IMPROVEMENTS IN PERCUSSIVE ROCK DRILLS
Year: 1876

page_text: LETTERS PATENT to Frederick Edward Blackett Beaumont, of No. 2, West-
minster Chambers, Victoria Street, Westminster, in the County of Middlesex,
and Joseph Foster, of St. Paul's Square Works, Preston, in the County
of Lancashire, for the Invention of "IMPROVEMENTS IN PERCUSSIVE ROCK
DRILLS."
Sealed the 16th September 1876, and dated the 31st March 1876.
PROVISIONAL SPECIFICATION left by the said Frederick Edward Blackett
Beaumont and Joseph Foster at the Office of the Commissioners of Patents on
the 31st March 1876.
FREDERICK EDWARD BLACKETT BEAUMONT, of No. 2, Westminster Chambers
Victoria Street, Westminster, in the County of Middlesex, and JOSEPH FOSTER, of
St. Paul's Square Works, Preston, in the County of Lancashire. "IMPROVEMENTS
IN PERCUSSIVE ROCK DRILLS."
In the Specification to a Patent granted to the said F. E. B. Beaumont on the
2nd April 1874, No. 1149, was described a construction of percussive rock drill
worked by fluid pressure, the cylinder ports whereof were governed by a cylindrical
slide moved by the pressure of the working fluid in accord with the movements of
the drill piston.
Our Invention relates to improvements in the construction of the said kind of
drill, whereby we are enabled to obtain greater simplicity and compactness of
structure, and greater efficiency and durability in working, as we will now
describe.
Instead of making the slide in several parts, which in consequence of the swells
or collars on the slide it was necessary to do for the purpose of introducing it into
the slide jacket, and coupling these parts together, we make the slide in one piece
with a single swell in its middle, presenting an annular area on each side on which
the working fluid alternately presses so as to move the slide, and we line the slide
jacket with two sleeve pieces, one at each end thereof, having ports formed in them.
As these sleeve pieces can be placed in the jacket along with the slide or after the
slide has been inserted, we are thus enabled to make the slide in one piece, and this
construction enables us also to make the cylinder and slide jacket in one piece. The
slide thus constructed is according to one arrangement made tubular and open at
[Price G 1

page_text: T
both ends to the atmosphere so as to serve as a discharge or exhaust passage for the
working fluid, which on issuing from the cylinder ports enters the interior of the
slides through numerous holes drilled in its middle swell.
According to another arrangement the piston being made as before double or
having a groove or hollow in its middle, we place the hollow permanently in com-
munication with the atmosphere by a passage formed by drilling a hole longi-
tudinally along the piston rod with a side opening to the air outside of the stufling
box, and also a side opening to the middle hollow or groove of the piston. By this
arrangement we dispense with the use of the interior of the slide as an exhaust
passage, and we are enabled materially to shorten the cylinder and the whole
apparatus. We provide elastic buffers at the ends of the slide jacket to receive the
blow of the ends of the slide at each end of its stroke instead of the buffers
formerly used to take the blow of the slide collars.
For advancing the drill apparatus, as the hole drilled by it becomes deeper, we
employ the following arrangement: We extend the piston rod through a stuffing
box in the back cover of the cylinder and taper its end nearly to a point; on this
projecting end of the piston rod a spring presses a roller mounted on a transversely
sliding pawl which engages with a ratchet wheel that works the advancing screw.
As long as the roller bears against the parallel part of the piston rod the pawl does
not move the ratchet wheel, but when owing to the deepening of the hole the
forward stroke of the piston rod is extended, then the roller bearing against the
taper part of the piston rod gives motion to the pawl, which in its return stroke
works the ratchet wheel and thereby turns the advancing screw, causing the
apparatus to advance in proportion as the hole in the rock is drilled deeper.
For securing the drill to the end of the piston rod we fix on the latter a ring
having in it a setting screw which bears upon a wedge picce let into a slot in the
side of the piston rod. The shank of the drill being inserted into the end of the
piston rod which is bored for its reception is secured in its place by the wedge
piece which is pressed by the setting screw of the ring against the shank of the drill.
In cases where the rock to be drilled is nearly uniform in hardness, we sometimes
modify the arrangement for advancing the drill in the following manner :--We
mount the advancing screw in line with the axis of the drill cylinder, fitting it
to work in a nut which is held in position longitudinally by a collar in the cylinder
cover, but which projects into the centre of the piston, and is made with a slot or
featherway so that it must revolve with the piston while the piston can slide
along it.
