Improvements in Dental Chairs.
Year: 1893

page_text: Date of Application, 11th Nov., 1893
Complete Specification Left, 21st July, 1894-Accepted, 27th Oct.,
1894
Improvements in Dental Chairs.
A communication by GEORGE WASHINGTON ARCHER, of 67, North St. Paul
Street, Rochester, in the County of Monroe and State of New York, United
States of America, Manufacturer.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of The Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool and 6, Bank Street, Manchester,
both in the County of Lancaster and 323 High Holborn in the County ol
Middlesex, Civil Engineer, do hereby declare the nature of this invention to be as
follows:-
The present invention has for its object to provide an improved chair particularly
adapted for the use of dentists, which is simple in construction and capable of easy
and rapid adjustment to any position in which it is desired to place the patient, and
it consists in certain improvements in construction and combination of parts, all as
will be hereinafter described.
The base of the chair consists of a base casting having spreading legs and a
central recess or socket for the reception of the hollow pedestal in which the
raising and lowering devices and the seat carrying standard are arranged to
operate. The pedestal is provided with a flange resting on the upper edge of the
socket in the base and is adapted to be turned thereon so that the rotary
position of the chair may be adjusted and is secured in position by means of a
cam pivoted in the base casting and provided with the upper and lower extensions,
respectively, by means of which latter the cam may be operated to lock or release
the pedestal by pressing on one or the other of said extensions.
The standard on which the chair seat frame is mounted is suitably guided in the
pedestal and adapted to be elevated by a vertically movable and tilting clamping
ring pivoted at one side to a link, which in turn is pivoted to the end of a foot
lever, the end of said lever being extended beyond the connection with the link
and having attached to it a spiral spring passing down inside the pedestal and
connected to it at its end as shown, or by any other suitable means, this spring
operating to return the outer end of the lever to an elevated position, and thereby
bring down the tilting clamp ring; the operation of this form of lifting device will
at once be understood by those skilled in the art and no further description of it is
therefore necessary. The operating foot lever is preferably made of two parts
pivoted together so that it may be broken and the outer end swung beneath the
chair body out of the way. On the outer section of the lever is pivoted a foot
piece which enables the operator to maintain a firm pressure on the lever when
elevating the chair and reduces the liability of his foot slipping off, as is apt to be
the case when a pivoted lever with a solid end is employed. The chair standard is
preferably hollow, and at its lower end is secured a nut tapped with a comparatively
steep pitch thread with which co-operates a vertically extending screw which is
rotated when the standard is elevated or depressed, as will be described. To the
lower end of the pedestal is attached a collar or cover which serves to support a
pan or bottom plate screwing on to it; said pan constituting a support for the
standard when it is being lowered.
Connected rigidly to the lower end of the screw is a tapered plug or block
arranged to engage a correspondingly shaped aperture in a spider, the end of the
screw passing through said block, spider, and through the bottom of the pan, but
the connection between the extension of the screw and the spider is a loose one

page_text: excepting when the tapered block is forced into the tapering aperture in the spider
by the weight of the chair. The upward movement of the screw is limited and the
-parts-held-properly in position by means of a small securing screw, the head of
which engages loosely the lower side of the aperture in the pan.
Arranged beneath the spider is a series of balls operating in suitable grooves in
said spider and the bottom of the pan to reduce the friction, and upon the outer
ends of the spider are pivoted weighted arms or wings having near their pivots
brake shoes arranged to co-operate with the vertical rim of the pan when the
spider is rapidly rotated and the weighted arms or wings are thrown outward
by centrifugal force. The standard is maintained in raised position by means of
a small roller operating in a tapering slot in the upper part of the pedestal; said
roller being forced down into the narrower portion of the slot by the chair standard
and operating to clamp and hold the latter, this downward motion also being assisted
by a foot lever pivoted to the pedestal and having a bifurcated end loosely embracing
the roller; the inner end of the lever and the roller being moved downward by a
spring arranged between the outer operating end and the standard.
