October 15, 1915.

THE COLLIERY GUARDIAN

777

Modern American Coal Mining Methods, with Some Comparisons.*

By SAMUEL DEAN.

The feature which stands out above all others, when
comparison is made between coal mining methods in
different countries, is the output per man in American
mines. A few weeks previous to the war the writer
visited mines in Germany, Belgium, and France, and
revisited mines in Great Britain, and he again affirms
his opinion that the principal reason why the United
States of America leads in production per man is because
large capacity mine cars are used in American mines.

Mr. S. F. Sop with, in discussing Mr. S. H.
Cashmore’s paper on “ The Reduction of Working Costs
at the Coal Face,”f said that his experience was that
fillers earning 6s. 9d. to 7s. a shift considered that they
had done a day’s work when they had filled 15 tubs. It
is assumed that he referred 'to tubs of a capacity of
10 cwt. each, which equals 7| tons per shift. Mr.
Cashmore had shown that only about a-fifth of the filler’s
time was actually occupied in filling, nearly the whole
of the remainder being spent (or wasted) in topping up,
tramming, and in waiting for empties. If Mr. Sop with
had used tubs of, say 3J tons capacity, it would only
have been necessary for the filler to load two tubs to
equal the output of 14 10-cwt. tubs. It is quite reason-
able to expect also that, if the filler is not engaged in
topping, tramming, or in waiting, he will be filling, and

Fig 1.—Side Elevation.
--------- J09" --------

Fig 3 —End View

CHAIN'

CHAIN

ROD

Figs. 1 to 4.—Steel Mine Cab with Oak Bottom.

COUPLING-
HOOK

OAK

561-inch Gauge.

Fig 4.-Rear View

OAK

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<- --- 30"------>'

Fig 2.-Plan of Bottom

iaai

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ROD ACROSS CAR

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5 Ol<j=

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Figs. 5 to 8.—All-steel Railway Type



will have little difficulty in loading, at least, three
3|-ton tubs. The writer quite expects to hear 'the
following objections to the use of such large tubs :—
“ Large tubs would not be practicable, on account of
bad roofs and unevenness of strata; and where large
trams are used, as in South Wales, the output per man
is no more than in the districts where small tubs are
in use.” In the anthracite regions of Pennsylvania the
seams pitch at all angles from the horizontal 'to the
vertical; the roofs in some anthracite mines could not
be much worse, and the roofs in South Wales are bad.
In the anthracite regions the capacity of the mine cars
ranges from two to five tons, the average being about
3| tons. One of the principal reasons why the output
per man is not higher in South Wales is because com-
paratively few coal-cutting machines and face conveyors
are in use. Locomotives and large cars are used with
single tracks, except at the “ pass-byes,” and the main
haulage ways are not as wide as similar roads in mines
where endless rope haulage is employed.

* From a paper read before the North of England Institute
of Mining Engineers.

f Trans. Inst. M.E., 1915, vol. xlix., p. 63.

Machine mining difficulties have been overcome to
a large extent in the United States, and coal-cutting
machines are being improved and introduced so rapidly
that it would appear to be only a matter of a few years
before hand mining becomes nearly extinct in the bitu-
minous mines. Methods of haulage, or transportation,
are being developed to a high degree, in order to ensure
plentiful supplies of empties at the coal face.

The modern mining man carefully plans his roads,
and chooses the best rolling stock. In order to secure
greater efficiency, he has (1) increased the weight of the
coal hauled in proportion to the weight of the car con-
taining it; (2) decreased the amount of drawbar pull
due to friction; and (3) decreased the delay due to
derailments and wrecks, and increased the number of
cars hauling coal in proportion to the number kept in the
repair shop.

Large car capacity is not attained by increasing the
height of the car, but by increasing the length and width,
along with wide-gauge tracks. The introduction of
roller-bearing wheels has reduced the drawbar pull due
to friction. Brass journals or brass-bushed wheels are
also an improvement. Cars fitted with spring draught
gear are now being used so as to reduce the heavy
starting load. Compressed air or electric locomotives

of Mine Cab used in West Virginia.

are employed to haul the long heavy trains of cars under-
ground, and cases are on record of starting 50 per cent,
more cars with spring draught than with solid bumpers.
Some of the best principles of railroad engineering are
being applied to underground haulage.

The opinion exists in some countries that great danger
is attached to the use of electric trolley locomotives in
coal mines. It is well to remember that electric loco-
motives are used in the mines of Westphalia, and the
accident rate has not increased since their introduction.
Countries that prevent by law the operation of trolley
locomotives are handicapped in world competition, and
the same remark applies to countries where pit tubs of
small capacity are used.

The output per man in Germany is low, coal-cutting
by machinery is in its infancy, and the mine cars and
track gauges are ridiculously small and narrow. In the
United States over 50 per cent, of the total production
of bituminous coal is mined by machines, and large
capacity cars and wide gauge tracks are used. The
output per man per annum in Germany was about 300
tons, and the average in the United States 760 tons,
despite the fact that the mines do not work with by

any means the same regularity of European mines.
German mines work on an average 300 days a year, and
American mines 238 days. There is food for much
thought in this comparison, because Germany is, in
many ways, more efficient than the United States of
America.