We provide the usual means for causing the drill and piston to turn partly round
at each stroke, that is to say, inclined slots on the piston rod entered by feathers in
the boss of a ratchet wheel, and the piston and the nut being thus caused to make
part of a revolution at each stroke the nut working on the fixed screw causes the
cylinder piston and drill to advance a certain distance at each stroke. This con-
struction enables us to dispense with separate ratchet mechanism for feeding, and to
get the direct thrust of the feeding screw acting centrally. When this arrangement
is adopted we make the inclination of the slots on the piston rod chiefly at their
back ends so as to permit a certain amount of forward stroke to be made without
feeding, and we arrange the feathers in the ratchet wheel so as to accommodate
themselves to the variation in the obliquity of the slots. By this arrangement of
central feeding screw a certain advance of the drill is effected at every complete
back stroke so long as the screw on which the feed nut works is prevented from
revolving. By slacking the said screw so as to permit it to revolve more or less
along with its nut, the advance of the drill may be varied, and the tightoning of the
screw may be made to depend on the extent of the forward stroke of the drill so as
to regulate the advance of the apparatus according to the depth of hole drilled.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said Frederick Edward Blackett Beaumont and Joseph Foster in the Great
Seal Patent Office on the 29th September 1876.
FREDERICK EDWARD BLACKETT BEAUMONT, of No. 2, Westminster Chambers,
Victoria Street, Westminster, in the County of Middlesex, and JOSEPH FOSTER, of
St. Paul's Square Works, Preston, in the County of Lancashire. IMPROVEMENTS
IN PERCUSSIVE ROCK DRILLS."
"
In the Specification of a Patent granted to the said F. E. B.. Beaumont on the
2nd April 1874, No. 1149, was described a construction of percussive rock drill
worked by fluid pressure, the cylinder ports whereof were governed by a cylindrical
slide moved by the pressure of the working fluid in accord with tho movements of
the drill piston.
Our Invention relates to improvements in the construction of the said kind of
drill, whereby we are enabled to obtain greater simplicity and compactness of
structure, and greater efficiency and durability in working, as we will now
describe.
Instead of making the slide in several parts, which in consequence of the swells
or collars on the slide it was necessary to do for the purpose of introducing it into
the slide jacket and coupling these parts together, we make the slide in one piece,
with a single swell in its middle, presenting an annular area on each side on which
the working fluid alternately presses so as to move the slide, and we line the slido
jacket with two sleeve pieces, one at each end thereof, having ports formed in them;
as these sleeve pieces can be placed in the jacket along with the slide or after tho
slide has been inserted; we are thus enabled to made the slide in one piece, and this
construction enables us also to make the cylinder and slide jacket in one piece.
The slide thus constructed is, according to one arrangement, made tubular and open
at both ends to the atmosphere so as to serve as a discharge or exhaust passage for
the working fluid, which on issuing from the cylinder ports enters the interior of
the slide through numerous holes drilled in its middle swell.
According to another arrangement, the piston being made as before described,
double, or having a groove or hollow in its middle, we place the hollow permanently
in communication with the atmosphere by a passage formed by drilling a hole
longitudinally along the piston rod, with a side opening to the air outside of the
stuffing box, and also a side opening to the middle hollow or groove of the piston.
By this arrangement we dispense with the use of the interior of the slide as an
exhaust passage, and we are enabled materially to shorten the cylinder and the
whole apparatus. We provide clastic buffers at the ends of the slide jacket to
receive the blow of the ends of the slide at each end of its stroke instead of the
buffers formerly used to take the blow of the slide collars.
For advancing the drill apparatus as the hole drilled by it becomes deeper we
employ the following arrangement-We extend the piston rod through a stuffing
box in the back cover of the cylinder, and taper its end nearly to a point. On this
projecting end of the piston rod a spring presses a roller mounted on a transversely
sliding pawl which engages with a ratchet wheel that works as a nut on the
advancing screw. As long as the roller bears against the parallel part of the piston
rod the pawl does not move the ratchet wheel, but when, owing to the deepening
of the hole, the forward stroke of the piston rod is extended, then the roller,
bearing against the taper part of the piston rod, gives motion to the pawl, which
in its return stroke works the ratchet wheel, and thereby turns the nut on the
advancing screw, causing the apparatus to advance in proportion as the hole in the
rock is drilled deeper.
