Improvements in and connected with Percussive Drilling Machines.
Year: 1891

page_text: Date of Application, 15th Sept., 1891
Complete Specification Left, 14th June, 1892-Accepted, 16th July, 1892
PROVISIONAL SPECIFICATION.
Improvements in and connected with Percussive Drilling
Machines.
I, PERCY JOHN OGLE, of No. 4, Bishopsgate Street Within, in the City of c
London, Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention relates to improvements in percussive drilling machines, whereby
I am enabled to use the compressed air or other motive fluid which has driven the
piston in one direction for driving it in the opposite direction, thereby effecting
considerable economy in motive fluid.
In carrying out my invention I employ two pistons (hereinafter referred to as
working pistons) of different areas on the drill spindle and 1 advantageously
employ a valve which is operated by the pressure of the motive fluid (hereinafter
referred to as air) the said valve being attached to a rod carrying two pistons of
different areas, between which pistons the air enters. The chamber in which the
valve with its pistons works, communicates at the end in which the smaller valve
piston is placed, with the atmosphere (or with the port hereinafter referred to as
No. 2) and at the other end with the main cylinder containing the working pistons
the space between the two pistons being in direct communication with the air
supply. The valve controls three ports or passages, one (hereinafter referred to as
No. 1) communicating with the cylinder in which the smaller working piston moves,
the second (hereinafter referred to as No. 2) with that in which the larger working
piston moves, and the third (hereinafter referred to as No. 3) with the atmosphere,
and the valve is arranged to place ports Nos. 1 and 2 and ports Nos. 2 and 3 in
communication alternately. Between the working pistons is a space and in order
to prevent dusty air from entering this space on the outward stroke it is placed in
communication with port No. 3 so that it will only receive pure air escaping from
the cylinders.
With the arrangement herein before described when the valve places ports Nos. 2
and 3 in communication air passes from the valve chamber through port No. 1 into
the cylinder of the smaller working piston moving the same outwards, and at the
same time the air in the larger cylinder passes through ports Nos. 2 and 3 to the
atmosphere. When the smaller working piston has reached nearly the end of its
stroke, the passage communicating with the space in the valve chamber behind the
larger valve piston is uncovered, allowing the air under pressure to pass from the
cylinder into the said
piston to move the space where it acts upon the surface of the said larger valve
to place ports Nos. 1 and 2, and consequently the two
working cylinders in communication, thereby allowing the air from the smaller
cylinder to pass into the larger cylinder where it acts upon the larger working
piston to return it. When during the return stroke the smaller working piston has
again passed the passage communicating with the space behind the larger piston in
the valve chamber, the air in the said space is free to exhaust into the space
between the two working pistons, thereby allowing the air in the valve chamber
between the two pistons to move the said valve to place port No. 1 again in com-
munication with the valve chamber, and ports Nos. 2 and 3 again in communication
with each other, when the operation hereinbefore described is repeated.
In the foregoing description I have assumed the motive fluid as being used when
under high pressure for moving the working pistons outwards. It is to be under-
tood however that when (as for instance in a vertical drill) the weight of the drill
pindle and pistons serves to assist in imparting force to the blow, the expending

page_text: air may be used for driving the drill outwards, the air under high pressure being
employed for again lifting the drill.
It will be obvious that instead of introducing high pressure air behind the
smaller working piston it can be introduced between the two working pistons, in
which case the space behind the smaller working piston is placed in communication
with port No. 3.
Although I have described the valve which I have found best to, answer in
carrying out my invention, it will be obvious that other forms of valve may be used.
Also that my improved valve may be used with drills operated in both directions
by motive fluid under high pressure.
Dated the 15th day of September 1891
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in and connected with Percussive Drilling
Machines.
1 PERCY JOHN OGLE, of No. 4, Bishopsgate Street Within, in the City of
London, 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 :-
This invention relates to improvements in percussive drilling machines whereby
I am enabled to use the compressed air or other motive fluid which has driven the
piston in one direction, for driving it in the opposite direction thereby effecting
considerable economy in motive fluid.
In carrying out my invention I employ two pistons (hereinafter referred to as
working pistons) of different areas on the drill-spindle and I advantageously
employ a valve which is operated by the pressure of the motive fluid (hereinafter
referred to as air) the said valve being arranged in conjunction with two pistons of
different areas.
To enable my invention to be fully understood I will describe the same by
reference to the accompanying drawings, in which:
Figure 1 is a longitudinal section of a percussive drilling machine in which live
air, that is to say, air at its full pressure, drives the drill-spindle outwards; and
Figure 2 is a section of the same on the line w, w, Figure 1.
Figure 3 is a similar view of a drilling machine in which the live air moves the
drill-spindle inwards; and
Figure 4 is a section on the line a, a, Figure 3.
Figure 5 is a longitudinal section of a percussive drilling machine illustrating a
modification hereinafter described; and
Figures 6 and 7 are sectional views on the lines y, y and, respectively of
Figure 5.
Figures 8 and 9 are sectional views at right angles to each other of a valve
arrangement which may be used in lieu of the valve arrangement shewn in
Figure 1; and
Figures 10 and 11 are views similar to Figures 8 and 9 respectively of another
modification.
Similar letters of reference indicate corresponding parts in the several figures.
a indicates the working cylinder of the drill, and the drill-spindle having the
two pistons, d'secured to it and working in the cylinder a. e is the valve-box
having the aperture for the admission of the motive fluid, and g is the valve
arranged in conjunction with two pistons h, i of different areas.
1, 2 and 3 indicate respectively the port or passage through which the live air
enters that part of the cylinder in which it operates and through which it escapes
after having completed its work; the port or passage for conveying the expanded

