IMPROVED DENTAL ENGINE,
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by the said Parsons Shaw at the Office
of the Commissioners of Patents on the 3rd January 1881.
PARSONS SHAW, of Manchester, in the County of Lancaster, Dentist.
IMPROVED DENTAL ENGINE,"
" AN
The object of my Invention is to secure a dental engine which is both simple
and effective. To this end among other arrangements I mount the driving wheel
on the side of a rigid upright arm or support, which arm arises from a tripod stand.
This makes that part of the stand compact. The driving wheel is also near to
the floor which causes the engine to run steadier.
At the top part of the rigid upright standard or arm I mount a horizontal arm.
This horizontal arm is attached to the upright standard by means of a telescope
tube at the apex of this standard, and a brace whose bearings surrounds this
standard. By means of the telescopic tube at top of standard and the bearing of
the brace, the horizontal arm swings freely around the upright standard or arm.
In this horizontal arm there runs a shaft which has one of its bearings over the
apex of upright standard, and the other in a joint piece hereinafter described at the
outer end of the horizontal arm. To the end of this shaft over the standard is
attached a driven pulley. In this driven pulley are two or more grooves of
different sizes by which different speeds are obtained. This driven pulley may be
made lighter, and the larger groove thrown nearer to or more over the centre of
the upright shaft by scooping out the side opposite to the grooves. By running
the driving cord in the groove with greatest diameter, I obtain especially in
combination with a small driving wheel that slow speed and small amount of friction
and heat so often times desirable; but when necessary or desirable more 'speed
can be obtained by running the driving cord over the smaller grooves in driven
pulley. To secure the proper tension of the driving cord when changed from one
groove to another, the upright arm can be lengthened or shortened by means of a
set screw attached to the telescopic tube, and another attached to the upright shaft
beneath the bearing of the brace to horizontal arm.

page_text: But the chief improvement in my dental engine is an universal joint. This is
attached to the horizontal arm and allows the shaft to which is attached the hand
piece to move in every direction. This universal joint consists of a double sleeve
fork jointed coupling of peculiar construction. In each part of the coupling there
is a cylinder of sleeve in which the above named shafts revolve. The part of the
coupling which is attached to the horizontal arm is able to revolve freely on that
arm; this gives one of the movements necessary to my universal joint. The other
movement is obtained by means of a spiral connection between the shaft in the
horizontal arm and the shaft which hangs or swings loose from the universal joint,
and also a novel hinge like construction and connection of the parts of the coupling
in which the shafts revolve. From the cylindrical parts of the couplings extends
two forks or lugs, which end in right angle or equivalent projections, quadrant
shaped by preference. These projections are connected together at their ends by
means of pins, so as to allow them to move freely on one another and form a hinge.
Between these forks or lugs lies the spiral which connects the two shafts. This
connecting spiral is protected from injury and prevented from buckling by a spiral
sheath which is attached to the cylindrical parts of the couplings, and is its
protected by the side of the fork or lugs between which it is placed. The object of
the peculiar shaped couplings with their forks or lugs is to maintain in the spirals,
however much the joint may be bent on its hinges, a curve that always represents
the segment of a larger or smaller circle, whereby the driven spiral will play freely
in its protecting sheath. Inside of the sleeves are arranged two stops to prevent
the couplings from doubling on each other or from bending, except in the side from
which the projections arise. By preference these stops should prevent the joint
from becoming quite straight, so as to prevent it turning round with the shafts and
its spiral connection. The change in the length of the connecting spiral as it is
curved or straight is provided for by allowing the upper shaft a little play in its
bearing, and also a little play to the lower or loose or swinging shaft or arm in its
bearings in the cylindrical part of the lower coupling of the universal joint.
Another improvement is my hand piece which dispenses with catches, springs,
screws, and other like devices for holding the instrument to be used in its place.
This consists of a shaft running in a sheath with the proper bearings. The exposed
end of the shaft has a slightly tapered opening for the reception of the slightly
tapered end of the instrument to be used. The other end is attached to a spiral
which connects it with the loose or hanging arm. This revolving spiral is covered
and protected by a spiral sheath, which is attached to the sheath of the hand piece
at one end, and at the other end plays freely on the loose or swinging arm.

