The times. [volume] (Richmond, Va.) 1890-1903, 1902-07-27
CUTTING COAL BY MACHINERY
Types of Machines Most Used in the
Mines in the United States.

Mines in the United States.
The two general types of coal cutting
machines in most common use IN the
mines Of the United States may be class
ed under the heads Of pick or punch
ing machines, and the "chain breast,
although a few 'logwall" machines are
in successful use in some OF the thin
seams Of the Western States. The meth
Cd of mining in America is usually some
adaptation Of. the "pillar-and-room" or
's'tall-and- pillar" system. and most Of
the longwall machines made in the
United States are shipped to Europe.
where that system of mining is generally
practiced. There are in the United
States seven extensive manufacturing
Establishments making a speciality OF coal
mining machinery. Three Of these make
pick machines and four manufacture
chain cutting machines. These types OF
mining machines have been brought to
such a degree of efficiency that, 1t is
safe to say, there are comparatively few
btuminous coal mines. operated upon an
extensive scale, that could not with ad-
vantage be equipped with mining ma
chimes. There is but one adverse condi-
ton that has not been successfully sur
mounted, and that is the inclination Of
the vein when the dip exceeds y degrees
or is degrees. Some Of the pick machines
have been used in mines where the IN
clination was as much as 50 degrees; but
the work was slow and difficult. and it
was only from the fat that the price or
labor was high that the machine was
able to compete with It. The trouble
does not lie so much in the actual cutting,
but in the difficulty Of moving the ma
chimes from place to place. Manufac-
turers do not care to run the risk Of fall
ing, and prefer not to install machines
where the dip exceeds. say. Il degrees.
By the use OF self-propellins trucks It
has been found possible to use chain ma
chimes in mines having this amount OF
inclination from the horizontal; but that
is about the maximum. The self-propel-
ling truck also enables the chain ma
chine to be used in mines where the
seam is so thin that 1t would be other
wise impossible to draw the machine or
move it up to the face of coal. as neither
horses nor mules could go into the room
unless some Of the floor were taken up
or the top taken down.
All of the pick machines in success
full operation at the present time are
driven by compressed air, although one
company claims to have developed an
electrically-driv pick machine which
mas overcome CQc lueClldlllCdl ull1lCuiC1eS
heretofore effective against the use Of
any other than an air-driven pick ma
chine. Most Of the chain machines and
all Of the few long-wall machines in
American use employ electricity as a mo-
tive power. In some of the long-wall
machines of British make compressed
air SUPPLIES the power. In some mines
where gas Is present in dangerous pro-
portions, and is apt to be exploded by
an electric spark. or where other condi-
tons are against electric installation,
chain machines operated by compressed
air are in use. One of the principal
objections offered to the use of air for
a chain machine is the low temperature
produced about the legs Of the operative
by the expanding air from the exhaust.
This cold is sufficient to cover the OK
haust pine with frost and to produce
rheumatism in the miners Iegs-E. W.
Parker. in the Mining and NIetallurgical
Number of Casters Magazine.