Year: 1886

page_text: Date of Application, 18th Nov., 1886.
Complete Left, 18th Mar., 1887.
Complete Accepted, 19th Apr., 1887.
COURTENAY WILLIAM THOMPSON Glenmore House, Underhill Road, Dulwich of
the county of Surrey, Mining Engineer, do hereby declare the nature of this
invention to be as follows:-
My invention relates to rock drills of the percussive type. The first part of my
invention relates to rocks drills operated by an elastic fluid such as compressed air &
has for its object the construction of one which shall, by the combination of a
specially constructed piston & a slide valve operated by an independant piston, give
the greatest amount of work for the least expenditure of fluid pressure. This result
is obtained by having a large piston area (a piston rod of 1 to 1 or 2 inches being
used) on the advanced side of the piston as well as on the rear side which, together
with the combination hereinbefore mentioned & a particular method of cushening, all
to be hereinafter described, shall have the following properties ;-
1. The method of cushening adopted is such that the pressure of the fluid in the
cylinder is equal to that of the entering fluid at the moment of its entrance & thus
prevents waste from clearance at the ends of the cylinder & reciprocates the piston
more quickly; there is very little clearance in the valve ports either as only entrance
of the fluid is governed by the slide valve.
2. The increased piston area on the advanced side, aided or not by cushening,
returns the piston & rod (carrying the drill) more regularly & prevents the drill
sticking in the hole after the blow is given.
3. The kynetic energy developed during the back stroke (2) is stored up by
cushening or enclosing & compressing the air in the rear of the cylinders; again any
energy stored in the forward stroke before the blow is given is used up in the back
stroke.
4. The increased total operative piston area (2 & 3) enables expansion to be
carried on more fully or alloys a lower pressure than usual to be used.
5. Power will not be wasted by the low temperature of the drill as heat will be
restored to it in the operation of cushening.

page_text: This rock drill is simple in construction, leaving few working parts, at the same
time that every requirement of mechanical science & practice is obtained.
I will now proceed to describe the particular parts & working of this drill for a
mean stroke of 5 inches & a possible stroke of 6 inches ;-
The main or central part of the piston may be 4 in. long-at a distance of 2 or 3 in.
on each side of this part the piston again swells out to fit the cylinder, thus leaving
annular grooves which must have communication, each with its respective end of
the cylinder; the length of groove & enlargement may be 5 in. on each side of the
main part.
An exhaust port, leading into the atmosphere directly, is placed in about the centre
of the cylinder. Inlet ports are placed cach 4 in. distant from the exhaust port but
on the opposite side of the cylinder. The ends of the cylinder may be 5 in. together
with an additional distance from each inlet port such that, when the main part of the
piston just covers one of the inlet ports, the air enclosed in its end of the cylinder
shall be at the same pressure as the fluid pressure in use, allowance being made for
the annular grooves & the communicating ports in connection with them.
In communication with the rear end of & parallel to the main cylinder is another
small one, in which reciprocates a piston attached to the slide valve; this slide valve
operates the inlet ports.
The working of this drill is as follows :
box;
At the commencement of the back stroke the exhaust port is closed & the enclosed
air is, oweng to the kynetic energy stored up in the mass of the piston &c. which
carries it beyond the inlet port, compressed beyond the pressure of that in the valve
this forces the valve piston forward, closing the advanced inlet port & opening
the rear one. The cushened air quickly returns the piston & drill. When the main
part of the piston uncovers the inlet port, the cushened air will have expanded down
to the pressure of the inflowing air & the piston will continue to be forced forward
with full pressure till the rear enlargement of the piston covers the inlet port; at this
point expansion commences & will continue till the exhaust port is uncovered by the
main part of the piston; the blow will be struck from to 1 in. in advance of the
rear side of the exhaust port. The valve piston, at the end of its forward stroke,
impinges on a rubber ring & thus lessens the effective area of its advanced side. The
valve is consequently not reversed until the pressure is thoroughly exhausted in the
rear of the main cylinder. Fluid pressure now enters the advanced end & the piston
is forced back under the same conditions of inflow & cushened air as in the rear of the
cylinder. Another blow is struck on the return of the piston & so on. A tap valve
may be placed at the advanced end of the cylinder to start the drill, when necessary.
The enlargement at the advanced end of the piston may be of a hollow cylindrical
shape working into an annular space & leaving a small annular passage on the inner
side, thus shortening the drill & at the same time giving a long bearing for the piston
rod. There may be additional exhaust ports from 3 to 4 in. from the centre of the
cylinder, to which the inlet port will bear the same relation as hereinbefore described;
these exhaust ports to be operated by the slide valve; or only one of these ports may
be used. The enlargement at the advanced end of the piston may be dispenced with,
when the rear surface of the valve piston will have to be larger than the side in
communication with the valve box, but these surfaces are to be made equal during the
second part of the forward stroke by a slot in the piston rod.
:
The second part of my invention consists in adapting the above mentioned drill to
be worked by a non-elastic fluid such as water. I do this by combining an air
chamber at the rear of the cylinder with a slight modification of the drill herein-
before described. The air may either enclosed by a small piston or a rubber
diaphragin this auxiliary piston or one passed through the rubber may work air
tight on the pinion & above the grooved portion thereof or the rubber may be used
by itself & may either be placed in the elongation of the cylinder or be made to
work in a small air-box bolted on to the side of the drill with a connecting port
between them. In the rear of the cylinder there will be a separate inlet & exhaust
port from 1 to 2 in. apart & so arranged that, as hereinbefore described, the pressure

