Improvements in Dental Engines.
Year: 1890

page_text: Date of Application, 1st May, 1890
Complete Specification Left, 28th Feb., 1891-Accepted, 18th Apr., 1891
PROVISIONAL SPECIFICATION.
Improvements in Dental Engines.
I, ROBERT BREWSTER, of 6 to 10, Lexington Street, Golden Square, in the
County of Middlesex, Manager of The Dental Manufacturing Company, Limited,
do hereby declare the nature of this invention to be as follows :—
The invention has for its object improvements in dental engines whereby greater
convenience is obtained combined with the prevention of injury to the flexible
coupling or couplings when the engine is either in use or at rest.
I place the driving wheel as low as possible, and in one form of engine I cause
the driving band to pass from the driving wheel, first around guide wheels, and then
around a horizontal driving pulley on a vertical bush working in a frame. The
upper portion of the said frame carries the tube support or outer casing carrying
internally a vertical driving rod, which passes through the bush of the horizontal
driving pulley, by which it is rotated, but is free to rise and fall therein for purposes
of adjustment in height of the head of the engine.
For regulating the tension of the driving cord, the lower side of the before
mentioned frame is connected to a rod which telescopes into a tube swivelling on
the bush of the foot wheel axle.
To permit of the vertical driving rod and tube support taking a position out of
the vertical, 1 fix a notched quadrant on the foot wheel standard and form a corre-
sponding opening in the swivelling upright which is fitted with a spring locking
bolt capable of entering the notches in the quadrant to enable the vertical rod to be
fixed at any desired inclination.
The vertical driving rod is fitted within a tube which is capable of sliding within
the tube or hollow standard fixed to the upper part of the before mentioned frame,
and such upper telescopic tube is capable of being adjustably fixed in any position
within certain limits to obtain any required elevation of the upper part of the
engine. The horizontal driving pulley is supported on a spring in order to reduce
friction.
If desired the vertical driving rod or shaft may be employed without capability
of adjustment in height, in which case the axis of the driving pulley may be mounted
at its lower end on a pivot. The vertical driving rod is connected at its upper end
to one end of a flexible shaft or coupling, which is enclosed in a projecting tube of
quadrant like form fixed to the upper end of the upper telescopic tube, and said
flexible shaft or coupling is at its other end connected to one end of a short rigid
horizontal shaft, to the other end of which is connected another flexible shaft or
coupling enclosed within a second quadrant shaped protecting tube, the end of which
is fitted to work freely in a box or socket carried by the end of the fixed quadrant
shaped protecting tube, so as to enable same to be turned freely around the axis of
said tubes.
The last mentioned flexible shaft or coupling is connected to a short rigid shaft
working in suitable bearings and connected to a flexible arm or shaft enclosed
within a flexible sheathing fitted at its end with the usual hand piece.
This arrangement of jointed protecting quadrant shaped tubes enables the flexible
arm or shaft to hang down normally in a vertical position without fear of kinking
or injuring the flexible shafts or couplings working within the protecting tubes and
yet allows of the flexible arm or shaft and hand piece being used at any desired
angle or elevation with facility. This arrangement of jointed protecting tubes of
quadrant form is an important feature of my invention.
According to a modified form of engine, I dispense with the before mentioned
vertical driving rod and parts connected therewith, and I carry the driving band

page_text: from the driving wheel, over a driving pulley carried at one end of a hort and
preferably telescope horizontal shaft at the top of the engine standard, and to the
other end of such horizontal shaft I concet a flexible shaft or compling, which in
the present modification works within a single protecting tube of quadrant lupe
fitted to the ter end of tube enclosing the horizontal Shaft, on to be capable
of turning around the axis of the same as hereinbefore described. The flexible
shaft or compling i. commeted at its outte e end to a short rigid shaft, to which is
connected the flexible grm or cable and sheath carrying the hand piece. In this
modification, guide wheels may be employed to carry the driving end compactly
near the side of the upright or stand.nl, and 1 for the latter with capability of
being lived in a pition, either sortied or otherwise, by the means here befor
de-cribd.
The lara i ma le telescopie for the purpose of adjusting the tension of
the dryine cond.
'
My invention all apporterable the engine to le driven
from th oppsite side of the chair to that wally adopt d.
For this purpose I cumploy a fram carrying at each end a crank lever, and 1
commet one end of one of such erunk levers by link to the crank of the driving
wheel, whilst the other erank lever is comeeted by a link with a swivelling treadle.
