IMPROVED MEANS OF OBTAINING RECIPROCATORY MOTION IN PERCUSSIVE ENGINES FOR DRILLING OR BORING ROCKS AND OTHER MINERAL SUBSTANCES PROVISIONAL SPATION
Year: 1873

page_text: LETTERS PATENT to John Darlington, of No. 2, Coleman Street
Buildings, Moorgate Street, in the City of London, for the Invention
of "IMPROVED MEANS OF OBTAINING RECIPROCATORY MOTION IN PERCUSSIVE
ENGINES FOR DRILLING OR BORING ROCKS AND OTHER MINERAL SUBSTANCES
PROVISIONAL SPECIFICATION left by the said John Darlington at
the Office of the Commissioners of Patents, with his Petition, on
the 13th May 1873.
I, JOHN DARLINGTON, of No. 2, Coleman Street Buildings, Moorgate
Strect, in the City of London, do hereby declare the nature of the said
Invention for "IMPROVED MEANS OF OBTAINING RECIPROCATORY MOTION IN PER-
CUSSIVE ENGINES FOR DRILLING OR BORING ROCKS AND OTHER MINERAL SUBSTANCES
to be as
IN MINING, TUNNELLING, QUARRYING, AND OTHER LIKE OPERATIONS,"
follows:-
,,
To consist essentially of a piston, with its rod attached, working
within a cylinder by the distribution of steam, air, or other clastic fluid

page_text: to the said piston without the intervention of any valve or distributing
arrangement other than the piston itself, the latter being so constructed
that in its stroke it opens and closes the necessary passages for dis-
tributing the fluid pressure so as to induce and control the motion of the
piston.
In carrying out the Invention, according to one modification, a
cylinder and motive piston is employed. The cylinder itself has an
ordinary inlet port way, a long induction passage, and an outlet port way.
The depth or length of the motive piston is proportioned to the position
of the several port ways, so that the induction port way and the exhaust
portway are alternately uncovered by the body of the piston, which thus
distributes the fluid pressure.
In one modification the clastic fluid exerts its force continually against
the smaller surface of the piston referred to. This piston in moving in
one direction first covers the exhaust port way, then uncovers the
induction port way, and permits the clastic fluid to exert its force on the
opposite side of the piston, which has a superior area to that on which
the pressure is constant. In the return movement which follows, the
induction port way is first covered, and immediately afterwards the
exhaust port way is uncovered, releasing the superior area of the piston
from the pressure, and allowing the constant pressure on the smaller
area to effect the opposite stroke.
In a second modification which gives a like action, instead of keeping
the fluid pressure continually acting against the smaller surface of the
motive distributing piston, the pressure is alternately admitted to and
exhausted from both sides of the piston. To effect this the piston is
made of sufficient length to admit of a recess being turned in it of such
a length as to always be in communication with the pressure port way
formed about the centre of the length of the cylinder. Two induction
passages and two exhaust port ways are also formed in the cylinder.
The motive piston in its passage across these said port ways admitting
the pressure to one induction port way communicating with one end of
the cylinder at the same time as it uncovers one exhaust port way,
and releases the pressure from the opposite end of the cylinder.
In a third modification similar to the first arrangement herein
described in having the pressure continually acting on the smaller area
of the motive distributing piston, the cylinder is formed of a slightly

page_text: larger diameter than the piston at the back end, and has also a groove
or recess formed near the middle of its length, which recess is in con-
nection with the exhaust port way. The piston itself has induction and
exhaust passages formed in it, which passages alternately communicate
with the enlarged parts or passages of the cylinder, and admit the fluid
pressure to and exhaust it from the superior area of the piston, the return
stroke being made by the pressure continually acting on the smaller
area of the piston.
In a fourth modification the piston is made of sufficient length to have
two grooves or recesses formed in it, which communicate with two sets
of passages in the body of the piston itself. These said grooves at either
end of the stroke of the piston come opposite to port ways in the cylinder,
two induction port ways, and one exhaust port way, placing one end of
the cylinder in communication with one pressure port way, by means of
one set of passages and corresponding groove in the body of the pistou
at the same time as the opposite end is opened to the exhaust port way
by means of the other set of passages and the corresponding groove.
The objects gained by the above method of obtaining reciprocatory
motion for rock drilling and boring and coal getting machines are,—
First. There is only one working or moving part used in obtaining
the motion of the piston with its rod attached, both being in one solid
piece without any loose or attached part to be loosened or destroyed
by the effects of rapid reciprocation and percussion.
Second. Being enabled to use large port ways and passages, which are
opened and closed quickly, without having any reference to or being
dependent on the movement of a valve, giving greater rapidity of motion
and efficiency of blow.
Third. Entire control of the speed and length of stroke, weight of
blow given by the machine, and great limit of variation in the length of
stroke, total freedom from stoppages due to displacement of valves, as by
this arrangement while the pressure is on the piston can never be in
equilibrium, but must start at any part of the stroke.
Fourth. Economy in working, as there is no clearance space to be
filled with pressure and exhausted to waste at every stroke, the pressure
being worked expansively to any degree required.
Fifth
Econome in manufacture and durability in working

