1114

THE COLLIERY GUARDIAN.

May 30, 1913.

haulage rope, which at the discharging position also
operates the mechanical end-discharge of the load (as
G-ibb’s).

2. A short carriage containing one tramload of coal ;
the operation of this carriage is similar to that of
Gibb’s, except that the discharge is through the floor,
and the rope haulage is operated by hand (as Bates’s). |

The advantages and limitations detailed with reference
to traveller conveyors have application also to the
power-driven carriage conveyor, but the provision in the
latter for delivering its load from either end distin-
guishes- it from all other conveyors. This type can
discharge the coal to a loading road at either end of the
face, or to a road in the centre, or any other inter-
mediate part of the face, or to two roads at the respec-
tive ends of the face. These features adapt this
conveyor to important services to which no other;
conveyors have yet been applied.

This conveyor may be loaded over its end (the chain !
being moved forward the while) at any part of the face,
and rubbish from falls may thus be rapidly cleared. |
This feature also adapts the carriage conveyor for
advancing end-on in the opening out of a face, or, while j
a coal-cutter is at work in coal, the conveyor may follow
it up for the removal of the holings, thus facilitating j
the clearance of maximum output during the filling
shift, or the conveyor may be at work on the filling
shift stripping the coal behind the coal-cutter as it
advances. The carriage conveyor delivers its load in
larger volume, and in shorter time than any other type,
so that the total amount of dust raised is less than
from those which discharge in smaller volumes during
longer time. This type can, owing to its shortness, be
well secured by timbering during stoppage of work in
times of holidays, strikes, &c.

Home-made Conveyors. — At some collieries where
treacherous roofs have occasioned loss by burying under
falls the steel framework of rigid full-length conveyors,
the management having experienced the economies of
the system have designed simple conveyors to suit their
own conditions. Many apparently crude expedients
have been devised, and are giving very good results,
because they are in the hands of the people who designed
and applied them, and who therefore have personal
interest in their success.

Auxiliary Conveyors.—In some cases where the nature
of the floor has precluded bottom ripping, auxiliary
conveyors in the gates have with advantage been used
to receive the coal from the face conveyor, and to raise
it to a height which permits of its discharge into trams.
In conjunction with traveller conveyors driven by main-
and-tail rope, the same motor may drive the face con-
veyor and the auxiliary conveyor in the gate. An
advantage incidental to auxiliary conveyors, of the
types that permit watering, is that in dusty seams the
dry coal from the face conveyor has a very low fall to
the auxiliary conveyor, and that the coal, well sprayed
with water at this first discharge, is damp when falling
from the greater height at the second discharge into the
trams, so that much less dust is raised.

Gate Conveyors.—Where ripping and maintenance of
loading-roads for face conveyors is expensive, gate con-
veyors of the endless chain or band types, and also of
the carriage type, have been used in narrow gates.
There are considerable possibilities of economy under
certain conditions in the more extensive application of
this system. The carriage type, in conjunction with a
carriage conveyor at the face, is especially adapted to
this service; in a narrow gate on a good track the
carriage may travel at the rate of about six miles per
hour at a distance of several hundred yards to the
loading station, and return while the face conveyor is
being refilled.

Power for Conveyors.—The cost of power for driving
conveyors has been referred to. This for full-length
conveyors is relatively high. Where electricity is the
motive power, the total cost is moderate. At an energy
cost of Id. per unit, the cost for eight hours for a
conveyor 100 yards long is about 3s. Where compressed
air is used the efficiency is much lower, and this is
emphasised by the fluctuating character of the load on
the air motor, because the amount of compressed air used
is more nearly proportional to the time of working than
to the load upon the motor. At a cost of 0 65d. per b.h.p.
delivered to the compressor (equivalent to Id. per unit
for electricity) the cost of power for eight hours’
running is about 10s., without allowing anything for
losses in transmission or leakage; providing for these
losses the cost is about 12s. for eight hours’ running.
However, the conveyor does not operate continuously.
The cost of power is usually overlooked in considering
conveying costs, but it will be seen that this is not a
negligible factor, especially for full-length conveyors
delivering only 50 to 60 tons per shift.

Hand-operated Conveyors.—In many thin seams

worked either by hand or by machine there is un-
doubtedly scope for hand-operated conveyors of the
carriage or of the tub type. The complications involved
in the use of power at the face, and the skilled super-
vision required, are seldom warranted where the output
per shift is less than 10 cwt. per lineal yard of face.

Causes of Failure and Essentials to Success.

Non-success may be attributed to any or all of the
following causes :—(1) Unfavourable physical conditions
at the working face; (2) unsuitability of the type of
conveyor selected, or to defects in its construction; (3)
lack of well-considered planning of the operations by
the superior officials ; (4) lack of interest or of
administrative ability and executive skill on the part of
subordinate officials; (5) inadequate transport arrange-
ments between the face and the pit-head.

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Fig. 2.—Conveyors on Hand operated Faces.

Fig. 3.

The writer ventures to think that machine mining by
coal-cutters and conveyors has a bearing upon colliery
administration which has not yet had adequate recogni-
tion. In nearly every other, industry there have been
during recent years immense developments in the pro-
ductivity of labour. These have been achieved by two
principal means : (1) by increased use of machinery, and
(2) by improved administration. The first is futile
without the second. The machinery must be controlled
by a higher order of executive ability and operative
skill. This argument cannot be elaborated here; it

must suffice to say that the organisation and personnel
which were good enough on hand-worked faces are not
good enough for machine mining.

When conveying as a mining policy is under con-
sideration at any colliery, a subject favourable to the
system should in the first instance be selected; not
necessarily the subject in which the prospective
economies are greatest, nor the one in which the known
difficulties will so tax the capabilities of the conveyor that
success in it will mean success in any other seam. One
of the impediments to the innovation is that suitable
preparation of the face and of the haulage facilities, and
the provision of adequate organisation involves con-
siderable expense. There is therefore a natural inclina-
tion to proceed tentatively, to get the conveyor started

TF/BLE n°I

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at the least outlay and to see how it will do, with the
intention to deal thoroughly with all the requirements
after the conveyor has shown its capabilities. This is
one of the roads to failure. It is very proper to exercise
caution in regard to the introduction of a system which
is pregnant with new and perplexing problems, but
when the step is decided the time for caution is past,
and a bold, determined and constructive policy is the
directest and surest means to success.

Mode of Operation.

Considerable controversy has centred on the relative
advantages of continuously-discharging conveyors, and
those of the traveller intermittently-discharging type.
It is true that the first-named type is capable of deliver-
ing at the rate of 30 to 40 tons per hour, but nobody
wants a face conveyer to deliver 300 tons per shift to