The operation of the standard and chair adjusting mechanism will now be under-
stood. The operator by a movement of the foot lever raises the standard with a
step-by-step motion and it is maintained in raised position, while the foot lever is
being returned, by means of the clamping roller, which is moved down into the
narrow portion of the slot by the spring. During the upward movement of the
standard, the screw is rotated, the thread being of comparatively steep pitch and it
is lifted slightly, so that the tapering block is lifted out of the socket in the spider
and the latter is not rotated. When it is desired to lower the chair, the operator
simply presses. on the foot lever thereby moving the holding roller into the wider
portion of the slot and the weight of the chair is thrown entirely upon the screw
which is forced down and the tapered portion engaged with the spider, causing the
latter to rotate with the screw and the weighted brake shoes to be thrown out in
contact with the edges of the pan with sufficient friction to effectually govern the
descent of the standard and the chair, this being accomplished noiselessly and with
perfect safety, and it may be arrested at any portion in its descent by reducing
the pressure on the lever and allowing the clamping roller to again engage
the standard and the lower portion of the tapered slot. As stated, the rotary
movements of the pedestal can be readily governed by means of the locking cam.
It will be noted that by employing the automatic holding roller the weight of
the chair is never on the screw or braking device until it is to be lowered, but when
the sustaining device proper is released then the governing device performs its
functions properly. This insures the proper operation of the latter at all times
and renders it less liable to wear or strain than would be the case if the screw and
braking device supported the chair even though restrained by other devices, from
operation.
The seat of the chair is, as usual, secured to the seat frame on upper end of the
standard and may or may not be provided with a tilting attachment; the usual
platform and foot rest being secured to its forward portion and the arms being of
the usual or any preferred construction.
Secured to the back of the seat, and in the present construction, the lower part
of the arms, is a back supporting casting having lugs at the upper portion to which
are pivoted notched links connected at their outer end by a loosely pivoted loop.
This back casting is also provided with lugs, at its lower portion, between which is
pivoted the lower end of a telescoping back support, the lower hollow section
having the bearing portion forward of the main cylindrical part and pivoted upon a
pin passing through it and through the lugs. The section is also provided with
laterally projecting lugs with which the notches in the pivoted links are adapted to
engage to maintain it in vertical or inclined position, as may be desired.
Sliding within the section is a second section having at its upper end a collar or
rim with which the bracket sections on the chair back are held in engagement by
means of an adjusting screw. The operating faces of these bracket sections are

page_text: provided with annular grooves engaging the edges of the circular portion of the
section, so that the chair back to which the bracket sections are secured, by
laterally extending flanges, may be adjusted around the annular portion and secured
in position by means of the clamping screw which draws the two sections tightly in
engagement with the annular end. One section is adjustable vertically in the other
section and is prevented from turning laterally and its vertical position is also
maintained, by means of a securing screw passing through the side of the one
section and entering a slight groove formed in the side of the other section.
From this it will be seen that the vertical and tilting movements of the back
can be readily accomplished, and when it is desired to adjust the chair-back forward
and back it may be accomplished by lifting the link, and engaging another of the
notches therein with the trunnions of lugs. The loop connecting the links, serves
not only as a handle for readily operating them, but also in case it is desired to
lower the back of the chair quickly and place the patient in a recumbent position
as in case of fainting or collapse, the back support can be disengaged entirely from
the links and moved to lowermost position, the loop then co-operating with the back
support, which as before turns on the pivot pin at its lower end.
The upper portion of the back is provided with a socket for the reception of the
bent arm carrying the head-rest, which latter embodies a pad to the rear portion
of which is secured a bracket having two arms and pivoted to the supporting stem,
the latter being constructed in two sections arranged to slide one within the other,
the outer section being pivoted to the bracket arms and the inner section having the
upward extension having the slot in which operates a pin connecting the bracket
arms.
The inner portion of the stem is cylindrical and is provided with a right-handed
screw thread and the outer end of the section is reduced and provided with a left-
handed thread engaging with the interior of the screw correspondingly threaded,
while the outer portion of said screw engages the thread in the outer section, the
arrangement being such that the rapid tilting adjustment of the head-rest pad can
be accomplished by simply turning the screw to the right or left, moving the inner
section in either direction by a rapid movement, the pad turning on the outer stem
section. The stem is secured to the bent arm by a screw having a loop in its upper
portion through which the stem passes, the threaded portion of the screw passing
through an aperture in the arm and having on its lower end an adjustable nut or
handle so that by loosening the nut the stem can be moved bodily in or out and
again secured. The rod is secured by a split clamp arranged on the chair back
and can be adjusted vertically or turned around as may be desired.
Dated this 10th day of November 1893.
WM. P. THOMPSON & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Dental Chairs.
A communication by GEORGE WASHINGTON ARCHER, of 67, North St. Paul
Street, Rochester, in the County of Monroe and State of New York, United
States of America, Manufacturer.