Keen competition and low selling prices, especially
in States east of the Mississippi River, are finding work
for the efficiency expert.

Mine Car Design.

The modern mine car is built of steel. The opinion
that steel cars are easily damaged and difficult to repair
is disappearing in most localities; small bends and
dinges can be taken out with a sledge hammer; while
heating with a blow torch helps materially. Bent sides
and ends can be straightened with a rail bender or
special appliance. Wooden cages, large enough to admit
a car, and jacks acting in opposite directions, are used
to straighten out the worst cases of distortion.

Opinions vary as to the best design, and the steel
bottom car has been discarded at some mines, the
practice being to have an oak bottom with sides and
ends of steel. It is claimed that the disadvantage of the
steel bottom is that it makes the car too stiff, the truck
gets knocked out of shape, the bottom plates rust quickly
away, and the truck becomes loose on the car bottom.
A car with the plates bolted to the binder, instead of
being riveted, is preferred by many, with the sides
made in separate sections, so that they can be taken
off and repaired quickly and easily in case of a wreck.
Figs. 1 to 4 show a steel car with an oak bottom; it
has a capacity of 83T% cu. ft., with a track gauge of
56| in.—the standard railway gauge. The cost of this
car, fitted with “ Whitney Wonder ” roller-bearing
wheels, is 1217 10s. 6d. (85 dols.). It is in use at a mine
in the State of West Virginia, the thickness of the
seam being 4 ft., the method of working room and pillar,
and the average pitch of the seam 2 degs. This car
has an end door, which is raised automatically in the
tippler or self-dumping cage. This wide track gauge
of 56| in. can be seen at numerous mines in West
Virginia, and it is significant that the cost of production
is lower in this State than in any other coal mining
region in the United States. The average total cost
per short ton (2,000 lb.) is 3s. 3d. (79 cents).

Figs. 5 to 8 show the type of cars used by the Lathrop
Coal Company, West Virginia. They are all of steel,
with bodies 9 ft. 4 in. long, Oft. Sin. wide, and 2 ft.
deep. The 14-in. wheels are pressed on to axles of
miniature railroad type, with M.C.B. type boxes and
springs. Spring draught gear is used with non-jamming
coupling links and pins. The body is so sloped as .to
facilitate operation on inclines without excessive spilling
of coal, and back-end corners are angled off in order to
prevent injury to the trip-rider in setting the brakes.
The cars stand only 35 in. above the rails, are 11 ft. 4 in.
long over the bumpers, and weigh about 4,000 lb. They
run on the comparatively narrow track gauge of 36 in.
The seam varies between 6J and 7 ft. in thickness, and
the pitch is usually in 100 in the mine where these
cars are used.

Figs. 9 to 12 show a car that is used in very thin
seams. It stands only 19 in. above the rail, and has
a capacity of 16 cu. ft. This car is sometimes made
with a flare board only 6 in. wide, instead of 11J in.
as shown, bringing the height of the car above the rail
down to about 15 in. This car runs on a 36 in. track
gauge, and the cost complete is approximately £5
(25 dols.).

Figs. 13 to 16 show a car used by the Houston Coal
and Coke Company in the Pocahontas coal field. This
car has a wooden bottom and steel sides, is fitted with
roller-bearing wheels, and costs approximately £22 12s.
(110 dols.). It has a capacity of 104| cu. ft., and runs
on a 44 in. track gauge.

The dust-proof steel car without end door is rapidly
coming into use, and is emptied into a rotary tippler.
But where trains of cars are hauled to the outside from
drift or slope openings, long tipplers, capable of dumping
18 to 20 cars at a time without detachment from the
haulage rope, are being installed, where main or main-
and-tail rope haulage is used. With this arrangement a
trip of empty cars, standing on the surface, is not
necessary, and fewer cars are required.

Mine Car Wheels.

As a rule, both the axles and the wheels revolve.
There are numerous types of wheels in use. The Hyatt
flexible roller-bearing is comparatively new in mine car
work, but has given successful service for many years
in shafting and machine work. A popular wheel is the
“ Whitney Wonder.” Prior to 1908, roller-bearing
wheels had not proved to be very successful, and it
was only in 1913 that this wheel came into prominence.
Actual tests have shown that this wheel has doubled
the speed of the locomotive haulage, and saved 58 per
cent, of electric power consumed, in comparison with
the solid hub wheel working under similar conditions.

Referring again to large cars and wide tracks, the
advantage claimed in West Virginia for the 56|-in.
track is that with this width of gauge the car may be
made lower, and at the same time there need not be so
great an overhang over the wrheels. A larger wheel can
also be used. If the car were made wide at the top
it would be awkward and top heavy with a narrow track
gauge, and would require too much weight to support
the sides where they projected over the wheels. But
by using the wide track a low strong car of large capacity
can be obtained. It is easier to load a low car than a
high one, because there is more clearance over the top
of the car, and the filler does not have to raise his shovel
so high. Larger lumps can be used for topping, because
there is more room for the larger lumps to go in.

The Mine Track.

The haulage roads in mines now receive more atten-
tion than formerly. In bituminous mines 20 years
ago rails weighing 20 lb. to the yard were used on main