IMPROVEMENTS IN ROCK DRILLS
Year: 1885

page_text: I ALFRED JULIUS BOULT of 323 High Holborn in the county of Middlesex
Engineer do hereby declare the nature of this invention for "IMPROVEMENTS IN
ROCK DRILLS" (a communication from Charles Seymour Westbrook of Spragueville,
New York, United States of America, Gentleman) and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement:-
'
Reference being bad to the accompanying drawings, which form a part of this
specification, and in which :-
Figure 1 is a longitudinal sectional view of this improved rock-drill.
Figure 2 is a similar view of the cylinder, taken through a plane at right angles
to Figure 1.
Figures 3 and 4 are similar views of opposite sides of the cylinder, the piston
having been removed in the three last views:-
Figure 5 is a perspective view. of the piston, removed from the cylinder.
Figure 6 is a cross-section through line xx.
Figure 7 is a perspective view of the chuck at the outer end of the drill-shaft ;
Figure 8 is a similar view, showing the opposite side of the chuck; and
Figure 9 10 11 and 12 are detail views, illustrating details of the construction of
the chuck.
Like letters of reference indicate corresponding parts in all the figures.
This invention has relation to rock-drills operated by steam compressed air or
any other suitable medium, and has for its object to simplify the construction of
the drill and at the same time increase its efficiency. To this end this invention
consists in certain improvements in the construction of the drill-cylinder the piston
and the chuck at the end of the piston-rod or drill-shaft in which the bit is
fastened.
In the accompanying drawings A denotes the cylinder one head of which is
provided with a stuffing-box B, which may be of any desired construction the other
cylinder-head is preferably provided with the usual steep-threaded screw and
ratchet C. for imparting the required turn or rotation to the piston and drill; but
any other suitable mechanism for revolving the drill shaft may be employed
if desired.
The live-steam port D opens into one side of the cylinder and a recess E is formed
around said port on the inside. On the same side of the cylinder and in a line with

page_text: °
the inlet port, D, and its recess, E, is, on one side a groove or channel, F, and on
the other side a similar groove or channel H, the said grooves or channels F, and H
being separated from the central recess E, by the shoulders, G, G, and extending
from shoulders to opposite ends of the cylinder.
It is preferable to construct these channels of gradually increasing width and depth
from their inner towards their outer ends, as clearly shown in the drawings for the
purpose of gradually increasing their capacity for carrying the steam, air, or other
actuating medium, and, by preference, the channel H which extends towards the
forward end of the cylinder, is made shorter and of less carrying capacity than the
channel F which extends to the rear end of the cylinder.
On the opposite side of the cylinder, and registering with the open channels F
and H are two similarly constructed channels Fi and H₁ separated from a recess E¹
exactly opposite E by shoulders or bridges, G¹ G¹ and in the inner walls of the
cylinder, in a plane at right angles to a plane laid through the axis of the cylinder
and through the middle of the duplicate flaring channels are cut, on one side, two
longitudinal narrow grooves or channels N and M and on the opposite side, the two
exhaust ports, L L.
The reciprocating piston, I has the drill-shaft J projecting from its forward end,
and is provided with an annular recess K around its middle part, somewhat longer
than the two opposite recesses E and E' so as to enable the annular recess in the
body of the piston to bridge over the opposite shoulders, G G and G¹ G' and thus
connect the recesses E and E¹ on opposite sides with either pair of channels F F1
and H H. The boty of the piston is provided on opposite sides of the said central
recess with stream-tight expausible packing-rings I of any desired construction.
From the foregoing description, taken in connection with the drawings, the
operation of this part of this invention will readily be understood. As steam or air
is admitted into the cylinder through the inlet port D the annular recesses E and E¹
will connect the inlet port, through the recess in the piston with the inner ends of
one of the pairs of grooves or channels F and F or H and H' which will thus
conduct the live steam or air to the space between the head of the cylinder and the
appropriate head or end of the piston allowing it to act against that end of the
piston so as to force it away from the head.
Before reaching the end of the stroke the solid part of the piston will reach the
shoulders between the inner end of the appropriate channels and the inlet recesses,
thus cutting off the connection between the same, while, at the same time, the solid
end of the piston will uncover the appropriate exhaust port which allows the steam
or air to escape.
But at this point, the annular recess in the piston will be in
position to connect the recesses E and E¹ with the channels at the other end of the
cylinder, admitting steam or compressed air to operate against that end of the
piston, thus driving the piston in the opposite direction until, on the return stroke,
it arrives at the point at which the solid part of the piston will shut off the
connection between the recesses at, and opposite to, the inlet port and the appro-
priate channels, at the same time uncovering the exhaust, whereupon the same
operation is performed in the opposite direction; and so forth, as long as the drill
is at work. A certain amount of steain or air will always, at each stroke, remain
in the ends of the cylinder, which will be compressed by the piston at the next
stroke in the opposite direction, and this steam or air, as the case may be, will serve
as a cushion for the piston and prevent the same from striking the heads of the
cylinder at the end of each stroke, and also serves by expansion in starting the
piston on its return stroke; this pressure being sufficiently low not to weaken the
force of the direct stroke of the piston.
It will be seen that by constructing the cylinder with the diametrically opposite
and registering recesses and channels, the piston will be held in equilibrium in the
cylinder, between an even pressure on opposite sides; but there will be a lateral
excess of pressure from the steam or compressed air in the narrow channels M
and N which, pressing against one side of the piston, operates to seat this closely
against the exhaust side of the cylinder, so that no live steam or air can leak

