IMPROVEMENTS IN ROCK DRILLS
Year: 1884

page_text: I ARTHUR WILLIAM LOVELL REDDIE of the Office for Patents 66 Chancery Lane
in the County of Middlesex Patent Agent do hereby declare the nature of my
Invention for "IMPROVEMENTS IN ROCK DRILLS" and in what manner the saine
is to be performed, to be particularly described and ascertained in and by the
following statement :-
The Invention relates to rock drills which are operated by steam or compressed
air.
The Invention consists in the novel combination with the cylinder and piston,
the cylinder having supply ports for admitting steam or other motive fluid to the
cylinder on opposite sides of the piston and an exhaust port situated between the
said supply ports and controlled by the piston, of an automatic valve for controlling
the admission of the motive fluid to the said supply ports as hereinafter inore fully
described.
The Invention also consists in a novel combination of parts hereinafter
particularly described whereby the piston is cushioned at each end of it's
movement.
The Invention also consists in a novel and simple combination of parts whereby
the rotation of the piston and drill-rod are effected.
The Invention also consists in the combination with the piston rod of a rock
drill, of a longitudinally divided cylinder head, having in its bore or interior an
annular groove for the reception of a packing and a tangential aperture or opening
extending from the exterior of the head into said groove and through which a
packing may be introducod as hereinafter more fully described.
The Invention also consists in a novel combination of parts for holding the
drill-rod in the chuck on the piston rod whereby the drill-rod will be clamped and
held at diametrically opposite points and concentric with the piston rod.
In the accompanying Drawing Fig. 1 represents a partly sectional side view of a
rock drill embodying my Invention, Fig. 2 is a transverse section on the dotted
line Fig. 1; Fig. 3 is a similar section on the dotted line y, y, Fig. 1; Fig. 4 is
a longitudinal section of the valve seats and a side view of the valve on a larger
scale; Fig. 5 is a transverse section of the valve on the dotted line 2, 2, Fig. 4;
Fig. 6 is a transverse section of the lower or front cylinder head and piston rod,
on the dotted line 1, 1, Fig. 1; Fig. 7 is a transverse section of the chuck and drill

page_text: rod on the dotted line 2, 2, Fig. 1; Fig. 8 is a side view of one of the clamping
bolts employed to hold the drill rod in the chuck and Fig. 9 is a plan of the drill.
Similar letters of reference designate corresponding parts in all the Figures.
A designates the back of the drill which is of ordinary construction and which is
secured in the usual way to a tripod or column, not here shewn, by a bolt a.
B designates the ported cylinder which is movable lengthwise of the back, in
ways or grooves b formed or provided in the back A and C designates the feed
screw which is mounted in a bearing 6', fixed to the back A and which may be
turned by a handle C. The feed screw engages with a nut b² secured in the
cylinder B, and by turning the screw in one direction or the other the cylinder
and all the parts carried thereby are fed forward or moved back in a well
understood manner.
.
D designates the piston which is provided with any suitable ring packing, and
which as here represented, is formed integral with the piston rod D¹. This piston
rod D¹ works through the lower or forward head B' of the cylinder B, and carries
at its lower or forward end a drill chuck D2 which may be secured upon the piston
rod D or formed integral therewith. When the chuck and the piston are both
formed integral with the rod D¹, I divide the forward head B' axially, or form it in
two longitudinal halves as best shewn in Fig. 9, the two halves or sections being
securely held together by bolts c to form the head.
The upper or back head B' of the cylinder consists of a solid and flat piece or
disc of metal made slightly larger. in diameter than the cylinder B, and rebated at
its periphery so as to project slightly into the cylinder and to slightly overlap the
end of the cylinder as shewn in Fig. 1.
E designates a piece of metal approximately annular in shape and made entirely
separate from and independent of the head B³, and formed with lugs or ears
through which are inserted bolts c¹ whereby the piece E is immovably secured to
the cylinder. The piece E has a hole through it for the passage of the feed
screw C, and as said piece is secured immovably and rigidly to the end of the
cylinder, it serves to retain the nut b' in its place in the cylinder, as shewn
in Fig. 1.
The piece E is bored out to the size of the head B2, and has within it an elastic
cushion E of rubber or analogous material which is externally about as large as the
head B and rests in contact therewith. This cushion is preferably annular so that
when compressed in a direction lengthwise of the cylinder it may crowd or expand
inwards.
F designates a "follower" which is formed with an annular rebate or shoulder c³
and enters the bore of the piece E.
The head B¹ and follower F are connected by bolts F' best shown in Fig. 9, and
the cushion E¹ serves to deaden a blow of the piston on either head B¹ or B³.
