made of steel are roughly of five types: continuous
rib; rib and post; rib and wallplate; rib, wallplate, and post; and full
circle rib. (1) A continuous rib system is usually made in two pieces for
maximum speed of erection, lowest first cost, and lowest erection cost.
Sometimes used in three or four pieces to meet special conditions and the
following methods of attack: full face, side drift, and multiple drift.
(2) A rib and post system is employed with the following methods of
attack: full face in tunnels whose roof arch makes an angle with the
sidewall; multiple drift and side drift in tunnels of such large size that
two-piece continuous ribs cannot be shipped and/or handled; and heading
and bench and top heading for support in the drift (with truss panels) for
early support to roof. (3) In a rib and wallplate system, the rib is also
usually made in two pieces for maximum speed of erection, lowest first
cost, and lowest erection cost. It is sometimes used in three or more
pieces to meet special conditions and with the following methods of
attack: heading and bench, top heading, and full face. This type is esp.
applicable to circular and high-sided tunnel sections where only a light
roof support is needed. (4) In a rib, wallplate, and post system, these
elements of support are used with the following methods of attack: heading
and bench and top heading--for quick support to a roof; side drift--in
large tunnels with bad rock conditions requiring quick support; and full
face--for favorable rock where support is not needed tight to the face,
for a tunnel whose roof makes an angle with the sidewall, and where post
and rib spacing differ; and (5) A full circle rib--this method is used
with the following attack: full face--in tunnels in squeezing, swelling
and crushed rock, or any rock that imposes considerable side pressure,
also where bottom conditions make it impossible to carry roof loads on
foot blocks, and in earth tunnel conditions sometimes encountered in rock
tunnels; and heading and bench--under earth tunnel conditions with joints
at spring line. The inverted strut is used where mild side pressures are
encountered and also to prevent the bottom from heaving. A full circle
with ribs closely spaced is heavily lagged for heavy loads associated with
squeezing conditions. See also:steel sets
Lewis