For securing the drill to the end of the piston rod we fix on the latter a ring,
having in it a setting screw which bears upon a wedge piece let into a slot in the
side of the piston rod. The shank of the drill being inserted into the end of the
piston rod which is bored for its reception, is secured in its place by the wedge

page_text: piece which is pressed by the setting screw of the ring against the shank of the
drill.
In cases where the rock to be drilled is nearly uniform in hardness we sometimes
modify the arrangement for advancing the drill in the following manner :-We
mount the advancing screw in line with the axis of the drill cylinder, fitting it to
work in a nut which is held in position longitudinally by a collar in the cylinder
covers, but which projects into the centre of the piston and is made with a slot or
featherway so that it must revolve with the piston while the piston can slide
along it.
We provide the usual means for causing the drill and piston to turn partly round
at each stroke, that is to say, inclined slots on the piston rod entered by feathers
in the boss of a ratchet wheel, and the piston and the nut being thus caused to
make part of a revolution at each stroke the nut working on the fixed screw
causes the cylinder piston and drill to advance a certain distance at each stroke.
This construction enables us to dispense with separate ratchet mechanisın for
feeding, and to get the direct thrust of the feeding screw acting centrally. When
this arrangement is adopted we make the inclination of the slots on the piston rod
chiefly at their back ends so as to permit a certain amount of forward stroke to be
made without actuating the feed, and we arrange the feathers in the ratchet wheel
so as to accommodate themselves to the variation in the obliquity of the slots. By
this arrangement of central feeding screw a certain advance of the drill is effected
at every complete back stroke so long as the screw on which the feed nut works is
prevented from revolving. By slacking the said screw so as to permit it to revolve
more or less along with its nut, the advance of the drill may be varied, and the
tightening of the screw may be made to lepend on the extent of the forward
stroke of the drill so as to regulate the advance of the apparatus according to the
denth of hole drilled
Fig. 1 shews a side elevation of one arrangement of our before described rock
drill; Fig. 2, a sectional plan; Figs. 3, 4, and 5, transverse sections taken respectively
on the lines X, X, Y, Y, and Z, Z, Fig. 2.
A is the drill cylinder with piston B and piston rod C to which the drill is
attached. At the side of the cylinder A is the valve casing D containing the piston
valve E that regulates the admission and exhaust of fluid pressure to and from the
cylinder. This piston valve has a piston El formed at its middle working in a
chamber D in the valve casing; this chamber is formed by the introduction of two
cylindrical lining pieces D², De, from each end of the valve casing, the pieces being
of such a length as to leave a space between them forming the chamber D. The
parts of the valve E, E, on each side of the piston E¹ fit the inside of the lining
pieces D accurately, having packing rings as shewn to prevent the escape of fluid
pressure.
At E, E, annular recesses are formed on the valve, which recesses
communicate with the fluid pressure entering the valve casing through passages F
(Figs. 2 & 4) connected by the pipe F1, and a flexible or jointed pipe with the
reservoir for fluid pressure. The valve casing communicates with the cylinder A,
firstly, by ports G, G, at each end; and secondly, with ports G, G³, at the middle
communicating with the chamber D¹.
The drill piston B has an annular recess B¹ round its middle which is in constant
communication with the atmosphere, by means of a longitudinal passage B2 in the
piston having side passages B3, B4, at each end communicating respectively with
the recess B and the atmosphere. The ends of the valve casing E also communicate
with the atmosphere by openings D. From this arrangement it will be seen that
if the piston is nearly at the end of its back stroke the port G will cominunicate
with the recess B', and the pressure on that side of the valve piston Et will
consequently be equal to that of the atmosphere, while the pressure on the other
side of the piston E¹ will be equal to that of the fluid pressure in the front end of

page_text: the cylinder, as the piston B will in its motion to the left have uncovered the port G³.
By this difference of pressure on each side of the piston E' the valve E will be moved
to the left from the position shewn in the Drawing, whereby the back end of the
cylinder A will be put in communication with the space E by the port G, so that
fluid pressure will now enter that end of the cylinder, while the front end of the
cylinder will be made to communicate through the port G¹ with the space at the
end of the valve chamber which is in communication with the atmosphere, so that
the fluid pressure will escape from that end of the cylinder.
