IMPROVEMENTS IN HAND PIECES FOR DENTAL ENGINES, AND IN OPERATING TOOLS THEREFOR."
Year: 1881

page_text: LETTERS PATENT to Sydney Pitt, of Sutton, in the County of Surrey, for
an Invention of "IMPROVEMENTS IN HAND PIECES FOR DENTAL ENGINES,
AND IN OPERATING TOOLS THEREFOR." A communication from abroad by
Eli T. Starr, of the City and County of Philadelphia, State of Pennsylvania,
United States, of America.
COMPLETE SPECIFICATION filed by the said Sydney Pitt at the Office of
the Commissioners of Patents on the 30th August 1881.
SYDNEY PITT, of Sutton, in the County of Surrey. "IMPROVEMENTS IN HAND
PIECES FOR DENTAL ENGINES, AND IN OPERATING TOOLS THEREFOR.' A communi-
cation from abroad by Eli T. Starr, of the City and County of Philadelphia, State
of Pennsylvania, United States of America.
The Invention relates to dental engines of the class embodying in their organi-
zation a motive power, a flexible rotary shaft driven by said power, and a hand
piece casing affording bearings for a spindle-chuck which is connected at its rear
end with the outer or front end of said flexible shaft so as to be given a rapid
revolving motion on its longitudinal axis. The interchangeable operating tools
driven by said spindle chuck may be moved freely about in different directions
owing to the flexure of the driving shaft by the hand which grasps the hand piece
casing, whereby said tools are permitted to be directed to the point at which they
are to do their work without interfering with the free transmission of the driving
power.
The object of the Invention is, first, to improve the construction of the hand
piece so that wear of the chuck in the casing of the hand piece may be readily
compensated for or taken up, and unsteady movements or "wabbling" of said'
chuck prevented without interfering with its free rotation upon its longitudinal
axis; secondly, to improve the tool-locking devices of the spindle chuck so as to
permit rapid and easy insertion of the operating tools in and their ready removal
from the socket of said chuck, while firmly and securely locking said tools therein

page_text: LOUIS, DU Guay
my
be compensated for in order to prevent all unsteady motion or lateral vibration of
the tools in the socket of the chuck while at work, whereby the operations of the
dentist may be performed with great ease and skill, saving the time of the operator,
and avoiding noise disagreeable to the patient.
The subject-matter claimed by the Invention is recited at the close of the
Specification.
In the accompanying Drawings,
Figure 1 is a view in elevation of a dental engine hand piece embodying-the
improvements:
Figure 2 is a longitudinal central section through the hand piece showing an
operating tool as locked-in the socket of the rotary chuck or tool holder.
Figure 3 is a cross section therethrough on the line 3, 3, of Figure 2 looking
towards the front end of the hand piece.
Figure 4 is a view in elevation of one of the improved operating tools, and
Figure 5 is a view of a portion thereof partly in section.
The hand piece casing A is shown in this example as.constructed of four tubular
sections, that is to say, it is shown as consisting, (1), of a handle section a which
gives bearing to and envelopes the tapered front end of the spindle-chuck B; (2),
of a second section or nut a', within which an externally screw threaded tubular
bushing C is adjustable for loosening a set screw c, which passes through said
section and impinges against the bushing to lock the section and bushing together
upon the front end of which bushing in front of said section the rear end of the
handle section a is screwed so as to be detachable and so as to perimit said bushing
to be screwed or adjusted endwise in said handle section; (3), of a third section a³,
which is screwed upon said tubular bushing C; in rear of the second section a', so
as to permit it to be readily detached from said bushing, and to permit access to
the adjustable ring b¹ on the rear end of the spindle-chuck; and (4), of a shank
section a³, which is connected with the third section a² by a swivel joint a¹ of well
known construction in order to permit the handle section which is grasped by the
hand (being ordinarily held centrally of the fingers and thumb of the operator,
somewhat after the fashion of holding a pen or pencil), to be turned relatively to
said shank section around the spindle chuck so as to conform to the turning move-
ments of the operator's hand in manipulating the tool.
