Year: 1887

page_text: Date of Application, 4th Aug., 1887.
Specification Accepted, 13th Sept., 1887.
Like letters represent similar parts in all the Figures.
The drill is provided with a cylinder C of ordinary construction, having the usual
supply passages 1, 1', and an exhaust passage E', in addition to which passages M, M',
are provided in the cylinder, and act in conjunction with passages Z, Z, formed in
the stuffing boxes at each end and the passages M2, M3, in the piston rod, for the
purpose of actuating the valve V as hereinafter described.
The piston P is also of ordinary construction, and may be fitted with one or more
packing rings to move air tight in the cylinder C
The piston rod runs the whole length of the body of the machine, and is for con-
venience of description referred to by the letters R, R¹, R², each representing a
different part in the length of such rod.

page_text: The part R moves in cylinder C, and in it is formed the passage M² above referred
to, such part R working through the stuffing box at the lower or forward end of the
cylinder, in which the hollow space Z is formed, and with which communicates
the passage M leading to the upper or rear end of small cylinder C2 in which the
valve piston P² works. The part R¹ works through the stuffing box at the other end
of cylinder C, and in it the passage M³ is formed, while in the stuffing box through
which it works is the hollow space Z communicating with passage M³, which leads to
the lower or forward end of small cylinder C₁ in which the valve piston P¹ works.
The part R¹ carries a rifled nut N for the purpose of rotating the drill as hereinafter
described.
On the part R2 of the piston rod is fitted a slotted cylindrical rifled bar B actuating
the feeding device as hereinafter described.
The valve V is of ordinary construction and is connected by a removable bar B1 to
the two small pistons P' and P2, respectively working in the small cylinders (and C,
formed in the opposite ends of the valve chest C³, and which pistons are actuated by
air or steam alternately admitted to and exhausted from such small cylinders from the
main cylinder C, by the passages M2 and M³ in the parts R and R¹ of the piston rod,
and the passages M and M at each end of the valve chest, through the hollow
spaces and Z in the stuffing boxes; these passages being brought into communication
at certain portions of the stroke of the piston.
The action is as follows :-
I
The piston. P having arrived at its full backward stroke, as shown in Fig. 1, air or
steam is admitted from cylinder C through passages M2, Z and M, to the rear side
of the valve piston P2, the passage M² in the piston rod R being so arranged as to
establish the necessary communication when the piston has nearly completed its back-
ward stroke. The steam or air acting on the rear of valve piston P2 moves it to the
position shown in Fig. 2, when the valve V (having been moved with the pistons P¹, P²)
will put the space below the drill piston P open to the exhaust, through passages
and E, and the passage M² being still in communication with such space below the
drill piston P, will also be open to the exhaust, and the steam will thus be exhausted
from behind valve piston P², through passages M, Z, M², I and E¹. At the same
time, as the movement of the valve will have opened the passage I¹ to the steam or
air in the valve chest, the steam or air will pass to and act upon the rear of drill
piston P, and effect the down or working stroke of the drill, such movement cutting
off both cylinders C and C2, both from steain and exhaust until the downward stroke
of the drill is nearly completed, when passage M³ in piston rod R¹ will establish com-
munication (through passages Z', M'), between the space which there will then be above
the piston P, and the rear of valve piston P¹, and the steam or air passing from such
space in cylinder C will act on piston P', and so reverse valve V, returning it again
to the position shown in Fig. 1, thus putting the space above piston P and at the rear
of piston P¹ open to the exhaust, and admitting steam through passage I to act upon
the underside of piston P, and so effect the return stroke, thus bringing the whole of
the parts back to the position shown in Fig. 1, when the action above described will
be repeated.
The rotation of the drill is effected by means of the nut N which is externally rifled
or provided with helical projections engaging corresponding grooves formed in the
inside of bush Y, so that as nut N, which is mounted ont he piston rod R¹, recipro-
cates with the latter, it will cause the bush to make a partial rotation during the
forward stroke of the drill. As the bush Y is prevented from rotating in the opposite
direction during the backward stroke of the drill by means of an arrangement of
pawls F, engaging the ratchet wheel U mounted on bush Y (as shown in Fig. 3), so
as only to permit the latter to revolve in one direction, it follows that during the
backward stroke of the drill, the rifled N will be caused to make a partial rotation
carrying with it the piston rod and drill, whereas during the forward stroke, the
pawls being free to slip over the teeth of ratchet wheel U2 (the inertia of which
and the bush Y is more than counterbalanced by that of the piston and its rod and

