Year: 1886

page_text: Date of Application, 12th Oct., 1886.
Complete Left, 5th July, 1887.
Complete Accepted, 12th Aug., 1887.
I, ARTHUR EDWARD ASH of 141 Maida Vale in the County of Middlesex, Manu-
facturer of Dental Appliances do hereby declare the nature of this invention to be as
follows:-
In the Specification of a former Patent granted to Parsons Shaw No. 20 in the year
1881 is described a driving spindle formed in two lengths or divisions which are
coupled together end to end by a flexible coiled spring. Each length is surrounded by
an outer tube forming a sheath either for the whole or part of its length. At the
flexible joint the ends of the sheath tubes are forked and the arms of the fork at the
end of one tube are jointed to the arms of the fork at the end of the other tube. One
tube forms part of a bracket called the head piece and swings freely in a horizontal
plane around the top of an upright standard and on the end of the spindle which
passes through this tube is fixed a pulley by which the spindle can be rotated. The
coiled spring forming the flexible joint of the spindle is surrounded by a flexible coiled
spring of larger diameter which forms a flexible sheath around it.
With a flexible driving shaft of this kind as heretofore made it is troublesome to
replace the inner driving spring should it become crippled or broken.
The driving pulley has first to be taken off to allow the elbow joint to be drawn
away from the head piece. The ends of the flexible sheath have to be disconnected
from the ends of the sheath tubes-afterwards the elbow joint has to be bent to bring
the two parts of the spindle side by side and parallel with one another before the
two parts of the spindle can be withdrawn from the sheath tubes. When the parts
of the spindle have been withdrawn the flexible spring which couples them together
can be removed and a new one substituted for it.
To replace the parts of the spindle into their sheaths the two parts must of necessity
be again brought side by side and consequently the new spring has to be bent in a
semi-circular bend of small diameter and if care is not taken the spring is from this
cause sometimes crippled before ever it has been used.
The object of my invention is to remedy these objections.
In place of making the sheath-tube of head piece with the socket of elbow joint
forming the bearing of spindle, I make the bearing for spindle in a separate piece
upon which the elbow joint is screwed on and which can be connected or disconnected
from the end of the sheath tube.

page_text: The spindle which passes through this bearing is as before made with a projecting
collar, upon the end of which the coupling spring is connected.
This bearing is a short tube or ferrule which is slipped on to the spindle and its end
brought up to and against this collar. The ferrule at this end has a screw thread cut
around its exterior to screw into the short tube or socket of the fork.
In rear of this screw is a milled edged collar oy which the ferrule can be held or
turned. In rear of the collar the ferrule is reduced in thickness and passes into
the end of the sheath tube. The spindle projects from the further end of the sheath
tube and on to it is fixed the driving pulley which secures the aforesaid bearing in.its
place.
With this construction the coupling spring can easily be got at it is only necessary
to disconnect the elbow joint from the screw ferrule by unscrewing it then to draw
away the elbow joint sliding it along the other spindle-in this way both ends of the
spring are at once exposed and the spring can be removed and a new one
substituted for it. Then a new spring can be put into place without bending it as
heretofore in a sharp semi-circular bend.
Dated this 12th day of October 1886.
CARPMAEL & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Flexible Driving Shafts of Dental Engines.
I, ARTHUR EDWARD ASH of 141 Maida Vale in the County of Middlesex Manu-
facturer of Dental Appliances 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 :-
The flexible driving shaft or spindle used for driving the drill of a dental engine
has before been formed in two lengths or divisions coupled together end to end by a
flexible coiled spring called the driving spring. The ends of the two lengths which
have been so coupled together have also been made to turn in bearings formed in
tubes or sockets at the ends of an elbow jointed fork piece which carries within it a
flexible sleeve to surround and enclose the driving spring.
The socket at the end of one fork has also been made to swivel freely in the end of
a tubular sleeve which surrounds and forms a sheath for one of the lengths of the
driving spindle. This tubular sleeve has been made to form part of a bracket
called the head piece of the dental engine and has been made to swing freely in a

