Improvements in Rock and like Drills.
Year: 1897

page_text: Date of Application, 12th Jan., 1897
Complete Specification Left, 17th Sept., 1897-Accepted, 23rd Oct., 1897
Improvements in Rock and like Drills.
We, SIDNEY PRATT BLACKMORE, residing at the George Goch Amalgamated
Gold Mining Company, Limited, Johannesburg, South African Republic, Electrical
Engineer, RICHARD OLIVER GARDNER DRUMMOND, of Commissioner Street,
Johannesburg, aforesaid, Electrical Engineer, and EDWARD JOHN WAY, General
Manager of the George Goch Amalgamated Gold Mining Company, Limited,
Johannesburg, aforesaid, do hereby declare the nature of this invention to be as
follows:-
This invention relates to percussive rock and other like drills capable of being
operated either by manu-motive, electro-motive or other power.
It is designed with the object of providing a simple and at the same time
efficient means for converting the rotary motion of the motor or driving part of
the drill into the necessary percussive reciprocating motion of the drill through
the drill bar or shaft.
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It consists essentially in the application to the bar or shaft of the drill of
cylindrical cam or a hollow cylindrical piece formed with a helical, approximately
helical or cam surface in combination with a preferably electric motor to which a
corresponding cylindrical cam is attached, the cam attached to the drill shaft
being connected with a spiral or like spring to impart the requisite percussive
motion to the drill immediately the cam affixed to the shaft reaches the limit of
its throw or maximum point of expansion.
In carrying out the invention we prefer to construct the shank or extremity of
the drill bar or shaft with a boss onto which a cylindrical cam or a hollow
cylindrical piece formed with a helical or cam surface is screwed or to which it
may be otherwise attached. The bar or shaft is also formed with an annular
projection or shoulder up to which the cam is screwed to take up the thrust.
On the drill bar or shaft in front of the cylindrical cam an electric motor
provided with a hollow armature shaft is mounted. This hollow armature shaft is
free to rotate on the drill shaft and has a cylindrical cam or hollow cylindrical
piece formed with a helical or cam surface screwed or otherwise suitably attached
thereto, corresponding to the cylindrical cam attached to the shank of the drill
bar into which it fits or with which it engages.
The shank of the drill bar or shaft is connected by means of an ordinary riffle
bar, working through the ratchet wheel supported in the cylindrical casing and
provided with the usual pawl or pawls, with a disc or cup shaped piece capable of
rotating and sliding freely to and fro in the cylindrical casing. Interposed
'between this cup shaped. piece and a further disc capable also of sliding in the
cylindrical casing is a suitable spiral or other buffer spring. Any convenient
means such as a screw or the like for regulating the tension of the spring, and
means for locking the screw in any desired position will preferably be provided.
In operation, as the armature shaft of the motor carrying with it the cylindrical
cam attached thereto is rapidly rotated round the drill shaft the other cam and

page_text: with it the drill shaft to which it is affixed is forced backwards-being prevented
rotating with the armature shaft by the riffle bar-and the buffer spring gradually
compressed until the cam has reached its limit of throw or maximum point of
expansion when it is propelled or forced forward by the sudden expansion of the
spring and the requisite percussive motion is thereby imparted to the drill.
Dated this 19th dow of Donambow 1000
Improvements in Rock and like Drills.
We, SIDNEY PRATT BLACKMORE, residing at the George Goch Amalgamated
Gold Mining Company, Limited, Johannesburg, South African Republic, Electrical
Engineer, RICHARD OLIVER GARDNER DRUMMOND, of Commissioner Street,
Johannesburg, aforesaid, Electrical Engineer, and EDWARD JOHN WAY, General
Manager of the George Goch Amalgamated Gold Mining Company, Limited,
Johannesburg, aforesaid, 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:-
This invention relates to percussive rock and other like drills capable of being
operated either by manu-motive electro-motive or other power.
It is designed with the object of providing a simple and at the same time
efficient means for converting the rotary motion of the motor or driving part of
the drill into the necessary percussive reciprocating motion of the drill bit through
the drill bar or shaft.
It consists essentially in the application to the bar or shaft of the drill of a
cylindrical cam or a hollow cylindrical piece formed with a spiral or approximately
spiral cam or screw surface, in combination with a preferably electric motor to
which a corresponding cylindrical cam or hollow cylindrical piece formed with a
spiral or approximately spiral cam or screw surface is attached, the cam attached
to the drill shaft being connected with a spiral, helical or other suitable spring to
impart the requisite percussive motion to the drill immediately the cam affixed
to the shaft reaches the limit of its throw or maximum point of expansion.
The invention will be further and fully described by means of the accompanying
drawings, in which
Fig. 1 is a longitudinal sectional clevation of a rock drill constructed in
accordance with this invention.
Fig. 2 a longitudinal sectional elevation of a portion of same shewing a modified
arrangement.
Fig. 3 an elevation from the motor end of the drill.
Fig. 4 a detached view of a portion of the cylindrical cams CC' drawn asunder
shewing the spiral or approximately spiral cam or screw surfaces c c¹.
The corresponding parts in the several figures of the drawings are indicated
by the same letters of reference.
.
In the arrangement shewn in Fig. 1 A is the drill bar or shaft, the shank or
extremity of which is formed with 'a boss a. The boss a is formed of approxi-
mately the same diameter as the internal diameter of the cylindrical
casing B, in which it is capable of sliding freely to and fro. The
boss.a is turned down to form shoulders thereon at a¹ a³. The turned down por-
tion 6 of the boss a is screwed to receive the cylindrical cam or hollow cylindrical

