Year: 1887

page_text: [Communicated from abroad by ARTHUR W. BROWNE, of Princes Bay, in the County
of Richmond and State of New York, one of the United States of America.]
1 SYDNEY PITT of Sutton in the County of Surrey Gentleman 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 :-
My invention relates to dental and surgical engines wherein a rapid revolving
motion is imparted to a driving shaft, and by said shaft to a tool holder, to drive an
operating tool carried by said tool-holder. The driving shafts of such engines are
either flexible shafts, such as wire-coil shafts, or are made up of stiff sections of
shafting, connected by flexible or universal joints, whereby the operating tool, driven
by the shafting, may be freely moved about within certain limits, to direct the tool to
the proper point, and at the proper angle, to do its work. The usual wire-coil shafts
are open to some objections, such as unsteadiness in operation, and lack of durability,
while in the other class of shafts, made up of stiff sections united by universal joints,
there is generally either a stiffness in the joints, or the same liability to unsteady
rotation as is observable with the wire-coil shafts. These defects in the stiff-sectioned
universally-jointed shafts of previous constructions seem to be due to imperfections in
the universal joints employed, both for the shafting and the tubes or sleeves which
envelop the shaft sections.
The object of the first part of my present invention is to improve the dental or
surgical engine as respects its stiff-sectioned driving shaft, connections, and bearings,
whereby, while the tool is free to be readily moved about to be directed to its work,
the shafting will be steadily and positively driven in whatever direction the tool may
be operating, with a like steady and positive operation on the part of the tool driven

page_text: by said shafting, and whereby, also, the durability of the shafting will be increased.
A further object of this part of my invention is, to improve the organziation of the
driving shaft and lateral engine arm, so that the shafting may he readily supported
horizontally by the top of the engine standard or upright, out of the way when not
in use.
The next part of my invention relates to the flexible driving spring connecting the
ends of the stiff shaft sections, so that greater torsional strength is given to the spring
and jumping or irregular action avoided, without interfering with the necessary
flexibility of the spring.
The next part of my present invention relates to the manner of jointing the vertical
engine standard or upright to the base or tripod of the engine, so as to readily
vary its angle of inclination or movement out of the perpendicular, at the will of the
operator.
The next part of my invention relates to the manner of connecting the foot-pedal
and attachments to the base or tripod of the engine, so as to avoid tilting the engine
upon an uneven floor, when the weight of the operator is thrown upon the pedal in
operating it.
In the accompanying drawings, which illustrate my improvements—
Figure 1 is a view in elevation of the improved engine looking in the line of the
revolution of the driving wheel.
Figure 2 is a side elevation of the engine, at right angles to Figure 1, showing the
vertical standard as adjusted slightly out of the perpendicular, and the shafting as
supported out of the way, as when the engine is not in use.
Figures 3 and 4 are enlarged views (Figure 3 being a section and Figure 4 a sido
view) of the adjustable friction connection between the vertical engine standard and
the base or tripod, by which said standard may be moved or adjusted out of the
perpendicular and back again, as required.
Figure is an enlarged bottom plan of the jointed connection between the foot
treadle and base or tripod of the engine; and
Figure 6 is a cross-section therethrough on the pivot line of the rocking pedal.
Figure 7 is a longitudinal section through the engine head and lateral engine arm
or sleeve, showing, more particularly, the rear end of the driving shaft as carrying a
brush-wheel to be rotated.
Figure 8 is a similar section to that of Figure 7, through the engine head and
lateral engine arm or sleeve, with a side view of the flexible or universal shafting, to
show the construction more clearly; and
Figure 9 is a view of the vertical fork for securing and supporting the swinging
section of the driving shaft and its sleeve and the hand-piece of the engine carried at
the outer end thereof.
Figure 10 is an enlarged elevation of a portion of the shafting and its sleeves, with
the outer shaft section at its extreme extended position.
Figure 11 is a similar view, with one section of the shaft bent at right angles to the
other.
Figure 12 is a view of the flexible or universal joint of the shaft at right angles to
the views previously shown, showing an edge or plan view of the connecting links
between the enveloping sleeves or tubes of the jointed shafting; and
Figure 13 is an enlarged elevation of a portion of the shafting and enveloping
sleeves, one section thereof being bent backwards, so as to lic substantially parallel with
the section beneath it.
Figure 14 is a view of the improved compound flexible wire-coil connection, or
driving spring, attached at one end to the rear end of the tool-holder of the hand-
piece, such a spring being applicable as the flexible connection of any two stiff shaft
sections of the engine.
Figure 15 is an enlarged view of the improved compound driving spring, partly in
section.
Figure 16 is an enlarged view of said spring in a curved or bent position; and
Figure 17 is an end view of said spring.

