IMPROVEMENTS IN TUNNELLING AND QUARRYING SLATE AND APPARATUS THEREFOR." PROAL
Year: 1882

page_text: LETTERS PATENT to George Hunter of Egham in the County of Surrey for
an Invention of "IMPROVEMENTS IN TUNNELLING AND QUARRYING SLATE
AND APPARATUS THEREFOR."
PROVISIONAL SPECIFICATION left by the said George Hunter at the Office
of the Commissioners of Patents on the 3rd July 1882.
GEORGE HUNTER of Egham in the County of Surrey
TUNNELLING AND QUARRYING SLATE AND APPARATUS THEREFOR'
IMPROVEMENTS, IN.
"
In the Specifications to Letters Patent granted to W. F Cooke and me on the
12th February 1866 N° 433 and to Letters Patent granted to W. F. Cooke on
the 11th September 1867 N° 2580 are described machines for boring circular
tunnels in slate rock and for undercutting or cutting a chase or groove in the
face of the rock so as to facilitate its removal in blocks fit for working into slates
or slabs. My invention relates to improvements in apparatus of the kind described
in the Specifications above referred to, and to nodes of employing the improved
apparatus so as to quarry slate cheaply and rapidly and obtain it in pieces of form
and size suitable for being worked into commercial slates or slabs.
In constructing the tunnelling machine I employ as framing two three armed
end frames connected together by a central tube. The arms of the frames are
provided at their ends with setting screws which can be screwed against the
interior surface of the part of the tunnel already bored so as to secure the machine
firmly in position. Two of the arms of each end frame, namely those which
extend obliquely downwards have mounted on them wheels or rollers on which the
machine can be run along the floor of the tunnel, when the setting screws are
released. Through the central tube passes a strong shaft which carries at its end
a two armed boring bead, each arm having at its outer end a circularly curved
plate at the front edge of which are fixed the cutters. The shaft is caused to
revolve slowly by a worm working a worm wheel on the shaft, the worm being
itself on a cross shaft mounted in bearings in the upper part of the frame. This
cross shaft or a shaft geared to it or connected to it by a strap may be driven by

page_text: bands from a distant motor or by a compressed air engine mounted on the framing.
By this arrangement of three armed framing having the lower arms spreading out,
and having all the gearing above the central shaft, great convenience is secured for
the removal of the core of the boring after it is detached from the rock. For
feeding the boring head onwards I apply at the rear end of the central shaft a screw
driven at a differential speed or kept at rest while the shaft revolves, and I apply
gearing to reverse this screw so as to withdraw the boring head rapidly when it
has cut its full depth.
The undercutting machine is according to my invention arranged so that it can
cut either above or below or both above and below the mass of rock that is to be
removed. For this purpose I provide a vertical shaft mounted in a framing and
caused to revolve by worm gear which may be worked as that of the tunnelling
machine. This vertical shaft has at either of its ends or at both ends a revolving
saw armed with cutters at its edge, either saw being removeable and capable of
⚫ being slid a little lengthwise along the shaft, so that the distance between the saws,
when both are used, can be varied when required. The frame is fitted to slide
along two horizontal bars secured to girders which are fixed in the working, and a
feed screw is provided to cause it to slide slowly along the bars according as the
cut effected by the saw advances. I arrange the frame so that the bars can be
inclined, and I employ them so inclined for beginning the cut the saw entering the
rock obliquely from a part already opened until it has descended in an inclined line
to the required depth, whereupon the bars can be set level, and the cut continued
in a horizontal direction. When the saw shaft and gear have travelled along the
bars to their end the screws that fix the framing are released and while the saws
remain stationary in the rock the framing is advanced its own length, and when it
is fixed again the cut is continued. By arranging the lines of cut so as to cross
the cleavage of the slate, blocks can readily be separated by the chisel from the
body of the rock, and when two saws are employed together, or when one saw is
employed under a floor already laid bare it is advantageous to make the space
between the saws or the depth of cut under the floor correspond with a dimension
of commercial slates or slabs so that the blocks separated can be cleft without
material waste.
In cases where a floor is already cleared, the saw spindle may be driven by a
wheel of considerable size as it may partly extend over the cleared floor while the
saw is cutting at the desired depth below the floor..
•
The tunnelling machine can be used to drive a boring into the body of the slate,
and then after clearing a space it can be turned into an attitude to drive other
borings at angles to this so as to suit the character of the stratification, and the
saws can then be employed to cut into the exposed faces, leaving pillars where
necessary to support the roof.
Sometimes in order to separate a mass along which saw cuts have been run I
employ the following method. A bar made in halves has each half hollowed so
that when the two halves are put together they present an internal cavity, this
hollow I charge with explosive and insert the bar along the bottom of the saw cut
so that when the explosive is fired the mass receives from the explosion a blow
which separates it from the body of the rock.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said George Hunter in the Great Seal Patent Office on the
30th December 1882.
GEORGE HUNTER of Egham in the County of Surrey. "IMPROVEMENTS IN
TUNNELLING AND QUARRYING SLATE AND APPARATUS THEREFOR
"
In the Specifications to Letters Patent granted to W. F. Cooke and me on the
12 February 1866 N° 433 and to Letters Patent granted to W. F. Cooke on the
11th September 1867 N° 2580 are described machines for boring circular tunnels
in slate rock and for undercutting or cutting a chase or groove in the face of the
rock so as to facilitate its removal in blocks fit for working into slates or slabs.
My invention relates to improvements in apparatus of the kind described in the
Specifications above referred to, and to modes of employing the improved apparatus
so as to quarry slate cheaply and rapidly and obtain it in pieces of form and size
suitable for being worked into commercial slates or slabs.
In constructing the tunnelling machine of which Fig 1 is an end view and
Fig 2 a longitudinal section, I employ as framing two three armed frames A¨ A
connected together by a central tube B. The arms of the frames A are provided
with setting screws a which can be screwed against the interior surface of the part
of the tunnel already bored so as to secure the machine firmly in position. The
two lower arms bave mounted on them wheels or rollers a¹ on which the machine
can be run along the floor of the tunnel when the setting screws a are released.
Through the tube B passes the shaft C which carries at its end a two armed boring
head D each arm having at its outer end a circularly curved plate d at the front
edge of which are fixed the cutters which form an annular groove in the face of the
rock. It is of advantage also to fix on the arms D cutting tools d¹ to give clearance
for the withdrawal of the boring head. The shaft C is caused to revolve slowly by
worm gearing c the worm being on a cross shaft E mounted in bearings on the
upper part of the hinder frame. The shaft E or a countershaft e geared to it as
shewn may be driven by straps from a distant motor or by a compressed air engine
mounted on the framing. The construction of the frames with their lower arms
spreading out, and the arrangement of the driving gear above the centre give
great convenience for the removal of the core of the boring after it is detached
from the rock. For feeding the boring head onwards I apply at the rear end of the
shaft a screw F driven at a differential speed or kept at rest while the shaft
revolves, and I apply gearing f to reverse the rotation of the screw so as to
withdraw the boring head rapidly when it has cut the full depth.
The undercutting machine is according to my present invention arranged so that
it can cut either above or below or both above and below the mass of rock that is
to be removed Fig 3 shews the machine mounted in the tunnel and cutting
laterally into the rock a plan of the machine being shewn at Fig 3ª. Fig 4 shews
it advanced beyond the side of the tunnel into the lateral cutting, Fig 5 is a side
view partly in section and Fig 5* a plan of a modified form of the machine. In
the form shewn in Figs 3 and 4 there is a vertical shaft G mounted in a framing
and caused to revolve by worm gear ġ which may be worked as that of the
tunnelling machine. The shaft G has at either of its ends or at both of its ends as
shewn a revolving saw armed with cutters at its edge, either saw being removeable
and capable of being slid a little lengthwise along the shaft, so that the distance
between the saws, when both are used, can be varied. The frame is fitted to slide
along two horizontal bars I secured to girders which are fixed in the working, and
a feed screw K causes the machine to slide slowly along the bars according as the

