IMPROVEMENTS IN ROCK TUNNELLING AND IN APPARATUS EMPLOYED THEREIN
Year: 1879

page_text: LETTERS PATENT to Horbert Newton Penrice, of Hatfield, in the County of
Herts, for the Invention of "IMPROVEMENTS IN ROCK TUNNELLING AND IN
APPARATUS EMPLOYED THEREIN.”
Sealed the 19th August 1879, and dated the 28th February 1879.
PROVISIONAL SPECIFICATION left by the said Herbert Newton Penrice
at the Office of the Commissioners of Patents on the 28th February 1879.
HERBERT NEWTON PENRICE, of Hatfield, in the County of Herts. "IMPROVE-
MENTS IN ROCK TUNNELLING, AND IN APPARATUS EMPLOYED THEREIN."
This Invention relates to methods and appliances to be made use of in rock
tunnelling.
The apparatus which I employ consists of a massive cast iron bed; it is semi cylin-
drical on its under side, with a diameter of say 12 inches, so that it may rost
steadily in a channel of corresponding form produced at the bottom of the tunnel
or heading in my method or system of working. This bed carries by means of
suitable standards or supports, certain rock borers to prepare holes for the charges
employed to blast the rock.
The bed serves as a firm and steady abutment for the rock borers, which may be
separate apparatus, such as are now well known and in common uso, or they may
be permanently attached to the bed. The bed carries a small engine for moving it
forward and backward as required; the engine turns a screw passing through a nut
supported by an abutment in rear of the bed.
By means of the rock borers carried by this machine I produce in the working
face four principal holes, one a principal hole in the centre of the curvature of the
underside of the bed, and three other holes, one on each side and one above it. A
fifth machine serves to put in shallow holes around the entrance to the principal
hole and at a few inches from it. The main holes are driven as far into the face as
conveniently may be, and when they are complete the machine is run back and the
Price 6d1

page_text: principal hole is charged with blasting gelatine or the most effective explosive which
I am able to obtain. This charge being fired has the effect of enlarging the cavity
within without much increasing the size of the mouth. The cavity charged and
fired a second and third time with the effect of increasing its size within until it is
large enough to form the channel for the bed of the machine. The neck or narrow
entrance to the cavity is next enlarged by firing charges in it and in the shallow
holes around it. The leading opening being thus formed, the sides first and then
the top are forced in by blasting charges fired in the holes produced at the sides
and top as already described. An upper hole is subsequently made overhead with
the top drilling machine while the debris below is being removed, which being fired,
gives the necessary height to the heading.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Herbert Newton Penrice in the Great Seal Patent Office on the 28th
August 1879.
.
"IMPROVE-
HERBERT NEWTON PENRICE, of Hatfield, in the County of Herts.
MENTS IN ROCK TUNNELLING, AND IN APPARATUS EMPLOYED THEREIN."
This Invention relates to methods and appliances to be made use of in rock
tunnelling.
The apparatus which I employ consists of a massive cast iron bed; it is semi-
cylindrical on its under side, with a diameter of say 14 inches, so that it may rest
steadily in a channel of corresponding form, produced at the bottom of the
tunnel or heading in my method or system of working. This bed carries by
means of suitable standards or supports certain rock borers to prepare holes for the
charges employed to blast the rock.
The bed serves as a firm and steady abutment for the rock borers, which may be
separate apparatus, such as are now well known and in common use, or they may
be permanently attached to the bed. The bed carries a small engine for moving it
forward and backward as required; the engine turns a screw passing through a nut
supported by an abutment in rear of the bed.
By means of the rock borers carried by this machine I produce in the working
face four holes, one a principal hole in the contre of the curvature of the under side
of the bed, and three other holes, one on each side and one above it. A fifth
machine serves to put in shallow holes around the entrance of the principal hole
and at a few inches from it. The main holes are driven as far into the face as con-
veniently may be, and when they are complete the principal hole is charged with
blasting gelatine," or the most effective explosive which I am able to obtain.
