IMPROVEMENTS IN PERCUSSION ENGINES FOR BORING ROCKS OR FOR OTHER SIMILAR PURPOSES."
Year: 1877

page_text: LETTERS PATENT to John Darlington, of No. 2, Coleman Street Buildings,
"
in the City of London, for the Invention of IMPROVEMENTS IN PERCUSSION
ENGINES FOR BORING ROCKS OR FOR OTHER SIMILAR PURPOSES."
PROVISIONAL SPECIFICATION left by the said John Darlington at the
Office of the Commissioners of Patents on the 2nd October 1877.
JOHN DARLINGTON, of No. 2, Coleman Street Buildings, in the City of London.
"IMPROVEMENTS IN PERCUSSION ENGINES FOR BORING ROCKS OR FOR OTHER
SIMILAR PURPOSES."
My improvements relate to engines designed to deliver rapid blows by the
reciprocation of the piston and rod, a tool or head of any well-known form being
fastened to the projecting end of the piston for boring or drilling rocks, or for other
purposes.
The first part of my improvements more particularly relates to the means of
obtaining the reciprocating movement of the piston.
The second, to the rotating the piston on its axis.
The third, to the moving the actuating cylinder and its piston towards or away
from the work to be done.
The fourth, to the attaching the tool or head to the piston rod.
For the better holding of the cylinder I form it round in section and cut a screw
thread on its outside circumference, throughout its whole length if required. This
screw cylinder is then inserted into a suitable screwed nut or holder, which may be
attached to any stand or carriage by well-known means. To advance the cylinder
it is only necessary to cause it to turn in the nut, when it will be screwed either
backward or forward through the nut. This movement may be given by hand, a
handle or hand wheel being attached to the cylinder for this purpose, or it may be
given automatically, a lever being arranged having its fulcrum on the nut or holder,
one end of it being operated on by the moving piston rod, and the other end
Price SJ1

page_text: operating on a ratchet wheel or similar contrivance attached to the cylinder in such
a manner as to cause it to be turned in either direction, as may be arranged.
In percussion rock boring or similar machines it is necessary that the cutting tool
should be turned into a fresh position after every blow; this may be done in several
ways, either by hand or automatically. If done by hand I attach the piston and
rod to the cylinder in such a way that while free to move in a longitudinal direction
it will be carried around with the cylinder as the cylinder is turned.
In this way
as the cylinder is turned or fed, forward or backward, the tool is carried with it; or
I insert a rod or rods into the rear end of the cylinder, which pass into a suitable
recess in the piston, allowing the piston to move freely longitudinally, but compelling
it to turn as the rod is turned. In this way the piston may be turned independently
of the cylinder, which cylinder may be turned automatically or by hand, as may be
desirable; or I so arrange a twisted or spirally fluted rod in the inside of cylinder
that it passes into the interior of the moving piston, which has a suitably-shaped
nut attached to it. At the upper end of the twisted or spirally fluted rod is carried
a ratchet wheel, which is free to turn in one direction, but held by pauls or dogs
from turning back again. In this way the piston moving in one direction turns the
ratchet wheel, but when moving in the opposite direction is obliged to turn itself
and follow the path of the spiral or twists on the bar, the ratchet wheel being held
from turning by the pawls; or I so arrange a ratchet wheel at the front end
of the cylinder that the piston rod shall pass through its centre, a spiral groove
or grooves is cut into the piston rod into which suitable projections from the
ratchet wheel fit. The ratchet wheel is free to turn in one direction, but is held
in the opposite one; or I impart the required rotary motion to the piston by
two ratchet wheels placed at the front end of the cylinder and around the piston
rod, the wheels being geared by feathers on their bosses into grooves on opposite
sides of the piston, one groove being spiral and the other straight or parallel to the
axis of the rod, and which wheels are detained from rotating in one direction by
pawls or dogs suitably arranged for that purpose.
To reciprocate the piston I take by preference the means secured to me by Letters
Patent on the 13th May 1873, No. 1734, but I do not confine myself to this com-
bination as I contemplate arranging a system of distributing the steam by means of
a valve or valves arranged at the rear end of the cylinder. The fluid pressure I
admit at the rear end of the cylinder through a revolving joint or cock, which
admits such pressure to the valve box or pressure chamber in any position of the
cock, thus allowing the cylinder to be turned while still keeping its interior in com-
munication with the pressure.
