Improved Hand Piece for the Tool-holders of Dental Engines and the like.
Year: 1894

page_text: Date of Application, 31st Mar., 1894
Complete Specification Left, 29th Dec., 1894-Accepted, 2nd Feb., 1895
[Communicated from abroad by EDWARD AUGUSTUS PEIRCE, 140, West 42nd
Street, New York, U.S.A., Dealer in Dental Supplies.]
Improved Hand Piece for the Tool-holders of Dental Engines and
the like.
I, HUGH DONALD Fitzpatrick, 70 Wellington Street, Glasgow, in the
County of Lanark, Registered Patent Agent, do hereby declare the nature of this
invention to be as follows:-
In the accompanying drawings,
Fig. 1 represents a longitudinal vertical section of a hand piece constructed
according to my invention, the tool being shown to be inserted in the same and to
be firmly gripped by the tool chuck;
Fig. 2 represents such a section of the principal part of the hand piece showing
the position of its parts after the tool has been withdrawn therefrom; while
Fig. 3 shows a vertical cross section of the device along line 3, 3 Fig. 2.
Corresponding figures throughout the different views refer to corresponding
parts.
The
The outer casing of the hand piece consists of a handle section 4, a shank
section 5, and an intermediate section 6, section 6 being attached to section 4 by
screwthread and to section 5 by means of a swivel joint, in the usual manner.
rear inner part of the shank section is provided with a screw thread for the purpose
of attaching thereto a flexible sheath as is usually employed in dental engines for
the purpose of protecting thereby a flexible power conveyer which communicates
with the spindle 7 of the hand piece through a driving shaft 8, journaled with
intermediate section 6, the driving shaft being provided at its rear end with
screwthread for thereby attaching to it the power conveyer, and having its front
end firmly secured to the rear end of the driving spindle by a pin 9. Endwise
movement of the spindle and driving shaft within the casing of the hand piece is
prevented owing to the fact that the rear end of such spindle is made to abut
against the inner front end of the casing section 6 while the front end of the spindle
engages with a proper shoulder in the interior of handle section 4 of the casing,
the screwthread between handle sections 4 and 6 thus permitting to enforce proper
contact between the ends of the spindle and its abutments. 10 is a double chuck
for receiving the shank 11 of a dental tool, spring jaws 12, 12 being provided on its
front as well as its rear end.
The outer end surfaces of such chuck are made tapering, the front surfaces to
approximately correspond with the adjoining interior surfaces of the spindle and
the rear surfaces to so correspond with the inner front surfaces of a hollow clamping
plug 13.
14 is a bar abuting against the rear end of plug 13. Parts 10 13 and 14
jointly and separately are capable of sliding longitudinal movement within the body
of spindle 7 in such a manner that forward movement of bar 14 will produce close
contact of double chuck 12 with clamping plug 13 as well as with the aforesaid
tapering surface in the interior of the spindle, and, if the shank of a tool has
previously been inserted in the chuck its front jaws as well as its rear jaws will
thereby be forced to bind upon and to firmly grip such shank.
On the other hand
If the forward pressure applied to bar 14 be made to cease, the spring power
nherent to the jaws 12 of the chuck will assert itself by compelling a rearward

