IMPROVEMENTS IN DENTAL ENGINES, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO OTHER PURPOSES
Year: 1874

page_text: LETTERS PATENT George Tomlinson Bousfield, of Sutton, in the
County of Surrey, for the Invention of "IMPROVEMENTS IN DENTAL
ENGINES, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO OTHER
PURPOSES." A communication from abroad by Nelson Stow, of
Binghamton, in the County of Broome, and State of New York,
United States of America.
PROVISIONAL SPECIFICATION left by the said George Tomlinson
Bousfield at the Office of the Commissioners of Patents, with his
Petition, on the 4th August 1874.
:
I, GEORGE TOMLINSON BOUSFIELD, of Sutton, in the County of Surrey,
do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN DENTAL ENGINES, PARTS. OF WHICH IMPROVEMENTS ARE APPLICABLE TO OTHER
PURPOSES," to be as follows:-
The accompanying Drawings shew all; the improvements as embodied
in the Inventor: abrionslu however some of:

page_text: 3. In combining the vibrating levers with a stand composed of sections
adjustable at an angle relatively to each other, to accommodate chairs
having a central support or screw.
The next branch of the Invention relates to the pitman connection
between the treadle and the crank of the driving wheel. Its objects are
to prevent the crank from resting on the dead centre to ensure it's
always starting in the right direction, and to give it a "live motion "
in passing the dead centres, to which ends the improvement consists,―.
4. In connecting a treadle rigidly with a spring pitman acting directly
on the crank of the driving wheel.
The next branch of the Invention relates to the connection between
the driving power and the driven mechanism. Its objects are to obtain
freedom of movement of such mechanism in a simple and effective
manner without deranging its connections while dispensing with the
vibrating arms, pulleys, and long belts heretofore employed, to which
ends the improvements consist,—
5. In combining the driving power directly with the driven mechanism
by an endless belt passing over a pulley suspended flexibly and capable
of being turned in all directions.¨
. 6. In mounting the driven mechanism in a bracket suspended by an
elastic connection so as always to maintain the tension on the driving
belt while leaving the bracket free to turn in its supports.
7. The improvement further consists in mounting a pulley bracket
directly on the top of the post or arm of the base or stand in such
manner that it may swing freely thereon in a horizontal plane.
8. The improvement further consists in combining a stand or baso for
the driven mechanism, a rocking arm mounted thereon and controlled
by a spring, a bracket frame capable of turning freely in a horizontal
plane on the rocking arm and a driven pulley, a flexible shaft, and a
tool holder mounted on or combined with said bracket frame.
9. The improvement further consists in combining a pulley driven
directly from the driving wheel and mounted in a bracket frame turning
freely in its supports in a horizontal plane, a flexible sheath connecting
the bracket frame and hand piece, and a wire coil connecting the pulley
and tool holder' whereby the tool may be freely turned in all directions.

page_text: The next part of the Invention relates to the flexible connection for
driving the drill. Its object is to render removable the rotating wire coil
to oil the various parts of the mechanism; to this end the improvement
consists, -
10. In passing the wire coil through a clamp mandril on which the
belt pulley is mounted, a nut on the mandril serving to clamp the wire
coil as required, whereby it may readily be inserted in and securely held
by the clamp, or it may readily be released therefrom.
The next part of the Invention relates to the hand piece, its object is
to hold the tool firmly therein while allowing it readily to be removed 1
or inserted, to which end the improvement consists,—
11. In slotting the tool holder longitudinally near its middle to givo
it a slight spring, tho end of the tool being flattened, so that when
inserted in the tubular socket its flattened end will act as a wedge to
force apart the slotted sides of the holder, thus securely holding the 1
tool.
12. The improvement further consists in combining with the flexiblo
shaft a sliding clevis so suspended and counterbalanced as to slide freely
on the shaft so as to counterpoise the weight of the hand piece and shaft
to prevent them from dropping into an inconvenient position when 2
released by the dentist, or to hold them in any desired position. An
upright arm, post, or frame A is firmly secured upon a suitable base,
stand, or tripod A'. A driving wheel B turns with a shaft 6 mounted in
suitablo bearings in the frame and is rotated by a crank and pitman. A
foot treadle C pivoted at one end on one foot of the tripod has a spring 2
pitman D firmly secured to its other end. This pitman slips on a crank
pin on the crank b¹ of the driving wheel axle, and is held thero by the
resilience of the spring only, so that in case of any obstruction getting
between the pitman and frame the pitman would be thrown off the
crank pin, by which means serious accidents to the operator and others
may sometimes be prevented. By using a spring pitman several
advantages are attained over the pitman ordinarily used in foot powers;
among such advantages may be mentioned those of the crank being
always stopped off the dead centre, of its being always compelled to
start in the right direction, and of the crank being thrown past the dead 3
centre on the upper part of its traverse by the spring with a "live
motion," the slight retarding action of the spring in passing the lower

