Improvements in Rock-drills.
Year: 1894

page_text: Date of Application, 17th Sept., 1894
Complete Specification Left, 15th June, 1895-Accepted, 20th July, 1895
Improvements in Rock-drills.
I, JAMES MCCULLOCH, of Bella Vista, Wolverhampton, Engineer, do hereby
declare the nature of this invention to be as follows:-
My invention relates to rock-drills.
According to one part of my invention I provide improved means for preventing
the rotation of the twist bar during the backward stroke of the drill.
The chief feature of this part of my invention relates to the provision of a twist
bar which can move axially as well as rotate in the drill casing.
According to another part of my invention I provide an improved tool or "bit,"
also an improved tool or "bit" holder and an improved device for easily and
readily fixing and clamping a rock-drill to work at different angles.
My invention further comprises improved means for preventing the wear of
guides and feed screws and nuts and for lessening the jar given to the operator
by the continual shock due to the recoil of the drill.
My invention also has for a further object to construct an improved valve for
controlling the admission and exhaust of the working fluid. An important feature
of this part of my invention is the novel means which I employ to actuate the
valve by the working fluid in the cylinder.
In carrying the first part of my invention into practice I so construct the drill
casing that the twist-bar shall be capable of a limited amount of backward and
forward movement therein and I provide the rear end of the twist bar with a
head having a toothed gear of any suitable form secured to or formed integral
therewith. During the backward stroke of the piston said toothed gear engages
with another toothed gear formed on or firmly secured to the drill casing and
prevents the rotation of the twist-bar thereby causing the drill to be rotated
during such stroke. The gears are disengaged during the forward stroke of the
piston and drill, consequently the twist bar being free to rotate, the drill is not
rotated.
At the commencement of the forward stroke when the drill moves forward the
friction between the twist-bar and the twist-nut of the piston through which it
passes causes the former to move forward out of engagement with the gear on
the drill casing so that said twist-bar is free to rotate. During the backward
stroke of the drill the twist-bar is moved backward in a similar manner and
engages with the stationary gear being thereby prevented from rotating and
causing the drill to rotate.
I sometimes provide that the working fluid in the cylinder shall assist the
friction between the twist-nut and the twist-bar to disengage the toothed gear
on the head of said twist-bar from and engage the same with the stationary
toothed gear.
For this purpose I provide suitable passages or channels through
one of which the working fluid is admitted to act on the rear face of the head
of the twist-bar and cause the said head and bar to move forward when the
drill is moving forwards. During the back stroke of the drill the fluid passes
through the second of said passages to act on the front face of the twist-bar
head and so.cause the bar to move backward.
My improved drill or bit is formed with two cutting edges; one of said edges
is curved and approximately semicircular and coincident with a portion of the

page_text: circumference of the hole to be drilled. The other cutting edge is straight and
forms a diameter of the hole to be drilled préferably meeting the curved cutting
edge midway between the ends thereof.
In constructing my improved tool, drill or "it" holder I form a key-way in
the walls of the recess in which the tool or drill is held. Said key-way is
tapered and provided with a corresponding taper key or wedge which can be
driven in so as to wedge the tool tightly in the holder. I preferably arrange
that the small, end of the wedge shall be at the forward end of the holder. By
this means the tool is very firmly held in position in the holder and can be easily
released therefrom by striking the small end of the wedge.
My improved device for easily and readily fixing a rock-drill to work at the
different angles required is constructed somewhat as follows, that is to say:
The cradle of the rock-drill has a projecting foot which is received in a suitable
groove formed in a clamp. which can slide and rotate on the bar or stand of the
rock-drill. A tapered key-way is formed in the clamp, and a wedge sliding in
the key-way serves for tightening the clamp on the bar.
To secure the clamp to the foot of the rock-drill cradle I provide the clamp
with a bolt adapted to be screwed thereinto and provided with a conical portion.
The axis of the bolt is preferably approximately parallel to the groove in the
clamp. I provide also a strip of suitable form which may be pivoted to the
clamp if desired and which can be so placed with regard to the foot of the cradle
.and: the conical portion of the aforesaid bolt that when the bolt is screwed into
the clamp the said strip is pressed tightly against the foot which is thereby firmly
secured in the groove in the clamp. When the bolt is screwed out of the clamp
the foot of the cradle is released.
