Improvements in Dental Hand Pieces.
Year: 1896

page_text: Date of Application, 7th Jan., 1896
Complete Specification Left, 3rd Sept., 1896-Accepted, 17th Oct., 1896
PROVISIONAL SPECIFICATION.
Improvements in Dental Hand Pieces.
I, JOHANNES THEODOR PEDERSEN, residing at the corner of Second Street
and Woodside Avenue, Woodside in the County of Queens and State of New
York, United States of America, Manufacturer, do hereby declare the nature of
this invention to be as follows:-
In dental hand pieces as heretofore constructed, the operating tool has been
held in the band piece by a chuck, and the engagement or liberation of the tool
in the chuck has been effected by mechanical devices that complicated the hand
piece and made the same expensive and required the use of both hands to release
the operating tool.
The object of my invention is to simplify the construction and lessen the cost
of the hand piece. The tool employed therein is firmly held by the clamping
mechanism in its normal position and released by. a direct lateral pressure upon the
hand piece, while being held in one hand.
In carrying out my invention I employ a flexible case, a tool-holder for holding
the operating tool, and internal mechanism for rotating the tool holder and tool.
While the flexible case and internal mechanism are axially in line, the tool-holder
firmly grips the tool, but when the axial line is disturbed by bending or altering
the alignment of one part of the case to the other, an elongation is produced which
releases the grip of the toolholder upon the tool. This grip is restored the
moment the pressure upon the flexible hand piece is released and the parts return
to a normal condition of alignment.
The hand piece case is made with the forward or pointed end rigid, and the
other part screwing therein, is provided with a helical spring secured to end collars,
and the same maintains the parts in alignment while the tool is in use. One end
collar connects with the forward and rigid end of the case and the other collar
connects with the covering of the flexible or motor shaft.
I prefer to employ a tubular case screwing at one end onto this latter collar
and covering the spring and bearing at its opposite end face against the collar
connected to the forward rigid end. This case may also be made with one part
rigid, and the other part provided with a pivotal or hinge joint.
The internal mechanism of the hand piece comprises a stem or shaft from the
dental engine, a coupling and the rotating sleeves, a spring tool-holder for gripping
the tool, an adjusting screw stem, a spring, a rod having a head bearing by the
action of the spring against a curved surface and curved rocking surfaces to the
parts that permit a deflection of the mechanism from a straight line when the flexible
case is bent in the hand, so as to effect the release of the operating tool from the
grip of the chuck.
Dated this 7th of January 1896
BREWER & SON,
London and Leeds, Agents for the Applicant.

page_text: CORE BELE DI CIFICATION.
Improvements in Dental Hand Pieces.
I, JOHANNES THEODOR PEDERSEN, residing at the corner of Second Street
and Woodside Avenue, Woodside, in the County of Queens and State of New
York, United States of America, Manufacturer, 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 and accompanying
drawings, that is to say :-
In dental hand pieces as heretofore constructed, the operating tool has been held
in the hand piece by a chuck, and the engagement or liberation of the tool in the
chuck has been effected by mechanical devices that complicated the hand piece
and made the same expensive and required the use of both hands to release the
operating tool.
The object of my invention is to simplify the construction and lessen the cost of
the hand piece. The tool employed therein is firmly held by the clamping
mechanism in its normal position and released by a direct lateral pressure upon
the hand piece while being held in one hand.
In carrying out my invention I employ a flexible case a tool holder for holding
the operating tool, and internal mechanism for rotating the tool holder and tool.
While the flexible case and internal mechanism are axially in line, the tool-holder
firmly grips the tool, but when the axial line is disturbed by bending or altering
the alignment of one part of the case to the other, an elongation is produced which
releases the grip of the tool-holder upon the tool. This grip is restored the moment
the pressure upon the flexible hand piece is released and the parts return to a
normal condition of alignment.
The hand piece case is made with the forward or pointed end rigid, and the other
part screwing therein, is provided with a helical spring secured to end collars and
the same maintains the parts in alignment while the tool is in use. One end collar
connects with the forward and rigid end of the case and the other collar connects
with the covering of the flexible or motor shaft.
I prefer to employ a tubular case screwing at one end onto this latter collar and
covering the spring and bearing at its opposite end face against the collar connected
to the forward rigid end. This case may also be made with one part rigid and
the other part provided with a pivotal or hinge joint.
The internal mechanisin of the hand piece comprises a stem or shaft from the
dental engine, a coupling and the rotating sleeves, a spring tool-holder for gripping
the tool, an adjusting screw stem, a spring, a rod having head bearing by the
action of the spring against a curved surface and curved rocking surfaces to the
parts that permit a deflection of the mechanism from a straight line when
the flexible case is bent in the hand, so as to effect the release of the operating
tool from the grip of the chuck.