page_text: movement of plug 13 and bar 14 while their grip upon the tool shank will be
simultaneously released and a withdrawal of such shank from the tool holder
will thus be made possible. Parts 10 13 and 14 I hereinafter term the tool locking
device.
15 is a latch interposed between the locking device and driving shaft 8.
Its front is provided with a wedging surface 16 of a slope corresponding with
another slope on the rear surface of the locking device where the same comes in
contact with such wedging surface. Latch 15 is adapted to slide along such slope
and within a suitable channel cut in said locking device, at right angles to the
spindle proper guiding slots being provided for such purpose in the latter. 17 is a
sleeve mounted on spindle 7 so as to slide thereon and fitting the interior surface of
handle section 4. It is provided with wedging surface 18 adapted to engage with
the upper surface of latch 15, which upper surface I preferably construct parallel
to it. The lower extremity of the latch which extends outside of the spindle and
also through a proper slot in said slide may be provided on its face with a bevel
conformning substantially with a bevel 19 at the front end of such slot. 20 is an
annular groove in the rear end of sleeve 17. 21 is an outer sleeve mounted on
section 4 of the casing and capable of sliding thereon. 22 is a pin provided with
screw-thread where it passes through said outer sleeve and having its inner end
extending into annular groove 20 in such a manner as to compel the two sleeves to
slide forward and backward together, while permitting the inner sleeve to rotate
with the spindle, without imparting its revolving motion to the outer sleeve.
The operation of the device is as follows:-
When it is desired to clamp the tool shank within chuck 10, sleeve 21 and with
it piu 22 and inner sleeve 17 are moved forward until they assume the positions
shown in Fig. 1, the upper slope on the latch co-acting meantime with the corre-
sponding slope on such sleeve, so as to force the latch downward and at the same
time by means of its wedging surface 16 compelling the forward movement of the
tool locking device and the gripping of the tool shank while the reverse movement
of the two sleeves will permit the upward movement of the latch, and such upward
movement will be enforced by the inherent spring power of the tool chuck
compelling a backward movement of clamping plug 13 and bar 14. If however,
for any reason binding of those parts upon each other and upon the spindle should
occur, so as to retain the latch in the position shown in Fig. 1, said latch will be
freed and will be forced out of its locking position whenever edge 19 strikes its
lower extremity. 23 is a slot in the upper surface of sleeve 17 to permit the
insertion through it of the latch when the hand piece is being put together.
Dated this 30th day of March 1801
H. D. FITZPATRICK,
70, Wellington Street, Glasgow.
COMPLETE SPECIFICATION.
Improved Hand Piece for the Tool-holders of Dental Engines and
the like.
I, HUGH DONALD FITZPATRICK of 70 Wellington Street, Glasgow, in the
County of Lanark, Registered Patent Agent, 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 :-
In this Specification reference is had to the drawings accompanying my
Provisional Specification, wherein
Figure 1 represents a longitudinal vertical section of a hand piece constructed
according to my invention, the tool being shown to be inserted in the same and to
be firmly gripped by the tool chuck.

page_text: Fig. 2 represents such a section of the principle part of the hand piece showing
the position of its parts after the tool has been withdrawn therefrom; while Fig. 3
shows a vertical cross-section of the device along line 3-3 in Fig. 2.
Corresponding figures throughout the different views refer to corresponding parts.
The outer casing of the hand piece consists of a handle section 4, a shank
section 5, and an intermediate section 6, section 6 being attached to section 4 by
screw-thread and to section 5 by means of a swivel joint, in the usual manner. The
rear inner part of the shank section is provided with screw thread for the purpose
of attaching thereto a flexible sheath as is usually employed in dental engines for
the purpose of protecting thereby a flexible power conveyer which communicates
with the spindle 7 of the hand piece through a driving shaft 8, journaled within
intermediate section 6, the driving shaft being provided at its rear end with screw-
thread for thereby attaching to it the power conveyer, and having its front end
firmly secured to the rear end of the driving spindle by a pin 9.
Endwise move-
ment of the spindle and driving shaft within the casing of the hand piece is
prevented owing to the fact that the rear end of such spindle is made to abut
against the inner front end of casing section 6 while the front end of the spindle
engages with a proper shoulder in the interior of handle section 4 of the casing, the
screw-thread between handle sections 4 and 6 thus permitting to enforce proper
contact between the ends of the spindle and its abutments.
10 is a double chuck for receiving the shauk 11 of a dental tool, spring
jaws 12, 12 being provided at its front as well as at its rear end. The outer end
surfaces of such chuck are made tapering, the front surfaces to approximately
correspond with the adjoining interior surfaces of the spindle, and the rear
surfaces to so correspond with the inner front surfaces of a hollow clamping
plug 13.
14 is a bar abutting against the rear end of plug 13. Parts 10, 13 and 14 jointly
and separately are capable of sliding longitudinal movement within the body of
spindle 7 in such a manner that forward movement of bar 14 will produce close
contact of double chuck 12 with clamping plug 13 as well as with the aforesaid
tapering surfaces in the interior of the spindle, and, if the shank of the tool has
previously been inserted in the chuck its front jaws as well as its rear jaws will
thereby be forced to bind upon and to firmly grip such shank. On the other hand,
if the forward pressure applied to bar 14 be made to cease, the spring power
inherent to jaws 12 of the chuck will assert itself by compelling a rearward move-
ment of plug 13 and bar 14 while their grip upon the tool shank will be
simultaneously released and a withdrawal of such shank from the tool holder will
thus be made possible. Parts 10, 13 and 14 1 hereinafter term the tool locking
device.
15 is a latch interposed between the locking device and driving shaft 8.
Its front is provided with a wedging surface 16 of a slope corresponding with
another slope on the rear surface of the locking device where the same comes in
contact with such wedging surface. Latch 15 is adapted to slide along such slope
and within a suitable channel cut in said locking device, at right angles to the
spindle, proper guiding slots being provided for such purpose in the latter.
17 is a sleeve mounted on spindle 7 so as to slide thereon and fitting the interior
surface of handle section 4. It is provided with a wedging surface 18 adapted to
engage with the upper surface of latch 15, which upper surface I preferably
construct parallel to it.
The lower extremity of the latch which extends outside of the spindle and also
through a proper slot in said slide may be provided on its face with a bevel
conforming substantially with a bevel 19 at the front end of such slot.
20 is an annular groove in the rear end of sleeve 17.
21 is an outer sleeve mounted on section 4 of the casing and capable of sliding
thereon.
22 is a pin provided with screw-thread where it passes through said outer sleeve
and having its inner end extending into annular groove 20 in such a manner as to