In order to prevent accidental unscrewing of the handle section a, or of the third
casing section a², from the intermediate union or tubular bushing C, while permitting
their ready disconnection when desired, I employ a slide D fitting a longitudinal
grooved in the exterior of the second casing section or nut a¹, and also fitting at
its ends corresponding grooves or recesses in the flanges d', d³, respectively of the
handle section a and third casing section a,.as clearly, shown in Figures 1 and 2.
This slide D is slotted longitudinally for the passage of a screw d³, for example,
which holds the slide in the groove in the second casing section or nut a', while
permitting it to mové end wise to a limited extent. When the slide is in the
position shown in Figures 1 and 2 it will be obvious that neither the handle
section à nor the third casing section a² can be unscrewed from the tubular bushing
or union sleeve C, while if moved end wise to carry it out of the groove of eitlier
said handle section a or said third section a², the disconnection of the free section
may be readily accomplished.
The slide is provided on its upper face with cross ribs or grooves, so that the
thumb nail may be applied to readily remove it.
The shank section a³ of the casing A is connected in the usual way with the
outer or free end of a flexible sheath or tube, while the butt-end of the spindle
chuck B is connected in the usual way with the outer or free end of a flexible
driving shaft or power conveyor enveloped by the before mentioned sheath or tube,
the inner or opposite end of said flexible shaft or power conveyor being connected
with a driven spindle or shaft of the engine to receive motion therefrom so as to

page_text: impart a rapid revolving motion to the spindle chuck in its bearings in the hand
piece casing.
The said flexible enveloping sheath or tube and said flexible shaft or power
conveyor may be similar to those in common use or to those shown in English
Patent, No. 2696, of 1874, but as neither said sheath and shaft nor the particular
organization of engine employed constitute the subject matter claimed herein it
is unnecessary to illustrate them in tho Drawings or describe them in detail
herein.
The front end of the spindle-chuck B is socketted for the reception of the shanks
of the interchangeable operating tools as usual, and has its bearing in the nose of
the handle section a of the casing A while the rear end of the chuck is extended
through the tubular bushing C so as to have its rear axial bearing therein. A
friction collar bhaving a cone or tapering surface is fitted loosely upon the spindle
chuck near its rear end so as to fit with its front cone end in a correspondingly
formed seat in the butt end of the tubular bushing C, the said collar being held
firmly to its seat in said bushing by an annular screw-ring. 6' which works upon
male threads formed upon the spindle chuck so as to be adjustable, said screw-
ring being locked to the spindle when properly adjusted by a set screw b², as
clearly shown in Figure 2. Said screw ring b₁ constitutes the pull journal or
shoulder of the spindle-chuck; that is to say, it constitutes a journal or shoulder
which prevents the endwise forward movement of the chuck in the casing when a
pulling or "draw cut is being made with the operating tool.
"
±
A friction collar b³ having a tapering or cone surface is fitted loosely upon the
spindle-chuck, so as to fit with its tapering or conical butt end into a corresponding
seat in the front end of the tubular bushing C. Said friction collar b³ is held to
its seat in the front end of the tubular bushing by a ring b fitting the spindle,
and locked thereto by a set screw, for example, as clearly shewn in Figure 2.
I preferably interpose between the front end of the cone collar and the rear end
of the ring b a plain loose friction collar or washer 65. The said ring & constitutes
the thrust journal or shoulder of the chuck, that is to say, it constitutes a journal
or shoulder which prevents the endwise, backward, or inward movement of the
chuck in the casing, when a pushing or thrust cut is being made with the operating
tool.
It will be seen from what has been said that no endwise movement of the
spindle-chuck can take place in the casing. It will also be seen that the chuck is
accurately centered in its casing at front by its tapered end which has a corre-
sponding bearing in the nose of the handle section, and at rear in the tubular
bushing by the cone collar and adjustable ring arrangements. When wear occurs
between the parts it is readily taken up or compensated for by loosening the set
screw c which locks the second casing section or nut a' to the tubular bushing C.
This permits said bushing to be adjusted or screwed into the handle section a to
the required extent, to cause the tapered front end of the chuck to fit snugly in its
tapered bearing in the front end of said section, and to cause the front end of said
bushing to fit closely upon the cone collar b³, and the said collar to be forced
against the thrust journal of the chuck. The casing section or nut a¹ is then
screwed firmly up against the butt end of the handle section, and it is then locked
to the bushing by its set screw, as shewn in Figure 2. The screw ring b¹ is then
adjusted to compensate for the adjustment of the tubular bushing, and when
properly adjusted it is fastened to the spindle by its set screw b².