The clamp is pierced to receive the bar and I prefer when the latter is
cylindrical that the hole in the clamp be of varying diameter, that is to say, about
half the area of the hole should be formed to a circle of larger diameter than the
remaining portion of the hole. The clamp can then, by means of the wedge, be
tightened on a bar which is not truly cylindrical and does not fit the hole in the
clamp. The necessity of turning the bar is thereby dispensed with.
For overcoming the wear of guides, feed screws and nuts in a rock-drill and also
for preventing jar to the handle of the operating mechanism, due to the shock
caused by the recoil of the drill, I construct the feed nuts for the feed screws and
the bushes for the guides, of a conical shape and split longitudinally. Said nuts
and guides are received in corresponding conical recesses formed in projecting
parts of the drill casing. I interpose spiral springs between the nuts on the feed
screw and between the bushes on the guide respectively. The spiral springs
operate to deaden or diminish the force of the shock or jar and automatically take
up any slack on the nuts or bushes.
In carrying into practice that part of my invention relating to the valve,
I construct the valve of cylindrical form, and arrange it to work in a cylindrical
chamber cast with or firmly secured to the cylinder of the engine. The axis of
said chamber is preferably perpendicular to the direction of motion of the cylinder
piston.
The valve chamber or seat is provided with preferably three openings or ports
in the side thereof. One of the said ports communicates with the fluid chest, the
other two communicate by passages one to one end and the other to the other end
of the working cylinder. The valve is provided with passages or channels so
.arranged that in one position of the valve a communication is opened between the
port deading to one end of the cylinder and the fluid-chest supply, while the port
leading to the other end of the cylinder is open to the exhaust through the valve.
In another position of the valve the steam or fluid-chest is in communication with
that end of the cylinder which was before open to exhaust, and the opposite end of
the cylinder is open to exhaust.
The valve chamber or seat can also be made with six openings or ports in the
side thereof two of which communicate directly with the steam or air-chest,

page_text: and two with the exhaust, the remaining ports being in communication with
opposite ends of the working cylinder. The valve is provided-with passages.or.
channels so arranged that in one position of the valve a communication is opened
between the port leading to one end of the cylinder and one of the steam or air
supply ports while the port leading to the other end of the cylinder is open to one
of the exhaust ports. In another position of the valve the port which was
formerly opened to the supply port is then open to the second exhaust port, and
the port.which was in communication with the first exhaust port is open to the
second supply port. Hence when the motive fluid is being admitted to one end of.
the cylinder the other end of the cylinder is in communication with the exhaust ;
on the valve being rotated to its second position steam or air is admitted to the
opposite end of the cylinder the first end being opened to exhaust.
The movement of the valve is regulated by the main piston working in the
engine cylinder which piston on nearing the end of its stroke uncovers in the body
of the cylinder, passages which form communication between the cylinder and two
supplementary cylinders.
When one of the said passages is uncovered, part of the working fluid, driving
the piston, enters said passage and presses on the end of a small auxiliary piston
in one of the supplementary cylinders. The other end of this auxiliary piston
presses on an arm or eccentric or wing out of the centre with the axis of the valve
fixed upon one end of the valve or made in one piece therewith and rotates the
same. When the main piston in its back stroke uncovers the second passage, the
first passage being then closed, the second auxiliary piston is caused to act in a
similar manner to the first on a second arm or eccentric or the like fixed to the
valve or in an opposite direction on the same arm as the first auxiliary piston acted
upon and rotate the valve in the opposite direction.
I sometimes arrange that the fluid pressure shall act directly on the aforesaid
arms or eccentrics or wings in order to rotate the valve without the intervention of
auxiliary pistons and cylinders as above described.
The arm or arms or eccentrics or projections are secured on or made solid with
the valve in such a manner that the valve will be balanced and will only alter its
position when positively operated. Such a balanced valve will work equally well
in any position and angle at which a rock drill may be required to be worked.