I, WILLIAM Phillips Thompson, F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 6 Lord Street, Liverpool, and 6, Bank Street,
Manchester, both in the County of Lancaster, and 323, High Holborn, in the
County of Middlesex, Civil Engineer, do hereby declare the nature of this inven
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
This present invention has for its object to provide an improved chair particularly

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от цени, wtren 15 витpre in construction and capable of easy
and rapid adjustment_to_any_position in which it is desired to place the patient, and
it consists in certain improvements in construction and combinations of parts, all as
will be hereinafter fully described and the novel features pointed out in the claims
at the end of this Specification.
In the drawings;
Figure 1 is a perspective view of a complete chair constructed in accordance with
this invention;
Figure 2 an enlarged sectional view of the base of the chair showing the lifting
and lowering mechanism;
Figure 3 a longitudinal section through the whole chair;
Figure 4 an enlarged view of the back adjusting device;
Figure 5 a sectional view of the same on the line x-x of Figure 1 ;
Figure
an enlarged sectional view of the adjustable head-rest ;
Figure 7 a plan view of the head-rest;
Figure 8 a sectional view of the lowering mechanism;
Figure 9 a sectional view on the line -z of Fig. 3.
Similar reference numerals in the several figures indicate similar parte.
The base of the chair consists of a base casting 1 having spreading legs and a
central recess or socket for the reception of the hollow pedestal 2 in which the
raising and lowering devices and the seat carrying standard are arranged to operate.
The pedestal 2 is provided with a flange 3 resting on the upper edge of the socket
in the base and is adapted to be turned thereon so that the rotary position of the
chair may be adjusted and is secured in position by means of a cam 4 pivoted in
the base casting and provided with the upper and lower extensions 41, 4' respectively,
by means of which latter the cam may be operated to lock or release the pedestal
by pressing on one or the other of said extensions, as shown in Figure 2.
5 indicates the standard on which the chair seat frame 6 is mounted; said
standard being suitably guided in the pedestal and adapted to be elevated by a
vertically movable and tilting clamping ring 61 pivoted at one side to a link 7, which
in turn is pivoted to the end of a foot lever 8, the end of said lever being extended
beyond the connection with the link and having attached to it a spiral spring 9
passing down inside the pedestal and connected to it at its end as shown, or by any
other suitable means, this spring operating to return the outer end of the lever to
an elevated position, (shown in Figure 2,) and thereby bring down the tilting clamp
ring 61; the operation of this form of lifting device will at once be understood by
those skilled in the art and no further description of it is therefore necessary. The
operating foot lever 8 is preferably made of two parts pivoted together at 10 so
that it may be broken and the outer end swung beneath the chair body out of the
way. On the outer section of the lever is pivoted a foot piece 11 which enables
the operator to maintain a firm pressure on the lever when elevating the chair and
reduces the liability of his foot slipping off, as is apt to be the case when a pivoted
lever with a solid end is employed. The chair standard 5 is preferably hollow and
at its lower end is secured a nut 12 tapped with a comparatively steep pitch thread
with which co-operates a vertically extending screw 13, which is rotated when the
standard is elevated or depressed, as will be described. To the lower end of the
pedestal 2 is attached a collar or cover 14 which serves to support a pan or bottom
plate 15 screwing on to it; said pan constituting a support for the standard when
it is being lowered.
Connected rigidly to the lower end of the screw 13 is a tapered plug or block 16
arranged to engage a correspondingly shaped aperture in a spider 17, the end of
the screw passing through said block-spider, and through the bottom of the pan 15,
but the connection between the extension of the screw and the spider is a loose one
excepting when the tapered block 16 is forced into the tapering aperture in the
spider by the weight of the chair. The upward movement of the screw is limited
and the parts held properly in position by means of a small securing screw 18, the
head of which engages loosely the lower side of the aperture in the pan.

page_text: Arranged beneath the spider 17 are a series of balls 19 operating in suitable
grooves in said spider and in the bottom of the pan to reduce the friction and upon
the outer ends of the spider are pivoted weighted arms or wings 20 having near
their pivots 21 brake shoes 21 Fig. 8 arranged to rub against the vertical rim of
the pan 15 when the spider is rapidly rotated and the weighted arms or wings
carrying the brake shoes are thrown outward by centrifugal force. The standard 5
is maintained in raised position by means of a small roller 22 Figs. 3 & 9 operating
in a tapering slot 23 in the upper part of the pedestal; said roller being forced
down into the narrower portion of the slot by the chair standard and operating to
clamp and hold the latter, this downward motion also being assisted by a foot
lever 24 pivoted to the pedestal and having a bifurcated end loosely embracing the
roller 22; the inner end of the lever and the roller being moved downward by a
spring 25 arranged between the outer operating end and the standard, as shown in
Figure 3.