page_text: air to that part of the cylinder in which it operates and then again returning it to
be exhausted; and the port or passage for conveying the said exhaust air to the
atmosphere. 4 indicates a passage between that portion of the cylinder in which
the live air operates and the part of the valve-chamber behind the valve piston of
larger area; and 5 indicates a passage connecting the rear end of the valve-box
with the atmosphere.
indicates the twist-bar having a ratchet-wheel k and pawl in conjunction
with it for causing the rotation of the drill-spindle in a well known manner.
The valve g is arranged to place the ports 1 and 2, and 2 and 3 alternately in
communication and also to open port i to the air supply.
In the arrangement of my invention shewn in Figure 1, the valve g, which is
actuated by a rod between the two pistons h, i is provided with two passages g', g,
the former of which serves to place the passages 1 and 2 in communication and the
latter the passages 2 and 3.
The operation of the machine or apparatus shewn in Figures 1 and 2 is as
follows: Assume the valve g to be in such a position that the passage 1 will be in
communication with the air under pressure in the interior of the valve-chamber e
and the passages 2 and 3 in communication through the passage in the valve.
The result of this position will be that the air under pressure will flow through the
passage 1 and act against the piston d to force the drill-spindle outwards to the
position shewn in Figure 1. Immediately, however, that the piston d commences
to uncover the passage 4, a portion of the air in the cylinder passes through the
said passage into the valve-chamber behind the piston hand owing to the fact that
the area upon which this air acts is much greater than the difference between the
areas of the two pistons with which the live air is in contact and that there is no
resistance at the rear of the smaller valve piston i owing to the passage 5 communi-
cating with the atmosphere, the said air from the cylinder acts upon the valve-
piston and moves the same to the position also shewn in Figure 1. The result of
this movement of the valve is that the passage 1 is cut off from communication
with the interior of the valve-chamber and placed in communication with the
passage 2 whereby the two ends of the cylinder are placed in communication so
that the air which has previously acted in one end of the cylinder to force the drill-
spindle outwards is now free to expand (through the passage 1, the passage y' in
the valve and the passage 2) into the opposite end of the cylinder, where it acts
upon the piston c of larger area than the piston d, thereby moving the drill-spindle
backwards. When, during this backward movement the piston d has passed
and again uncovered the passage 4, the space behind the valve piston h is placed
in communication with the space between the pistons c, d which latter space is also
in communication with the atmosphere through the passage 3* communicating with
the exhaust so that, owing to the difference in the areas of the piston and
the piston of the valve g, the pressure of the air moves the said valve to
uncover the port 1 and place the ports 2 and 3 again in communication, when live
air again acts upon the piston d and the air which had acted upon the piston c
passes to the exhaust.
The object of placing the space between the pistons in communication with the
atmosphere through the exhaust passage is that during the outward stroke of the
said pistons pure air escaping from the cylinder shall enter the said space instead
of dusty air as would be the case if the said space was placed in direct communi-
cation with the atmosphere.
In the foregoing description I have referred to the live air as being used for
moving the working piston outwards but it is to be understood that it may also
be used for moving the drill-spindle inwards. This arrangement is especially
applicable in the case of a drill which may be required to work in a vertical
position when as the combined weights of the drill-spindle and connected pistons
serve to assist in imparting force to the blow, the expanding air may be used for
driving the drill outwards, the live air being employed for lifting the drill. Such
an arrangement is shewn in Figures 3 and 4 where the two pistons are represented

