IMPROVEMENTS IN DRILLING OR ROTATORY CUTTING APPARATUS SUITABLE FOR DENTAL OPERATIONS
Year: 1876

page_text: LETTERS PATENT to John Lyon Field, of Manor House, Broadwater, in the
County of Sussex, for the Invention of "IMPROVEMENTS IN DRILLING OR ROTATORY
CUTTING APPARATUS SUITABLE FOR DENTAL OPERATIONS."
Sealed the bill Ontakes 1976 and dated the 20th Nov 1976
PROVISIONAL SPECIFICATION left by the said John Lyon Field at the
Office of the Commissioners of Patents on the 20th May 1876.
JOHN LYON FIELD, of Manor House, Broadwater, in the County of Sussex.
"IMPROVEMENTS IN DRILLING OR ROTATORY CUTTING APPARATUS SUITABLE FOR
DENTAL OPERATIONS."
This Invention of improvements in drilling or rotatory cutting apparatus suitable
for dental operations has reference to apparatus in which a drill or rotatory cutter
is used for delicate operations, such, for example, as the drilling or cutting of teeth
preparatory to stopping them, and is designed to enable the rotatory motion of the
drill or cutting tool to be stopped instantaneously or nearly so without stopping the
inachinery by which the tool is actuated.
For this purpose I make the shaft or spindle to which the tool is attached inde-
pendent of the shaft or spindle connected to the primary actuating mechanism, and
arrange the two shafts or spindles near to each other in a common axial line within
a tube or case in which each shaft or spindle is capable of being rotated. At the
extremity of the shait or spindle connected to the primary actuating mechanism I
provide ratchet teeth or projections or recesses arranged to gear with corresponding
recesses or projections at the inner end of the shaft or spindle to which the tool is
connected. When the parts are in their normal positions the two shafts or spindles
are kept automatically out of gear with each other. In one arrangement this is
done by the action upon the portion of shaft connected to the primary actuating
mechanisin of a spring, which spring may be a helix forming a flexible rotary motion
communicator to which separately I lay no claim. With the two shafts or spindles
arranged as described within the tube or case I combine means for bringing the two
shafts or spindles into gear. This device may consist of a fork, whose prongs are
inclined or of a wedge shape, these prongs being arranged one at each side of a
neck or narrow part of one of the shafts or spindles and the stem or connecting
portion of the fork projecting beyond the outer circumference of the tube or case.
A spring serves in this arrangement to keep the prongs in a position in which the
shafts or spindles are out of gear with each other, but by the operation of the user's
[Price 6d.1

page_text: finger upon the projection of the fork the prongs are caused to act upon a collar
of the one shaft or spindle and thereby to move it into gear with the other.
It will be evident that on releasing the projection of the fork it and the shaft it
has moved end wise will be automatically returned to their relative normal positions,
thus the shaft or spindle connected to the primary actuating mechanisın will be out
of gear with the shaft or spindle connected to the tool, the rotation of which will
thereupon cease.
Another arrangement consists in the use of a pin or projection carried by a
spring and arranged to operate in conjunction with a cam-shaped groove formed
in one of the portions of shaft or spindle, the said groove having a step in it.
The apparatus may obviously be modified so that the two lengths of shaft will be
in gear with each other when the several parts are in their respective normal posi-
tions and out of gear when the device for moving the one shaft endwise is in
operation.
The details of the contrivance by which the two shafts or spindles arranged as
described for operating a drill or rotatory cutter are placed in or out of gear as
required may obviously be modified to suit circumstances without departing from
the distinctive character of my Invention, which may be stated to consist in the
combination in apparatus for delicate drilling or rotatory cutting operations of means
for instantaneously connecting or disconnecting two shafts or spindles arranged
within a tube or case, the one shaft or spindle carrying the tool, the other connected
to the primary actuating mechanism, so that the drilling or cutting action of the tool
may be arrested instantaneously, or nearly so, as herein-before explained.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said John Lyon Field in the Great Seal Patent Office on the 17th November
1870.
JOIN LYON FIELD, of Upper Norwood, in the County of Surrey, late of Manor
House, Broadwater, in the County of Sussex. "IMPROVEMENTS IN DRILLING OR
ROTATORY CUTTING APPARATUS SUITABLE FOR DENTAL OPERATIONS."
This Invention of improvements in drilling or rotatory cutting apparatus
suitable for dental operations has reference to apparatus in which a drill or
rotatory cutter is used for delicate operations, such, for example, as the drilling or
cutting of teeth preparatory to stopping them, and is designed to enable the
rotatory motion of the drill or cutting tool to be stopped instantaneously, or nearly
so, without stopping the machinery by which the tool is actuated.
Fig. 1 of the Drawings is a central longitudinal section of an apparatus according
to my Invention.
•
Fig. 2 is a plan view shewing the two shafts or spindles.
The bored shaft or spindle a to which the tool a* is attached in a usual way, as
shewn, is made independent of the shaft or spindle b (in this case also bored)
connected to the primary actuating mechanism, and the two shafts or spindles are
arranged near to each other in a common axial line within a tube or case c, in
which each shaft or spindle is capable of being rotated. At the extremity of the
shaft or spindle b connected to the primary actuating mechanism I provide teeth
or projections d (or recesses may be used) arranged to gear with corresponding
recesses or projections at the inner end of the shaft or spindle a to which the tool
is connected. The shaft or spindle b is capable of receiving rotary motion, and also
of as much end motion as is necessary to throw it out of gear with the shaft or
spindle a, which shaft or spindle has only a rotary motion governed by the groove
and pin a. The shaft or spindle b in its normal state is pressed in gear with the
shaft or spindle a by means of the springe pushing the collar against the
shoulder by means of the piece Z and the pin m, thus when the parts are in their
normal positions (as shown in Fig. 1) the two shafts or spindles are kept auto-