$
The loose cone friction collars b, b³, the rings b', 6', and the loose friction collar 6;
may be readily replaced by new ones when too much worn.
The loose conical friction collars b, b³, protect the tubular bushing C from wear
due to the draw and thrust of the chuck, inasmuch as they are prevented from
turning with the chuck by the friction between their tapered or conical ends and
the said bushing, and consequently receive the wear of the chuck instead of the
bushing.
There is an annular chamber formed between the front end of the spindle-

page_text: chuck B, and the end or nose of the casing through which the tool shank is passed
on its way to the chuck, and this chamber is for the purpose of arresting the
passage into the front bearing and chuck-socket of saliva, grit, &c., taken up by
the revolution of the tool and furthermore to prevent the exudation of oil from
said front bearing to the outside of the handpiece which would soil the fingers of
the operator and face of the patient, but I do not claim this feature as of my
Invention.
The shank of the operating tool E adapted to the improved hand-piece, is
provided with a conical or tapered enlargement or shoulder e, and with a double
transverse locking notch or groove e¹, e', with which the tool locking devices of the
spindle chuck engage, as will be presently explained. Said shank at its extreme
rear end is reduced or cut away, and said reduced end has a lug e² projecting from
it which constitutes the driving surface of the tool, and is acted upon by a suitable
pin or projection in the socket of the chuck, as shewn in Figure 2. The portion
of the tool shank in front of the tapering enlargement or shoulder e is preferably
reduced in size and terminates at the extreme front end in a cutting burr drill, or
other operating point commonly employed for dental operations.
The operating tools may be constructed either in a single piece as usual or in
sections; one section of a tool is shown in Figure 5. The rear end of the section
carrying the operating point will be fitted in the socket formed in the front end of
the main shank section, and the two sections will then be secured together, for
instance, by a transverse pin or rivet or by solder.
The front end of the conical or tapered enlargement e of the tool fits snugly the
opening in the nose of the hand-piece, through which the shank is passed on its
way to the socket of the chuck, while the rear end of said enlargement fits snugly
in the mouth of said socket, as shewn clearly in Figure 2.
The tool is positively driven when inserted in the socket of the chuck by the
pin or projection f1 crossing or extending into said socket, and engaging the lug e
or driving surface of the tool, while the tool is locked from endwise movement or
withdrawal by the tool locking devices, shown as consisting of two springs F, F,
fastened at their rear ends directly opposite each other in longitudinal recesses in
the spindle chuck, and having a tendency at their front ends to move outward or
laterally when not compressed by a sleeve or thimble G surrounding the chuck,
and movable endwise thereon.
The front ends of the laterally-movable locking springs are provided each with
a. tapering, inclined, or cam lug projecting into a lateral opening intersecting the
bore or socket of the chuck, and each lug comes in contact when compressed with
the rear wall of one of the locking notches e¹ of the tool shank, and thereby as
the lugs are forced down into the notches force the tool backwards and crowd or
draw its tapered surface or conical enlargement or shoulder firmly into its seat
in the mouth of the chuck socket, whereby the tool is not only firmly locked from
withdrawal, but is also prevented from wabbling or rattling in the socket. Any
wear that may occur between the tool and socket is also compensated for, and the
tool always driven firmly and without rattling or loose movement.
The sleeve G is thrust forward to compress the lug ended tool locking springs by
means of a coiled spring H, also surrounding the chuck, and compressed between
the fixed ring b* at rear, and the annular shoulder formed by the butt end of the
sleeve at front, the force of said spring H being at all times exerted to thrust the
sleeve forward to compress the laterally yielding locking devices into engagement
with the notches of the tool shank, as shown in Figure 2.