page_text: cut effected by the saws advances. Sometimes it is necessary to cut at a level
below that of a part of the rock already opened. In such a case I set the bars I in
an inclined direction and cut downwards on the slope to the required depth,
whereupon the bars can be set level and the cut can be continued in a horizontal
direction. When the frame carrying the saw shaft and gearing has travelled along
the whole length of the bars I the screws that fix the framing of the bars are
released, and while the saws remain stationary in the rock, the bars with its
framing are advanced, and being again fixed the cut is continued. In the modified
form of machine shewn in Figs 5 and 5 the saws revolve round central bosses h.
and are driven by pinions on a vertical shaft G worked by worm gear g. The
frames carrying the saws can be separately caused to turn round the vertical
countershaft G by means of worm gearing L, and thus the saws may be made to
cut in a circular path. In using such machines it is of advantage to make the lines
of cut cross the cleavage of the slate, so that blocks can be readily separated from
the body of the rock by the chisel. Also when two saws are employed together or
when one saw is employed to cut under a floor already laid bare it is advantageous
to make the space between the saws or the depth of the cut under the floor
correspond with a dimension of commercial slates or slabs so that the blocks can
⚫ be cleft without material waste Fig 6 is a side view and Fig 7 a plan of the
undercutting saw arranged in a manner similar to that described with reference to
Fig 5, the dotted line R in Fig 7 shewing how the cut may be carried in a circular
as well as in a straight path. Fig 8 is a side view, Fig 9 a part front view and
Fig 10 is a plan shewing an arrangement of framing for the double saws cutting
vertically down the side of a pit. It is often of advantage to run into the rock a
chase sufficiently wide to admit the shaft and boss of the saw, for which purpose I
arrange the undercutting machine as shewn in front view at Fig 11 and part plan
at Fig 12. In this case I provide a second vertical shaft L on which I fix a cutting
head of cylindrical form, armed with cutters which are preferably arranged helically
upon it. This head being caused to revolve more rapidly than the saw which is
driven by reducing gear from it, cuts a chase as shewn in Fig 13 in which chase
it is followed by the saw. The cutting head on L is in this case shewn to be
enlarged at its lower end so as to cut the chase at its lowest part wide enough to
admit the boss of the saw. By making this enlarged part of the chase of some
depth I am enabled to use it as a guide for the saw spindle by giving lateral
bearing for a roller M mounted on the spindle.
.
I have thus described various forms of the machines which I have found most
convenient for the usual quarrying operations, but it is obvious that the forms and
proportions of their framings may be modified to suit particular cases. In general
the sequence of operation with them may be as follows. The tunnelling machine
can be used to bore into the body of the rock to any required depth. A space can
then be cleared and the machine can be turned into such attitudes as to carry
borings at angles to the initial bore so as to suit the character of the stratification.
The saws can be employed to cut into the exposed faces of the tunnel as indicated
in Fig 3, or to extend the lateral cut as in Fig 4. In many cases it is of advantage
to sink a vertical shaft for access to the rock, and then the saws can be used to cut
vertically along the sides of the shaft as shewn in Fig 8.
In Witness whereof I the said George Hunter have hereunto set my hand
and seal this Twenty Seventh day of December in the year of our Lord
• One thousand eight hundred and eighty-two