page_text: horizontal plane around the top of an upright standard. The length of the spindle,
which passes through the tubular sleeve has had a pulley fixed on its end by which
it could be rotated. A flexible driving shaft of the above kind is described in the
Specification of a former Patent granted to Parsons Shaw No. 20 in the year 1881.
With a flexible driving shaft of this kind as heretofore made it is troublesome to
replace the inner driving spring should it become crippled or broken.
The driving pulley has first to be taken off to allow the elbow joint to be drawn
away from the tubular sleeve or sheath of the head piece. The ends of the flexible
sheath carried by the elbow joint have to be disconnected from the elbow joint
sockets afterwards the elbow joint has to be bent to bring the two lengths or divisions
of the spindle side by side and parallel with one another and if the outermost length
or division of the spindle is covered with a tube or sheath (to prevent the whiskers
of the operator being twisted round it) the hand piece carried at the end of this
length of the spindle must also be removed before the two parts of the spindle can be
withdrawn from the sheath tubes. When the parts of the spindle have been with-
drawn the flexible spring which couples them together can be removed and a new one
substituted for it.
To replace the parts of the spindle into their sheaths the two parts must of necessity
be again brought side by side and consequently the new spring has to be bent in a
semi-circular bend of small diameter and the spring is from this cause sometimes
crippled before ever it has been used.
The object of my invention is to remedy these objections.
In place of making the end bearing for the length of the spindle which passes
through the tubular sleeve of the head piece in one piece with the socket of the elbow
joint, I make the bearing for the spindle in a separate piece upon which the elbow joint
is screwed so that it can readily be connected or disconnected from the end of the sheath
tube.
The length of the spindle which passes through this bearing is as before made with
a projecting collar and the coupling spring is connected to its end.
The bearing piece is a short tube or ferrule which is slipped on to the spindle and
its end brought up to and against this collar. The short tube or ferrule at this end
has a screw thread cut around its exterior to screw into the socket of the elbow
joint.
In rear of this screw is a milled edged collar by which the ferrule can be held or
turned. In rear of the collar the ferrule is reduced in thickness and passes into and
can swivel freely in the end of the sheath tube.
With this construction the coupling spring can easily be got at, it is only necessary
to disconnect the elbow joint from the screw ferrule by unscrewing it then to draw
away the elbow joint sliding it along the other spindle or along a tubular sheath
surrounding this length of the spindle if there be one-in this way both ends of the
spring are at once exposed and the spring can be removed and a new one substituted
for it. Thus a new spring can be put into place without bending it as heretofore in a
sharp semi-circular bend.
The drawings annexed shew various views of the flexible elbow joint of a driving
shaft formned as above described.
Figure 1 is a side view, Fig. 2 a plan, Figure 3 a longitudinal section of the elbow
joint.
Figure 4 shows separately the jointed forks and outer flexible sheath of the elbow
joint.
Figure 5 shows separately the bearing F which screws into one of the fork sockets
and Figure 6 shows separately portions of the driving spindle with the flexible coil
which connects them.
A A are the two forks jointed together and formed as described in the Specifica-
tion of the above mentioned patent. B is a coiled spring passing from the socket of
one fork to the socket of the other fork-it forms a flexible sheath for the driving
spring C by which the two parts D D₁ of the driving spindle are coupled together.
E is a sheath tube within which the part D of the spindle is enclosed-this sheath tube as

page_text: described in the above mentioned specification forms part of an arm or bracket capable
of swinging freely in a horizontal plane.
In place of forming the bearing for the end of the spindle D in one piece with the
fork A as heretofore I make the bearing in a separate piece F formed at one end to
slip into the end of the sheath tube and at the other end to screw into the socket of the
fork as will be seen clearly by the drawings.
The portion D¹ of the spindle on the opposite side of the elbow joint is shown
without any sheath tube but it might be provided with a sheath tube if desired and
the end of the sheath tube be made to pass into the fork socket so that when required
the socket may be slidden endwise along it.
In the event of a new driving spring being required it is only necessary to
unscrew the piece F from the fork socket and then to slip the elbow joined fork
pieces end wise along the spindle D (or tubular sheath covering such spindle if there be
one) the driving spring Cis thereby exposed and can be disconnected and a new one
put in its place without having to disconnect any other part of the flexible arm or
head piece and also without bending the spring. The elbow jointed fork pieces can
then be slidden back so as to cause the flexible coil B to surround the driving spring C
and when the piece F has been screwed into the fork socket the flexible driving shaft
is again ready for use.
It will thus be seen that the damaged driving spring C can at any time be rapidly
taken out and be replaced by a new spring without its being necessary to bend the
spring to put it into place and consequently without any risk of crippling the new
spring when putting it in.
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 I claim as my
improvements in the flexible driving shafts of dental engines.
1. Making the socket at one end of the elbow jointed fork piece to screw on to the
end of a tubular piece F which forms a bearing for the end of the length D of
the driving shaft whereby the elbow joint can be disconnected from the piece F
and be drawn end wise along the length D' of the shaft to leave the driving spring C
uncovered so as to allow of its being taken away and replaced by another without
any bending of the spring being necessary.
2. The construction of the flexible driving shaft of dental engines substantially
as herein before described and illustrated in the drawing annexed.
Dated this 4th day of July 1887
ARTHUR EDWARD ASH.