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12 COAL AND TIMBER April, 1905
sans for rope haulage and compressed air
have much to say for their respective
methods, but the operators who use electric
locomotives seemingly have no quarrel with
their judgment in their selection. The electric
locomotives as used in coal mines IIMIVC
been employed mainly in hauling coal on
the main headings, but in some mines, they
have also been employed for gathering, the
cars from the mouths of the rooms, the
cars in such instances having been pushed
out of the room to the headings by the
miners or their assistants This practice, is,
of course, limited to mines where the cars
are small and the tracks of the rooms arcpractically
level, or have a slight natural
slope toward the headings. The gathering
of cars from the "face workings" in rooms,
or headings, is yet done largely by mule
power, and this generally constitutes the
largest per centage of the cost of transporting
coal from the "face workings" to
the tipple or the bottom of the hoisting
this system is dangerous to any great degree.
They point to the comparative saftey
with wdiich mines equipped with this installation
are operated.
But few deaths ever
occur from contact with the trolley wire, for
this is placed at the side of the mine roof
and away from likelihood of being touched
by the miners as they walk to and fro in
the headings.
The partisans for the electric system of
power haulage point to the generality of
its use as a strong argument that it is
everything which they claim for it, else
why its greMit popularity? There is no doubt
tluit electric mine haulage as in operation
today in the mines of this and other countries
is very satisfactory in operation Mind
very economical. The champions for it
invite the closest inspection and have never
feared to accept challenges from the parti-
SMUIS of either rope haulage or compressed
air to determine the relative merits of the
systems.
tion of power equipment for a coal mine.
It is claimed by those interested in this
form of mine equipment
mine
that the older a
the greater are the possibilities for
the sudden Mind unexpected formation of
gas and tluit the compressed air system is
a perfect safe-guard against explosion from
haulage machinery.
As a question of economy the partisans
for this form of applied power claim that it
takes firstplace. Compared with rope haulage,
it is argued that the wear and tear oi
wire cables will throw the balance of expense
well in favor of the compressed air
power. As to electric haulage, the question,
they state frankly, is more open to debate.
It is freely admitted that there is more room
for honest difference of opinion in regard
to the comparative expense of these two
systems. It is admitted that a special test
made of electric installation, under the best
conditions, will, if properly designed and
constructed, undoubtedly show considerably
Compressed Air Locomotive—Made by the H. K. Porter Company, Pittsburg, Pa.
shaft. The success of the electric mine
locomotive in hauling coal on main headings
has created a demand for a better,
cheaper and more satisfactory method of
gathering coal, or in other words, an efficient
substitute for the mule for this class
of work. To meet this demand some manufacturers
have designed and built small
locomotives especially adapted for switching
in mines and hauling the pit cars from
the "face workings" to the entry to the main
headings. There the cars are picked up by
the larger locomotives and hauled in long
trains to the tipple or the foot of the main
shaft.
The illustrations with this article show
modern electric mine locomotives and how
they are operated. They work exactly like
the modern trolley car, whether they are
given power by an overhead trolley wire
or by means of 3 third-rail running in a slot
between the rails.
The advocates of the
trolley wire decry the attempts to show that
COMPRESSED
AIR.
The latest system for underground
and
surface haulage is that for which the power
is furnished by compressed air. Those who
favor this sort of equipment for the conveying
or transporting of mine cars from
one part of the workings to another, claim
that among the practical advantages of compressed
air, the most obvious and that
which should appeal with greatest force
to operators as peculiarly advantageous for
underground work in coal mines where
there is the faintest possibility of danger
from mine gas, is that compressed air locomotives
are absolutely and positively safe
against any danger of setting fire to mine
gas, and producing such disastrous accident^
as have unhappily taken place in almost
every coal field of the world, both in the
bituminous and anthracite regions. This,
then, is a consideration which they urge as
one of paramount importance in the secgreater
efficiency than any single test can
show made along the same lines of haulage.
It is further frankly admitted that if an
electric haulage plant could be operated
always and continuously at the highest rate
of efficiency as shown by special test, it
would be impossible to maintain any claim
for air haulage of equal or greater economy
and efficiency. It is then asserted that
it is impossible to, in practical daily work,
maintain the high efficiency in an electric
plant which may be shown in a special test.
Here, the sponsors for compressed air
claim that their system is par excellence—
that it shows to best advantage when reviewed
by the results of the daily practical
workings of the new system. It is asserted
that in electrical haulage the power has to
be used as fast as made when, on the other
hand, the power for compressed air is never
lost. It is claimed for this system that the
compressor is working continuously at practically
the same speed all day long, and that