The operation of the standard and chair adjusting mechanism will now be
understood. The operator by a movement of the foot lever 8 raises the standard
with a step-by-step motion and it is maintained in raised position, while the foot
lever is being returned, by means of the clamping roller 22, which is pressed down
into the narrow portion of the slot by the action of the spring 25 and lever 24.
During the upward movement of the standard, the screw .13 is rotated, the thread
being of comparatively steep pitch and it is lifted slightly, so that the tapering
block 16 is lifted out of the socket in the spider and the latter is not rotated.
When it is desired to lower the chair, the operator simply presses on the foot
lever 24 thereby moving the holding roller 22 into the wider portion of the slot 23
and the weight of the chair is thrown entirely upon the screw 13, which is forced
down and the tapered portion engaged with the spider, causing the latter to rotate
with the screw and the weighted brake shoes 21 to be turned outwards on their
pivots so as to rub against the inside periphery of the pan with sufficient friction
to effectually govern the descent of the standard and the chair, this being
accomplished noiselessly and with perfect safety, and it may be arrested at any
portion in its descent by reducing the pressure on the lever 24 and allowing the
clamping roller to again engage the standard and the lower portion of the tapered
slot. As stated the rotary movements of the pedestal can be readily governed by
means of the locking cam 4.
It will be noted that by employing the automatic holding roller 22, the weight
of the chair is never on the screw or braking device until it is to be lowered, but
when the sustaining device proper is released then the governing device performs
its functions properly. This insures the proper operation of the latter at all times
and renders it less liable to wear or strain than would be the case if the screw and
braking device supported the chair even though restrained by other devices, from
operation.
The seat 26 of the chair is, as usual, secured to the seat frame 6 on upper end of
the standard and may or may not be provided with a tilting attachment; the usual
platform and foot rest 27 and 28 being secured to its forward portion and the
arms 29 being of the usual or any preferred construction.
Secured to the back of the seat, and in the present construction, the lower part
of the arms, is a back supporting casting 30 having lugs at the upper portion to
which are pivoted notched links 31 connected at their outer end by a loosely pivoted
loop 32. This back casting is also provided with lugs 33 at its lower portion
between which is pivoted the lower end of a telescoping back support, the lower
hollow section 34 having the bearing portion 35 forward of the main cylindrical
part and pivoted upon a pin 36 passing through it and through the lugs. The
section 34 is also provided with laterally projecting lugs 37 with which the notches
in the pivoted links 31 are adapted to engage to maintain it in vertical or inclined
position, as may be desired.
Sliding within the section 34 is the section 38 having at its upper end a collar or
rim 39 with which the bracket sections 40, 40, on the chair back are held in

page_text: engagement by means of an adjusting screw 41. The operating faces of these
bracket sections are provided with annular grooves engaging the edges of the
-circular-portion-39-of-the-section-38, so that the chair back 42 to which the bracket
sections are secured, by laterally extending flanges 43, may be adjusted around the
anunlar portion 39 and secured in position by means of the clamping screw 41,
which draws the two sections tightly in engagement with the annular end.
The
section 38 is adjustable vertically in the section 34 and is prevented from turning
laterally, and its vertical position is also maintained, by means of a securing
screw 44 passing through the side of the section 34 and entering a slight groove 60
formed in the side of the section 38. From this it will be seen that the vertical
and tilting movements of the back can be readily accomplished, and when it is
desired to adjust the chair-back forward and back it may be accomplished by
lifting the link 31 and engaging another of the notches therein with the trunnions
of lugs 37. The loops 37 connecting the links, serves not only as a handle for
readily operating thein, but also in case it is desired to lower the back of the chair
quickly and place the patient in a recumbent position as in case of fainting or
collapse, the back support can be disengaged entirely from the links 31 and moved
to lowermost position, shown in Figure 3, the loop 32 then co-operating with the
back support, which as before turns on the pivot pin 35 at its lower end.