In order to afford a rapid exhaust the ports G, G₁, cominunicate with annular
passages round the lining pieces D2, which passages communicate through a number
of holes with the interior of the valve casing, as shown. The piston B will now
make its forward or working stroke, thereby again reversing the communications
of the ports G2, G3, and causing the valve to move over to the right, and this in its
turn will cause the piston B to perform its back stroke again. At each end of the
cylinder A as also of the valve casing E are provided buffers H, II', consisting of
rings of caoutchouc covered by metal plates, and leather to receive the blow of the
piston and valve at the end of each stroke.
It will be seen that by constructing the valve casing with the lining pieces De
the whole of the valve E can be made in one piece, the parts De being inserted into
the valve casing either at the same time as or after the valve is introduced, and
secured in position by the covers of the valve casing which are formed in one piece
with the covers A, A, of the cylinder A. The piston valve E is made hollow, as
shewn for the sake of lightness; its one end has a screwed socket E" into which can
be screwed a rod passed through a hole in the valve cover, for the purpose of
moving the valve by hand if required.
The advance of the drill cylinder and drill as the bore hole deepens is effected as
follows:—The drill cylinder is arranged to slide to and fro on a plate I which is
connected by a circular base I' to a saddle on the drill stand. The plate I carries a
screw spindle K which passes through a screwed bush L, capable of revolving
inside a sleeve M formed on the side of the drill cylinder. The bush L projects
beyond the sleeve at each end, having at the one end a screwed collar and at the
other end a ratchet wheel N fixed on it. In gear with this ratchet wheel is, firstly,
a pawl O carried by the sleeve M which prevents the ratchet wheel, and con-
sequently the bush L from turning in one direction; and secondly, there is a pawl P
carried by a slide P¹ through a loop of which passes a rod C extending from the
back end of the piston through the cylinder cover, and having its end tapered as
shewn. The slide P₁ is carried by a bracket on the cylinder cover which has a
spring Qtending to draw the slide backwards, and consequently to draw back the
pawl P over the teeth of the ratchet wheel; this motion is however prevented by a
roller P on the slide bearing against the rod C, so long as this does not travel
sufficiently far at the forward stroke of the piston to bring its tapering end through
the loop of the slide. When, however, owing to the deepening of the bore hole the
forward stroke of the piston carries the tapering end of Cthrough the loop,
the slide and pawl will be drawn back sufficiently for the pawl to fall into the
next tooth of the ratchet wheel, and on the next back stroke of the piston the rod C¹
in passing back through the loop will push the pawl and slide forward into their
original position, whereby the pawl will be made to turn the ratchet wheel and
bush L partially round upon the screw K, thus causing the drill cylinder to advance
on its slide I. From this arrangement it will be seen that the advance of the drill
cylinder is rendered entirely dependent on the deepening of the bore hole, the
screw K is prevented from rotating by a pin K¹ passed through the screw at its
bearing.
For drawing back the drill cylinder again when the bore hole is completed the
pin K¹ is removed and the screw spindle is rotated by hand, the bush L being
caused by a bolt R pressing against the side thereof, to move with sufficient friction
in the sleeve to prevent the bush from turning when the screw K is rotated.
partly rotating the drill at each back stroke the piston rod C has formed in its
For

page_text: front end, firstly, two oblique grooves C², C³, in which fit studs or feathers in
a ratchet wheel S through which it passes, and secondly, it has two parallel
grooves C³, C3, into which fit feathers in a second ratchet wheel T. Both ratchet
wheels being prevented by spring pawls U from rotating in one direction, it will be
seen that during the back stroke the oblique grooves C2 in passing through the
ratchet wheel S will cause the piston rod, piston, and drill, to turn slightly in the
direction of the arrow, Fig. 5, S being prevented by its pawl from turning in the
contrary direction, while T is carried round by C in the direction of the arrow.
During the forward stroke the piston rod is prevented from turning back again by
the ratchet wheel T, which is held against such motion by its pawl S, being on the
other hand made to revolve in the direction of the arrow as the oblique grooves C
pass through it.
The piston rod C is formed with a socket at its end, into which
fits the end of the drill spindle, this being secured therein by means of one or more
screws V screwing through a ring V1 and bearing upon a wedge picec V2 let into
a slot in the side of the piston rod, so as to be pressed by the screws against the
drill spindle.
