AN IMPROVED DEVICE FOR. HOLDING THE DRILL OR TOOL IN A ROCK-DRILLING MACHINE
Year: 1880

page_text: LETTERS PATENT to James McCulloch, of Camborne, in the County of
Cornwall, Engineer, for an Invention of "AN IMPROVED DEVICE FOR.
HOLDING THE DRILL OR TOOL IN A ROCK-DRILLING MACHINE."
PROVISIONAL SPECIFICATION left by the said James McCulloch at the
Office of the Commissioners of Patents on the 6th December 1880.
JAMES MCCULLOCH, of Camborne, in the County of Cornwall, Engineer. "AN
IMPROVED DEVICE FOR HOLDING THE DRILL OR TOOL IN A ROCK-DRILLING
MACHINE."
My Invention relates to an improved holding device to be employed in a rock
drilling machine for holding the drill or tool in the same more securely, and main-
taining it more accurately in its proper position during the working of the machine
than has been practicable with the devices heretofore commonly used for this
purpose. The device made according to my Invention is also more durable.
The said improved holder or holding device is constructed as follows, that is to
say-It is formed of hardened steel or other suitable metal, and with a socket for
the insertion of the piston rod, to which it is secured by a cotter or by other
suitable means. It also has in its forward end a parallel hole or socket for the
reception of the shank of the drill or tool; the holder is provided with blocks or
pads, which are inserted in slots or apertures in the holder, and are so formed and
arranged as to bear upon the shank of the drill or tool when the same is inserted
in its socket. The outer surfaces of the blocks or pads have the same inclination
as the surfaces of the holder and collar, and the action of the latter in securing and
releasing the tool is hereinafter described.
Instead of providing the blocks or pads the socket may be slit or divided,
preferably in such a manner as to form three jaws, which hold the drill or tool
between them. The outer surface of this part of the holder is made taper or
inclined, in such a manner that its diameter is the largest at its forward end.
Over this inclined portion of the holder I fit a metal hoop or collar, which is put
on from the piston socket end before the same has been secured to the piston by
the cotter or other fastening device. The interior surface of the collar has the
.