The upper portion of the back 42 is provided with a socket for the reception
of the bent arm 45 carrying the head-rest, which latter embodies a pad 47, to
the rear portion of which is secured a bracket having two arms 48 and 49
pivoted to the supporting stem, the latter being constructed in two sections
arranged to slide one within the other, the outer section 50 being pivoted to the
bracket arms 49, and the inner section 51 having the upward extension having
the slot 54 in which operates a pin 52 connecting the bracket arms 48. The
inner portion of the stem 50 is cylindrical and is provided with a right-handed
screw thread and the outer end of the section 51 is reduced and provided with
a left-handed thread engaging with the interior of the screw 53 correspondingly
threaded, while the outer portion of said screw engages the thread in the outer
section 50, the arrangement being such that the rapid tilting adjustment of the
head-rest pad 47 can be accomplished by simply turning the screw 53 to the
right or left moving the inner section in either direction by a rapid movement,
the pad turning on the outer stem section 50. The stem 50 is secured to the bent
arm 45 by a screw 55 having a loop in its upper portion through which the stem
passes, the threaded portion of the screw passing through an aperture in the
arm 45 and having on its lower end an adjustable nut or handle 56, so that by
loosening the nut the stem can be moved bodily in or out and again secured. The
rod 45 is secured by a split clamp 57 arranged on the chair back and can be
adjusted vertically or turned around as may be desired.
The term pedestal in the claims, except when used in connection with the
particular base 1 shown herein, is to be understood as meaning any adequate
support for the parts, using it in its broad sense.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is;
1. In a chair, the combination with the supporting-base having the socket, of
the pedestal on which the chair is mounted, supported and adapted to be rotated
therein, the locking cam pivoted in the supporting-base with its face engaging
the pedestal and having the two operating arms on opposite sides of the pivot,
whereby upon pressing upon one or the other of said arms, the cam can be engaged
or disengaged from the pedestal, substantially as described.
2. In a chair, the combination with the chair standard and lifting devices therefor,
of the pedestal having the inclined groove, the roller operating on the standard
located therein, the foot lever having the bifurcated end engaging the roller and
the spring operating the foot lever, substantially as described.

page_text: 3. In a chair, the combination with the base or pedestal, the chair standard,.
lifting devices therefor, and an automatic sustaining device operating directly on
the standard, of the rotatable screw engaging the standard, and a brake or
governor detachably connected with and actuated by the screw when moved in
one direction only, substantially as described.
4. In a chair, the combination with the base or pedestal, the chair standard,
lifting devices therefor, and a sustaining device, of the screw engaging the standard,
and having the tapered block and the rotary brake or governor having the tapered
socket for the block on the screw, substantially as described.
5. In a chair, the combination with the base or pedestal, the chair standard,
lifting devices therefor, and a sustaining device, of the screw engaging the standard
and having the tapered block, the rotary spider having the weighted arms and
brake shoes and the socket for receiving the block on the screw, substantially as
described.
6. In a chair, the combination with the pedestal, the chair standard, lifting
devices therefor, and a sustaining device, of the screw engaging the standard and
having the tapered block thereon and the extension at the end, the rotary spider
having the tapered socket and the weighted brake arms mounted on said extension,
the rim with which the arms co-operate and the securing screws, substantially
as described.
7. In a chair, the combination with the base having the socket, the pedestal
supported therein, the standard, the standard raising and sustaining devices in
the pedestal and the bottom pan secured to the lower end of the pedestal, of
the screw operating in the standard having the tapered block, the rotary spider
provided with the socket and the brake arms thereon, said spider supported on
the bottom of the pan and the securing screw engaging the end of the first
mentioned screw, substantially as described.
8. In a chair, the combination with the seat, of the back supporting standard,
the notched arms or links pivoted to the seat and engaging projections on the
back support, and the depending loop loosely connected to the links and passing
around the back supporting standard, whereby the back may be supported by the
links, or may be lowered and supported in extreme position by the loop, substantially
as described.
9. In a chair, the combination with the seat, the telescoping back support, one
section having the annular head and the other pivoted to the seat, of the bracket
sections secured to the back co-operating with the head, the securing screw
engaging the bracket sections clamping them to the head, and the notched links
pivoted to the seat and engaging the back support, whereby the back may be
adjusted vertically and the support tilted, substantially as described.
10. The combination with the head rest pad having the two rearwardly
extending arms, of the supporting stem constructed in two telescoping parts, both
parts being pivoted to the head rest, and provided with right and left threads
and a screw screwing into one section and onto the other to provide for their
relative adjustment, substantially as described.
Doted this 20th day of July 1894
WM. P. THOMPSON & Co.,
Agents.