page_text: dead centre being more than compensated by the capacity of the
operator to exert his full force on the down stroke of the treadle..
In order to enable the dentist to operate the driving wheel from either
side of the chair in which the patient sits, two rocking levers E, E, are
mounted on fulcrum pins e, e' so as to vibrate freely in a vertical plane.
These levers are arranged end to end, the outer end of the lever E being
linked to the treadle O, while the inner end is linked to the adjacent
end of the other lever E³, which in turn is pivoted at its outer end loosely
to a treadle O' on the opposite side of the chair. This treadle it will bo
noted can be swung round into any desired position relatively to the
rocking levers, and still operate them with equal efficiency. The two
levers it will be observed are necessary in order that both treadles may
work together, that is, that both may always be started on the down
stroke; thus not only ensuring the starting of the crank in the right
direction but enabling the power of two operators to be applied if
deemed requisite. This however will rarely be required in dental
operations, but will bo found very useful in heavier work.
In order to render these levers and the loose treadle movable around
the base, they are mounted on a frame F which is pivoted to the floor
near the base, say at f*, Figure 1, so that the outer end of the frame
may be moved around this pivot to any position most convenient to the
operator.
In order to allow the levers to work without interference from the
central support, or the adjusting screw common in dentists' chairs, said
levers are mounted in a stand or frame made in sections F, F', adjustable
round a pivot f. These sections may be locked in any desired relation
to each other by means of a pin f¹ passing into holes in the overlapping
parts of the two sections, or other equivalent detonts may be used.
In order to obtain freedom of movement for the driven mechanism,
said mechanism is mounted in a bracket frame & suspended by a cord H
from a crane post on the stand A' (see Figure 2), or from the ceiling,
walls, or gas fixtures of the room (see Figure 1), and drive it by a belt J
running directly from the driving wheel B to the driven pulley I, by
which means the bracket frame can be swung around into any desired
position without interfering with the working of the driving belt.
In order to permit of a lateral movement of the bracket frame, and to
compensate the shortening of the belt or the radial movement of the

page_text: bracket frame around the driving shaft, the suspending cord II is made
of rubber, coiled wire, or other yielding material which will admit of the
· necessary play..
•
The driven pulley I is fixed on a tubular mandril i turning and
moving freely endwise in bearings in the bracket framo G. A flexible
tube or sheath K connects the bracket frame with a hand piece N.
This sheath is composed of an envelope of leather or other flexiblo
material covering a body made of spirally coiled wire. A wire coil
passes through the tubular mandril i, the outer projecting end of which
is split and provided with a screw nut i, thus forming a clamp to grasp
'the wire coil firmly while allowing it readily to be removed or replaced.
This wire coil is made by twisting together several strands of steel wire
which ensures its strength and clasticity, thus forming a central cord
which is enclosed in a layer or envelope of wire wound at the same
pitch, and with its spirals running in the same direction as those of tho
central cord, which gives additional strength to the wire coil without
diminishing its flexibility. The wire coil unites with a tool holder m
turning in bearings in the hand piece N. The front portion of this tool
holder is made tubular, and it is slotted longitudinally near its centre.
The tool is made with a round shank flattened at its rear end, and
having a projecting shoulder on each side of this flattened central portion
(see Figure 11), so that when the tool is inserted in the holder its
flattened part enters the slot and wedges itself therein, being tightly
held by the. springing of the walls of the slotted portion of the holder.
The shoulders regulate the depth to which the tool is inserted in the
holder. It can be removed simply by pulling it out of the holder, and
inserted simply by pushing it in. The advantages of thus dispensing
with fastenings, screws, locking pins, or springs, separate from the holder,
are obvious. A clevis O capable of sliding freely on the flexible sheath
or hand piece is suspended by a cord o passing over a pulley and pro-
vided with a counterbalance O', so that the hand piece instead of falling
into an inconvenient position when released by the operator may bo
retained in or moved to any desired position where it can most con-
veniently be reached.
Figures 3 and 14 shew another way of applying the improvements.
The bracket frame in which the pulley is mounted consists in this
instance of a horizontal tube G' carrying a vertical tube or spindle
which is inserted in a socket in the post or arm A of the engine, or a