My improved valve is not subject to much or uneven wear since it has a rotary
reciprocating motion in place of a sliding reciprocating motion, moreover the valve.
may be very easily constructed of such a design as will enable the drill to be made
short and light which attributes are of especial advantage in rock-drills.
Dated this 17th day of September 1894.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.
I, JAMES MCCULLOCH, of Bella Vista, Wolverhampton, Engineer, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
My invention relates to rock-drills, and comprises the improvements hereinafter.
described.
According to one part of my invention I provide improved means for preventing.
the rotation of the twist-bar during the backward stroke of the drill. The chief
feature of this part of my invention relates to the provision of a twist-bar which

page_text: can move axially as well as rotate in the drill casing. It is by the axial movement
of the twist-bar that the locking and unlocking of the said bar is effected.
According to other parts of my invention I provide an improved holder for the
tool or "bit," and an improved device for easily and readily clamping the drill
casing at any desired angle.
My invention further comprises improved means for taking up slack due to the
wear of the guides, feed screws and nuts of the rock drill and for lessening the jar
given to the operator by the shocks caused by the recoil of the drill.
My invention also has as a further object the construction of an improved valve for
controlling the admission and exhaust of the working fluid. An important feature
of this part of my invention is the novel means which I employ to actuate the valve
by the working fluid in the cylinder.
In order that my invention may be clearly understood I will now describe the
same with reference to the accompanying drawings in which
Figure 1 is a longitudinal central section through the drill casing and parts
contained therein.
Figure 2 is a transverse section taken on the linea a of Figure 1.
Figure 3 is a section on the line y y Figure 2.
Figure 4 is a central longitudinal section through the rear end cover of the drill
casing showing a modification hereinafter described.
.
Figure 5 is a longitudinal section through the cylinders for operating the valve,
showing a modification hereinafter described.
Figure 6 is an elevation of my improved holder for the "bit"
Figure 7 is a section on the line zz of Figure 6.
Figure 8 is a central transverse section of my improved clamp.
Figure 9 is a plan, and
Figure 10 is a side elevation of the clamp.
or tool.
Figure 11 is a side elevation of a portion of the drill casing, showing the device
for preventing the wear of the guides.
Figure 12 is a transverse section of a modified form of valve and ports.
A is the drill casing; B is the twist-bar; C is the piston of the drill.
I provide the rear end of the twist-bar with a head B' having teeth or
projections B2 of any suitable form secured thereto or formed integrally therewith.
The said head works in a chamber A° formed in the rear end cover of the drill
casing and is capable of a limited axial movement in said chamber. D is a toothed
gear so fitted to the said rear end cover of the casing A that it cannot turn; it is
adapted to engage with the teeth B2 when the twist-bar is in its rearmost
position. When the teeth B2 are engaged with the gear D the twist-bar B cannot
rotate.
At the commencement of the forward stroke of the drill the friction between the
twist-bar B and the twist-nut F of the piston C through which the twist-bar
passes causes the latter to move forward, whereupon the teeth B2 become
disengaged from the gear D and the twist-bar is then free to rotate. During the
backward stroke of the drill the twist-bar is moved backward by the friction
between it and the twist-nut and its teeth B2 are caused to re-engage with the
stationary gear D by which means the twist-bar is again locked. The drill will
thus be caused to turn during its backward stroke but will be free to move without
turning during its forward stroke.
I sometimes provide that the working fluid in the cylinder A shall assist the
friction between the twist-nut F and the twist-bar B to disengage the teeth B³
from and re-engage the same with the stationary toothed gear D. For this
purpose I provide suitable passages or channels G, G¹ in the casing. The
channel G communicates with the port leading to the rear end of the cylinder and
with the space between the gear D' and head B', and the channel G₁ communicates
with the cylinder at a point near the forward end thereof and with the chamber A°
at a point in front of the head B'. During the forward stroke of the drill the
working fluid enters the passage G and acts ou the rear face of the head B¹ of

page_text: the twist-bar, thus causing the said head and bar to move forward. During the
backward stroke of the drill the fluid enters the passage G¹ and acts on the front
face of the twist-bar head and so causes the bar to move backward. In this
manner the twist-bar is locked during the backward stroke of the drill and
unlocked during the forward stroke.