The two crank ver, are connected together preferably by means of link connecte
to an intermediate double ended lever mounted at its centre on a tu or axis
carried by the frame, which latter of lagt utficient to extend from une side of
the chair to the other, ur of other convenient length.
Batal thin but leaf Von Th
•
ROBERT BREWSTER.
By Hair & MIL,
23. Southamptin Buildings, London, Agents,
I. Rom
Comms Middle
do hereby decla
The performed, to be
Statement:
OMPLETE SPLIFF AHON,
Improvements in Dental Engines.
WSH, of 6 to 10, Laxingon Street, Golden Square, 'n the
Mager to The Dental Manufacturing Company. Limited,
thn mature of the invention, atal in what aner them is to
particularly decribed and „-certained in end by the following
.
The invention l for it object improvements in dental engines whereby greater
convenience et ned embined with the prevention of injury to the Hexible
coupling when the engine is either in use or at rest.
I place the driving wheel as low as possible on a foot wheel standard and I curry
the driving band from the driving wheel over a driving pudley carried at one end of
short horizontal shaft working within a sleave or tube fixed to a swelling bracket
having a vertical haft or stem titting freely a tubular -ochet formed in a vertically
adjustable part of the engine standard, and to the other and of such horizontal shaft
connect a flexible shaft or compling, which works within a rigid protecting tube
of quadrant shape fitted to the outer end of the sleeve or tube enclosing the
horizontal shaft so as to be capable of turning around the axis of the same.
The Hexible shaft or coupling is commerted at its onter end to a short rigid shatt
working in a suitable bearing in the onter end of the quadrant shaped protecting
tube and commerted to one end of a flexible arm or shafi enclosed within a flexible
sheathing fitted at its opposite end with the usual hand-piece.
This arrangement of jointed protecting quadrant shaped tube enables the flexible
arm or shaft to hang down normally in a vertical position without fear of kinking
or injuring the flexible shaft or coupling working within the same, and yet allows
of the flexible arm or shaft and hand piece being used at any desired angle or
elevation with facility, and such arrangement of jointed quadrant shaped protecting

page_text: tube forms an important feature of my invention; if desired guide wheels may ne
employed to carry the driving cord compactly near the sides of the upright or
standard. also form the latter with capability of being fixed in a position either
vertical or otherwise for this purpose I mount the upright or standard on an axis
of motion at the upper part of the foot wheel standard with capability of rocking
thercon within certain limits and I form or fix a notched quadrant on the foot wheel
standard and form a corresponding opening in the rocking upright or standard,
which is fitted with a spring locking bolt capable of entering the notch in the centre
of the quadrant to hold the said standard in a vertical position, hut when the latter
is used in an inclined position, such upright is caused to rest against a lug at one or
other extremity of the quadrant. In either of these inclined positions of the
upright or standard, the operator is enabled to work the treadle with the latter
more directly under his body than when the upright or standard is in an upright
position.
The standard or upright being made telescopic, as before described, enables the
tension of the driving cord to be readily adjusted.
And in onder that my said invention may be more clearly understood and readily
carried into effect, I will proceed aided by the accompanying drawings, more fully
to describe the same.
DESCRIPTION OF THE DRAWINGS.
Figures 1 and 2 are elevations drawn at right angles to each other of a dental
engine constructed according to my invention.
Figure 3 is a plan of parts drawn on the line 1-1 of Figure 1.
Figure 4 is an elevation partly in section showing the upper part of the foot
wheel standard, the lower portion of the rocking upright or standard, the driving
wheel, axle of the same, crank, connecting rod, and part of the treadle full size.
Figure 5 is a sectional elevation of some of the parts shown at Figure + drawn
at right angles thereto, and
Figure 6 is a sectional view of the upper parts of the engine drawn full size.
a is the foot wheel standard, is the treadle, which is hinged to a radial arm b¹,
pin jointed to one of the feet a' of the foot wheel standard at a point perpendicularly
below the driving wheel axis e, is the driving wheel, the crank, and the
connecting rod, which is connected to the treadle by a ball and socket joint, as
fully represented at Figure 4. is the rocking upright or standard, which is
mounted on the axis e with capability of rocking thereon within certain limits, being
fitted with a steel bush or bearing sleeve fitting such axis.