page_text: tubular spindle fitting over the post (as shewn in Figures 5 and 6) may
be employed, the object being to allow this horizontal tube to siving
freely around its pivot. The pulley I is mounted on a tubular shaft I'
rotating in the bracket tube G', and the wire coil passes through this
tube.
.:
Figures 5 and 6 shew a rocking -arm A³ made of two-interlocking
sections by preference. The arm rocks on a pivot formed by the band'
wheel shaft b. A spring a connects the lower end of this rocking arm
with the base A¹. A bracket frame G' is mounted on the upper end of
the rocking arm. A spindle on the bracket fits in a socket on the arm
so as to turn freely horizontally thereon. The flexible sheath K is con-
nected at one end with the horizontal tube of the bracket frame.
SPECIFICATION in pursuance of the conditions of the Lotters Patent,
filed by the said George Tomlinson Bousfield in the Great Seal
Patent Office on the 3rd February 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
TOMLINSON BOUSFIELD, of Sutton, in the Oounty of Surrey, sond
greeting.
:
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourth day of August, in the year of our
Lord One thousand eight hundred and seventy-four, in the thirty-seventh
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said George Tomlinson Bousfield, Her special
licenso that I, the said George Tomlinson Bousfield, my executors,
administrators, and assigns, or such others as I, the said George Tom-
linson Bousfield, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully.might
make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for ¨“IMPROVEMENTS IN DENTAL ENGINES, PARTS OF WHICH IMPROVEMENTS ARE
APPLICABLE TO OTHER PURPOSES."-A communication to me from abroad by
Nelson Stow, of Binghamton, in the County of Broome, and State of
New York, United States of America, upon the condition (amongst

page_text: Figure 12, a side cievation of the swinging pulley bracket and flexiblo
connections, partly in section, on an enlarged scale.
The first branch of the Invention relates to the treadle power; its
object is to enable the dentist to operate with equal efficiency from either
ide of his chair, to which end the Invention consists,—-
Figure 12, a side clevation or the swinging pulley bracket and flexiblo
connections, partly in section, on an enlarged scale.
The first branch of the Invention relates to the treadle power; its
object is to enable the dentist to operate with equal efficiency from either
side of his chair, to which end the Invention consists,-
1. In combining with a treadle power vibrating levers pivotted
together, and operated by separate treadles from cither end of the
levers.
. 2. In mounting the vibrating levers on a stand movable around the
base of the treadle
power.
3. In combining the vibrating levers with a stand composed of sections
adjustable at an anglo relatively to each other, to accommodate chairs
having a central support or screw.
The next branch of the Invention relates to the pitman connection
between the treadle and the crank of the driving wheel. Its objects are
to prevent the crank from resting on the dead centre, to ensure its
always starting in the right direction, and to give it a "live motion" in
passing the dead centres, to which ends the improvement consists,—
4. In connecting a treadle rigidly with a spring pitman acting directly
on the crank of the driving wheel.
The next branch of the Invention relates to the connection between
the driving power and the driven mechanism. Its objects are to obtain
freedom of movement of such mechanism in a simple and effective
manner, without deṛanging its connections, while dispensing with the
vibrating arms, pulleys, and long belts heretofore employed, to which
ends the improvements consist,―
5. In combining the driving power directly with the driven mechanism
by an endless belt passing over a pulley suspended flexibly, and capable
of being turned in all directions.
6. In mounting the driven mechanism in a bracket suspended by an
clastic connection, so as always to maintain the tension on the driving.
belt, while leaving the bracket free to turn in its supports.
7. The improvement further consists in mounting a pulley bracket
directly on the top of the post or arm of the base or stand, in such
manner that it may swing freely thereon in a horizontal plane.