page_text: the drill), the bush Y will be caused to turn instead of the piston rod. The pawls F
are acted upon by springs to ensure their proper engagement with the teeth of ratchet
wheel U³.
In order to avoid all chance of the breaking of the pawls F or of the teeth of
ratchet wheel U² should the drill encounter any obstruction to its rotation, the ratchet
wheel U is mounted on a conical seat formed on bush Y, and is held fast thercon by
the friction of the contact surfaces caused by the action of a powerful spring S¹. If
only a slight or no obstruction presents itself to the rotation of the drill, the action
of the spring will cause the ratchet wheel U2 to act as though it were keyed to the
bush and prevent its rotation during the backward stroke, but should any considerable
opposition present itself, the strain will cause the bush to slip within the ratchet
wheel U2, and thus prevent all chance of the pawls F or the teeth of the ratchet
wheel U being broken.
The part of the piston rod is surrounded by a hollow cylindrical rod B, in which
the part R can revolve, but to which latter the rod B is secured by a nut B³, so that
it is caused to reciprocate with the piston rod. This rod B is rifled or provided with
external helical projections engaging corresponding grooves in the inner surface of
the boss of a crank K mounted loosely on the rod: To the arm of crank K a pawl Fl
(acted upon by a spring) is pivotted and engages the teeth of a ratchet wheel U, to the
hub of which a wheel W is secured. The wheel W gears with a pinion W₁ secured to
the feed screw Q, working through nuts N¹ fixed to the slide or saddle S on which
the machine is mounted.
The rod B is prevented from rotating by means of a longitudinal slot running the
greater portion of its length, with which a bar G engages, such bar passing through
the bearing Land casing E to which latter it is secured, as shown in Fig. 5.
On the completion of the forward stroke of the piston P, the pawl F is forced into
engagement with one of the notches or teeth of ratchet wheel U and locks same, so
that on the return stroke the rifling of rod B, imparting a partial rotation to crank K,
will cause the pawl F¹ to impart a similar movement to wheel U, and through wheel W
gearing with pinion W, such movement will be transmitted to feed screw Q, and by
causing it to work through the nuis N' on saddle S, thus advance or feed the machine
forward. In consequence of this advance the next forward stroke of the piston will
not be a full stroke, and will not be a full stroke again until the length of the forward
movement has been bored by the drill, and until this takes place the pawl F cannot
enter a fresh notch or tooth of wheel U, but will move freely backward and forward
over such wheel without actuating same. Immediately that the piston regains its full
stroke the pawl will engage a fresh notch or tooth, and a further advance will be given
to the machine.
The pawl F, as shown in Fig. 4, has a head F2, capable of sliding freely on the
curved bar or yoke J as the crank K reciprocates. From bar J two arms J³ extend,
and are mounted on eccentrics on spindle J2 mounted on the casing, so that by turning
said spindle by means of the crank or handle J at one end, the pawl F1 will be raised
clear of ratchet wheel U, and permit of the drill being screwed back on saddle S after
having been advanced to the full extent of the feed. The end of feed screw Qis
fitted with crank handle H, to enable same to be turned by hand for the purpose of
moving the machine backward or forward on the saddle S as required, the pawl F
being first raised clear of ratchet wheel U as above described.
Two circular bars Q₁ running parallel with the feed screw Q, work through the
saddle S, and are keyed firmly to the body of the machine and further held by nuts,
as show in Fig. 6.
To prevent excessive wear on the feed screw Q and nuts N', the former is fitted
with a strong spring S at its lower end, as shown in Figs. 1 and 6.
In action the machine is attached to a carriage or column by the saddle arm B³.
The drill or borer D has a projection D' (see Figs. I and 7) for fixing it in its
socket in the lower end of the piston rod R, the socket having a longitudinal slot
from the end of which a transverse slot leads, the latter being in the form of part of