I sometimes form the teeth B2 on a conical shaped head B' adapted to engage
with a correspondingly conical shaped gear D as shown in Figure 4.
My improved holder E Figures 6 and 7 for the tool, drill or "bit" is provided
with a key-way E' formed in the side of the socket in which the tool or bit H is
held. The said key-way is made of increasing depth from the forward to the rear
end and it is fitted with a corresponding taper key or wedge J. At the rear end
of the key is an extension J' that projects through an opening in the rear end of
the holder. By striking the end of the extension J₁ the tool will be wedged
tightly in the holder and be thereby very firmly held in position. It can be easily
released again by striking the opposite end of the wedge which projects from the
front end of the holder.
Figures 8, 9 and 10 illustrate my improved clamp for easily and readily fixing a
rock-drill to work at the different angles required. It is constructed as follows,
that is to say the clamp, which can slide and rotate on the bar or stand of the
rock-drill, is furnished with a fixed jaw L and a movable jaw L' between which is
received the projecting foot A3 Figure 1 provided on the cradle A² of the rock
drill. A tapered key way M is formed in the clamp, and a wedge N sliding in
the said key-way serves for tightening the clamp on the bar. A stud N' which
projects into a slot or groove N' in the wedge N serves to prevent the accidental
loss of the wedge.
The hole P that receives the bar of the rock-drill is not truly cylindrical but
about half the area of the hole and preferably that part in which the key way for
the wedge is located forms part of a cylinder of larger diameter than the remaining
portion of the hole as shown in Figure 8. The clamp can then be readily applied
to and tightened on a bar which is not truly cylindrical and which does not fit the
hole P in the clamp. The necessity of having a truly cylindrical bar is thereby
avoided. The jaw L' of the clamp is pivoted at L2 and is supported by a conical
bolt O which fits an inclined curved recess L³ formed in the back of the jaw. The
ends of the bolt O are parallel or cylindrical and they are received in lugs or
ears O¹ formed on the body of the clamp. One end of the bolt is screw-threaded
and screws into the corresponding lug O for the purposes of adjustment. When
the bolt is screwed into the clamp the jaw L' is pressed tightly against the foot A³
of the cradle A² of the drill which is thereby firmly secured between the two jaws.
By unscrewing the bolt O, the foot of the cradle is again released. O2 is a chain
attached to the bolt to prevent loss of the same.
Figures 2 and 11 show my improved means for taking up slack due to the wear
of guides, feed screws and nuts in a rock-drill and also for lessening or preventing
the jar occasioned at the handle of the operating mechanism by the recoil of the
drill. According to this part of my improvements I construct the feed nuts Q
Figure 2 for the feed screw R and the bushes Q Q Figures 2 and 11 for the
guide R', of a conical shape and split them longitudinally at Q2. The said nuts Q
and the bushes Q', Q' are received in corresponding conical recesses S S formed in
projecting parts or lugs T T of the drill casing. The large ends of the conical
bushes and nuts face each other as indicated with respect to the bushes in
Figure 11. I interpose a spiral spring U between the bushes Q Q on the
guide R' and a similar spring between the feed nuts Q which are on the other side
of the casing and not shown in Figure 11. The spiral springs U operate to deaden
or diminish the force of the shock or jar and to automatically take up any slack
in the aforesaid nuts and bushes.
In carrying into practice that part of my invention which relates to an improved
valve for controlling the admission and the exhaust of the working fluid to the
cylinder A of the drill I construct the valve V Figures 1 and 2 of cylindrical

page_text: form, and I arrange it to work in a cylindrical chamber W formed in the drill
casing A. The axis of said chamber is preferably perpendicular to the direction
of motion of the piston C.
with a
The chamber W forming the valve seat is in the construction shown in Figures 1
and 2 provided with three openings or ports W1, W2, W³ in the wall thereof. The
port W communicates with the fluid chest Wo, the other two ports W2 W³ com-
municate by passages one to one end and the other to the other end of the working
cylinder Ai
The valve V is provided with exhaust ports V1 V2 that communicate
common outlet V4, and it is also provided with an admission port or
passage V³. The ports are so arranged that in one position of the valve as shown
in the drawing. Figure 1 a communication is opened between the port W³ leading
to one end of the cylinder A' and the fluid-chest W° through the passage Vs in the
valve, while the port. W2 leading to the other end of the cylinder is open to the
exhaust through the port V₁ in the valve. In another position of the valve
the finid-chest W° is in communication with that end of the cylinder which was
hefore open to exhaust and the opposite end of the cylinder is open to exhaust.
