IMPROVEMENTS IN PERCUSSIVE ROCK-DRILLS
Year: 1879

page_text: LETTERS PATENT to John Imray, of No. 28, Southampton Buildings, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN PERCUSSIVE
ROCK-DRILLS." A communication from abroad by Charles William Burton,
of Paris, France, Engineer.
Sealed the 30th January 1880, and dated the 10th October 1879.
PROVISIONAL SPECIFICATION left by the said John Imray at the Office
of the Commissioners of Patents on the 10th October 1879.
JOHN IMRAY, of No. 28, Southampton Buildings, in the County of Middlesex.
"IMPROVEMENTS IN PERCUSSIVE ROCK-DRILLS." [A communication from abroad
by Charles William Burton, of Paris, France, Engineer.]
This Invention relates to percussive rock drills of the kind that are worked by
hand, and consists in an arrangement and construction of the mechanism for turning,
advancing, and retracting the drill, and of the frame work for supporting it in such
manner as to secure simplicity, portability, and steadiness while the apparatus is at
work along with facility of changing or replacing the drills, as will now be described.
A flywheel shaft, which may be worked by winch handles or by a band, is mounted
in bearings on a light frame attached to a cylinder in which works a piston. The
piston rod extends through both ends of the cylinder, the lower end holding the
drill or boring tool, and the upper end being fixed to a sleeve which is put on in
halves, held together by screwed rings. In the lower part of this sleeve is fitted a
ring, which is free to turn round the piston rod as an axis. A couple of cams on
the flywheel shaft bear against this ring, so that in every revolution of the shaft
the piston rod is twice raised and left free to descend. In rising the piston com-
presses the air in the cylinder above it, and the compressed air causes the piston to
make a rapid and forcible outstroke working the drill. In order to provide for
supply of air above the piston to make up for leakage, and also to cushion the piston
in its downstroke, the lower portion of the piston rod is enlarged to form a trunk
with an annular space surrounding it. During the ascent of the piston air enters
this space through a check valve, and during its descent a portion of that air
passes through a check valve and passage to the upper side of the piston.
To prevent the pressure in the cylinder from becoming excessive the upper end
of the cylinder has a spring or loaded safety valve. The sleeve to which the upper
end of the piston rod is attached contains a central nut, in which works a screw of
Die G2

page_text: rapid pitch that can be turned by a winch handle either for advancing or retracting
the drill, and this nut, as well as the sleeve, is provided with ratchet and pawl
gear or with friction bands that are tightened in the one direction and slackened
in the other, so that by means of an arm moving along an incline on the framing
the sleeve, and with it the piston rod and the drill, as well as the nut, is turned
partly round at each stroke without advancing the drill, but when the drill in any
stroke advances beyond a certain distance a projection on the sleeve strikes a
spring slide, which, acting on the ratchet or friction band of the nut, causes a
partial rotation thereof relatively to the sleeve, so that the drill is fed a little
forward. When it is desired to advance or retract the drill by hand a small key is
inserted to prevent the piston rod from turning when the feeding screw is turned.
The whole machine is mounted on a tripod stand having legs adjustable in length
and in inclination, and having sockets provided at their upper jointings so that
the drill cylinder can be set on them vertically or horizontally. The cylinder
and its framing can also be attached in a horizontal position to a vertical
bar or column fixed in a tunnel or leading so as to drill forwards, and it
can be set at any desired height, the cam shaft being driven by a band when it is
not conveniently situated for direct working by hand.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Imray in the Great Seal Patent Office on the 25th March
1880.
JOHN IMRAY, of No. 28, Southampton Buildings, in the County of Middlesex.
"IMPROVEMENTS IN PERCUSSIVE ROCK DRILLS." A communication from abroad
by Charles William Burton, of Paris, France, Engineer.
This Invention relates to percussive rock drills of the kind that are worked by
hand, and consists in an arrangement and construction of the mechanism for turning,
advancing, and retracting the drill and of the framework for supporting it in such
manner as to secure simplicity, portability, and steadiness while the apparatus is at
work along with facility of changing or replacing the drills, as will now be described.
A fly wheel shaft, which may be worked by winch handles or by a band is mounted
in bearings on a light frame attached to a cylinder, in which works a piston. The
piston rod extends through both ends of the cylinder, the lower end holding the
drill or boring tool, and the upper end being fixed to a sleeve which is put on in
halves, held together by screwed rings. In the lower part of this sleeve is fitted a
ring, which is free to turn round the piston rod as an axis. A couple of cams on
the fly wheel shaft bear against this ring, so that in every revolution of the shaft
the piston rod is twice raised and left free to descend. In rising the piston com-
presses the air in the cylinder above it, and the compressed air causes the piston to
make a rapid and forcible outstroke working the drill. In order to provide for

page_text: the nut G; this nut having collars n working in recesses of the sleeve E being thus
turned partly round causes the piston rod and drill to descend a little relatively to
the sleeve, thus providing the forward feed as the hole formed by the drill is
deepened. Obviously ordinary ratchet and pawl arrangements might be used
instead of friction pawls both for turning the drill and effecting its forward feed.
In order to maintain in the cylinder above the piston a sufficient supply of air to
act by its compression by the ascent of piston as a spring to accelerate the descent
of the piston there is provided at the lower end of the cylinder (see Fig. 6) a
suction valve q, by which, as the piston ascends, air enters the annular space sur-
rounding its trunk. During the descent of the piston this air is discharged by the
spring valves and passage r, through a port o, into the upper part of the cylinder
above the piston. The cylinder cover is provided with a safety valve to allow
escape when, by the accumulation of air in the upper part of the cylinder the
pressure exceeds a certain limit. The valves 7, 8, and passager might be dispensed
with by forming one or more grooves in the cylinder extending from the bottom
upwards a certain height, so that when the piston passes their upper ends a portion
of the air below the piston, compressed by its descent, shall pass by the grooves to
the space above the piston. For rapidly withdrawing the drill the screw t is
turned by a handle u. The rod which passes through the piston is made with a
key way, in which fits a feather v (see Figs. 7 and 8), which can be withdrawn by
retracting a spring button . The apparatus is mounted for drilling downwards
on three adjustable legs I, jointed to the cylinder. For drilling upwards or
laterally it may be mounted on a column, as indicated in Figs. 10 and 11.
Having thus described the nature of the said Invention and in what manner the
same is to be performed, as communicated to me by my foreign correspondent I
claim,―
First. The construction and arrangement of percussive rock drill herein described
with reference to the accompanying Drawings.
Second. The means of turning and advancing the drill herein described with
reference to Figs. 3, 4, and 5 of the accompanying Drawings.
Third. The arrangement of cylinder and piston with means of maintaining pres-
sure above the piston herein described with reforence to Figs. 1 and 6 of the
accompanying Drawings.
Fourth. The use of the revolving antifriction ring 6 in combination with the
cams or wipers C, substantially as and for the purpose herein set forth.
In witness whereof, I, the said John Imray, have hereunto set my hand
and seal, this Twenty-fifth day of March, in the year of our Lord Ono
thousand eight hundred and eighty.
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