The upper end of the foot wheel standard a is formed with a notched quadrant a',
and an opening or recess d² is formed in the lower end of the rocking standard d,
which opening is fitted with a spring locking bolt d capable of entering the notch a
in the centre of the quadrant a to hold the standard or upright in a vertical position,
whilst one or other of the inclined faces d at the lower end of such upright, is
capable of resting against one or other of the lugs at the extremities of the
quadrant by these means the upright or standard d can be caused to assume a
position either vertical or at an inclination on either side thereof, according to the
convenience of the operator.
The driving bande passes from the driving wheel over a driving pulley "fixed
to one end of a short horizontal shaft working within a sleeve or tube d³ fixed to
a swivelling bracket having a vertical shaft or stem a fitting freely a tubular
socket d formed in a vertically adjustable telescopic part d' of the engine standard d,
which is capable of being fixul at the desired elevation by means of the screw
clamp To the other end of such horizontal shaft. I connect a flexible shaft
or coupling y, which works within a rigid protecting tube / of quadrant shape fitted
to the outer end of the sleeve or tube by a screw coupling piece du so as to be
capable of turning freely around the axis of the shaft.
The flexible shaft or coupling 7 is connected at its outer end to a short rigid
hollow shaft i working in a suitable bearing in the outer end of the protecting tube h.

page_text: A solid short shaft j fits freely within the hollow shaft, but is caused to rotate
therewith by a stud or pin fixed in such hollow shaft and entering a groove
formed in the shaft j, by which means the latter, while controlled to rotate with the
hollow shaft ¿, is capable of moving to and fro therein within certain required limits.
The shaft is connected to a flexible arm or shaft & enclosed within a flexible
sheathing fitted at its end with the usual hund piece m, to which the tools are
fitted in the well known manner.
The part of the upright or standard being made telescopic and being provided
with a screw clamp enables the tension of the driving cord to be readily
adjusted.
If desired guide wheels may be employed a little above the driving wheel e to
carry the driving cord compactly near the sides of the upright or standard, but. I
have found this to be unnecessary,
By placing the driving wheel as low as possible and immediately under the
driving pulley, and by swivelling the shaft as described, I obtain a long length
of driving lande and afford facility for turning the upper part of the engine round
to any angle without risk of the band running off the driving pulley 1'.'
r
Having now particularly described and ascertained the nature of my sand
invention, and in what manner the same is to be performed, I declare that what 1
claim is
1. In dental engines, the improved combination and arrangement of parts,
substantially as herein shown and described and for the purposes stated.
2. In dental engines, an adjustable upright or standard mounted on an axis at the
upper part of the foot wheel standard and a spring locking bolt in the lower part of
the said upright or standard acting in combination with a locking quadrant at the
upper end of the foot wheel standard for the purpose of enabling the said upright
or standard to be used in a vertical position or at an inclination thereto, substantially
as herein shown and described.
3. In dental engines, the combination with the sleeve or bearing carrying a short
horizontal driven shaft at the top of the machine, of a swivelling rigil quadrant
shaped protecting tube, within which the flexible shaft or coupling works and which
connects such sleeve or bearing with the flexible shaft or arm carrying the hand
piece, by which means the said flexible shaft or arm is enabled to be used at any
desired angle and to hang down normally in a vertical position without fear of
kinking or injuring the flexible shaft or coupling, substantially as herein shown and
described.
4. In dental engines, the combination of a swivelling treadle connected by a link
with a crank on the driving axle, a driving wheel on such axle, a foot wheel
standard carrying such axle, and the swivelling treadle, an adjustable standard
or upright rocking on the driving axle, a spring locking bolt in the lower end of
such upright, and a lorking quadrant on the upper part of the foot wheel standard,
substantially as herein shown and described.
5. In combination with the parts mentioned in the 4th claim, a short horizontal
driving shaft working in a sleeve or bearing carried by a swivelling bracket
supported in the upper end of a vertically adjustable part of the upright or standard,
a driving pulley on one end of such horizontal shaft, a flexible shaft or coupling
connecting the other end of such horizontal shaft to the flexible arm or shaft giving
motion to the tools mounted in hand piece and a quadrant shaped rigid protecting
tube, within which the flexible coupling works, substantially as herein shown and
described.
ROBERT BREWSTER.
By Harris & Mills,
23, Southampton Buildings, London, W.C., Agents.