page_text: same inclination as the surface of the holder in which it fits. When the drill or
tool is inserted between the said jaws it is made fast therein by means of the said
collar by forcing the same toward the front end of the holder, and thereby
compressing the jaws tightly on the shank of the drill or tool. When it is desired
to release the tool the said collar may be forced back by gently tapping the same.
I desire it to be understood that my improved tool holder does not actually form
part of the piston rod but is attached thereto by the cotter or otherwise, and may
be readily removed. This arrangement affords considerable advantage.
My said Invention affords the means for very quickly fixing and changing or
replacing the tool, and ensures its firm retention in its place, as the action of the
tool upon
the rock or other surface being drilled tends to draw the collar forward
on the holder; moreover the said tool will be kept in its proper position, that is to
say, central with the piston rod of the machine. The said tool can moreover be
made of any desired strength to prevent breakage, for the holder being fastened to
the piston rod there is no limit as to size.
It does not wear all on one side of the socket hole; this occurs in some of the
devices heretofore used, and throws the tool out of the centre with regard to the
piston.
It can be adapted to any class of reciprocating or percussion rock drill.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said James McCulloch in the Great Seal Patent Office on the 6th
June 1881.
"AN
JAMES MCCULLOCH, of Camborne, in the County of Cornwall, Engineer.
IMPROVED DEVICE FOR HOLDING THE DRILL OR TOOL IN A ROCK-DRILLING
MACHINE."
My Invention relates to an improved holder or holding device to be employed
in a rock drilling machine for holding the drill or tool in the same more securely
and maintaining it more accurately in its proper position during the working of
the machine than has been practicable with the devices heretofore commonly used
for these purposes.
My improved device is moreover more durable than devices for
the same purpose as heretofore constructed.
My Invention is illustrated in the accompanying Drawing, in which-
Figure 1 is a side view of one form of my improved holder secured to the piston
rod and with the drill or tool clamped therein, and
Figure 2 is an end view of the said holder.
Figure 3 is a longitudinal section on line x, x, Figure 2, and
Figure 4 is a transverse section on the line x, x¹³, Figure 1.
Figure 5 is a side view of a modified form of my improved tool holder with the
tool therein, and
Figure 6 is an end view of the same with the drill or tool removed.
Like letters indicate the same parts throughout the Drawing.
My improved holder or holding device a is constructed as follows, that is to
say -It is formed of hardened steel or other suitable metal and is provided with
a socket a¹ for the insertion of the piston rod b to which it is secured by a cotter c
or by other suitable means. It also has in its forward end a parallel hole or
socket & for the reception of the shank e¹ of the drill or tool c. The outer surface a*
of this end of the said holder is made taper or inclined in such a manner that its
diameter is the largest at its forward end. Over this inclined portion of the holder
I fit a metal hoop or collar f which is placed on the holder a from the piston socket
end of the same, and prior to the securing of the said holder to the piston by the
cotter c or other fastening device. In the device shewn in Figures 1, 2, 3, 4, the
interior surface of this collar fis taper and adapted to fit over a series of blocks or
pads g which are inserted in slots or apertures in the forward end of the holder a.
These blocks or pads are so formed and arranged as to bear upon the shank e¹ of
the drill or tool e when the same is inserted in its socket d, and the outer
surfaces of the said blocks or pads have the same inclination as the surface of the
forward end of the holder and the interior of the collar; therefore, when the said
collar is driven or forced forward over the said blocks g it will cause the same to
firmly grip the shank e' of the tool, and the repeated blows of the drill or tool upon
the rock or other material being bored will tend to force the collar still further
forward and increase the grip of the blocks upon the said tool. The latter however
may be readily released on forcing the collar f back by gently tapping the
same.
Instead of providing the holder with blocks or pads, as above described, the
taper forward end of the said holder may; in some cases, be slit or divided, as
shewn in Figures 5 and 6, and preferably in such a manner as to form three
jaws a², which are designed to hold the drill or tool between them. In this case,
also, the interior surface of the collar f (which is passed over the holder in a similar
manner to that above described, that is to say, prior to the connection of the latter
with the piston rod) is made taper or inclined to correspond with the inclination of

page_text: the forward end of the said holder. When the drill or tool is inserted between the
said jaws it is made fast therein by means of the said collar, by forcing the same
toward the front end of the holder, and thereby compressing the jaws tightly on
the shank of the drill or tool. When it is desired to release the tool the said collar
may be forced back by gently tapping the same. It is an important feature of this
Invention that my improved tool holder is not formed on or solidly with the piston
rod, but is made separately therefrom and is attached thereto by the cotter or
otherwise, and may be readily removed. This arrangement is very advantageous,
as it allows the said holder to be made much larger and stronger than would be
practicable with a holder formed on the end of the piston rod, and, therefore, all
danger of breaking the said holder is obviated. Moreover, my Invention permits
the tool to be very quickly fixed in the holder, and changed or replaced, and
ensures its firm retention in position, as the action of the tool upon the rock or
other surface being drilled tends, as above stated, to draw the collar forward on
the holder; the said tool will be kept in its proper position, that is to say, the
holder will not wear all on one side of the socket hole as in the devices heretofore
used, and therefore the tool will not be thrown out of the centre or axis of the
piston. It is obvious that the said holder can be adapted to any class of
reciprocating or percussion rock drills.
Having thus fully described my said Invention, and the manner of performing
the same, I wish it understood that I make no claim to a piston rod of a rock
drilling machine having a holding device formed solidly or in one piece with the
same, or to any device which would not allow the collar to be placed on its smaller
or inner end and pushed over its inclined outer end, but I claim,-
The improved holder suitably constructed to be attached to the piston rod of a
rock drilling machine, and having a taper or inclined forward portion larger in
diameter than its rear portion, which holder has in it a hole or socket for the
reception of the drill or tool, and is provided with the sliding collar in combination
with the blocks or pads (or with the jaws) so arranged that the said tool may be
secured or released thereby, substantially as set forth.
In witness whereof, I, the said James McCulloch, have hereunto set my hand
and seal, this Fourth day of June, in the year of our Lord One thousand
eight hundred and eighty one.
JAMES MCCULLOCH. (L.S.)