In the drawing,
Figure 1 is a longitudinal section of my improved dental hand piece.
Figs. 2 to 9 inclusive represent elevations of the parts of the internal
mechanism.
Fig. 10 is an elevation of a modification of my flexible case, and Fig. 11 is a
cross section at .r, r, of Fig. 10, and Fig. 12 is an elevation of a modification of
my flexible case.
Fig. 13 is a lungitudinal section representing my improved hand piece in a
simpler form, and Fig. 14 is an elevation of the same.
Figs. 15 to 27 inclusive represent elevations of the parts of the internal
mechanism, and Fig. 28 is a longitudinal section representing the elongation
produced by deflecting the parts from a straight line.

page_text: The figures show the parts of about twice the usual size.
Similar letters of reference on the sheets of drawing represent corresponding
parts.
The case of my dental hand piece is preferably composed of the rigid taper
case A whose exterior is preferably roughened or ribbed to provide a firm hold
for the hand, and the case B composed of the helical spring a, the collar a' and
collar a². These collars usually have knurled surfaces and in Fig. 1, there are
cylindrical portions thereof that extend into the ends of the spring and to which
the spring is soldered to form firm connections. The collar a¹ is united by a screw
coupling at 2 to the taper case A and the end of the collar a is threaded for
connection with the sleeve that receives the end of the flexible covering for the
shaft of the dental engine.
In Fig. 13 the collar a' receives within it one end of the helical spring a and the
collar a is threaded for a longer distance and the tubular case I screws thereon
and surrounds the spring a and extends into the enlarged end of the collar a¹ and
the end bears against said collar and the case can be turned to strain the helical
spring a to apply any desired tension thereou, the respective ends of such spring
being soldered to the collars.
In the modification shown in Figs. 10 and 11, the case is made in two parts D D',
the sides of the part D being reduced to form opposite flat faces 3 and the
tongues 4 extend out from the part D' upon the faces 3, and pins 5 pass through
these parts to pivot the parts D and D' together. The spring 6 serves to draw
these parts into alignment. In the modification shown in Fig. 12, this portion of
the case is cut in two parts E E', and a hinge joint 7 connects said parts together,
the latch spring 8 on one part engaging the other part holds them together when
in their normal position.
In either of the forms shown, the outer case can be acted upon by one hand and
the upper part turned or deflected so as to stand at an angle to the lower
portion for liberating the tool from the tool-holder, and when released from the
action of the hand the parts are brought axially into line for grasping the tool as
hereafter set forth.
Fige. 2, 3, 15 and 16 show separately the sleeves bb' that screw together, and
Fig. 4 a short sleeve c that occupies a position adjoining the end of the sleeve b'
(Figs. 1 and 3) and in line therewith. The sleeve b is provided with an enlarge-
ment 9 Fig. 2, and the tapering case A has a shoulder 10, Fig. 1, against which
the enlargement 9 comes when the sleeve b is introduced into the tapering case A.
When the case A and collar a' are screwed together as shown in Fig. 1, the end
of the coupling 2 comes adjacent to the other end of the enlargement 9 so that a
bearing is provided in the case A for the sleeves 6 and to prevent end
movement.
A similar construction is shown in Fig. 13, wherein a hard metal collar b³ is
held between the end of the case A and an internal rib on the collar a', which
collar forms a stop around the back end of the sleeve t, thus holding the
sleeves within the tubular case and preventing end motion but allowing them
to be revolved freely.
The forward end of the sleeve b is tapering to conform to the interior of the
case A and it is also internally tapered to act on the holding jaws d, Figs. 1 and 5,
or d', Figs. 13 and 17, and these jaws form the tool-holder. The back end of the
sleeve is made with an internal rib 11, Figs. 1 and 3.
The holding jaws d d', Figs. 5 and 17, are made with an open center to receive
the tool and slotted longitudinally to allow the jaws to spring, and the forward
ends are tapering and received into the tapering sleeve & so that a longitudinal
movement of the holding jaws either contracts them to grip the tool or permits of
their expansion to liberate the tool. The back end of the tool-holder, Fig. 5, is
reduced and fits into one end of the sleeve e, Fig. 6.
The adjustable stems f¹, Figs. 7 and 18, each have a threaded portion 12 and
screw into the tapering split end of the sleeves e or e¹, Figs. 6 and 19. These

page_text: stems and feach have a screw driver notch 13 at one end, and the stem f,
Figs. 1 and 7, has a head 14 with a cup-shaped recess at the other end.
The rod has a screw threaded end to connect with the dental engine shaft,
and in Figs. 1 and 8 its inner end is made with a neck and a head h¹ in the end
of which is the cup-shaped recess 15.
The split toggle bar i, Figs. 1 and 9, is between the head 14 of the stem and
the end of the rod h, and it has rounded ends entering the cup-shaped recesses in
said head 14 and the head of the rod h.