page_text: The
piece C formed with a spiral or approximately spiral cam or screw surface c.
construction of the cylindrical cams CC is more clearly shewn in Fig. 4 which
is a view of the same drawn asunder and shewing the spiral cam or screw
surfaces cc. The cylindrical cam C is tapped to correspond with the portion b
of the boss a on to which it is screwed. The shoulder a¹ up to which the cam
is screwed takes up the thrust and prevents the possibility of the stripping of the
screw thread. Between the shoulder a2 on the shank of the drill and the cover b¹
on the end of the cylindrical casing B a preferably spiral spring D is inserted.
The extermity of the shank of the drill is bored out centrally at E as shewn
and is partially tapped to receive the riffle nut F through which the ordinary
riffle bar G works to impart the requisite twist or rotary motion to the drill bit.
The cavity E is made sufficiently deep to permit of the stroke of the drill. The
end of the riffle bar G projects through the flanged cover b¹ of casing B which
forms a bearing for it and has keyed or otherwise attached to it the ratchet or leaf
wheel H. The pawls J are pivoted in gear with wheel H on pins ; passing into
the flange of cover. 61. A cup shaped piece K capable of sliding in the exterior
cylindrical casing L, is pinned or keyed as at k to the flange b' and forms a bearing
for the extremity of the riffle bar G.
at
For the purpose of adjusting the tension of the spring D a screw M passing in
through the end of casing L is attached to the cup-shaped piece K by means of
the pin m.
An operating wheel N is attached to the screw M and a lock nut or
locking device n is provided for locking the screw in any desired position. As
the parts are drawn forward or forced backwards by means of screw M to regulate
the tension of the spring D the casing B slides freely within the part L' of the
exterior casing of the drill.
The other cylindrical cam C¹ which is a counterpart of the cam C. attached to
the drill shaft A is screwed into the hollow armature or rotor P of the motor and
is provided with a bush O which forms the bearing for the rotating part of the
motor. P is the rotor and Q the stator of a preferably polyphase electric motor
coupled up with the dynamo or other generator of electricity. The motor is
enclosed by the part L2 of the exterior casing. The cap R which forms the bearing
for the drill bar A is affixed to the annular piece S bolted to the casing L².
In Fig. 2 an arrangement is shewn in which the cylindrical cams CC₁ are
mounted on the drill bar A at the exterior of the motor: The cam C₁ is screwed
or otherwise conveniently attached to the extension piece or continuation T of the
hollow armature or rotor shaft U of the motor. A packing ring V is provided to
prevent the passage of the lubricant from the external casing L' in which the
cams work into the interior of the motor casing L³. The several other parts in
this arrangement are similar to 'those previously described with reference to
Fig. 1.
It will be evident that the cam or screw surfaces cc' might be formed on a solid
instead of a hollow cylinder as shewn and be attached to their respective parts by
means of suitable exterior devices, and that in lieu of the spiral spring Da
pneumatic or air spring might be employed.
If desired any suitable form of differential gearing may be interposed between
the driving and driven parts of the drill.
Although the drill shewn in the drawings is designed to be driven by means
of an electric motor, it will be obvious that by substituting for the motor other
suitable means motion may otherwise be imparted to the operative parts of the
drill.
In operation, as the armature or rotor P of the motor carrying with it the
cylindrical cam C, is rapidly rotated round the drill shaft A the other cam C and
with it the drill shaft A is forced backwards--being prevented rotating with the
armature or rotor P by the riffle bar G-and the buffer spring D gradually com-
pressed until the cam C has reached its limit of stroke or maximum point of
expansion when it is propelled or forced forward by the sudden expansion of the

page_text: spring D and the requisite percussive motion thereby imparted to the drill bit
through the drill shaft A.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed we declare that what
we claim is :-
1. In rock and like drills a cylindrical cam or cylindrical piece formed with a
spiral or approximately spiral cam or screw surface attached to or connected
with the driving part of the drill, gearing or engaging a corresponding cylindrical
cam or cylindrical piece formed with a spiral or approximately spiral cam or screw
surface attached to or connected with the drill shaft, substantially as and for the
purposes herein described.
2. In rock and like drills the combination with the cylindrical cam C attached
to or connected with the drill shaft A of the corresponding cylindrical cam C¹
attached to the hollow armature or rotor P of the electric motor P Q and a spring
for imparting the percussive motion to the drill bit when the cams have reached
their limit of stroke substantially as described.
3. A rock drill constructed and arranged, substantially as described and shewn
with reference to either Fig. 1 or Fig. 2 of the accompanying drawings.
100%
S. P. BLACKMORE.
R. OLIVER G. DRUMMOND.
EDWARD J. WAY.
Witness:
CHAS. OVENDALE,
International Patent and Trade Mark Agent,
Steytler's Buildings, (P.O. Box 3146), Johannesburg, S.A.R.