Year: 1886

page_text: Date of Application, 5th Aug., 1886.
Complete Left, 1st Mar., 1887.
Complete Accepted, 1st Apr., 1887.
We, GEORGE CLAUDIUS ASH, WILLIAM ASH, WILLIAM HENRY ASH, HENRY
CLAUDIUS ASH, CLAUDIUS JAMES ASH, and ARTHUR EDWARD ASH, all of Nos. 6,
7, 8 and 9 Broad Street Golden Square, in the County of Middlesex Manufacturers
of dental materials do hereby declare the nature of this invention to be as follows:-
This Invention has for its object an improved dental chair.
In our improved chair there is an under frame with suitable legs, and an upper
moveable frame on which is the seat. The upper frame is capable of being raised and
lowered in relation to the under frame and also of rotating about a vertical axis.
Upon the under frame an hydraulic cylinder is carried, it contains a piston provided
with cupped leathers and having a rod projecting vertically upwards. The cylinder is
charged with oil or other liquid. Near the upper end of the piston rod there is a boss
or collar upon it, and on this the upper frame with the seat is supported so that it can
rotate whilst the piston remains stationary. There is an outer cylinder or casing on
the upper frame and this surrounds and encloses the hydraulic cylinder which is
received loosely within it. There are ratchet teeth formed on the exterior of this outer
cylinder and a pawl carried by a treadle lever engages with these teeth.
There is a
passage through the piston and in this passage a double valve is fitted; a large coned
valve opening downwards permits the free passage of liquid from the upper to the
under side of the piston, but closes automatically to prevent any return of the liquid ;
and a small conical valve fitted in a central passage formed through the larger valve
is opened when required to allow the liquid to pass the piston in an upward direction.
This small valve has a stem passing up through the piston rod which is hollow and
a hand lever is provided to operate upon the stem and to open the valve against the
pressure of the liquid. The valve rod has a collar upon it, and a coiled spring
abutting upon this collar and also upon a surface within the piston, presses the rod
upwards and so serves to hold both the valves to their seats except when they
LD 017
are

page_text: displaced either by the hand lever or automatically by the liquid when the pressure
above the piston is greater than below.
The treadle lever is carried upon the under frame, and springs in connection with it
raise the end to which the foot is applied, and draw down the inner end which carries
the pawl engaging with the rack forming part of the upper frame. The pressure of
the foot on the treadle overcomes the springs and lifts the pawl and with it the upper
frame for a short distance. The upper frame carries up with it the piston rod and the
piston, leaving a space beneath the piston which is instantly filled by liquid descending
from the upper side of the piston. When the foot is removed from the treadle the upper
frame and the seat of the chair remain supported by the liquid beneath the piston. If
desired the upper frame can then be further raised by again depressing the treadle, and
so on until the seat has been brought to the height desired. To lower the seat all that
is requisite is to depress the small valve by means of the hand lever, liquid then escapes
from beneath the piston, passes to the upper side and allows the seat quietly with it to
descend.
Dated this 5th dow LA100%
CARPMAEL & Co.,
Agents for the Applicants.

page_text: We, GEORGE CLAUDIUS ASH, WILLIAM ASH, WILLIAM HENRY ASH, HENRY
CLAUDIUS ASH, CLAUDIUS JAMES ASH, and ARTHUR EDWARD ASH, all of Nos. 6,
7, 8 and 9 Broad Street, Golden Square in the County of Middlesex, Manufacturers
of dental materials (a communication to us from abroad by Daniel O'Connel Finigan
of 68 Jägerstrasse, Berlin, Dentist) 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 improvements relate to dental chairs of that class in which the chair body is
supported upon the top of a plunger or piston which rests on liquid in a cylinder in
which the piston or plunger works, and in which the piston or plunger is also capable
of being raised by mechanism worked by means of a treadle.
The object of the improvement is to simplify and improve the construction.
The improvements are shown in the drawings hereunto annexed.
Figure 1 is a side elevation partly in section of the chair.
Figure 2 is a side elevation of the chair pedestal with the upper portion partly in
section.
Figure 3 is a plan view of the pedestal.
Figure 4 is a vertical section of the cylinder-the piston within it is shown in
elevation.
Figure 5 is a vertical section of the piston.
Figure 6 shews separately on a larger scale parts of the lifting mechanism.
Figure 7 shews an end view of the lifting pawl and of the links and springs which
draw downwards the end of the treadle lever by which the pawl is carried.
A is a pedestal with three or four legs-B are bearers attached to the pedestal and
carrying a cylinder C which is closed at bottom-D is a piston fitting within the
cylinder and having extending upwards from it a hollow piston rod E-F is a casting
to which the upper part of the chair or chair body is secured and which is free to
swivel around the upper end of the rod and is supported by a collar projecting out-
wards from it. The casting F has also secured to it a cylinder G which encloses the
cylinder C and forms a cover to it. It has also formed on its exterior a toothed rack
by which the raising of the chair body is effected as hereinafter explained.
The piston is hollow and carries two concentric valves H and I-the larger one H
for allowing liquid to pass freely from the upper part of the cylinder to the lower when
the piston is raised-the smaller one I (when it is held open) to allow liquid to pass
from the lower part of the cylinder to the upper part thereby allowing the piston and
chair body to descend.
The piston is formed of a short tube a with a block b screwed into its upper end
and a block c into its lower end. The lower end of the hollow piston rod E screws
into the upper block and through this block are also passages d for the passage of
liquid to or from the hollow interior of the piston-The piston is provided with two
cup leathers e one held between the top of the tube a and the upper block and the
other between the bottom of the tube a and the lower block. The lower block has a
vertical central opening formed through it and closed at the bottom by the two con-
centric valves H and I-both opening downwards. The valve H is kept closed by the
pressure of the liquid upon its under side. The valve I is kept closed by the pressure
and by a spring ♬ and has a rod K extending upwards from it through the hollow

