Improvements in and relating to Rock Drill Heads or Chucks.
Year: 1899

page_text: Date of Application, 24th July, 1899
Complete Specification Left, 21st Apr., 1900-Accepted, 23rd June, 1900
[Communicated from abroad by The Firm of CHAPIN AND MANION, LIMITED, of
15, Harrison Street, Johannesburg, in the South African Republic, Machinery
Importers.]
Improvements in and relating to Rock Drill Heads or Chucks.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 322, High Holborn, in the County of Middlesex, 6, Lord Street,
Liverpool, and 6, Bank Street, Manchester, both in the County of Lancaster,
and Lower Temple Street, Birmingham, in the County of Warwick, Civil
Engineer, do hereby declare the nature of this invention to be as follows:-
This invention has reference to the chucks or heads of rock drilling machines,
or to the device which forms the connection between the rock drill, rock drilling
bit or other boring tool and the piston rod or other reciprocating member of
the rock-drilling machine.
It has for its object to provide an efficient chuck of simple and cheap con-
struction; capable of being operated with facility to securely hold the drill in
the desired position and to release the same when it is required to remove the
drill to substitute another therefor; also to provide arrangements or tools for
use in the operation of withdrawing and inserting the drills and for removing
the gripping pieces from the chuck body when required.
In carrying out the invention I prefer to form the body of the head or chuck
on the end of, and in one piece with, the piston rod of the machine, although
it may if found more convenient be formed as a separate part and be suitably
attached to the extremity of the piston rod.
The body which may be of conical or other suitable form externally, is pro-
vided with a central, preferably conical, cavity or recess expanding inwardly,
or with the diameter gradually increasing as it recedes from the exterior.
Within this cavity a tapered bush is arranged, constructed of several sections
in the form of wedge shaped gripping jaws or dogs. The several sections of
the bush are tapered toward their forward extremity and rounded externally
to correspond to the conical cavity in which they can slide longitudinally within
certain limits. When assembled within the body these several sections form a
bush or lining enclosing and gripping the end of the drill on all sides when
inserted between them. The inner parallel faces are formed with a shallow
V groove to accommodate the edges or corners of the drill and they may be
constructed to accommodate drills of octagonal section or of any other section of
drill steel. I prefer to employ four gripping jaws or to split the bush up into
four equal sections, but more or less may be used if desired. The jaws are so
constructed and arranged that when gripping the end of the drill a small amount
of space or clearance is left between them, and they are secured in position within
the chuck body in the event of the drill being removed, by being forced forward
until they bear and bind upon one another.
At the rear of the jaws or several sections of the bush a strong, preferably

page_text: involute, spring is arranged fitting within an annular recess formed at the
bottom of the conical cavity which acts to maintain the spring central. The
spring completely surrounds or encircles the inner end of the drill and is prefer-
ably arranged with its base or convolution of greatest diameter bearing on the
inner ends of the jaws and the other end bearing against the chuck body within
the recess, so that as the jaws are depressed or forced inwards the spring is placed
in compression to act to force the jaws outward when released. The inner ends
of the jaws are formed with a curved groove in which the spring rests.
jaws are forced inwards the tendency of the spring to expand or spread at the
base keeps the jaws tight against the walls of the cavity and thus causes them
to leave and release the drill. In place of the involute spring a spiral, helical
or other like spring may be substituted therefor.
As the
An inner annular recess is formed in the body in the centre of the recess pro-
vided for the spring to receive the extremity of the drill. When placed in
position in the chuck the drill is passed between the jaws and through the open
centre of the spring until the extremity enters the inner recess and abuts against
the body, thus taking up the thrust direct and preventing any appreciable
amount of concussion being transmitted to the gripping jaws...