This charge being fired has the effect of enlarging the cavity within without
much increasing the size of the mouth. The cavity is charged and fired a second
and a third time if necessary, with the effect of increasing its size within until it
is large enough to form the channel for the bed of the machine. The neck or narrow
entrance to the cavity is next enlarged by firing charges in it and in the shallow
holes around it. The leading opening being thus formed, the sides first and then
the top are forced in by blasting charges fired in the holes produced at the sides and
top as already described. An upper hole is subsequently made over head with the
top drilling machine while the debris below is being removed, which when fired
gives the necessary height to the heading.
In order that my Invention may be fully understood and readily carried into
effect, I will proceed to describe the Drawings hereunto annexed.
VEDVAR
Figure 1 is a longitudinal vertical section of a heading or tunnel in process of
formation by the method above described; it shows the enlarged principal hole or
cavity before the neck or entrance to it is broken away. A side view partly in
section of the machine is also shown in this Figure; Figure 2 is a transverse section
of the machine and of the heading or tunnel, showing the position of the holes in
the working face; Figures 3 and 4 are transverse sections, and Figure 5 is a plan
view of the machine; Figure 6 is a cross section of the tunnel with dotted lines
indicating the effect of the successive blasting operations.
a is the bed; b, the crank shaft of an air engine of any suitable construction; o
is the screw which is to pass through a nut carried by a fixed abutment. In the
machine shewn provision is made for turning the screw at different speeds, as

page_text: described in the Specification of a former Patent granted to me, No. 794, in the
year 1876, so as either to slowly feed the machine forward or move it more quickly
backwards or forwards whon the drills are not at work, but in most cases the
machines may be constructed with one feed motion only; d, d, are the air cylinders
used for giving a very rapid to and fro motion to the rock borers; e is a shaft
driven by bevil wheels at an increased speed from the crank shaft of the engine.
For controlling the admission of air to the cylinders of the rock borers, I uso by
preference valves such as described in my former Patent before mentioned, which
give two strokes of the drill for each to and fro movement of the valve, and I give
motion to the valves of the several rock-borors from one eccentric on the shaft e.
The motion for rocking or rotating the several drill stems may also be given by.
another eccentric g on the same shaft, or the drill stems may each be twisted in a
rifled bearing. Where a very rapid stroke is not required, in place of giving motion,
to the shaft e through multiplying gear from the crank axis of an air engine, .the
shaft e may itself form the crank shaft of the engine. The rock borers are worked
by compressed air led to them by flexible pipes, as is well understood.
The principal bore hole and the hole immediately above it are bored parallel to,
one another and in the direction that the heading or tunnel is being formed. The
two side holes must however be bored somewhat at an angle inclining downwards
and outwards to give room for the cylinders of the rock borers which bore these
holes when the machine is moved forwards to commence drilling a fresh set of holes.
To allow of these side holes being bored at an angle, the bearings h which support
the drill stems and the cylinders d of the rock borers which bore these holes are made
adjustable, so that as the bed moves forward during the boring of the holes the
cylinders and bearings may from time to time be moved downwards and outwards
so that the drill stems may always be kept working in the same straight line. The
length of the rods driving the valves of these cylinders will be adjusted by couplings,
as shewn. The bearings h are mounted, as shewn at Figure 3, on inclined parts of
the bed and can be moved by screws to and fro along these inclines.
The cylinders d of the rock borers for boring the side holes are carried by blocks
i. When at work these blocks can be moved a short distance outwards and down-
wards in a recess in a slide k. The blocks i have on their two opposite sides
inclined recesses o, into which enter corresponding projections from the sides of
the recess in the slide k; n, n, are screws by which the blocks i can be raised
or lowered as required; the screws pass through slots in the top and bottom of the
frame k, so that as the blocks i are raised or lowered and consequently at the same
time moved inwards or outwards the screw may move to and fro in the slots.