I prefer to attach the tool or head to the piston rod in the following way :-A
suitably tapered hole is formed in the centre of the end of the piston rod, and the
tool or head has a similarly tapered end or shank formed on it; a cotter hole is
formed near the inner end of the said taper hole, so that the tool or head may be
forced out by driving a cotter in behind it, or otherwise such cotter hole may be
formed in the head of the boring tool itself in such position that when the tool is
fixed for boring purposes the hole is partly within the piston rod and partly exposed,
the latter sufficient to admit of receiving a cotter and of drifting the tool from its
taper holder; or a ring or shoulder may be placed on the tapered end of the tool or
head, and the tool or head drifted from the taper hole by a wedge or key inserted
between the end of the piston rod and ring or shoulder referred to.

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 March
1878.
"
JOHN DARLINGTON, of No. 2, Coleman Street Buildings, in the City of London.
IMPROVEMENTS IN PERCUSSION ENGINES FOR BORING ROCKS OR FOR OTHER
SIMILAR PURPOSES."
My improvements relate to engines designed to deliver rapid blows by the recip-
rocation of the piston and rod, a tool or head of any well-known form for boring
being fastened to the projecting end of the piston.
The first part of my improvements more particularly relates to the means of
obtaining the reciprocating movement of the piston.
The second, to the rotating the piston on its axis.
The third, to the moving the actuating cylinder and its piston towards or away
from the work to be done.
The fourth, to the attaching the tool or head to the piston rod.
For the better holding of the cylinder I form it round externally and cut a screw
thread on its outside circumference throughout its whole length if required. This
screw cylinder is then inserted into a suitably screwed nut or holder, which may be
attached to any stand or carriage by well-known means. To advance the cylinder
it is only necessary to cause it to turn in the nut, when it will be screwed either
backward or forward through the nut. This movement may be given by hand,
a handle or hand wheel being attached to the cylinder for this purpose, or it may be
given automatically, a lever being arranged, having its fulcrum on the nut or holder,
one end of it being operated on by the moving piston rod, and the other end
operating on a ratchet wheel or similar contrivance attached to the cylinder in such
a manner as to cause the cylinder to be turned in either direction, as may be
arranged
In percussion rock boring or similar machines it is necessary that the cutting tool
should be turned into a fresh position after every blow; this may be done in several
ways, either by hand or automatically. If done by hand I attach the piston and
rod to the cylinder in such a way that while free to move in a longitudinal
direction it will be carried around with the cylinder as the cylinder is turned. In
this way as the cylinder is turned or fed forward or backward, the tool is carried
with it; or I insert a rod or rods into the rear end of the cylinder, which pass into
a suitable recess in the piston, allowing the piston to move freely longitudinally, but
compelling it to turn as the rod is turned. In this way the piston may be turned
independently of the cylinder, which cylinder may be turned automatically or by
hand, as may be desirable, or I so arrange a twisted or spirally fluted rod in the
inside of the cylinder that it passes into the interior of the moving piston, which
has a suitably shaped nut attached to it. At the upper end of the twisted or
spirally fluted rod is placed a ratchet wheel, which is free to turn in one direction,
but held by pauls or dogs from turning back again. In this way the piston moving
in one direction turns the ratchet wheel, but when moving in the opposite direction
is obliged to turn itself and follows the path of the spiral or twists on the bar, the
ratchet wheel being held from turning by the pauls; or I so arrange a ratchet
wheel at the front end of the cylinder that the piston rod shall pass through its
centre, a spiral groove or grooves is or are cut into the piston rod, into which
suitable projections from the ratchet wheel fit. The ratchet wheel is free to turn
in one direction, but is held in the opposite one; or I impart the required rotary
motion to the piston by two ratchet wheels placed at the front end of the cylinder
and around the piston rod, the wheels being geared by feathers on to bosses in their
grooves, in opposite sides of the piston rod, one groove being spiral and the other
straight or parallel to the axis of the rod, and which wheels are detained from
rotating in one direction by pauls or dogs suitably arranged for that purpose.

page_text: To reciprocate the piston I take by preference the means secured to me by
Letters Patent on the 13th May 1873, No. 1734, but I do not confine myself to
this combination as the reciprocation of the piston may be effected by distributing
the steam by means of a valve or valves attached to the rear end of the cylinder.
The fluid pressure I admit at the rear end of the cylinder through a revolving joint
or cock, which admits such pressure to the valve box or pressure chamber in any
position of the cock, thus allowing the cylinder to be turned while still keeping its
interior in communication with the pressure.