When the piston strikes the lower bead B the latter moves outward slightly,
and the follower F is moved inward, it being cushioned on E¹. When the piston
strikes the head B' the latter yields and moves outwards slightly, it being cushioned
on E¹.
It will be observed that inasmuch as the piece. E is rigidly secured to the
cylinder it cannot yield, and said piece therefore forms a guide wherein the head B
can move outward and the follower F can move inward, the cushion E¹ being
confined between the head and follower in the guide E.
The piston D is formed with, or has secured to it, an extension or head D³ which
is of a size to work freely in the cylinder and is somewhat longer than the length
of piston stroke. This head or piston extension D³ is grooved spirally from end to
end on its exterior, and the grooves are preferably ratchet shaped in cross section,
as shewn in Fig. 2.
G designates a spring actuated movable nut section, which as here shown
consists of a cylindric piece fitted in a socket or slideway B' which projects from
the side of the cylinder as shewn in Figures 2 and 9. The inner end of the nut G
is concave so as to approximate to the circumference of the piston extension D³

page_text: as shewn in Fig. 2 and in the inner end or face of said nut section, are teeth which
are adapted to engage with the spiral grooves of the piston extension as also shown
in Fig. 2.
It will be observed that the centre of the nut section G is not radial to, the piston
extension D³ and that a line drawn through the centre of said section would be
tangential to a circle smaller in diameter than the said piston extension. This
arrangement enables me to make the nut section of sufficient size to engage with
several of the spiral groves and still have the faces of the teeth of the nut section
and the corresponding faces of the spiral grooves approximately radial to the
piston extension D³. If such faces of the teeth and grooves were not radial or
approximately radial to the piston extension D³, a stronger spring would be
required to prevent the nut section being forced outward by the action of the
piston extension in its backward movement.
The outer end of the socket B³ is closed by a plug & and between the inner end
of the plug and the nut section G is arranged a spring d³, the nut section being
hollow so as to receive the spring within it.
The nut section G may therefore be moved outwards or away from the piston
extension D³ against the force of the spring d, and by such movement the teeth of
the nut section will be entirely disengaged from the grooves of the piston
extension D³, but when the nut section is relieved of outward pressure, tho
spring will return it into engagement with the piston extension D³.
On the nut section G is a shoulder which, by coming against a shoulder d³ in
the socket Bs, limits the inward movement of the said nut section and forins a stop
therefore. The length of the nut section G inward of the shoulder is such that
when the nut section is in its inward position its inner end will not press upon the
piston extension and tend to force the latter against the opposite side of the
cylinder, although the teeth of the nut section will be in strong engagement with
the spiral grooves.
In Fig. 2 it will be seen that the shoulder a² is against the shoulder d³, and yet
the surfaces of the teeth of the nut section are out of contact with the surfaces of
the grooves of the piston extension D³, although the said teeth extend into and are
in engagement with said grooves.
Although I consider the stop for preventing the nut section G from pressing
against the piston extension D³ as very desirable, still it is not indispensable, and
the nut section might be made in the form of a straight cylinder destitute of a
shoulder.
The cylinder is provided with supply ports e. e¹ and the steam or other motive
fluid enters the cylinder through the port e¹ to produce the forward working stroke
of the piston D. Between the piston D and the piston head or extension D³ is an
annular groove or. recess e which permits the steam to pass from the port el
entirely around the piston, and enables the steam to pass freely through all the
grooves of the piston extension D³ to the back end thereof. Before the piston
commences its forward or working stroke the steam acting upon the inner end of
the nut section G forces the latter back or outwards into the socket B³, and
entirely disengages the teeth of the nut section from the grooves of the piston
extension D. The piston is then forced directly forward by the steam pressure
behind it, the nut section G being held out of engagement with the grooves of the
piston extension D³ during its whole forward movement. As soon as the pressure
behind the piston is relieved by the opening of the exhaust, and before the piston
commences its backward movement, the nut section G is forced inwards by the
spring so that its teeth enter the spiral grooves of the piston extension D³, and
during the backward movement of the piston, the piston rod and piston are turned
by the engagement of the spiral grooves of the piston extension with the nut
section G. During the whole backward movement of the piston the nut section is
supported by the shoulders d. d³ and hence the said nut section does not force the
piston extension against the opposite side of the cylinder and produce friction
and wear.

page_text: In the plug d. I have shown an opening . which gives free vent to the
socket B³, and prevents the nut section from being retarded in its outward
movement by pressure behind it, or retarded in its inward movement by the
formation of a partial vacuum behind it. The plug d'might be unperforated, but
the nut section would then be less active in its movements and a stronger spring d'. '5
would be necessary.