page_text: 8. The improvement further consists in combining a stand or base for
the driven mechanism, a rocking arm mounted thercon and controlled.
by a spring, a bracket frame capable of turning freely in a horizontal
plane on the rocking arm, and a driven pulley, a flexible shaft, and a
tool holder mounted on or combined with said bracket frame.
5
9. The improvement further consists in combining a pulley driven
directly from the driving wheel, and mounted in a bracket frame turning.
freely in its supports in a horizontal plane, a flexible sheath connecting.
the bracket frame and hand piece, and a wire coil connecting the pulley
and tool holder, whereby the tool may be freely turned in all directions. 10
The next part of the Invention relates to the flexible connection for
driving the drill. Its object is to render renovable the rotating wire coil
to oil the various parts of the mechanism; to this end the improvement
consists,―
10. In passing the wire coil through a clamp mandril on which tho 1
belt pulley is mounted, a nut on the mandril serving to clamp the wire-
coil as required, whereby it may readily be inserted in and securely held
by the clamp, or it may readily be released therefrom.
The next part of the Invention relates to the band piece. Its object is
to hold the tool firmly therein, while allowing it readily to be removed 2
or inserted, to which end the improvement consists,―
11. In slotting the tool holder longitudinally near its middle to give
it a slight spring, the end of the tool being flattened so that when
inserted in the tubular socket its flattened end will act as a wedge
to force apart the slotted sides of the holder, thus securely holding the 2
tool.
12. The improvement further consists in combining with the flexible
shaft a sliding clevis, so suspended and counterbalanced as to slide freely
on the shaft so as to counterpoise the weight of the hand piece and
shaft to prevent them from dropping into an inconvenient position when 3
released by the dentist, or to hold them in any desired position. An
upright arm, post, or frame A is firmly secured upon a suitable base,
stand, or tripod A'. A driving wheel B turns with a shaft b mounted
in suitable bearings in the frame, and is rotated by a crank and pitman.
A foot treadle C, pivotted at one end on one foot of the tripod, has a g
spring pitman D firmly secured to its other end. This pitman slips on i

page_text: a crank pin on the crank b' of the driving wheel axle, and is held there
by the resilience of the spring only, so that in case of any obstruction
getting between the pitman and frame the pitman would be thrown off
the crank pin, by which means serious accidents to the operator and
others may sometimes be prevented. By using a spring pitman several
advantages are attained over the pitman ordinarily used in foot powers;
among such advantages may be mentioned those of the crank being
always stopped off the dead centre, of its being always compelled to
start in the right direction, and of the crank being thrown past the
dead centre on the upper part of its traverse by the spring with a live
motion," the slight retarding action of the spring in passing the
lower dead centre being more than compensated by the capacity of
the operator to excrt his full force on the down stroko of tho
treadle.
86
In order to enable the dentist to operate the driving wheel from either
side of the chair in which the patient sits two rocking levers E, E¹, are
mounted on fulcrum pins e, e', so as to vibrate freely in a vertical plane.
These levers are arranged end to end, the outer end of the lever E being
linked to the treadle C, while the inner end is linked to the adjacent end
of the other lever E', which in turn is pivotted at its outer end loosely
to a treadle C¹ on the opposite side of the chair. This treadle, it will be
noted, can be swung round into any desired position relatively to the
rocking levers, and still operate them with equal efficiency. The two
levers, it will be observed, are necessary in order that both treadles may
work together, that is, that both may always be started on the down
stroke; thus not only ensuring the starting of the crank in the right
direction, but enabling the power of two operators to be applied if
deemed requisite. This however will rarely be required in dental
operations, but will be found very useful in heavier work.
In order to render these levers and the loose treadle movable around
the base they are mounted on a frame F, which is pivotted to the floor
near the base, say at f³, Figure 1, so that the outer end of the frame
may be moved around this pivot to any position most convenient to the
operator.
In order to allow the levers to work without interference from the
central support or the adjusting screw common in dentists' chairs, said
levers are mounted in a stand or frame made in sections F, F¹, adjust-