When it is required to draw the cylinders inwards sufficiently to allow of the
machine being freely moved forward a distance in the tunnel, the slides k can be
drawn inwards by turning the screws 1, 7; p is the cylinder of a rock borer for
boring the small holes r around the principal hole; this cylinder is mounted on a
pivots, which is concentric with the central line of the cylinder d employed for
boring the principal hole. The cylinder p can therefore be set in position for
boring any of the holes r. The valve for controlling the admission of air and its
escape from the cylinder may be worked by an eccentric u on the shaft e.
The cylinder & of the top drilling machine is carried by a vertical moveable stem
v, and can be raised or lowered for the purpose hereinafter mentioned by turning a
nut w on the screw . The guide for the drill stem of this drilling machine can
also be similarly raised and lowered.
The cross section, Figure 6, shews the effect of the successive blasting operations.
The principal hole is first enlarged by firing within it repeated charges until it is
approximately of the dimensions shewn by the dotted line 1, 1; the neck of the
hole is then enlarged to the same dimensions by firing charges introduced into it
and subsequently into the shallow holes by which it is surrounded. Charges are
then fired in the two side holes, forcing in the sides of the principal hole, as indicated
by the line 2, 2. In very hard rock it may be necessary to use the supplemental

page_text: cylinder z, to form an intermediate hole y on the right hand side of the tunnel,
which is left larger for the passage of the debris. For this reason the upper holes
are inclined to the right. The sockets of all the drill bars will strike the frame
before the pistons touch the back ends of the cylinders, and the air will be cushioned
at the front ends. The air will be gradually cut off from the drills which cut the
quickest to maintain as equal an advance as possible. Afterwards a charge is fired
in the hole above the principal hole and the material below this hole blown down-
wards, somewhat as represented by the dotted line 3, 3. While the debris thus
produced is being cleared away another hole at the top of the heading or tunnel
is bored and a charge finally fired in it, and the tunnel or heading brought roughly
to the form indicated by the full lines 5, 5.
By forming a tunnel or heading in the manner herein before described, the work
may be carried on very rapidly as the number of holes required to be bored is
reduced to a minimum, and the holes can be bored simultaneously, and powerful
fixed machines be used for working the drills.
When a tunnel is to be formed vertically through hard rock, as in sinking shafts,
the same system of working is followed; only in this case the principal hole is made
in the centre, and four side holes are bored at equal distances apart around it. The
principal hole is first enlarged by firing charges within it; the neck of the hole is
subsequently enlarged; charges are then fired in two opposite side holes and sub-
sequently in the two other side holes.
Having thus described the nature of my Invention, and the manner of performing
the same, I would have it understood that I claim,―
First. The method of producing a tunnel or heading in hard rock by the
following successive operations:-
==
1. Drilling by means of rock drills a principal hole, and two holes, one on either
side of it and also one above it.
2. Enlarging the principal hole by repeatedly charging and firing.
3. Removing the neck of the enlarged hole.
4. Forcing inwards into the principal cavity the rock at its sides and above it,
first that at the sides and then that at the top, leaving the bottom of the principal
cavity to serve as a guide or way for the bed of the boring mechanism.
Second. The apparatus for conducting the aforesaid operations, substantially as
described.
Third. Mounting the cylinders and guides of the rock borers used for boring the
side holes in such a manner that the cylinders and guides can be moved down-
wards and outwards as the machine moves forward, and so allow of these holes
being bored at an angle to the direction of the tunnel or heading.
Fourth. The modification of the method adopted for forming a tunnel when the
tunnel to be formed is a vertical one, substantially as herein-before described.
In witness whereof, I, the said Herbert Newton Penrice, have hereunto set
my hand and seal, this Twenty eighth day of August, in the year of our
Lord One thousand eight hundred and seventy nine.
T TENDIAN