A helical spring k, Fig. 1, surrounds the rod h between the collar c and the pin ¹
that passes through the rod h, and the action of this spring is to force the rod h
backward causing the head to bear firmly against the internal rib 11 of the
sleeve b' and to keep the parts normally in axial line.
The parts shown in Fig. 1 are put together in the following manner and
order:
The rod is dropped into the sleeve b', the rib 11 arresting the head h.
The collar and spring k are then slipped over the rod h, the spring com-
pressed and the pin inserted through the rod, thus connecting these parts.
The holding jaws d are inserted in the sleeve e from the left hand and the
adjustable stem from the right hand and the sleeve and stem are screwed
together. The sleeve b is now passed over the holding jaws d, sleeve e and
stem f. The toggle i is then inserted in the sleeve and the sleeves b and b
are screwed together at the enlargement 9. These parts are then inserted in the
taper case A and the case B is passed over the rod h, and the cases A and B are
screwed together at the coupling 2, thus holding the internal parts in place at the
enlargement 9. A screw driver can be inserted in place of an operating tool and
it engages the stern fat its notch 13, and by rotating said stem in the sleeve, the
parts are adjusted in their axial line to provide for slight variations in the
dimensions of the tool shanks so as to bring sufficient pressure by the holding jaws
to grip the operating tool C. This adjustment also provides for wear of the parts.
The dental engine rotates the rod h and the parts within the connected cases A
and B that extend from such shaft to the tool-holder.
To release the operating tool from the grip of the holding jaws, it is only
necessary to bring one part of the case at an angle to the other part and thereby
produce an elongation of the axis of the hand piece. This is accomplished by one
hand while holding the hand piece by a pressure of the thumb and fingers bending
the helical spring a out of line with the tapering case A, and in so doing moving
the rod into the dotted position shown in Fig. 1.
This movement rocks the head h¹ upon the rib 11 and swings the toggle into
the dotted position shown, thus altering the axial line of the toggle and shortening
its length between perpendiculars and at the same time relieving the pressure on
the stem and bolding jaws. The holding jaws d expand as their tapering end is
drawn back within the inner tapering surface of the sleeve b, and a slight longi-
tudinal movement is imparted to the holding jaws d, sleeve e and stem f, and
the operating tool is released and can be removed and another inserted. The
release of pressure upon the hand piece permits the springs a and k to act and
return the parts to a normal condition of alignment, and by this movement the
pressure upon the holding jaws is restored and the operating tool firmly gripped by
the toul-holder.
In the modification shown in Figs. 10 and 11, the spring 6 acts to press the
parts D D of the hand piece normally in line and when a pressure by the hand
brings the part D at an angle to the part D', the internal parts act as herein before
described to release the tool.
In the modification shown in Fig. 12, the spring 8 is to be unlatched before the
part E of the hand piece can be brought at an angle to the part El to operate the
internal parts as herein before described. This latch spring 8 maintains the parts
normally in alignment.
The object of splitting the toggle is that the end parts thereof may

page_text: automatically yield to a slight extent and approach one another in the cup of the
head 14 and shorten the axial length of the parts in case it develops after the
insertion of the operating tool in the tool holder that there is too much pressure
upon the parts as they approach the axial line owing to slight variations in
Perfect alignment is thus ensured in the normal position of the parts.
In the modification shown in Figs. 13 to 28 inclusive, the spring tool-holder d
is tapered at both ends and one end of the sleeve el is recessed to receive one end
thereof.
The rod from the dental engine shaft is connected by a pin 17 with the
collar c. A screw stem or rod n is provided with a head n¹ and adjacent neck,
there being a flaring hole through the head . This head n' is received within
the collar e' behind the internal rib 11 and a pin 16 passes through the flaring hole
and tonnects the head and collar together, and the end of the collar c¹ is provided
with rocking faces 19. A head block o that surrounds the rod n is provided with
curved rocking faces 18 receiving the faces 19, and the block o fits into and bears
against the end of the sleeve b¹.
This rod n screws into the sleeve m and around the rod n between the sleeve m
and end of the sleeve is the expansive spring & whose action is to force the
sleeve m forward and so hold the head n' against the rib 11. The opposite
ends of the sleeves m and e' are notched and the opposite ends of the thrust
piece are reduced and received in said notches, one end bearing against the
threaded stem, and the other and notched end bearing against and receiving
the reduced end of the rod n. In the operation of the parts the clamping nut
prevents the collar a turning upon the sleeve 6 after the parts have been
adjusted.