page_text: able round a pivot f. Theso sections may be locked in any desired
relation to each other by means of a pin f¹ passing into holes in the
overlapping parts of the two sections, or other equivalent detents may
be used.
In order to obtain freedom of movement for the driven mechanism, 5
said mechanism is mounted in a bracket frame G suspended by a cord H
from a crane post on the stand A¹ (sec Figure 2) or from the ceiling,
walls, or gas fixtures of the room (see Figure 1), and drive it by a belt J
running directly from the driving wheel B to the driven pulley I,
by which means the bracket frame can be swung around into any 1
desired position without interfering with the working of the driving
belt.
In order to permit of a lateral movement of the bracket frame, and
to compensate the shortening of the belt or the radial movement of the...
bracket frame around the driving shaft, the suspending cord H is made 1
of rubber, coiled wire, or other yielding material which will admit of
the necessary play.
Q
The driven pulley I is fixed on a tubular mandril i turning and
moving freely ondwise in bearings in the bracket frame G. A flexible
tube or sheath K connects the bracket frame with a hand piece N. This 2
sheath is composed of an envelope of leather or other flexible material
covering a body made of spirally coiled wire.
A wire coil 7 passes
through the tubular mandril i, the outer projecting end of which is split
and provided with a screw nut , thus forming a clamp to grasp the
wire coil firmly while allowing it readily to be removed or replaced. 2
This wire coil is made by twisting together several strands of steel wire,
which ensures its strength and clasticity, thus forming a central cord
which is enclosed in a layer or envelope of wire wound at the samo
pitch, and with its spirals running in the same direction as those of the
central cord, which gives additional strength to the wire coil without 3
diminishing its flexibility. The wiro coil unites with a tool holder m
.turning in bearings in the hand piece N. The front portion of this
tool holder is made tubular, and it is slotted longitudinally near its
centre. The tool m' is made with a round shank flattened at its rear
end, and having a projecting shoulder on each side of this flattened 3
central portion (see Figure 11), so that when the tool is inserted in the
holder its flattened part enters the slot and wedges itself therein, being

page_text: 3. The combination, substantially as herein-beforo set forth, in a
treadle power of the treadles and pivotted connecting levers mounted
upon a bed plate composed of hinged sections, for the purpose specified.
4. The combination in a treadle power of a treadle with a spring
pitman rigidly attached to it at one end, whilst its other end is pivotted
on the crank axle.
5. The combination, substantially as horein-before set forth, of a
bracket frame in which the driven mechanism is mounted, suspended by
cords or equivalent flexible connection, the driving wheel and the belt
passing directly from the driving wheel to the driven pulley on the
bracket frame.
'
6. The combination, substantially as herein-before set forth, of the
driving wheel, the bracket frame, the driving belt passing directly from
the driving wheel to the driven pulley on the frame, and an elastic sus-
pending cord H which permits the lateral movement of the bracket 1
frame.
7. The combination, substantially as hercin-before set forth, of the
base, its rigid upright arm, the pulley bracket suspended to swing
freely thercon in a horizontal plane, the pulley, and the flexible
shaft.
8. The combination, substantially as herein-before set forth, of the
suspended bracket frame, the pulley therein driven directly from the
driving wheel, the hand piece, the flexible sheath connecting the bracket
frame and hand piece, and the wire coil connection between the driven
pulley and the tool holder.
9. The combination of the wire coil, flexible shaft, and hollow clamp
mandril carrying a belt pulley by which the flexible shaft is to be
driven.
10. The combination, substantially as herein-before set forth, of the
tubular-ended slotted tool holder having elastic walls and the flattened
tool shank.
11. The combination, substantially as herein-before set forth, of the
flexible sheath, the hand piece, and the counterbalancing suspended
traversing clevis,

page_text: 12. The combined arrangement of dental engines, substantially as
herein described and shewn at Figures 1, 2, 3, 4, 5, 6, and 7 of the
Drawings hereunto annexed.
In witness whereof, I, the said George Tomlinson Bousfield, have
hereunto set my hand and seal, this Sixteenth day of November,
in the
year of our Lord, One thousand eight hundred and seventy-
four.