page_text: of the air in the chamber may equal that of the inflowing. fluid at the moment of
inflow. The advanced end of the cylinder may always be full of the fluid under
pressure, the advance end of the piston being of smaller area than the rear side, or, if
the exhaust is also under considerable though diminished pressure, a port for inlet &
exhaust must also be supplied for the advanced end. There may either be an exhaust
port to be uncovered, or an enlargement at the rear end of the piston to cover the
inlet port, at the end of the forward stroke ;-The pressure is thus reduced & the
valve piston forced back, the valve being reversed: exhaust will then be continued
during the back stroke till the rearmost exhaust port is closed by the piston: the
pressure in the cylinder will now soon preponderate & advance the valve piston, when
the rear of the cylinder will again be under pressure, the blow again given & the
piston returned-& so on. The port communicating with the valve piston may be
placed in advance of the rubber diaphragm. The area. at the rear of the piston may
be reduced, for high pressure water, by causing a second piston to work in a hollow
recessed in its rear end this piston is fixed on the end of the grooved pinion. The
bearing, working into these grooves, is so arranged that there is plenty of passage
way for water to pass in & out of the hollow piston during the process of recipro-
cation, that is, of the annular space between the grooved pinion & the inside of the
hollow piston.
The principle objects sought in this drill are:-
The method of reciprocating the valve piston combined with storing energy during
the back stroke, which approximates to that of the hereinbefore mentioned drill for
using compressed air.
The small area of piston combines with large ports; which method has the
advantage of reducing the friction consequent on using water pressure, & thus
allowing the drill to freely deliver its blow.
Dated this 18th love of Navambon 100e

page_text: I COURTENAY WILLIAM THOMPSON of Glenmore House Underhill Road Dulwich
in the County of Surrey Mining 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 of the percussive type operated by an elastic
fluid such for example as compressed air, and my Invention has for its principal
object to provide a drill which shall give a maximum amount of work with a
minimum expenditure of power. This result I obtain by providing a method of
cushioning as hereinafter explained and arrangements generally which will give
marked advantages over drills as heretofore constructed.
I will describe a drill constructed according to my Invention with reference to the
accompanying drawings chosing two examples vizt. one arrangement in which a slide
valve distinct from the piston is used and another arrangement in which the same
construction of piston acts entirely as its own valve.
Figure 1 is a longitudinal section representing the arrangement with a valve
distinct from the piston. A is the drill Cylinder and B is the piston to the rod C of
which the drill is connected. D is the ordinary helically grooved spindle, working in
the bearing or guide on the piston for rotating the drill. Around or partly around
the piston, are two grooves or recesses 662 the groove b communicating by a passage
or by passages as at 6 with the space at the rearward end of the cylinder and the
groove 62 communicating by a passage or by passages as at 63 with the space at the
forward end of the cylinder. At a is an exhaust port, opening to the atmosphere.
At a¹ and a² are inlet ports. The proportions and distances apart of the piston and
cylinder ends and the ports are so arranged relatively to each other, that when the
part of the piston between the grooves b and 63 just covers either of the inlet ports a¹
or a² the air or motive fluid enclosed in the corresponding end of the cylinder will
be at (or approximately at) the same pressure as that which is to actuate the drill,
allowance being made for the grooves 66 and the passages 163 in connection with
them. This arrangement prevents waste from clearance at the ends of the cylinder,
and causes a quicker reciprocation of the drill, than would otherwise be the case.
E is the valve casing with the inlet for the motive fluid at e. In this slides the valve F
for alternately opening the inlet ports to supply motive fluid to the cylinder A,
alternately to one and the other end of the said Cylinder. In communication with
the interior of the valve casing, is the small cylinder G, also in communication with
the rear end of the main Cylinder, in which Cylinder G slides the piston ƒ formed
with or connected to the valve F.
The operation of the drill is as follows:-
Shortly after the commencement of the back stroke the exhaust port a is closed
and (owing to the energy stored up in the mass of the piston and its adjuncts) the
fluid enclosed in the rear of the cylinder is compressed so that the piston f of the valve
is forced forward closing the forward inlet port a² and opening the rearward inlet
port a. In figure 1 I have shewn a piston of equal areas at either end but I may
make the rear area larger than the front area. This is clearly shewn in Figure 14.