page_text: stem of the valve H and through the hollow piston rod E. Its upper end projects
above the top of the piston rod. Here it has two collars formed upon it between
which the end of the shorter arm of a lever L enters the pivot of this lever is
carried by the casting F which carries the chair body and which is free to swivel
around the top of the hollow piston rod. By raising the outer end of the lever L the
valve I can be held open and liquid be thereby allowed to pass from below the piston
into the hollow stem of the valve and out from thence through a small passage into
the hollow interior of the block c and out from thence into the hollow interior of the
piston through the passages h. M is a valve by which liquid can be drawn off from
the cylinder C.
We will now describe the means by which the chair body is raised. The cylinder G
which surrounds the cylinder C has on one side of it a rack N. The pedestal A has
pivoted to it a lever O the inner and shorter arm of which carries a pawl P to engage
with the teeth of this rack. The outer arm of the lever carries at its extremity a
treadle plate Q-R R are springs for drawing downwards the inner end of the lever
which carries the pawl. S is a spring for causing the pawl to engage with the rack N.
T is a stop by which the pawl is held away from the rack when the treadle is in its
highest position. When the treadle is depressed the pawl rises away from the stop
and engaging with the rack lifts the chair body. When the pressure of the foot is
taken off the treadle, the treadle is raised to its normal position by the springs R. As
the chair body is raised liquid passes from above to below the piston and upholds the
chair body in its raised position.
Having now particularly described and ascertained the nature of our said invention
and in what manner the same is to be performed we declare that what we claim is :-
1. A dental chair constructed substantially as hereinbefore described and illustrated
in the drawings annexed.
2. The combination of the pedestal A carrying a vertical cylinder C filled with
liquid. The hollow piston D with hollow piston rod E rising up from it. The chair
body supported by and capable of swivelling around the top of the piston rod. The
concentric valves H and I at the bottom of the piston. The passages d for allowing
liquid to pass freely between the interior of the piston and the interior of the cylinder
above the piston. The rod K and lever L for opening the valve I. The cylinder G
descending from the chair body and encircling the cylinder C and mechanism for
acting upon the exterior of this cylinder to raise it whenever required.
3. The mechanism for raising and upholding the chair body consisting of the
pedestal A, cylinder C filled with liquid, piston D with valve for allowing liquid to
pass freely from above to below it, piston rod with the chair body supported by and
capable of swivelling around its upper end. Cylinder G descending from chair body
and surrounding the cylinder Crack N on exterior of cylinder G-treadle lever Ŏ
pivoted to pedestal A and carrying a pawl P to engage with the rack N and raise the
chair body when the treadle is depressed.
4. The mechanism for lowering the chair body consisting of the pedestal A
cylinder C filled with liquid, piston D upholding the chair body, central valve I, rod K
passing up from valve through hollow piston rod E, lever L for depressing rod K and
valve I and passages through piston for allowing liquid to pass from below the piston
to above it when the valve I is so opened.
5. The piston D formed of a short cylinder a, blocks b and c screwed into its
ends, cup leathers e, passages d through the upper block b, concentric valves H
and I carried by the lower block c, spring f for keeping the valve I closed.
11
1007
CARPMAEL & Co.,
Agents for the Applicants.