It is obvious that the exhaust from the cylinders Z Z takes place simultaneously
with that from the two ends of the working cylinder A'.
In a modification shown in Figure 12 the valve chamber or seat has six openings
or ports in the side thereof.
Two of the said ports riz. W₁ and W* communicate directly with the fluid
chest Wo, the two ports W2 and W³ communicate with the opposite ends of the
working cylinder. A as before, and the two remaining ports W and W are
exhaust ports. The valve is provided with ports V₁, V and V³ of which V₁
and V2 are in communication with one another. The passages are so arranged
that in one position of the valve as shown a communication is opened between the
port W leading to one end of the cylinder A¹ and the fluid supply port V³ while
the port W2 leading to the other end of the cylinder is open to the exhaust
port W through the ports V1 V2 in the valve. In another position of the valve
the port W which was formerly opened to the supply port V³ is then opened to
the second exhaust port W, and the port W2 which was in communication with the
exhaust port W' is open to the supply port V. Hence when the motive fluid is
being admitted to one end of the cylinder the other end of the cylinder is in
communication with the exhaust; on the valve being turned to its second position
the working fluid is admitted to the opposite end of the cylinder, and the first
named end is opened to the exhaust.
For working the valve I provide small cylinders Z Z Figure 3 having pistons cc
working therein and also having ports or passages a a¹ which communicate with
the working cylinder A'. The valve is provided with wings or arms & d' that
project above the pistons c, c' and that are operated by said pistons when the latter
move up and down. When the piston C in the working cylinder A' approaches
the end of its forward stroke it uncovers the passage a and allows the working
fluid to enter the cylinder Z and act on the small piston therein. The said
piston c is thereby raised and caused to act on the arm d of the valve and thus
turn the valve. When the piston C in its backward stroke uncovers the other
passage a (the passage a being then closed) the piston c¹ of the cylinder Z' is
raised and caused in the same manner, to turn the valve V in the opposite direction.
The ends of the passages a, a¹ indicated by dotted lines in Figure 1 are really in
front of the plane of section.
I sometimes provide only one arm or wing d on the valve as shown in Figure 5
and I then place the two cylinders Z Z' on opposite sides of the said arm so that
the pistons cc of the cylinders Z Z¹ may act alternately on the said arm but in
opposite directions.
I may employ more than two cylinders such as Z, Z'.
I sometimes arrange that the fluid pressure shall act directly on the aforesaid
arms d, d' in order to rotate the valve without the intervention of cylinders and
Distons as above described

page_text: The arms or projections are secured or made solid with the valve in such a
manner that the valve will be balanced and will only alter its position when
positively operated. Such a balanced valve will work equally well in any position
and angle at which a rock drill may be required to be worked.
My improved valve is not subject to much or uneven wear since it has a rotary
reciprocating motion in place of a sliding reciprocating motion, moreover the valve
may be easily constructed of such a design as will enable a drill to be made short
and light which are attributes of especial advantage in rock-drills.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In a rock-drill the axially movable and rotatable twist-bar furnished with
teeth B in combination with the non-rotatable gear D, substantially as, and for
the purpose, specified.
2. The tool holder in combination with the key J, substantially as described.
3. The clamp having a fixed and a movable jaw, the latter arranged in com-
bination with a conical screw-threaded adjusting bolt, substantially as described,
and for the purpose specified.
4. The clamp constructed substantially as described with reference to the
drawings and for the purposes specified.
5. The means for taking up slack due to the wear of the feed screws, guides and
bushes and for preventing jar at the handle of the operating mechanism, sub-
stantially as described.
6. In a rock-drill, the several forms of valves herein described in combination
with the means for operating the same, substantially as described.
7. A rock drill having incorporated therewith, the various improvements herein
described with reference to the accompanying drawings.
Dated this 15th day of June 1895
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.