page_text: The cushioned fluid quickly returns the piston B and drill until the mid part of the
piston Buncovers the inlet port a' after which the cushioned fluid will have
expanded down to the pressure of the motive fluid entering the apparatus and the
piston B will continue to be forced forward with full pressure owing to the motive
fluid entering the rearward space of the Cylinder by the groove band passages b¹
until the part of the piston B to the rear of the groove b covers the inlet port a and
at this point expansion of the fluid in the rearward space of the Cylinder, and will
continue until the exhaust port a is uncovered (as shewn in the drawing which
illustrates the position now arrived at)-On exhaustion taking place owing to the
uncovering of the exhaust port the valve piston f is reversed owing to the difference
of pressure at its two ends-The cushioned fluid in the forward space of the cylinder
will return the piston B so that the motive fluid enters by the port a' and groove b
and passages and the piston B is forced back under the same conditions of
cushioning and inflow and exhaust as in the forward stroke-The piston is then again
returned as first described and so on a blow being struck by the drill at each forward
stroke of the piston- A valve may be placed at the advanced or the rearward end of
the cylinder to start the drill, in the former case the said valve being open to the
atmosphere and in the latter communicating with supply of motive fluid. The
advanced end of the piston may as shewn in Figure 1B be of a hollow cylindrical
shape at working in an annular space 62× between the cylinder end and the inward
bearing thus shortening the drill and at the same time giving a long bearing for
the piston rod forming the stem of the drill.
My Invention may of course be applied only to the actuation of the drill on the
forward stroke the back stroke being effected by ordinary methods-Figure 3
represents an arrangement on this plan. The parts which correspond with those
shewn in Figure 1 are marked with the same letters of reference-The advanced end
of the piston is always under pressure by reason the inlet port a² not being covered
by the slide valve F which only covers and uncovers the rearward port a¹. The
valve F is otherwise like that shewn in Figure 14. The groove band passages b¹ in
the rear end of the piston are like those described with regard to Figure 1. The
port of the piston between 1 and 2 is made long enough not to open to the exhaust
for the advanced end of the cylinder.
Figure 2 illustrates in longitudinal section the arrangement wherein the slide
valve F and its adjuncts are dispensed with the two inlet ports being always open to
the pressure of the motive air or fluid and being opened and closed by the piston
which therefore acts as its own valve-The parts which correspond to those shewn in
Figure 1 are marked with the same letters of reference the air or motive fluid
entering the space at each end of the cylinder A alternately when the piston uncovers
the corresponding inlet port so that it communicates with the space at the end of the
cylinder by the groove and passages in the piston B-The central part of the piston
between the grooves 662 may be shortened by providing a separate exhaust for each
end of the cylinder to be uncovered for exhaust at the proper times by the move-
ment of the piston. Figure 4 represents an arrangement on this plan. Figure 5 is
a cross section of the piston on the linear. The parts which correspond with those
shewn in the preceding Figures are marked with the same letters of reference-The
part of the piston between the grooves &¹³ is made shorter than in the preceding
Figures and there are two exhaust ports a³ and a one at each end of the cylinder
covered and opened alternately by the portions of the piston at 6 6 which also
uncover and open the inlet passages a¹ a². The arrangement here shewn is one in
which the piston acts as its own valve after the manner of the arrangement Figure 2
but the separate valve as in Figures 1 and 14 may be used with it if so desired.
Having now particularly described and ascertain the nature of my Invention and
in what manner the same is to be performed I declare that what I claim is :-
First: The rock drill constructed or arranged substantially as hereinbefore
described and illustrated by the examples explained with reference to the accompanying
drawings.

page_text: Second: In rock drills the means for cushioning the piston in such a manner that
the pressure of the fluid retained in the cylinder is equal (or approximately equal) to
that of the inflowing air or fluid at the moment of its entrance to actuate the drill
whether this be applied to both ends of the piston or to the required end only
substantially as and for the purposes herein before described.
Third: In rock drills operating substantially as hereinbefore described the piston
of equal diameter throughout and with grooves and passages in it arranged substan-
tially as hereinbefore described and illustrated by the accompanying drawings.
Fourth In rock drills operating substantially as described the valve and its
adjuncts arranged and operating in conjunction with the piston substantially as
hereinbefore described and illustrated by Figures 1 and 1ª of the accompanying
drawings.
Fifth The several modifications of rock drill consisting of the parts con-
structed arranged and combined as separately herein before described and illustrated
respectively by Figures 1, 2, 13, 3 and 4 of the accompanying drawings.