9
When the hand piece is bent in the hand, the tubular case rocks upon the end
of the collar a' as a fulcrum, the helical spring a is bent and the rod swung into
approximately the position shown in Fig. 28. This operation disturbs the
alignment of the internal mechanism and causes the rocking face 19 of the
collar c to move up the curved surface 18 of the head block o and so draw
the rod and head n' and sleeve m longitudinally, compressing the spring k and
releasing the parts r, el and so that the tool-holder is free to expand and release
the tool.
When the pressure of the hand is released, the springs return the parts to their
Dormal position of alignment and the tool is again gripped.
Figs. 1, 13 and 14 show the most compact and acceptable form of flexible case,
but I do not limit myself to any particular form of flexible case for dental baud-
pieces.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
First. In a dental band piece the combination with the spring tool holding
jaws and a flexible connection between the same and the dental engine shaft for
rotating such jaws, of an enclosing case capable of being bent out of a straight
line while held in the hand and mechanism acted upon by the bending of the
case for releasing the tool from the spring holding jaws, substantially as set
forth.
Second. The combination in a dental hand piece with the rotating shaft, of a
tool holder, a jointed connection from the holder to the dental engine shaft, a
sleeve within which the tool holder is revolved and a flexible portion connected
with the sleeve and adapted to be bent out of a straight line, substantially as
specified, whereby an end motion is given that liberates the tool, substantially as
set forth.
Third. In a dental hand piece the combination with a flexible case capable of
being bent out of a straight line while held in the hand, of a tapering tube, spring
tool-bolding jaws that slide in said tapering tube, a flexible connection between the

page_text: engine shaft and the holding jaws, whereby said holding jaws are actuated by the
bending of the flexible case, substantially as set forth.
Feurth. The combination with the holder for the operating tool and a surrounding
tube, of a flexible connection from the holder to the dental engine shaft for rotating
the tool, a tubular case to receive the aforesaid parts and composed of two separable
parts screwed together, the one part being rigid and the other part flexible and
capable of being bent as held by the hand to deflect the axial line aud effect an
elongation that releases the grip of the holder on the tool, substantially as specified.
Fifth. In a dental hand piece, the combination with the holder for the operating
tool, means for rotating the same and which means are adapted to be deflected
from their axial line, of the rigid case A, the helical spring a and collars a¹ a³
connected to the ends of the helical spring and forming a flexible case, the collar a
screwing into the case A and the collar a connecting with the covering of the
engine shaft, substantially as and for the purposes set forth.
Sixth. In a dental hand piece the combination with the tool holder for the
operating tool, and the tubular case, of the connecting sleeves bb, the stem f, the
sleeve e for the said tool-holder and stem, the rod h from the dental engine shaft,
the collare and the spring upon the rod h and the holding pin through the
rod h, means for holding the rod / in its relation to the sleeve b' and a toggle or
equivalent device between the stem and rud h, substantially as and for the
purposes set forth.
Seventh. In a dental hand piece, the combination with the tool-holder for the
operating tool and the tubular case, of the sleeve & having an internal rib 11, the
rod h, and a head on the same bearing against the rib 11 and having a cup-
shaped end recess 15, the stem having a head 14 with a cup-shaped end recess,
the split toggle i with rounded ends resting in the said cup-shaped recesses,
substantially as set forth.
Eighth. The combination in the dental hand piece, of a tapering spring tool-
holder and its surrounding sleeve, means for moving the tool-holder end wise to
clamp the tool and a screw intervening hetween the parts for adjusting the tool-
holder to different tools, such screw having at its end adjacent to the opening in the
tool-holder a notch or engaging device for a screw driver introduced through the
tool-bolder, substantially as specified.
Ninth. In a dental hand piece, the combination with the sleeves, of the tool
holding jaws, the internal sleeve e, the threaded adjusting stem, the rod from the
dental engine shaft and a toggle between the adjusting stem and said rod,
substantially as and for the purposes set forth.
Tenth. In a dental hand piece, the combination with the sleeves, of the tool
holding jaws, the internal sleeve e, the threaded adjusting stem f, the rod from the
dental engine shaft, and a split toggle i between the adjusting stem fand said rod,
substantially as and for the purposes set forth.
Eleventh. In a dental hand piece, the combination with the holder for the tool,
of the sleeve b, the connecting sleeve b having an internal rib 11, the rod / having
a head h¹ bearing against the rib 11, a collar c around the rod h bearing against
the end of the sleeve 6', a pin k or stop upon the rod and a helical spring k
around the rod between the pin k and collar c acting to keep the head seated
against the rib 11, substantially as specified.
Twelfth. In a dental hand piece the combination with the holder for the tool,
of the sleeve 61 connected therewith, the rod h passing into the sleeve b', the
collar cand spring k surrounding the rod and a pin or stop k connected to said
shaft, whereby the axial line may be made angular to actuate the tool-holder,
substantially as set forth.
Dated this 3rd day of September 1896.
BREWER & SON,
London and Leeds, Agents for the Applicant.