page_text: Figure 18 is a view, similar to the view shown in Figure 15, of the old form of
flexible driving spring, and Figure 19 is an end view thereof.
The base A of the engine is preferably the tripod base, as usual, having an upright
or forked post A', to receive the driving pulley, B. Said pulley is mounted between
the forks of the post A, and keyed to revolve with its crank shaft C, the bearings of
which are formed in the upper ends of said post A'. The lower forked end of the
vertical engine standard or upright, D, also straddles the driving pulley B, and is fitted
to rock or be adjusted on the extended ends or bosses of the forked end of the post A¹
in the common way. The said engine upright or standard D, is maintained in its
adjusted position by a frictional connection with the post A, of the base or tripod A,
and said connection is preferably organized by extending the lower forked ends of the
engine upright below their pivotal connection with the post. A', and fitting thereto, on
cach side of said post preferably (although one side would do), friction plates, E. E.
the upper ends thereof being secured by screws e. e. to the lower ends of the upright,
and the lower ends of said plates being secured to the post A' or bosses thereof, by
screws ele, passing through longitudinal slots e², e, in said plates into the sides of
said post A. By tightening said screws any required amount of friction can be
exerted upon the lower end of the engine standard or upright D, and it may conse-
quently he readily rocked or adjusted to the desired vertical inclination, and will there
remain until again adjusted to the normal perpendicular or other position desired.
Motion is imparted to the driving pulley B, through a crank c, on the end of the
crank shaft C by a foot treadle F and pitman G as usual. In order to avoid any
rocking or tilting of the engine upon an uneven floor, when weight is thrown upon the
foot pedal, I pivot said pedal F, by its cross wise rocking pivot, to a base piece, heel
plate, or arm H and in turn joint said base piece plate or arm to one of the legs A²
of the base or tripod A by a longitudinal pivotal connection h, whereby the pedal F,
may rock or move independently upon and in longitudinal line of said leg A of the
base or tripod. The weight therefore, that is thrown upon the pedal is accommodated
by the movement of the pedal and its connections, without tilting the base or tripod.
The upright standard D, of the engine is preferably, a sectional adjustable one, as
usual to secure the proper adjustment and tension of the driving belt, which passes
from the driving pulley B over the driven pulley J, of the engine-head K mounted at
the upper end of said engine upright or standard as usual. Said engine head is fitted
to turn or swing around the upper end of the upright or standard D, as usual by the
usual socket and pivot connection, shown in Figure 7 and is fitted with a bearing for
the rear stiff section L of the revolving driving shaft carrying the driven pulley Jas
usual. Said pulley J is keyed upon said driving shaft section, L, and rapidly revolves
or drives it when the driving pulley B, is revolved by the foot treadle. An arm or
sleeve M. connected with or forming part of the engine head K, extends out laterally
from said head, as usual, and being tubular forms a bearing or bearings for the pulley
section L, of the driving shaft. This shaft section L is a stiff shaft, and it extends to
the outer tubular end m. of the lateral arm or sleeve M where it is connected by a
wire coil driving spring N with the inner end of a second stiff shaft section O, which
is also fitted to turn in a tubular sleeve or bearing P, the outer end of which is
preferably connected by the usual flexible wire sleeve connection, Q with the rear end
of the usual hand piece casing R. The outer end of said second section O, of the
driving shaft is, or may be also connected, by the usual wire coil driving connection N¹
to the rear or butt end of the tool holder W fitted in said hand piece casing, to
revolve said tool holder, and the operating tool wc, carried thereby, when the shaft is
revolved.
It is desirable that the connection between the outer end of the sleeve or tubular
lateral arm M and the inner end of the sleeve P, should be an universal connection
and such that, in the movements of the sleeve P, and shaft section carried thereby,
relatively to the lateral arm and shaft section 1. thereof, there will be no straining or
uneven bending or buckling of the wire coil connection N, and consequently no
unsteady jumping or irregular motion in the driving shaft, and consequently also, none
in the rotating operating tool. The wire coil or driving spring N should take its