I prefer to attach the tool or head to the piston rod in the following way:-A
suitably tapered hole is formed in the centre of the end of the piston rod, and the
tool or head has a similarly tapered end or shank formed on it; a cotter hole is
formed near the inner end of the said taper hole, so that the tool or head may be
forced out by driving a cotter in behind it, or otherwise, such cotter hole may be
formed in the head of the boring tool itself in such position that when the tool is
fixed for boring purposes the hole is partly within the piston rod and partly exposed,
the latter sufficiently to admit of receiving a cotter and of drifting the tool from its
taper holder, or a ring or shoulder may be placed on the tapered end of the tool or
head, and the tool or head drifted from the taper hole by a wedge or key inserted
between the end of the piston rod and ring or shoulder referred to.
In order that my said Invention may be fully understood I shall now proceed
more particularly to describe the same, and for that purpose shall refer to the several
Figures on the annexed Sheets of Drawings, the same letters of reference indicating
corresponding parts in all the corresponding Figures on Sheet 1.
Figure 1 is a longitudinal section through the centre of a boring machine, taken
through the steam supply and distribution ports.
Figure 2 is a longitudinal section and end view of a forwarding nut fitted with
friction rollers; Figure 3 is also a longitudinal section of the same machine, but
taken through the exhaust ports and passages.
Figure 4 is an external view of a similar machine, but showing an arrangement
attached for causing the cylinder to be advanced automatically.
Figure 5 is a cross section taken on the line C, D, of the machine, shown in
Figure 4; Figure 6 is also a longitudinal section of my improved single-acting
boring machine; and No. 7 is a cross section on the line A, B, showing the arrange-
ment of ratchet wheel and detents of the rotating motion.
In the machine shewn in the above Figures I have taken the means secured to
me by Letters Patent dated 13th May 1873, N° 1734, for reciprocating the piston;
and to these are added the various improvements I shall now proceed to
describe.
a, a, is a cylinder made circular in form on the outside, and having a screw thread
formed on its exterior surface throughout its length. This screw is fitted into a
suitable nut b, or a cylindrical cradle formed to receive it. This nut may be attached
to any fixed support by clamping or clipping, either by trunnions, as shown at t, t,
in Figure 6, or by a boss C and face plate d, as shewn at Figure 4, or by any other
well-known means.
To prevent the occurrence of any cross strain between the screw-threaded
cylinder and the nut during the rotatory progression of the cylinder, friction rollers
are placed partially or wholly throughout the length of the nut, or they may be
placed at the ends of the nut itself. Figure 2 shows the application to this purpose
of the friction rollers a, b, c, two of them fixed, the upper one a adjustable by means
of set screws d. It will be evident, however, that if desirable additional rollers
may be employed.
To advance the cylinder it will only be necessary to cause it to rotate; this may
be done either by band or automatically.
Figure 1 shows a hand wheel e, e, attached to the cover of the cylinder; by
turning this wheel the cylinder is turned, and thus advanced as required.
Figures 4 and 5 show a means of advancing the cylinder automatically. f.f, is a
flat bar lying alongside the cylinder, and passing freely through an eye g fixed to

page_text: the nut b, through which the cylinder travels. The front end of this bar is carried
beyond the front of the cylinder, and its point is curved in so as to be struck by the
end of the piston rod when at or near the extremity of its stroke. This causes the
point of the rod to be depressed and the rear end to be elevated, carrying) with it
the ratchet case h and ratchet paul i, thus operating on the ratchet wheel k, which
is attached to the cylinder by the slot and feather 'm, and causing the cylinder to
rotate. A movable ring his attached to the front end of the cylinder, so as to
carry the barf with it, while still allowing it to be raised or depressed. A spring
may be attached anywhere to the bar f for returning it to its position should it be
required.
The steam pressure is brought into the cylinder through a revolving joint or cock
shown in Figure 8, Sheet 2; the pressure is thus kept constantly in the chamber 1,
Fig. 1, whence it is conveyed by the passage 2 and the holes 3 into the cylinder.
The action of the steam in the cylinder is the same as that secured by Letters
Patent, No. 1734, of 1873, 2, 2, being the inlet steam passage, 4 and 5 being the
steam distributing passages to the top and bottom of the cylinder respectively, and
6 and 7 the exhaust ports and passages.