page_text: matically in gear with each other. n is the flexible motion communicator (to which
I lay no claim), and which may be fitted into a square hole or recess in the end of
the shaft or spindle b, so as to allow of a slight end motion, if necessary, whilst
revolving. With the two shafts or spindles arranged as described within the tube
or case I combine means for moving the one shaft or spindle out of gear with the
other. The arrangement for this purpose consists of a pin or projection f carried
by a spring g and arranged to operate in conjunction with a groove / and cam-
shaped step-recess i formed in the shaft or spindle b.
Assuming the apparatus to be in operation the parts will be in the relative
positions shewn in Fig. 1. If it be now desired to arrest the rotation of the drill
the operator must press down the pin or projection f, which will enter the cam-
shaped part of the groove (seen best in Fig. 2) resting on the step i. As the
shaft or spindle b rotates the curved part of the step will bear against the pin f
thus gradually moving the shaft or spindle b backwards out of gear with the shaft
or spindle a, and the pin f will descend from the step into the groove h, thus
keeping the rotating shaft or spindle b out of gear with the shaft or spindle a until
the pin is released, whereupon its spring g will lift it out of the groove h, and by
the action of the helical spring e the rotating shaft or spindle b will be again
moved into gear with the shaft or spindle a, thus causing it and the tool to rotate.
The apparatus may obviously be modified so that the two lengths of shaft will
be out of gear with each other when the several parts are in their respective
normal positions and in gear when the device for moving the one shaft endwise is
in operation. This may be done by forming the cam-shaped step-recess i at the
opposite side of the groove h, shifting the position of the pin f to correspond, and
interposing a compression spring between the adjacent or clutch ends of the two
shafts a and b to keep them normally out of gear when not governed by the pi
The arrangement may be further modified as follows:-The device for moving
the one shaft endwise may consist of a fork carried by the spring g, and having its
prongs inclined or of a wedge shape, these prongs being arranged one at each side
of a neck or narrow part of one of the shafts or spindles, like the narrow part
formed by the groove h, and the stem or connecting portion of the fork projecting
beyond the circumference of the tube or case so as to be held by the spring, the
prongs passing through slots or openings in the case c. A spring recessed slightly into
the adjacent or clutch ends of the shafts a and b serves in this arrangement to keep
the prongs in a position in which the shafts or spindles are out of gear with each
other, but by the operation of the user's finger upon the projection of the fork the
inclined surfaces of the prongs are caused to act upon one side of the groove (as
ath without the step i) of the one shaft or spindle, and thereby to move it into gear
with the other, the spring between the two shafts a and b being then in compression.
It will be evident that on releasing the projection of the fork in the arrangement
just described it and the shaft it has moved endwise will be automatically returned
to their relative normal positions, thus the shaft or spindle connected to the primary
actuating mechanism will be out of gear with the shaft or spindle connected to the
tool, the rotation of which will thereupon cease.
The details of the contrivance by which the two shafts or spindles arranged as
described for operating a drill or rotatory cutter are placed in or out of gear as
required may obviously be modified to suit circumstances without departing from
the distinctive character of my Invention as herein stated.
Having now described the nature of my said Invention, and in what manner
the same is to be or may be performed or carried into practical effect, I hereby
declare that I do not claim as of my Invention, or the exclusive use of the several
parts herein-before described and referred to, except when the same are employed in
and for my said Invention, which I hereby declare to consist in the combination, as
shewn in the Drawings and as herein-above described in apparatus for delicate drilling
or rotatory cutting operations of means for instantaneously connecting or dis-
connecting two shafts or spindles (a, b) arranged within a tube or case (c), the onc
shaft or spindle carrying the tool, the other connected to the primary actuating

page_text: mechanism, so that the drilling or cutting action of the tool may be arrested
instantaneously, or nearly so, as herein-before explained.
In witness whereof, I, the said John Lyon Field, have hereunto set my hand
and seal, this Seventeenth day of November, in the year of our Lord One
thousand eight hundred and seventy-six.
JOHN LYON FIELD. (L.S.)