When the nut section G is forced outwards its outer end closes against the
plug d. and prevents the escape of steam through the aperture d*.
Not only does the nut section G operating as described form a more simple and
effective rotating device than any heretofore used, but the forcing back and holding 1
of the nut section G out of all contact with the piston extension D³, during the
working stroke frees the piston entirely from all connection with the rotating
device and enables it to be operated with less friction.
The piston may be readily turned by hand in the direction of the arrow shewn
in Fig. 2 as the nut section G will yield readily when the inclined faces of the
grooves on the piston extension D³ act upon the inclined faces of its teeth.
B' designates the valve chest to which steam or other motive agent is admitted
by the pipe f and H designates the valve whereby the admission of the steam to
the ports c. e¹ is controlled.
The steam coming through the pipe enters an annular helt or recess fl. in the
valve chest, and thence passes under control of the valve H to the port e. or the
port e-The said valve H which is actuated by the inflowing steam is made in
the form of a double puppet valve, and is adapted to close upon either of the
seats e. 3. between which it works. The valve has but a slight movement, and as
shewn in Figures 1 and 4, has just moved to the left to close on the seat e². and
open the seat e³. to admit steam to the port e¹ but the piston has not yet commenced
its forward movement, it being in its rearmost position. The position of the valve
is the same in Figures 1 and 4.
The seats e. c. as here shewn are formed on the adjacent ends of tubular
pieces H H best shown in Figure 4. These are both inserted into the valve
chest B' from. one end thereof and the end is then closed by a plug ƒ³.
The end of the piece H¹ bears against a shoulder f³, and a shoulder on the
exterior of the piece H bears against a shoulder f' in the valve chest. The distance
apart of the seats e². c³. is thus determined.
The valve H has arms or webs f5 projecting from opposite sides into the seat
pieces H¹ H², and serving to properly guide the valve without materially interfering
with the free passage of steam through the seats, and at the outer ends of these
webs or arms f³I have shewn small discs f° against which the steam strikes or
impinges as it passes to the one side or the other.
The cylinder is provided between the two supply ports e. e¹ with an annular
exhaust belt and port g. g', from which extends an exhaust pipe g². shewn in
Figures 3 and 9. This exhaust is unprovided with any valve and is always open
to the atmosphere, except while the annular port g¹ is covered by the piston in its
movenients.
The operation of the fluid controlling valve H is as follows.
As represented in the drawing the said valve has just moved to close the seat e³.
and admit steam through the seat e. and port e¹, but the piston D. D³. has not
yet moved. At this time the cylinder B forward of or to the left of the piston D is
open to the atmosphere through the exhaust port g¹. and belt g. Consequently
there is but a very slight pressure on the left side of the valve H, and said valve
is held strongly against the seat e². by the pressure of steam on its right side.-The
steam rushing to the right through the seat e³. and striking against the disc f. has
a tendency to draw the valve away from the seat e. but cannot do so while the
exhaust from the cylinder is open to the atmosphere.
The piston D is now forced forward under full pressure of steam but as soon as
it covers the exhaust port gl. the low steam remaining in the forward end of the
cylinder is trapped and compressed to such an extent as to create a pressure on the

page_text: left side of the valve H. The pressure thus created is not nearly so great as
the pressure on the right side of the valve, but it relieves the valve to such an
extent that the "drawing" force produced by the steam striking on the disc ƒª is
sufficient to move the valve to the right and open the seat c. The valve H is
thus moved to the right, and steam admitted through the seat e². just before the
piston completes its stroke, but the momentum aided by pressure on the back of
the piston, causes the drill to strike with full force, and steam acts on the piston to
make the return stroke. The piston in its forward stroke having passed beyond
the exhaust port g'. there is a free exhaust from the right hand of the piston D,
during its return stroke, until it covers and passes the exhaust port g', but as soon
as this occurs the steam is trapped on the right-hand side or back of the piston and
compressed until it relieves the valve H sufficiently to allow it to be drawn off to
the left by the action of the steam, whereupon the operation is repeated.
"
At each stroke of the piston the valve moves before the completion of movement
of the piston, and therefore there is no liability of the piston striking violently
against the heads of the cylinder.
In order to pack the piston rod D' in the head B³, I form in the head an
annular groove h. and a hole or aperture h¹. tangential to said groove, as best
shown in the transverse section Fig. 6. The outer end of the tangential
aperture ¹, is closed by a plug h³, and when said plug is removed a strip or piece
of flexible packing h³. inserted through the aperture ³, will follow the groove h.
and on being forced in will be compacted tightly in the groove and round the
rod D' The strip or packing may be forced or driven in through the aperture h¹.
with a punch, and whenever the packing becomes worn and there is any leakage
around the rod the plug . is removed and additional pieces of packing are driven.
in until the packing is tight.