The tool for releasing or withdrawing the drill comprises a bifurcated lever
formed with a circular boss or projection at the base of the bifurcated portion
to engage the outer ends of the jaws or several sections of the bush to depress
the same in order to release the drill. Catches are pivoted to the outer ends of
the prongs of the lever, constructed with notches or projections adapted to engage
or embrace a flange, projection or recess of the chuck body. To release and
withdraw the drill from the chuck the lever is placed so as to present the boss
to the outer ends of the jaws-the drill projecting through the prongs-and the
pivoted catches turned over to engage the flange, projection or recess and the
lever then drawn forward and being fulcrummed about its pivotal connection
with the catches depresses the jaws which release the drill and permit it to be
withdrawn.
The appliance for detaching or extracting the dogs or jaws from the chuck
body comprises a jack or bridge piece.to span the mouth of the body, to one end
of which a catch is pivoted formed with a curved projection or ledge adapted to
engage a flange, projection or precess of the body. The catch at the other end
of the bridge piece is preferably formed in one piece therewith or rigidly fixed
thereto and provided with a curved projection similar to the pivoted catch.
The bridge piece is tapped to receive a set screw or screwed bolt and a cod piece
or detached circular plate is employed cut away or formed of a shape to engage
three only of the four gripping jaws. On the back of the cod piece or circular
plate a boss or projection is formed to enter the jaws to centre and support it,
and on the front it is provided with a recess for the end of the set screw or bolt.
In use the tool is temporarily fitted over the mouth of the chuck body and the
cod piece placed between the jaws so as to engage three only, the set screw is
then screwed forward to force the cod piece inwards to depress the three jaws,
thus releasing and permitting the free jaw to be extracted. The set screw is
then screwed back to enable the other jaws to be withdrawn.
In a modification the chuck may be provided with two three or more gripping
jaws so as to grip the drill on two or more opposite sides or faces instead of all
round as in the construction previously described. In this arrangement one
spring may be employed to operate both or all the jaws or separate springs may
be employed for the several jaws and the body of the chuck be suitably constructed
to receive them.

page_text: Improvements in and relating to Rock Drill Heads or Chucks.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 322, High Holborn, in the County of Middlesex, 6, Lord Street,
Liverpool, and 6, Bank Street, Manchester, both in the County of Lancaster,
and Lower Temple Street, Birmingham, in the County of Warwick, Civil
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:-
This invention has reference to the chucks or heads of rock drilling machines,
or to the device which forms the connection between the rock drill, rock drill bit,
or other boring tool and the piston rod or other reciprocating member of the
rock-drilling machine.
It has for its object to provide an efficient chuck of simple and cheap con-
struction, capable of being operated with facility to securely hold the drill in
the desired position and to release the same when it is required to remove the
drill to substitute another therefor; also to provide arrangements or tools for
use in the operation of withdrawing and inserting the drills and for removing
the gripping pieces from the chuck body when required.
In order that the invention may be clearly understood appended hereto is one
explanatory sheet of drawings marked with letters of reference corresponding to
the following description thereof.
In the drawings
Fig. 1 represents a longitudinal sectional elevation of a chuck constructed in
accordance with this invention, shewing a drill secured in position therein.
Fig. 2 is a front elevation of same.
Fig. 3 is an inner end elevation of one section of the tapered bush or of one of
the wedge shaped dogs or gripping jaws detached.
Fig. 4 an elevation of same from the other end.
Figs. 5 and 6 are side and front elevations, respectively, of the tool or appliance
for releasing or withdrawing the drill, drawn to a reduced scale.
Figs. 7, 8, and 9 are sectional, side and front or end elevations, respectively,
of the tool or appliance for detaching or extracting the sectional tapered bush or
wedge shaped dogs or gripping jaws from the body, also drawn to a reduced
scale.
Figs. 10 and 11 are front and side elevations respectively of the cod piece or
plate L drawn to an enlarged scale.
A designates the body of the chuck which in the construction illustrated, is
formed in one piece with the piston rod B of the rock-drilling machine, but
it will be evident that it may be formed as a separate or independent part, if
preferred, or found more convenient in practice, and be provided with any suitable
means for attaching it to the extremity of the piston rod B. Whilst it is pre-
ferred to give it a more or less conical formation externally as shewn, it may
assume any other desired form.