page_text: past the piston and through the exhaust ports while the piston is making its
stroke.
The second part of this invention relates to the chuck for fastening the bit in the
drill-shaft, and is illustrated in the several figures on sheet 2 of the drawings,
Inserted into the outer end of the recessed drill shaft designated by the letter J' is
a metallic bushing made in two parts of a semi-cylindrical shape, as shown at O
and O¹ so as to leave narrow slots o diametrically opposite each other. The bushing
is prevented from falling out of its recess by rivets P the inner ends of which
project into slots or recesses p cut in the sides of the parts O and O¹ The
bushings 001 bears against keys or locking-pieces R and Ri inserted through slots
cut into the recessed part or head J¹ of the drill-shaft, which are, in turn, held in
place, respectively, by a wedge-shaped key S and a binding screw T which works
through a threaded boss U on one side of the collar V through a slot v in which
the wedge-shaped-key S is inserted and held in place by the set-screw or binding-
screw 8 Thus it will be seen that the two parts of the bushing O and O¹ may be
clamped against the bit which is inserted into the recessed head of the drill-shaft
by means of the key S and binding-screw T which bear, respectively, against the
locking-pieces R and R' which, in their turn, bear respectively against the part o
and 0 of the sectional or divided bushing. In this manner, the bit is fastened in
the end of the drill-shaft in such a manner that it cannot possibly slip or become
accidentally loosened while, at the same time, it may readily be removed and
another substituted, simply by loosening the wedge S and the binding screw T.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed as communicated to me
by my foreign correspondent I declare that what I claim is
First: In a rock-drill the combination with the cylinder A having recess E
supplied with the fluid pressure, expanding recesses F F and H H¹ which convey
the pressure to the ends of the cylinder and exhaust recess E¹ of a piston I recessed
all round as at K the whole constructed and operating substantially as described.
Second-The combination, in a rock-drill, of the cylinder having the open
wedge-shaped recesses arranged longitudinally, diametrically opposite to one
another, and the recessed piston balanced in the cylinder between said recesses, and
having expansible packing-rings whereby a steam-tight joint is formed between the
heads and the piston and the solid inside part of the cylinder; substantially as set
forth.
Third: In a rock-drill the combination with the cylinder A having on two of
its sides, the open recesses arranged longitudinally and facing one another, and on
its other two sides the exhaust port and the narrow longitudinal channels M N
arranged opposite to the same of the recessed piston I having expansible packing-
rings at each end of its solid heads on opposite sides of the recess K substantially
as and for the purpose shown and set forth.
Fourth-The combination of the recessed drill-head; the divided bushing
inserted into the recess, and having means, substantially as described, for holding it
therein; the locking-pieces inserted through slots in the recessed head and bearing
with their inner sides against the sides of the divided bushing; the collar having
the slot v and screw-threaded boss U the wedge shaped key inserted through the
slot in the collar; and the two binding-screws; the whole constructed and combined
to operate substantially as and for the purpose herein shown and set forth.
ALFRED J. BOULT.