For rotating the piston in the above-described machines I employ a spiral fluted
bar O, which enters a suitably fluted nut fixed in the piston; the head of this bar,
which is square, passes into a ratchet wheel p fitted into the cover of the cylinder,
as sliewn in Figs. 1 and 7.
Two detents are fitted to this wheel, so that it is free to move in one direction,
but held in the other. In moving in one direction the piston turns the bar, and
with it the ratchet wheel under the detents, while in the other direction the piston
is compelled to follow the path of the spiral grooves on the bar O, since this is held
by the detents and prevented from turning.
Fig. 8, Sheet 2, is an arrangement having a cylinder similarly formed, with a screw
thread on its exterior surface, but the reciprocating and turning motions are differently
obtained.
Fig. 8 is a longitudinal section through the centre.
Fig. 9 is a half plan and a half section on the line A, B.
Fig. 10 is a cross section on the line C, D.
Fig. 11 is a cross section on the line E, F; and Fig. 12 is a cross section on the
line G, H, showing the ratchets and detents of the turning motion.
And Fig. 13 is a longitudinal section through the end of piston rod, showing the
method of attaching a tool or hammer head or similar article to the end of the
piston rod.
Figs. 14 and 15 also show methods of obtaining the same object.
In Figs. 8 to 15 inclusive, a is the cylinder; b, the piston rod; c and c', two pistons,
with a space between them, which is always in communication with an exhaust
port d.
At the rear end of the cylinder is fixed a valve box containing an ordinary
slide valve e, covering two admission ports f and g, and one exhaust port h.
The slide valve is moved by means of two small pistons d, d', working in suitable
cylinders, one on each side of it. Steam is admitted alternately to these pistons by
the main piston blocks c and c³, which pass alternately holes e and e¹ formed in the
cylinder, which communicate by passages fl and f" with the valve piston.
Steam is admitted to the valve closet g through a revolving cock, which allows the
steam pressure to be in constant communication with the valve box g while the
cylinder is being turned, and is distributed by the slide valve to the front and rear
of the main piston, the main piston at or near each end of the stroke passing the
holes e and e, and admitting the steam alternately to the valve pistons, and thus
reversing the slide valve and the motion of the piston.
The turning of the piston after each blow is effected by the means described and
illustrated in the Letters Patent granted to Jordan and Darlington, 29th of November
1867, No. 3386, where the piston rod passes through two ratchet wheels, and which
piston rod is geared to the wheels by feathers &¹ and g₁ in their bosses, working in
suitable grooves formed in the piston rod, one groove S being spiral, while the other

page_text: is straight or parallel to the axis of the rod; one wheel having a feather S¹, which
gears into the spiral slot, whilst the other has a feather g", which gears into the
straight slot.
There are two detents to each wheel, so arranged that the wheels can only move
in one direction. By this arrangement it is evident that the spiral slot in the piston
rod will have the effect of turning the wheel, the feather of which works within it,
in one direction during the up stroke, and in the opposite direction during the down
stroke, but since the wheel can move in one direction only the rod itself will be
forced to turn when the said upper wheel is detained; and as the lower wheel,
whose feather works in the straight slot, will prevent the rotating of the rod in the
down stroke, the upper wheel must turn and take up a new position for continuing
the required rotary action; or I employ only one ratchet wheel having a feather in
its boss gearing into a spiral slot in the piston rod, as I have found from experience
that the weight of the piston rod, together with the friction to which the piston and
rod are subjected, are quite sufficient to cause them to follow a straight line of
motion on the down stroke, and so turn the upper ratchet wheel into a fresh
position without the assistance of the lower ratchet wheel gearing into the straight
Blot.
.
I prefer to attach the borer or hammer head to the end of the piston rod in the
following manner:-A taper hole is formed in the end of the piston rod, and a
similarly tapered end is formed on the boring tool or other article to be fixed; the
effect of the blow is thus utilized in driving the tool firmly into the hole and fixing
it. To remove it I form a cotter hole in the piston beyond the end of the taper end
of the tool, as shown in Fig. 13, so that a cotter may be driven in behind, and thus
force it out; or I form a cotter hole in the tool head, so that it may be partly within
the rod and partly without when the tool is fixed in its place, as shown in Fig. 14,
sufficient being outside to insert a cotter into the hole formed in the tool for the
purpose of drifting it out, or, as in Fig. 15, I place a collar on shoulder t on the tool
head, leaving sufficient space between it and the end of the piston rod to insert a
cotter or wedge piece, and so drift it out; or the cotter may be provided with a short
screw to bear upon the piston rod in such manner that by slightly turning the screw
itself the tool head will be loosened for removal.