The body A is constructed with a central preferably conical cavity or recess C,
expanding inwardly, or with the diameter gradually increasing as it recedes
from the exterior.
D D1 D2 D3 are the several sections of the tapered bush or the wedge shaped
gripping jaws or dogs arranged within the cavity C. These several sections are
tapered towards their forward extremity d and rounded externally, as seen at d¹
to correspond to the conical cavity C in which they can slide longitudinally within
ertain limits. When assembled within the body these sections form a bush

page_text: or lining enclosing and gripping the end of the drill or bit E on all sides when
inserted between them. The inner parallel faces are formed with a shallow
V groove to accomodate the edges or corners of the drill E. The drill is
shewn of octagonal section and the several sections of the bush or the gripping
jaws grooved accordingly, but it will be obvious that they may readily be con-
structed to accomodate any other section of drill steel. It is preferred to employ
four gripping jaws or to split the bush into four equal sections D D D D but
more or less may be used if desired. The jaws are so constructed and arranged
that when gripping the end of the drill a small amount of space or clearance is
left between them-as indicated at 3 Fig. 2-and they are secured in position
within the chuck body, in the event of the drill or bit being removed, by being
forced forward until they bear and bind upon one another.
F is a strong preferably involute spring located at the rear of the jaws D D¹
Da D and fitting within an annular recess of formed at the bottom of the conical
cavity C, which acts to maintain the spring central. The spring F completely
surrounds or encircles the inner extremity of the drill and is preferably arranged
with its base or convolution of greatest diameter bearing on the inner ends of
the jaws D D1 D2 D3 and the other end bearing against the chuck body within
the recess f so that as the jaws are depressed or forced inwards the spring F is
placed in compression to act to force the jaws outwards when released. The inner
ends of the jaws are formed with a curved groove d in which the spring F rests.
As the jaws are forced inwards the tendency of the spring F to expand or spread
at the base keeps the jaws tight against the walls of the cavity C and thus causes
them to leave and release the drill or bit. In place of the involute spring, which,
however, is at present preferred, a spiral, helical or other like spring may be
substituted therefor.
G is an inner annular recess formed in the body A in the centre of the recess f
to receive the extremity of the drill or bit. When placed in position in the
chuck the drill E is passed between the jaws and through the open centre of the
spring F until the extremity enters the recess G and abuts against the body A
thus taking up the thrust direct and preventing any appreciable amount of
concussion being transmitted to the gripping jaws.
Referring to Figs. 5 and 6, in which the tool or appliance for releasing or
withdrawing the drill is illustrated, H is a lever bifurcated or formed with two
prongs or branches h¹ at one end. 2 is a circular boss or projection formed
at the base of the bifurcated portion and provided to engage the outer ends of
the jaws or several sections D D1 D2 D3 of the bush to depress the same in order
to release the drill or bit. h3h are catches pivoted to the outer ends of the
prongs or branches h h¹ and constructed with notches or projections to engage
a recess formed by a flange or projection h of the chuck body A. When it is
desired to release and withdraw the drill or bit from the chuck the lever is placed
so as to present the boss h² to the outer ends of the jaws D D D D³ the drill or
bit projecting through the prongs hand the catches h³ h4 turned over to
engage the flange h and the lever then drawn forward and being fulcrumed
about its pivotal connection with the catches h³ h depresses the jaws D D1 D2 D³
which releases the drill or bit and permit it to be withdrawn. When a fresh
drill or bit is to be substituted the jaws are kept depressed until it is inserted
and the lever then moved forward to permit the jaws to close on the shank of
the drill or bit.