page_text: a screw thread. The projection D¹ on drill D is first inserted in the longitudinal slot
in the socket, and forced to the end of same, when by a twist being imparted to the
drill, the projection is caused to enter the transverse groove and moving over the
inclined plane thereof forces the end of the drill or boror tightly against the bottom
of the socket. The direction of the transverse groove is opposed to that in which
the drill is caused to rotate, so that the latter may have no tendency to loosen in
its socket.
The upper part of cylinder C is turned to receive the bearings L and L', the latter
being turned to fit same, and being fixed by screws to the casing E of the machine.
The stuffing boxes are each closed by annular plates T (see Fig. 1), the packing O
and the plates T₁ fitting compactly on each other, with the spaces Z and Z' in the
centres, from each of which a channel proceeds for placing the passages M and M'
respectively in communication therewith. The upper box is finally closed and the
packing compressed by the screw nut L2, and the lower box by the gland G.
The rifling of nut N and bush Y and also that of rod B and crank K can be
arranged with the projections on either part to enter the grooves in the other part.
Having now particularly described and ascertained the nature of our said
Invention, and in what manner the same is to be performed, we declare that what
we claim is :-
1. The means for actuating the valve of rock drills, consisting in arranging the
valve between two pistons capable of reciprocating in suitable cylinders provided in
the valve chest, and from the outer end of each of which a passage leads through the
stuffing boxes or glands of the main cylinder into the latter, the passage from each
valve piston cylinder passing through the stuffing box at the opposite end of the main
cylinder to that at which it is itself situated, the usual passages for the admission and
exhaust of steam or air to and from the main cylinder being arranged between the
ports or passages leading to the valve piston cylinders, and two separate passages
formed in the rod of the main or drill piston, and each serving to control the supply
and exhaust of one of the valve piston cylinders, all substantially as specified.
2. Constructing the stuffing boxes or glands of the cylinder of rock drills with
passages through then communicating with such cylinder and also with one end of
one of two cylinders, in which are arranged pistons carrying between them the valve
for actuating the main piston of the drill, substantially as specified.
3. The arrangement of mechanism for rotating the drill piston and its rod at each
backward stroke of the drill, consisting in a rifled nut carried by the piston rod and
engaging a bush or sleeve which is correspondingly rifled, while its outer surface is
formed with a conical seat against which a ratchet wheel is forced by a spring (so as
to enable the bush to turn in the wheel in the case of any unusual obstruction during
the backward stroke of the drill), and suitable pawls arranged to engage such wheel
and prevent its rotation during the backward stroke, the whole arranged and operating
substantially as specified.
4. The arrangement of mechanism for feeding the drill forward as the work
progresses, consisting in mounting on the piston rod of the drill a hollow rifled rod
provided with a longitudinal groove, with which a bolt projecting through the drill
casing engages, so as to prevent its rotation on the piston rod, while allowing it to
reciprocate therewith, such rifled rod engaging the boss of a crank mounted so as to be
capalle of a circular rocking movement thereon, and upon the arm of which is pivotted
a pavl which engages a ratchet wheel, to the boss of which a toothed wheel is con-
nected and gears with a pinion fixed to the feed screw, working through a nut or nuts
carried by the slide or saddle on which the whole machine is mounted, all arranged
and operating substantially as specified.
5. The means for disengaging the pawl F1 from ratchet wheel U, when required to
move the drill in relation to the slide or saddle by hand, such means consisting in the
shaft J2, mounted so that it can be rocked in suitable bearings, and provided with
eccentrics engaging the arms J³ of a curved bar or yoke J, on which an arm or

page_text: head F of the pawl F¹ is free to slide, all arranged and operating substantially as
specified.
6. The means for connecting the drill to the piston rod by causing a projection on
the drill to enter and pass to the bottom of a longitudinal slot in the drill socket, and
then by imparting a partial rotation to the drill causing such projection to enter a
transverse slot leading from the longitudinal slot, and made in the form of part of
a screw thread, substantially as specified.
7. The general construction, arrangement, and combination of parts constituting
the improved rock drill, all operating substantially as and for the purposes specified.
Dated this 4th day of An 1887
ALLISON BROS.,
Agents for the Applicants.