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Darlington in the Great Seal Patent Office on
the 13th November 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
DARLINGTON, of 2, Coleman Street Buildings, Moorgate Street, in the
City of London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirteenth day of May, in the year
of our Lord One thousand eight hundred and seventy-three, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Darlington, Her special license
that I, the said John Darlington, my executors, administrators, and
assigns, or such others as I, the said John Darlington, my executors,
administrators, or assigns, should at any time agree with, and no
others, from time to time and all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVED MEANS
OF OBTAINING RECIPROCATORY MOTION IN PERCUSSION ENGINES FOR DRILLING OR
BORING ROCKS AND OTHER MINERAL SUBSTANCES IN MINING, TUNNELLING, QUARRYING,
AND OTHER LIKE OPERATIONS," upon the condition (amongst others) that I,
the said John Darlington, my executors or administrators, by an instru-
ment in writing under my hand and scal,. should particularly describe
and ascertain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the Great
Scal Patent Office within six calendar months next and immediately
after the date of the said Letters Patent.
NOW KNOW YE, that I, tho said John Darlington, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement, reference being had to the accompanying Drawings
and to the letters and figures marked thereon, that is to say :-
My said Invention consists essentially of a peculiar combination or
arrangement of inlet and exhaust ports or passages with a piston having
its rod attached, and working within the cylinder of a percussive engine
for drilling or boring rock and other mineral substances, whereby the

page_text: distribution of steam, air, or other clastic fluid to the said piston is
effected without the intervention of any valve or distributing arrange-
ment other than the piston itself, the latter being so constructed and the
ports so arranged in reference thereto that in its stroke it opens and
closes the necessary passages for distributing the fluid pressure so as to
induce and control the motion of this piston, the said piston being free
to be rotated on its longitudinal axis by means of a turning bar or other
suitable or well-known contrivance.
In carrying out my Invention I purpose to use a cylinder and piston,
the cylinder baving an ordinary inlet port, a long induction passage, and
an outlet or exhaust port cast therein. The depth or length of the
piston is determined by the distance which separates the several ports,
so that the induction port and the exhaust port may be alternately
uncovered by the body of the piston, and thereby distribute the fluid
pressure.
According to one modification the clastic fluid exerts its force con-
tinually against the smaller surface of the piston referred to. This
piston in moving in one direction first covers the exhaust port, then
uncovers the induction port, and permits the elastic fluid to exert its
force on the opposite side of the piston, which has a greater area to
that side on which the pressure is constant. In the return movement
which follows the induction port is first covered, and immediately after-
wards the exhaust port is uncovered, releasing the greater area of the
piston from the pressure, and allowing tho constant pressure on the
smaller area to effect the opposite stroke.
According to a second modification which gives a like action, instead
of keeping the fluid pressure continually acting against the smaller area
of the piston the pressure is alternately admitted to and exhausted from
both sides of the piston. To effect this the piston is made of sufficient
length to admit of a recess being turned in it of such a length as always
to be in communication with the inlet port formed at or about the
centre of the length of the cylinder. Two induction passages and two
exhaust ports are also formed on the cylinder. The piston in its passage
across these ports admits the pressure to one induction port, com-
municating with one end of the cylinder, at the same time that it
uncovers one of the exhaust ports, and releases the pressure from the
opposite end of the cylinder.