Referring to Figs. 7, 8, 9, 10 and 11, in which is illustrated the tool or appli-
ance for detaching or extracting the sectional tapered bush or the wedge shaped
dogs or gripping jaws D D1 D2 D3 from the chuck body A. In the drawings J
designates a jack or bridge piece to span the mouth of the body A of the chuck,
to the diameter of which it is approximately equal in length. To one end of the
bridge piece J is pivoted or hinged an arm or member j formed at its outer
extremity with a curved projection or ledge j¹ on the inside, and j2 is a like arm
or member provided at the other extremity of the bridge piece J, of which it

page_text: a part or to which it is rigidly attached, said arm or member being
likewise constructed at its outer extremity with a curved projection or ledge
on the inside. The curved projections or ledges of the members are
provided to fit or engage the recess h. The curved form of the projections
5 illustrated in the drawings is designed more particularly for use when the chuck
body A is, as illustrated, formed with an external flange at the mouth, forming
a circumferential recess 6 in which the curved projections fit. The bridge
piece Jis tapped to receive a set screw or screw bolt K. L is a cod piece or
detached circular plate which is cut away at 7-see Figs. 10 and 11-or formed
of a shape to engage three only of the four gripping jaws or sections D D D2 D³
of the tapered bush. It is formed with a boss or projection on the back, which
enters the jaws to centre and support it when placed in position in the mouth
of the chuck A, and it is provided with a recess 12 at the front for the extremity
of the set screw or screw bolt K.
5
73 is a boss formed on the bridge piece J to prevent the possibility of the
stripping of the thread when the appliance is in use.
shewn, located nearer the rigid or fixed arm or member so as to concentrate
The set screw K is, as
the force transmitted through it on those jaws engaged by the cod piece or
plate L. It will be obvious that instead of constructing the cod piece L to
engage three of the jaws it may be formed of such a shape to engage two only
of said jaws. It is preferred to construct it as previously described as being the
⚫more practicable arrangement.
In using the tool or appliance the fixed arm or member is fitted over the
flange formed at the mouth of the chuck body A so that the circular projection
or ledge engages the recess h6. The pivoted arm or member is then placed so
that its projection engages the recess he on the opposite side. The cod piece L
is now placed with the boss projecting into or between the gripping jaws in
such a way that it engages three only of the jaws, the set screw K being then
screwed forward in the bridge piece J to force the cod piece L inwards and
thereby depresses the three jaws, thus releasing and permitting the remaining
and free jaw to be extracted. The set screw K is thereupon screwed back and
the appliance removed from the mouth of the chuck body A thus enabling the
other sections of the bush or gripping jaws and their operating spring F to
be withdrawn. In assembling the parts or fitting the chuck together the spring F
is first placed in position in the cavity f and the three sections of the tapered
bush placed in position. The tool is then brought into position to depress the
three jaws against the spring F to enable the fourth jaw to be inserted. On
removing the appliance the spring Facts to force the whole of the jaws forward
simultaneously until they bear and bind upon one another inside the body.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same
me by my foreign correspondents I declare that what I claim is :--
to be performed as communicated to
1. A 1ock drill chuck constructed of a body formed with a taper cavity or
inwardly expanding recess in which a sectional taper bush or wedge shaped
gripping jaws or dogs are arranged in such a way that they are closed or
contracted to grip the end of the drill or bit when forced forwards in the body,
and opened or expanded to release the drill when forced backwards, the bush or
aws being operated to close on the drill by means of a spring or springs arranged
vithin the body, substantially as described.
2. A rock drill chuck comprising a body formed with a taper cavity or recess,
orrespondingly tapered gripping jaws or dogs arranged within said cavity, and
spring, interposed between the inner ends of the gripping jaws and the bottom
f the cavity, which acts to close the jaws on the end of the drill or other tool
ubstantially as described..
3. A rock drill chuck consisting of a body or main part provided with an
nwardly expanding hollow or cavity, a correspondingly externally tapered

page_text: sectional bush or lining arranged therein, and a spring arranged within the
cavity at the rear of the taper bush and bearing against the ends of each of the
several sections thereof to close them on the drill or other tool when it is inserted
between them, substantially as described.