When the head B' is divided as here shewn, the parts may be separated to
permit of the worn out and worthless packing being removed from the groove h,
but such clearing out of the groove is not necessary, as packing may be driven in
from time to time to maintain a tight joint around the rod D'.
The drill-rod I is fitted in a socket in the chuck D², and is clamped therein by
means of two bolts I' each having a head i. which is cut away or formed with a
concave surface i. of the same curvature as the drill-rod.
These bolts are inserted through the chuck D. in opposite directions as shewn
in Fig. 7 and their concave surfaces ¹ bear on the rod I at diametrically opposite
points. By tightening the nuts of these bolts, the rod I, is securely clamped
and held, and by loosening the said nuts, the rod is released.
As here shewn, the heads, i. of the bolts are excentric to their bodies, and hence
the bolts are prevented from turning in the chuck.
The use of two clamping bolts is desirable because the drill-rod will be clamped
at diametrically opposite points, and will always be held centrally in the chuck.
If one bolt only were used the drill-rod would always be forced towards one side of
the socket and would not be held concentric with the piston rod.
Although I have herein frequently referred to steam as the motive agent
employed, the Invention is applicable to drills operated by compressed air, or
steam.
Having now particularly described and ascertained the naturo of my said
Invention and in what manner the same is to be performed I declare that what
I claim is:
First. In a rock-drill in which the exhaust port is controlled by the piston, the
combination with the ported cylinder and the piston, of a fluid controlling valve
actuated by the inflowing motive fluid, substantially as herein shewn and
described.
Second. In a rock drill, the combination with a cylinder and piston, the cylinder
having supply ports for admitting a motive agent theroto on opposite sides of the
piston, and an exhaust port arranged between said supply ports and controlled by

page_text: the piston, of an automatic valve for controlling the admission of the motive fluid
to the said supply ports, substantially as herein described.
Third. The combination with the cylinder B, having supply ports e. e', and an
exhaust port g² between said supply ports, of the piston D, having a movement
across and considerably beyond the said exhaust port at each stroke, and the
automatic valve, H moveable between the valve seats e². e. for controlling the
admission of a motive fluid to said supply ports e. e¹ substantially as described.
Fourth. The combination with the cylinder B, having supply ports e e'. and an
.exhaust port g'. between said supply ports, of the piston D, having a movement
across and considerably beyond the said exhaust port and each stroke, and the
automatic vàlve H, moveable between the valve seats e². e³, and provided with the
discs f upon which the motive fluid acts to move the valve, substantially as herein
described.
Fifth. The combination of the cylinder B, the head B¹, the "follower” F, and
bolts F'. connecting said head and follower, the head B. having its diameter
slightly larger than the cylinder and formed with an annular rebate so as to enter
the cylinder, the piece E rigidly secured to the cylinder and forming a cylinder
guide wherein the said head B2 and follower F may move, and the cushion E.
arranged in said guide E between the head and follower, substantially as herein
described.
Sixth. The combination with the cylinder of a rock-drill, of a piston having a
head or extension which is spirally grooved externally and a spring-actuated nut-
section engaging with the spiral grooves of the piston head or extension and capable
of being forced back by the action of the motive fluid upon its face or inner end, to
free it entirely from the spiral grooves of said piston head or extension, substantially
as and for the purpose herein described.
Seventh. The combination with the cylinder of a rock-drill, of a piston-head or
extension having a spirally grooved exterior, a spring-actuated nut-section engaging
with the spiral grooves of said head or extension and capable of being forced back
by the pressure of the motive fluid upon its face to free it entirely from said spiral
grooves, and a stop for limiting the inward movement of said nut-section,
substantially as and for the purpose herein described.
Eighth. The combination of the cylinder B having the transverse socket or
slideway B³, provided with the shoulder d³. the spirally grooved piston extension D³,
the movable nut-section G, engaging with the grooves of said piston-extension and
provided with the shoulder, d³, the spring d¹. and the plug d. closing the outer end
of said socket, or clideway B³, substantially as herein described.
Ninth. The combination with the piston-rod D¹. of the longitudinally-divided
cylinder head B, having the annular packing groove h. and tangential aperture h¹.
substantially as herein described.
Tenth. The combination with the chuck D' and the drill-rod I fitting therein,
of the bolts 1 having their heads formed with the concave bearing surfaces i¹.
inserted through the chuck from opposite sides and serving to clamp the drill-rod
at diametrically opposite points substantially as herein described.
Dated this orth day of March 1994