In
Fig. 6 shews a longitudinal section; Fig. 7, a cross section on line X, X; and
Fig. 8 a part plan of a modified arrangement of our before described rock drill.
this case the screw spindle K for advancing the drill cylinder A on its slide I is in
line with the axis of the cylinder, being held in the bridge piece I fixed to the
slide, and passes through an internally screwed tube L, which is held by a collar in
the cylinder cover in such a manner that it is free to rotate but cannot move
longitudinally. This tube projects into the hollow of the piston B, as shewn, and
is made with a slot into which fits a feather in the hollow, so that the tube must
turn with the piston while this can slide to and fro upon it. The piston rod has,
similar to the previous arrangement, an oblique slot C acting in combination with
a ratchet wheel S held by a pawl U for partially rotating the drill, piston rod, and
piston at the back stroke, so that during the back stroke the piston will. also
partially rotate the tube L, which in turning upon the fixed screw spindle K will
cause the drill cylinder to be advanced.
The slot C is formed, as shewn in the part plan at Fig. 8, with the front part
parallel or nearly so to the axis of the rod, the curvature being confined to the back
end. By this means the turning of the piston rod and piston, and consequently
the forward motion of the drill cylinder, will only be effected when the bore hole
has become sufficiently deepened to cause the back part of the piston rod having
the curved part of the slot to pass through the ratchet wheel S; the stud S¹ in the
ratchet wheel which fits into the slot is free to turn on a pin, so as to adjust itself
to the variation in the obliquity of the slot.
The second ratchet wheel, described in the former arrangement, for preventing the
turning back of the piston and piston rod at the forward stroke is here dispensed
with, as the tube L turns with sufficient friction on the screw K to prevent this.
The piston valve E is in its action similar to that of the first described arrangement,
but instead of the communication between the atmosphere and the annular recess B¹
of the piston being effected by means of passages through the piston rod, it is
effected by means of an opening A³ in the middle of the cylinder communicating
with an annular space D in the valve casing and with a passage A* opening to the
atmosphere. The ends of the valve casing D are closed, and the exhaust from the
cylinder at the end of each stroke passes from the ports G, G¹, into the hollow of
the piston valve E, whence it escapes through the perforations E into the annular
passage D', and thence through A' into the atmosphere. The fluid pressure is
introduced into the annular recesses E, E³, through the passages F. The ring V¹
for securing the drill spindle in its socket is in this case hinged at V³, and the two
halves are drawn together by a screw at V, so as to press the wedge piece V
against the drill spindle. The other parts of the machine are indicated by
the same letters of reference as the first described one and need not be further
described.
Having thus described the nature of our Invention and in what manner the same

page_text: is to be performed, we claim in respect of percussive rock drills of the kind herein
described,-
First. Arranging the piston valve in combination with cylindrical lining pieces to
the valve casing, so that the entire valve can be made of one piece, substantially as
herein described.
Second. Constructing the piston valve hollow, and with perforations at its middle
operating in combination with an annular passage in the valve casing, so as to serve
as a passage for the exhaust of the drill cylinder, substantially as herein described
with reference to Figs. 6 and 7 of the Drawings.
Third. Constructing the drill piston rod with a longitudinal passage communicating
at one end with the atmosphere and at the other end with the annular recess in
the drill piston, whereby such recess is permanently in communication with the
atmosphere, substantially as herein described with reference to Figs. 1 to 5 of the
Drawings.
Fourth. The arrangement of advancing mechanism for the drill cylinder, consisting
of a rod with tapered end moving with the drill piston and operating in combination
with a slide carrying a pawl in gear with a ratchet wheel on the bush or nut of the
advancing screw, in such manner that the advance of the drill cylinder is only
effected when the piston performs its full stroke or nearly so, substantially as herein
described with reference to Figs. 1 to 5 of the Drawings.
Fifth. The arrangement of advancing mechanism for the drill cylinder, consisting
of a screwed tube or nut carried within the drill cylinder and rotated upon a
central fixed advancing screw by the rotation of the drill piston, such rotation being
effected by a groove on the drill piston curved only at its back end, and operating
in combination with a ratchet wheel with swivelling stud substantially as herein
described with reference to Figs 6 to 7 of the Drawings.
Sixth. The arrangement of the wedge piece V2 contained in a slot in the piston
rod and operating in combination with the ring V₁and screw V for securing the
drill spindle in its socket, substantially as herein described.
In witness whereof, I, the said Joseph Foster, have hereunto set my hand and
seal, this Twentieth day of September, in the year of our Lord One thousand
eight hundred and seventy-six.
JOSEPH FOSTER. (L.S.)