Where the rod is of small diameter, and would not be of sufficient strength to
withstand the action of the tapered tool head, I fix a strengthening ring around it,
as in Fig. 13, either by shrinking on or by tapering the outer surface of the rod
slightly, and driving it on, or by other well-known means.
The cylinder of the machine above described may be advanced by hand by means
of the hand wheel shown in Figs. 8 and 9 attached to the cover of the cylinder, or
it may be advanced automatically by the means above described, and illustrated in
Figs. 4 and 5.
Figs. 16 to 20 inclusive show an arrangement in which the cylinder is similarly
formed to the ones before described, with a screw thread on its exterior, but the
reciprocating motion is obtained in a different manner, and the piston and cylinder
are so arranged that while the piston is free to move longitudinally it is compelled
to turn as the cylinder is turned. In this way the tool is constantly being turned
while the cylinder is being turned and advanced; Fig. 10 is a longitudinal section
through the centre of the cylinder; Fig. 17 is a cross section on the line A, B; Fig. 18
is a cross section on the line C, D; Fig. 19 is a cross section on the line E, F; and
Fig. 20 is a cross section on the line G, H.
a, a, is the cylinder having a screw thread cut in its exterior circumference; b, b,
is the piston and rod; and c is a spirally grooved bar which enters a nut f fixed in the
piston head. The upper end of this rod projects through the cylinder cover into a
chamber d formed in the cylinder cover. A conical face e is formed on the bar,
which fits against a suitable seating made in the cylinder cover to receive it, so that
the bar may have a rotary motion given to it, and still keep steam-tight to prevent
the steam passing from the steam chamber d around the rod into the cylinder. The
upper end of the rod c, which projects into the steain chamber d, has a socket g

page_text: keyed on, having a projection h, Fig. 17, on one side of it. This projection strikes
against projections formed on the back of the slide valve i, which cover the admission
and exhaust portways. Sufficient space is left between the projections on the valve
to allow the piston to travel a portion of its stroke before striking the valve, and
this I vary as occasion may require, as by giving more or less space here a
greater or less degree of expansive working is attained in the cylinder, as the steam
may be left on throughout the stroke, or may be cut off immediately the piston
begins to move.
The action is as follows:-Steam being admitted to the steam chamber d, the
piston being at one end of its stroke, and the slide valve being consequently thrown
over so as to admit steam behind it the piston is driven forward, and being com-
pelled to move in a straight line by the cotter K, which runs in the grooves 1, 1,
causes the spirally grooved bar to turn, carrying with it the socket g and projection h,
which latter striking against the projections on the back of the slide valve moves it
and carries it forward until the steam admission port is first cut off, and later put
into communication with the exhaust at the same time as the other admission is
opened to the steam, and the motion of the piston reversed.
The steam is admitted to the chamber d through a steam-cock or joint the same
as described above, and illustrated in Fig. 8.
CLAIMS.
Having now fully described the said Invention, and the manner in which the same
may be carried into effect, I would observe that I do not confine myself to the
precise arrangements herein-before described and illustrated, but what I do consider
novel and original and therefore claim are,-
1st. The arrangement of the ports and passages in the cylinder or cylinders and
pistons of rock borers or pecussion engines of that class, so as to produce a recipro-
catory motion, and to allow of a variable stroke of the piston without the use of a
separate or special distributing valve; also to allow of the turning of the piston and
tool holder, in combination with a screw thread cut on the external surface of the
cylinder, substantially as herein-before described and illustrated.
2nd. Obtaining reciprocatory movement in the pistons and rods of rock borers or
percussion engines of that class by means of a distributing valve moved by valve
gear in combination with a screw thread cut on the external surface of the cylinder,
substantially as herein-before described and illustrated.
3rd. Obtaining rotary and reciprocatory motion of the piston and rod of rock
borers or percussion engines of that class, in combination with a screw thread cut
on the external surface of the cylinder, substantially as herein-before described and
illustrated.
4th. The use of friction rollers in, with, or attached to the screw threaded nut in
combination with a screw thread cut on the exterior surface of the cylinder, substan-
tially as herein-before described.
In witness whereof, I, the said John Darlington, have hereunto set my hand
and seal, this Twelfth day of March, in the year of our Lord One thousand
eight hundred and seventy-eight.
JOHN DARLINGTON. (L.S.)