page_text: According to a third modification similar to the first arrangement
hercin described (inasmuch as it maintains the pressure continually
acting on the smaller area of the piston), the cylinder is formed of a
slightly larger diameter than the piston at the back end, and has also a
groove or recess formed at or near the middle of its length, which recess
is in connection with the exhaust port. The piston itself has induction
and exhaust passages formed in it, which passages alternately com-
municate with the enlarged parts or passages of the cylinder, and admit
the fluid pressure to and exhaust it from the greater area of the piston,
the return stroke being made by the pressure continually acting on the
smaller area of the piston.
According to a fourth modification the piston is made of sufficient
length to have two grooves or recesses formed in it which communicate
with two sets of passages in the body of the piston itself. These said
grooves at cither end of the stroke of the piston coincide with ports in
the cylinder, there being two induction ports and one exhaust port pro-
vided in such cylinder, thus placing one end of the cylinder in com-
munication with one induction port by means of one set of passages and
corresponding groove in the body of the piston, whilst at the same time
the opposite end of the cylinder is open to the exhaust port by means
of the other set of passages and the corresponding groove.
And in order that my said Invention may be fully understood I shall
now proceed more particularly to describe the same, and for that pur-
pose shall refer to the several Figures on the annexed two Slicets of
Drawings, the same letters of reference indicating corresponding parts
in all the corresponding Figures.
Figure 1 (Sheet 1) of my Drawings is a plan viow of one of my
improved percussive engines; Figure 2 is a longitudinal section of the
same taken through the centre thereof; and Figure 3 is a cross section
taken along the line X, X, in Figure 1.
The cylinder A, A, is mounted on bars or other suitable guides on
which it is capable of being moved or fed forward, as is well understood,
as the cutting operation proceeds, and has an ordinary inlet port b
through which the motive fluid enters, a long induction passage c with
two port ways d and e, and an outlet or exhaust port f. The body of
the piston is of such a length that the induction port d and the
exhaust port are alternately uncovered admitting the motive fluid

page_text: from the space in front of the piston to the space i behind the piston,
where acting on the full or larger area it forces the piston towards the
front of the cylinder, which piston in its passage uncovers the exhaust
portf, and releases the pressure from the back of the piston, allowing
the constant pressure on the smaller area in front of the piston to effect
the back stroke.
I prefer to rotate the piston and drill by the arrangement shown in
Figures 1 and 2 (Sheet 1), which consists of a turning bar 1 fitted into
the rear end of the cylinder a, so as to turn freely therein. This bar
projects under the cylinder, and enters a feathered nut fixed in the
piston, the feathers in the nut engaging into corresponding spiral
grooves or slots 2, 2, made in the turning bar. A ratchet wheel 3 is
fixed on the outer end of the turning bar, and into the teeth of this
wheel engages a detent which prevents any rotation of the bar during
the backward motion of the piston, which piston is consequently com-
pelled to make a slight rotatary movement, but during the forward
stroke of the piston the bar being free does not rotate the piston, but
is rotated thereby. I lay no claim however to this method of imparting
rotatory motion to the said piston.
In a second modification shewn in Figures 4, 5, 6, and 7 on Sheet 2
of my Drawings, instead of keeping the fluid pressure continually acting
against the smaller area in front of the piston the pressure is alternately
admitted to and exhausted from both sides of the piston.
Figure 4 is a plan view of the apparatus; Figure 5 is a longitudinal
section through the centre; Figure 6 is a front end view, and Figure 7
is a cross section taken along the line X, X, in Figure 5.
A, A, is the cylinder; b, b, the piston, which is made of a sufficient
length. to have a recess c, c, turned in the body of it, which recess is
always in communication with the pressure inlet port d. Two induction
ports e and are formed in the cylinder, the one e leading by a passage
to the back end of the cylinder, and the other by another passage to
the front end of the cylinder. Two exhaust ports g and h are also
formed in the cylinder, both of which communicate by passages cast
in the cylinder with the central exhaust port i common to the two..
The action is as follows:-The piston b being moved from the position
shewn in Figure 5 towards the back end of the cylinder, the port e
leading to the back end of the cylinder is opened to the pressure and