page_text: SPECIFICATION-in pursuance of the conditions of the Letters Patent filed by
the said Parsons Shaw in the Great Seal Patent Office on the 1st July 1881.
PARSONS SHAW, of Manchester, in the County of Lancaster, Dentist.
IMPROVED DENTAL ENGINE."
"AN
The object of my Invention is to secure a dental engine which is both simple
and effective.
Figure 1 is a general elevation of the machine as I prefer to construct it. I
mount the driving wheel a on the side of an upright arm or support b, which
arm arises from a tripod stand c. The driving wheel is near to the floor, which
causes the engine to run steadier.
At the top part of the upright standard or arm 6 I mount a horizontal arm d.
This horizontal arm is attached to the upright standard by means of a telescope
tube at the apex of this standard and a brace e whose bearing f surrounds this
standard.
The telescopic arrangement is as follows:-6 is a tube forming the upper part
of the standard; 62 again is a stem or tube fixed to the horizontal arm d, and
entering within 6, in which it is raised or lowered in order to tighten the band;
62 has a collar clamped upon it by a set screw b*, and the bearing ƒ can be shifted
along 6 and secured by a set screw in the proper position. By means of the
telescopic tube at top of standard and the bearing the horizontal arın swings
freely around the upright standard or arm. In the horizontal arm & there runs a
shaft which has one of its bearings over the apex of upright standard, and the
other in a joint piece h, hereinafter described, at the outer end of the horizontal arm.
To the end of this shaft g, over the standard, is attached a driven pulley h. In this
driven pulley there may be two or moore grooves of different sizes, by which
different speeds are obtained. This driven pulley may be made lighter and the
larger groove thrown nearer to or more over the centre of the upright shaft by
scooping out the side opposite to the grooves. To secure the proper tension of the
driving cord when changed from one groove to another, the upright arm can be
lengthened or shortened by the means already described.
But the chief improvement in my dental engine is an universal joint.
Figure 2 is a side elevation full size of the joint; Figure 3 shows it in another
position to a smaller scale; Figure 4 is a plan of the joint as it appears when its
two shafts are aligned. This joint is attached to the horizontal arm and allows the
shaft i, to which is attached the hand piece, to move in every direction. This
universal joint consists of a double sleeve fork jointed coupling of peculiar
construction. In each part of the coupling there is a cylinder or sleeve / in which
the above named shafts revolve. The part of the coupling which is attached to
the horizontal arm is able to revolve freely in the bearing m; this gives one of the
movements necessary to my universal joint. The other movement is obtained by
means of a spiral connection between the shaft 9 in the horizontal arm and the
shaft which hangs or swings loose from the universal joint. And also a novel
hinge like construction and connection of the parts of the coupling in which the
shafts revolve. From the cylindrical parts l, l, of the couplings extend two forks
or lugs,, which end in right angle or equivalent projections, quadrant shaped
by preference. These projections are connected together at their ends by means of
pins n, so as to allow them to move freely on one another and form a hinge.
Between these forks or lugs lies the spiral which connects the two shafts g and i.
The shafts g and i have caps or collars screwed or formed upon them which
prevent their drawing out of the parts l, l, of the coupling in which they turn.
The spiral is a close coil of wire into which the ends of the shafts or the caps enter
for a sufficient distance, fitting very tightly. This connecting spiral is protected from

page_text: injury and prevented from buckling by a spiral sheath, which is attached to the
cylindrical parts of the couplings fitting on to bosses formed upon them, as the
Drawings show. The sheath is itself protected by the side of the fork or lugs
between which it is placed. The object of the peculiar shaped couplings, with their
forks or lugs, is to maintain in the spirals, however much the joint may be bent on
its hinges, a curve that always represents the segment of a larger or smaller circle,
whereby the driven spiral will play freely in its protecting sheath. Inside of the
parts,, of the sleeves are arranged two stops *, *, to prevent the couplings
from doubling on each other or from bending except in the sides from which the
projections arise.. By preference these stops should prevent the joint from
becoming quite straight, so as to prevent its turning round with the shafts and
their spiral connection. The change in the length of the connecting spiral, as it is
curved or straight, is provided for by allowing the upper shaft g a little play in its
bearing and also a little play to the lower, or loose, or swinging shaft or arm in its
bearings in the cylindrical part 1 of the lower coupling of the universal joint.
Another improvement is my hand piece which is shown in section, full size in
Figure 5. It dispenses with catches, springs, screws, and other like devices for
holding the instrument to be used in its place. This hand piece consists of a
shaft o running in a sheath p with the proper bearings. The exposed end of the
shaft has a slightly tapered opening o¹ for the reception of the slightly tapered
end of the instrument to be used. The other end is attached in the manner
previously described to a spiral which connects it with the loose or hanging arm i.
This revolving spiral is covered and protected by a spiral sheath which is attached
to the sheath g of the hand piece at one end, and at the other end to a ring which
plays freely on the loose or swinging arm.
Having thus described the nature of my said Invention, and the manner of
performing the same, I would have it understood that I claim my improved dental
engine, and also especially the double sleeve fork jointed coupling, and the novel
hand piece, substantially as described.
In witness whereof, I, the said Parsons Shaw, have hereunto set my hand
and seal, this Thirtieth day of June, in the year of our Lord One thousand
eight hundred and eighty one.