page_text: natural curve or bend, and thereby avoid changing the length of said spring N either
by stretching or compressing it. To attain these ends I preferably form the adjacent
ends of the two sleeves M. P. each with a fork, and unite the opposing arms or members
thereof together by a compound link connection, whereby in bending one section of
the driving shaft and its enveloping sleeve relatively to the other, in operating with the
engine, the wire coil driving spring connection N, will always be bent substantially in
the arc of a circle, and without varying its length or contracting it when in such bent
position. The curves formed by said wire coil connection or spring N in its various
positions, due to bending the stiff shaft sections, are substantially segments of circles
of various radii (see dotted lines Figures 10 and 11) and the shafts occupy the
positions of tangents to the various circles.
This compound link connection consists, preferably, of four curved links, two of
said links $, S, being pivotted at their inner or rear ends to opposite sides of the
tubular lateral arm or sleeve M, or the forked end thereof, and at their front ends to
the opposite sides of the rear forked end of the sleeve, P, and the other two links T, T,
(the counterpart of the links S, S.) being pivotted by their rear ends to the front
forked end of the sleeve M, in advance of the pivots of the links S, S, with said sleeve,
and by their front ends to the opposite sides of the forked end of the sleeve P, in
advance of the pivots of the front ends of the links S, S, with said sleeve P. The links
are curved and cross each other. as shown whereby the sleeves M, P, with their
contained shaft sections, may be extended in approximately a straight line, as shown in
Figure 10, until limited by the abutment of the pivot connections of the links, or may
be bent towards each other through a range of motion substantially approximating to
a parallel position, as shown, for example, in Figures 1, 2, 8 and 13. This (in
connection with the flexible connection at the butt end of the hand piece and tool
holder thereof) gives all the motion of the driving connection necessary to enable the
handpiece and operating tool carried thereby, to be freely moved about to work at
the point desired, and at the same time insures durability of the flexible driving spring
connection with a steady uniform rotation of the driving shaft and operating tool.
In order to give greater freedom of movement to the hand-piece of the engine,
and to provide for holding the front shaft section O, and its sleeve or bearing P out of
the way, when the engine is not in use, I form the front end m of the lateral engine
arm, bearing or sleeve M in the form of a swivelling or turning sleeve (see Figure 8),
whereby the driving shaft and the sleeve or bearing P, universal connections, and
hand-piece, may be turned around or axially, or be rocked sidewise, relatively to the
rigid lateral engine arm, bearing or sleeve M. By this organization also, the front
sleeve P, and connected parts, may be turned around relatively to the lateral engine
arm M and the said sleeve P', and its contained shaft folded back parallel with said
engine arm, to fit in the vertical retaining fork U, mounted on the engine-head, as
clearly shown in Figures 1, 2, 7, 8 and 9, so as to be held out of the way of the
operator when not in use.
Instead of the ordinary flexible driving spring or connection N, between the shaft
sections L, O, and such a spring N₁, between said section O, and the butt end of the
tool-holder W, of the hand-piece of the engine, I preferably employ an improved
compound driving spring constructed of two or more flat ribbon-shaped pieces, bars
or strips n, n, of steel preferably assembled so as to lie closely side by side and wound
edgewise upon a mandrel to produce a flexible driving spring or power transmitter.
I have discovered that by constructing the driving spring of flat strips placed side by
side and wound together into a compound spring, as clearly shown in Figures 14, 15,
16 and 17, a very superior flexible driving spring is produced. It has more strength
torsionally, less liability to jump or rotate unsteadily, and less recoil or back-lash,"
than a driving spring made out of one strip, in the usual way, as shown in
Figures 18 and 19.
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 combination, with the engine base, of the engine upright or standard

page_text: movable thereon, and a friction holding or locking connection between said base and
said standard, substantially as described.
2. The combination, with the base, of the treadle, the heel plate or arm to which the
treadle is pivotted, and the pivottal connection between said heel-plate and said base,
substantially as described.
3. The engine-head or lateral arm provided with a vertical fork thereon, to support
the horizontally bent driving shaft, substantially as described.
4. The combination of the stiff sections of a driving shaft connected by a wire coil
or spring driving connection, with the bearings or sleeves of said shaft sections united
by a compound link connection, substantially as described.
5. A compound joint, substantially as described, for the sleeves or bearings of a
flexible driving shaft, whereby said sleeves or bearings are retained in their various
movements in lines tangential to the curve of said shaft at the joint, as herein before
set forth.
6. The compound driving spring consisting of two or more flat ribbons or bars
wound side by side into a flexible driving spring, substantially as described.
CARPMAEL & Co.,
Agents for the Applicant.