4. A rock drill chuck comprising a body constructed with an inwardly expand-
ing conical cavity or recess, a sectional bush, or gripping jaws or dogs completely
surrounding the extremity of the drill or other tool arranged therein, tapered
and rounded externally to fit and slide within the conical cavity and shaped
internally to embrace the drill or tool, a spring arranged with its base or convolu-
tion of greatest diameter bearing against the inner ends of the several sections
of the bush or the gripping jaws and resting within a recess formed at the bottom
of the conical cavity, which acts to maintain it in a central position said spring
being concentrically disposed relative to the drill or tool which projects through
its open centre substantially as set forth.
5. In a rock drill chuck, in combination, the body A formed with an inwardly
expanding conical cavity C, the sectional taper bush or wedge shaped gripping
jaws DD1 D2 D3, tapered and rounded on their outer surfaces d' to fit and
slide within the cavity C and' shaped on their inner faces to accomodate the
extremity of the drill or tool, the involute or like spring F arranged at the rear
of the several jaws.or sections D D1 D2 D3 and concentric with the drill or tool.
the curved grooves formed in the inner ends of the jaws to receive the end of
the spring F, the recess f for the spring F formed at the bottom of the cavity C
to maintain the spring central, the cavity G formed within the recess f and
beyond the spring to receive the extremity of the drill when in position within
the chuck substantially as described and shewn in Figs. 1 and 2 of the accompany-
ing drawings.
6. In combination, the piston rod B of the rock drilling machine, the body or
main part A of the chuck formed on the extremity thereof, the inwardly expand-
ing conical cavity C of the body A the wedge shaped gripping jaws or sectional
conical bush D D D D³ constructed to fit and slide within the cavity C and to
embrace the extremity of the drill, the involute spring F encircling the drill
with its base or convolution of greatest diameter bearing against the inner ends
of the several gripping jaws or sections of the conical bush, the curved grooves d'
provided in the inner ends of the jaws in which the spring rests, the recess f for
the spring formed at the bottom of the conical cavity C, the cavity G formed
within the recess of and beyond the spring F to accomodate the end of the drill,
and the flange h of the body A forming the projection or groove h6 substantially
as described and shewn with reference to Figs. 1 to 4 of the accompanying
. drawings.
7. The tool or appliance for releasing or withdrawing the drill from the chuck
consisting of a bifurcated lever formed with a circular boss or projection around
or at the base of the bifurcated portion adapted to engage and depress the outer
extremities of the several gripping jaws or sections of the bush and with catches
pivoted to the ends of the forked part to engage a projection or recess of the
chuck body substantially as described and illustrated in Figs. 5 and 6 of the
drawings.
8. The tool or appliance for use in extracting or detach- the gripping jaws
or dogs, consisting of a bridge piece constructed so as to engage the chuck body
said bridge piece being tapped to receive a set screw or screw bolt and a cod piece
_formed of a shape to engage and depress several of the gripping jaws as the set
screw is screwed forward thus enabling the disengaged or free jaw or jaws to be
removed from the chuck body substantially as described.
9. The tool or appliance for extracting or detaching the sectional tapered bush
or gripping jaws from the chuck body comprising a jack or bridge piece to span
the mouth of the chuck body, said bridge piece being formed with a rigid member
provided with a projection or ledge to engage an external projection or recess of
the chuck body and a pivoted member formed with a corresponding projection

page_text: ngage the external projection or recess of the chuck body, the bridge
piece being tapped to receive a set screw or screw bolt and a cod piece constructed
to engage three sections of the tapered bush or gripping jaws thus enabling the
remaining jaw to be removed substantially as herein described with reference
to Figs. to 11 of the accompanying drawings.
Dated this 20th day of April 1900.
W. P. THOMPSON & Co.,
Of London, Liverpool, Manchester and Birmingham.