page_text: compel the two sleeves to slide forward and backward together, while permitting
the inner sleeve to rotate with the spindle, without imparting its revolving motion
to the outer sleeve.
The operation of the device is as follows:
When it is desired to clamp the tool shank within chuck 10, sleeve 21 and with
it pin 22 and inner sleeve 17 are moved forward until they assume the positions
shown in Fig. 1, the upper slope of the latch coacting meantime with the corre-
sponding slope on such sleeve, so as to force the latch downward and at the same
time by means of its wedging surface 16 compelling the forward movement of the
tool locking device and the gripping of the tool shank, while the reverse movement
of the two sleeves will permit the upward movement of the latch, and such upward
movement will be enforced by the inherent spring power of the tool chuck
compelling a backward movement of clamping plug 13 and bar 14. If, however,
for any reason binding of these parts upon each other and upon the spindle should
occur, so as to retain the latch in the position shown in Fig. 1, said latch will be
freed and will be forced out of its locking position whenever edge 19 strikes its
lower extremity.
23 is a slot in the upper surface of sleeve 17 to permit the insertion through it of
the latch when the hand piece is being put together.
I have found in practice that it is best to make the sloping cortact surfaces
between the latch and the tool locking device very small as compared with the full
cross-section of the latter, in order to ensure the prompt upward movement of the
latch when the tool shank is to be withdrawn and for such purpose I reduce bar 14
in depth where it adjoins the face of the latch as shown more particularly in
Fig. 1.
While the drawings show a very efficient form of construction, I do not wish to
confine myself to the details illustrated therein. Thus it will be seen that plug 13
and bar 14 might be consolidated, as the principal reason for making them separate
is, that I am thereby enabled to insert washers between these parts whenever it
becomes desirable to do so in order to compensate for their wearing upon the latch
and the chuck.
I prefer to employ a double chuck, as 10, in order to obtain the benefit of two
sets of spring jaws in clamping the tool and also in forcing upward the latch when
the tool shank is to be withdrawn, but it will be seen that any other proper form of
a chuck or of a tool locking device, which will accomplish these objects, may be
employed instead. Clamping plug 13 is shown to be hollow so as to accommodate
the rear extremity of the tool shank which is generally provided with notches
intended to make it capable of being secured in other dental hand pieces employing
latches engaging directly with the tool shank.
It will also be seen that the lower extremity of latch 15 might be modified
in form and that the means for moving said latch transversely might also be
varied.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is :
1. The construction of a dental hand piece, with a casing, a spindle, a split or
spring jawed tool locking device, a wedge adjusted to slide transversely to the
spindle and along the surface of such locking device, and means for enforcing
operative contact between the wedge and said locking device, such wedge adju-ted
to move the tool-locking device end wise for the purpose of clamping the tool, and
to receive motion from the tool locking device when such means for enforcing
operative contact cease to operate.
2. The construction of a dental hand piece, with a casing, a spindle fitted to
rotate therein, a split clamp tool locking device, a sliding wedge, proper surfaces
for guiding it transversely to the spindle, and means for moving it along such
guides.

page_text: 3. The construction of a dental hand piece, with a casing, a spindle, a split
clamp tool locking device, a sliding wedge, proper surfaces for guiding it, and a
slide for compelling its movement and provided with a sloping surface adjusted to
engage with the wedge.
4. The construction of a dental haud piece, with a casing, a spindle fitted to
rotate therein, a split clamp tool locking device, a sliding wedge, proper surfaces
for guiding it transversely to the spindle, and a slide having two surfaces for
engaging with the wedge, whereby such wedge may be moved in opposite
directions.
5. The construction of a dental hand piece, with a casing, a spindle, a split clamp
tool locking device, a wedge, a channel in the tool locking device wherein the wedge
slides, and means for moving the wedge along such channel.
6. The construction of a dental hand piece, with a casing and spindle, split clamp
tool locking device 12, 13, 14, connecting bar 8, sliding wedge 15, inner slide 17,
outer slide 21, and intermediate pin 22.
Dated this 28th day of December 1894.
H. D. FITZPATRICK,
70, Wellington Street, Glasgow.