page_text: as being of the same diameter but of different working areas and the passage 1 is
placed at the lower end of the cylinder and the passage 2 in communication with
the upper end. The valve shewn in connection with this modification is formed
integral with its pistons, but, in order to prevent the valve from turning upon its
axis, arrange at one end of the valve-chamber a square or other guide m upon
which the valve and its pistons slide, as shewn. Also, the valve is provided with
only a single passage through which the ports 1 and 2, and 2 and 3 are alternately
placed in communication. The operation of this apparatus is substantially the same
as that hereinbefore described. In the drawings, the ports are shewn in the
position which they occupy after the supply of live air to the bottom of the
cylinder has been cut off and the valve moved to place the passages and 2 in
communication. The air from the lower end of the cylinder now passes to the
upper end of the same and, acting upon the piston c, which has a relatively larger
area than the piston d, drives the same downwards to impart the blow, the force of
which is augmented by the weight of the drill-spindle and pistons. When the
piston d during the downward movement of the drill-spindle has passed the end of
the passage +, the air under pressure behind the piston flows into the space
between the two pistons c and d and thence into the atmosphere through the hole 6,
thereby the air entering through the aperture, owing to the unequal areas of the
opposing faces of the pistons and i, moves the valve g as hereinbefore described
to place the passages 2 and 3 in communication and the passage 1 in communication
with the air-supply. The live air then acts upon the piston d to raise the drill
spindle and the air behind the piston e passes to the exhaust port 3. The hole 6 in
addition to serving the purpose referred to above also serves to prevent the
piston d from being forcibly driven against the front cover of the cylinder as,
after the drill-spindle has moved a certain distance and before the piston d reaches
the said cover the hole 6 is uncovered by the piston thereby allowing the air
pressure to escape.
Instead of introducing high pressure air at one end of the working cylinder and
allowing it to act expansively in the other end thereof 1 may provide for intro-
ducing the live air between the two pistons or in the middle of the cylinder. This
arrangement I have shewn in Figures 5, 6 and 7 wherein the piston d is designed to
be acted upon at one side by the live air and upon the other side by the expanding
air, the space behind the piston e in this case. communicating with the atmo-
sphere through the passages 7 and 8 and the exhaust passage 3. The arrange-
ment of the valve also in this case is similar to that in the modification last
described.
In the operation of this apparatus the live air, entering through the passage 1
after driving the drill-spindle in one direction by acting upon the side of the
piston d of smaller working area passes through the passages 1 and 2 to the side of
the piston of larger working area and moves the said piston in the reverse
direction. In this modification also the space behind the smaller valve piston,
instead of being placed directly in communication with the atmosphere, is placed
in communication with the passage 2 through the passage 9, so that, after the
piston d, during its inward movement, has passed the passage 4, the pressure of the
air at the two ends of the valve will be equalized and the latter is therefore free to
move under the pressure entering through the aperture.
"
It is to be understood that I may us: any form of valve-mechanism in connection
with my invention whether such valve-mechanism is operated by mechanical means
or by the air-pressure.
In Figures 8 and 9 I have shewn how the valve represented in Figures 3 and 5
may be used in conjunction with the drill shewn in Figure 1, and these figures
will be understood without further description, as the letters denoting the parts
in these figures are the same as those denoting corresponding parts in other
figures.
In the arrangement of valve shewn in Figures 10 and 11 the air instead of being
introduced between the valve pistons, is introduced at one end of the valve-

page_text: chamber opposite to the piston and is moved in one direction to uncover the
passage 1 by the live air-pressure upon it. The movement in the reverse direction
is effected by the air-pressure from the cylinder through the passage 4, the area of
the piston being so proportioned to that of the piston that the pressure on the
piston will be greater than upon the piston i when communication is made with
the cylinder by the piston d uncovering the port 4. In this case the space behind
the piston is always open to the atmosphere and preferably through the exhaust
as shewn in order to prevent the entrance of dusty air.
In order to prevent the entrance of dusty air into the valve chamber through
the passage 5 I connect the said passage with the exhaust passage by a suitable
pipe or I may form a passage through the piston as indicated by dotted lines in
Figure 8 communicating with the exhaust passage in which case the passage 5 may
be dispensed with.
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. A percussive drilling machine in which the motive fluid, after having been
utilized in one part of the working cylinder to move the drill-spindle in one
direction, is allowed to expand into another part of the working cylinder to move
the said drill-spindle in the reverse direction before being exhausted, substantially
as described.
2. The combination with a percussive drilling machine operating in the manner
indicated in the preceding claiming clause of a distribution valve actuated by the
motive fluid, substantially as set forth.
3. In a percussive drilling machine, a valve having two pistons of different areas
and adapted to be moved in one direction by the pressure of the live air in the
valve chamber and in the reverse direction by air from the working cylinder,
substantially as described.
4. In a percussive drilling machine having pistons of different diameter placing
the space between the working pistons in communication with the exhaust passage
for the purpose of excluding the entrance of dusty air, substantially as described.
5. The improvements in percussive drilling machines substantially as herein-
before described and illustrated in Figures 1 and 2, Figures 3 and 4, and Figures 5, 6
and 7 of the accompanying drawings.
Dated the 14th dow of Tune 1000
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.