page_text: at the same time the exhaust port is opened, releasing the pressure
from the front of the piston; this effects the forward stroke, forcing the
piston across the ports towards the front end of the cylinder. In its
passage it first closes the ports e and h, shutting off the pressure from
the back of the piston and closing the exhaust from the front of the
piston. The expansion of the clastic fluid now contained in the back
end of the cylinder and in the induction passage e is sufficient to
complete the forward stroke of the piston, the pressure port leading
to the front of the cylinder is then opened, and simultaneously with it
the exhaust port g, thereby releasing the pressure from the back of the
cylinder whilst it exerts its action on the front end of the piston to
perform the back stroke.
A third modification shewn in Figures 8, 9, 10, and 11 (Sheet 1)
resembles in its action the first arrangement herein-before described in
so far as the pressure is continually acting on the smaller area in front
of the piston.
Figure S is a longitudinal section through the centre of the cylinder;
Figure 9 is a cross section taken along the line X, X, in Figure 8;
Figure 10 is a cross section taken along the line y, y; and Figure 11 is
a cross section taken along the line <,.
The cyliner A, A, is formed slightly larger in diameter at the back
end b, and has also an annular groove or recess c formed at or near the
middle of its length, which recess is in communication with the exhaust
port d. The piston e has induction passages f,f, and exhaust passages
9, 9, formed in it.
passages
The action is as follows:-The pressure on being admitted by the
port to the space i, i, in front of piston is led by the induction
ff, to the back end of the cylinder, where acting on the full area of
the piston e it drives it forward towards the front end of the cylinder,
closing the outlets of the passages f, f, and continuing its motion by the
expansion of the clastic fluid contained in the space brings the outlets
of the exhaust passages into communication with the exhausting
annular recess c and exhaust port d. The pressure is thus releasod
from the back of the piston, and the return stroke is made by the
constant pressure on the front of the piston, the piston in the back
stroke closing the exhaust passages g, and then opening the induction
passages as before. Instead of the induction and exhaust passages

page_text: being confined to the piston they may be extended into the piston rod
and the motive fluid discharged into a chamber formed in the gland and
provided with an outlet, or otherwise discharged from the rod beyond
the gland.
A. fourth modification illustrated by Figures 12, 13, and 14 (Sheet 1)
is similar to the second arrangement, inasmuch as the pressure is
alternately admitted to and exhausted from both sides of the piston.
Figure 12 is a longitudinal section through the centre of the cylinder;
Figure 13 is a cross section taken along the line X, X, in Figure 12;
and Figure 14 is a cross section taken along the line y, y.
The cylinder A, A, is formed with two induction ports f and y, and
one exhaust port h. The piston b, b, has formed within it one set of
passages c, c, communicating between an annular recess or groove e
formed in the piston and the space m in front of the piston; a second
set of passages d, d, are provided in the said piston communicating
between another annular recess or groove in the piston and the space n
at the back of the piston.
The action is as follows:-The pressure on being admitted by the
induction passage i, and the piston being moved forward from the
position shewn in Figure 12 towards the front end m of the cylinder,
such pressure is led by the set of passages c into the space m, at the
same time the space at the back of the cylinder is placed in communi-
cation with the exhaust by means of the annular recess and the set
of passages d, d. The pressure thus acting on the front side of the
pistou drives it back, closing the ports and h, and the motion being
continued by the expansion of the fluid contained in the space m.,
and the passages c, c, opens the opposite port ways f, h, thus placing
the back end of the cylinder in communication with the pressure
through the groove or recess 7, and the passages d and the front end
into communication with the exhaust through the annular groove e
and the passages c, c, thereby giving the forward stroke or blow.
Having now described and particularly ascertained the nature of my
said Invention, and in what manner the same is or may be used or
carried into effect, I would observe in conclusion, that I am aware
that it has been proposed to construct the piston of a motive-power
engine with ports or passages therein working in connection with
other ports in the cylinder, whereby the distribution of the steam or

page_text: other medium employed may be effected without the use of separate
and special distributing valves, and therefore I lay no claim thereto;
moreover, as in such an engine the stroke of the piston is invariable
or nearly so and the piston is solely confined to the stroke movement,
the said arrangement is inapplicable to what are known as "rock
jumpers "wherein the piston usually turns and the stroke of the
piston is constantly changing; but what I consider to be novel and
original, and therefore claim as the Invention secured to me by the
herein-before in part recited Letters Patent is, the arrangement of
ports and passages in the cylinders, or in the cylinders and pistons of
rock bores or percussion machines of that class so as to produce recipro-
cating motion, and to allow of a variable stroke of the piston without
the use of separate or special distributing valves, and also to allow
of the turning of the piston and tool holder during its reciprocating
movement, substantially as for the purpose herein-before described and
illustrated by the Drawings annexed.
In witness whereof, I, the said John Darlington, have to this
my Specification set my hand and seal, the Thirty-first day of
October One thousand eight hundred and seventy-three.