When a tool has been inserted and locked in the socket and it is desired to
withdraw it the sleeve G is retracted against the force of the spring H so as to
permit the locking ends of the springs F, F, to spring outward, which operation
releases the tool and enables it to be withdrawn. This retraction of the sleeve is
preferably accomplished. by means of a lever or finger piece I pivoted between
suitable lugs on the exterior of the casing, the front end of the lever being provided
with a lip or extended end i, which works through an opening in the side of

page_text: the casing, and. engages when the rear end of the lever is raised with an annular
shoulder on the sleeve to retract it as the lip of the lever moves backwards
around the pivot of the lever. The lever when not raised to manipulate the tool-
locking devices lies closely down upon the casing so that its lip remains out of the
way of the sleeve G, and does not interfere with the turning movements of said
sleeve with the chuck when at work:
I have so organized the lever I which actuates the tool locking devices that it is
raised in a forward direction, and moves the controlling sleeve G backward to
permit the tool locking devices to movo laterally to release the tool, and this
capacity of the lever to be lifted or rocked upwards and forwards to operate the
tool locking devices is a valuable one in the manipulation of a dental engine hand
piece, rendering its operation easy and rapid, and enabling the thumb of the hand
that holds the hand-piece to be used to, work the lever with great case while the
other hand is at the same time free to remove or insert the tool or perform other
offices. .
The lever is also so organized as not to interfere with the ready disconnection of
the handle section of the casing.
I have described the operating tool as having a shoulder or enlargement and a
double locking notch with rear walls to be acted upon by two locking devices from
opposite sides, in order to draw said enlargement into the mouth of the chuck
socket, and this construction is preferred, but it will be obvious that only one such
notch and a single locking device to act upon its rear wall would serve an excellent
purpose with a tool having a conical or tapered enlargement.
I claim as my Invention,-
First. The combination, substantially as herein before set forth, of the casing, the
spindle chuck, the tubular bushing, the cone friction collars surrounding the chuck
and fitting in corresponding seats in the front and rear end of said bushing, and
the thrust and pull journals or shoulders of said chuck working against said cone
collars.
Second. The hand piece casing having three detachable tubular sections, in
combination with the slide carried by one of said sections to prevent their
accidental separation while adjustable to permit the sections to be readily discon-
nected, as set forth.
Third. The combination, substantially as herein before set forth, of, the casing,
the spindle chuck mounted therein so as to turn axially, a tool locking device
carried by said chuck, and a lever pivoted externally on the casing so as to rock in
a direction from rear to front of the hand-piece to manipulate the tool locking
device when moved by the operator, whereby a hand piece is produced permitting
of the easy operation of the tool locking device by the thumb of the hand which
grasps the hand piece in operation.
Fourth. The combination, substantially as hereinbefore set forth, of the casing,
the spindle chuck, the laterally movable tool locking device carried by said chuck,
the sleeve to compress said locking device, the spring acting to thrust said sleeve
forward, and a lever pivoted externally on the casing and engaging said sleeve to
move it in a backward direction to permit said locking device to move laterally to
release the tool, while capable of being rocked upon its pivot out of contact with
said sleeve, so as to offer no obstruction to the free revolution of the chuck.
Fifth. The combination, substantially as hereinbefore set forth, of the casing,
the socketted spindle chuck, and a laterally moveable tool locking device, having a
tapering lug or cam end to engage a notch in the tool to lock said tool in the
socket of the chuck while drawing the shouldered conical enlargement of the tool
firmly in its seat in the mouth of said socket.
Sixth. The combination, substantially as hereinbefore set forth, of the casing,
the socketted chuck, the laterally moveable tool locking devices upon opposite
sides of the chuck, having tapering lugs or cam ends to engage locking notches in
the tool shank to lock said shank in the socket of the chuck, and force or draw the
shouldered or conical enlargement of said shank into the mouth of said socket, the

page_text: sliding sleeve to compress said tool locking devices, the spring acting upon said
sleeve to throw it forward, and the lever on the casing to retract said sleeve.
Seventh. An improved operating tool having a shouldered or conical enlargement
to determine its extent of movement into a chuck socket, and provided with a
locking notch or notches, and with a driving end or surface.
In witness whereof, I, the said Sydney Pitt, have hereunto set my hand and
seal, this Twenty ninth day of August, in the year of our Lord One
thousand eight hundred and eighty one.
SYDNEY PITT. (L.S.)