Improvements in Dental Chairs.
Year: 1894

page_text: Date of Application, 17th May, 1894-Accepted, 21st July, 1894
Improvements in Dental Chairs.
I, ARTHUR WILLIAM BROWNE, of Prince's Bay, in the County of Richmond,
and State of New York, United States of America, Manufacturer, 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:-
My invention relates to certain improvements, substantially such as hereinafter
described and claimed, in means for imparting a wide range of vertical adjustment
to the bodies of dental chairs which are adapted to be horizontally turned and
vertically tilted or inclined, as well as raised and lowered, and maintained in any
desired position of adjustment.
In the accompanying drawings, which show my improvements as suitably applied
to a dental chair of well known construction in various features,
Fig. 1, Sheet 1, is a view mainly in side elevation, whilst showing in section
some portions of the chair the particular construction of which is not essential to
my invention.
Fig. 2, Sheet 2, is a plan view showing details of supplementary elevating and
lowering mechanism, and connecting parts.
Fig. 3, Sheet 2, is a rear elevation of the supplementary elevating and lowering
mechanism with some other parts in elevation and section.
Figs. 4 and 5, Sheet 3, are views designed to show in side elevation different
positions of adjustment of the supplementary elevating and lowering mechanism.
Fig. 6, Sheet 4, is a view partly in side elevation and partly in vertical section
showing a modification of my invention; and Fig. 7, Sheet 4, is a similar view
showing a further modification.
Figs. 8, 9 and 10, Sheets 5 and 6, represent another modification, Fig. 8 being a
view mainly in side elevation, with portions of a suitable chair body in section;
Fig. 9 a plan view with said chair body omitted; and Fig. 10 a. rear elevation
showing a portion of the plunger and its bracket for pivoting the parallel arms of
the supplementary elevating and lowering mechanism.
Figs. 11, 12 and 13, Sheets 5 and 6, are side elevations showing additional
modifications.
Referring now to Figs. 1 to 5, inclusive, Sheets 1, 2 and 3 of the drawings, my
improvements are shown as applied to a dental chair such in many features of
construction as shown in Letters Patent of the United States of America,
Nos. 197,441 and 483,807, dated respectively November 20, 1877, and October 4,
1892, and in Letters Patent in Great Britain for the said inventions, No. 4,662 of
the year 1877, and No. 17,677, dated October 4, 1892. As in said Patents there
is provided a support (bereinafter termed the main elevating and lowering support)
for the chair body A, said support consisting of the plunger A' having vertically
adjustable connection with the base or pedestal A and actuated by means of the
jointed elevating lever A and co-operating devices, the lever being jointed to the
cylinder B which is adapted to turn horizontally in the pedestal and to be locked
therein by the locking lever B₁. The vertically adjustable support A' has no
horizontal or turning movement in the cylinder B to which the elevating lever is
attached, and the manner of upholding and of lowering the support is as fully
explained in the above-mentioned Patents.
Supplementary elevating and lowering mechanism is interposed between the chair
body, which it carries, and the main elevating and lowering support A, so as to
increase the range of vertical adjustment of the chair body. This supplementary

page_text: GACYTING 10wering mechaMISM ப its preferred construction 18 How 10 D0
explained.
Two pairs or sets of parallel arms C C CC, one pair at each side of the main
elevating and lowering support, have jointed connection at their inner ends with
the upper end of the main elevating and lowering support by way of a suitable
bracket-like attachment D of this support removably and rigidly secured in place
in manner such as set forth in the before-mentioned Patent No. 483,807. The
pair of arms C C are pivoted at dd to the rigidly attached bracket D, the one
above the other; and the pair of arms C¹ C¹ are similarly pivoted at d₁d to the
bracket. The lower arms of the pairs, it will be seen, are pivoted to the forks or
downwardly projecting arms D¹ D¹ of the bracket. At their outer ends the parallel
arms are jointed to a chair body carrier E, the pair of arms CC being pivoted to
the carrier at ee, and the pair of arms CC pivoted thereto at ele. It will of
course be understood that the distance between the pivots of either pair of arms at
their outer ends is the same as that between the pivots at their inner ends, so as to
prevent tilting of the carrier and maintain it in proper upright position throughout
the vertical adjustments imparted to it by rocking the parallel arms about their
pivotal connections with the main support. The chair body has suitable supporting
connection with its carrier E constituting a part of the supplementary elevating
and lowering mechanism. To hold this mechanism in its adjusted position detent
devices are provided as follows:-A pawl I on a rock shaft J carried by the
carrier E is adapted to be thrown into and out of engagement with a ratchet rack
or detent teeth I¹ carried by one of the lower arms of one of the pairs of parallel
arms. A handle J' serves to actuate the rock-shaft to operate the pawl which
normally is in engagement with the ratchet rack. But three positions of adjustment
of the supplementary elevating and lowering mechanism independently of the main
elevating and lowering support are provided in the construction shown, the rack
being provided with three teeth. More or less teeth might be provided if desired,
and the parallel arms lengthened or shortened as occasion might require.
The chair-body is jointed to its carrier of the supplementary elevating and
lowering mechanism, journals or trunnions F F of the carrier entering bearings ff
of the chair-body, so that the chair-body may be tilted vertically upon the
supplementary elevating and lowering mechanism to vary its inclination by being
rocked about the trunnions of the carrier portion of this mechanism. The chair-
body tilting and securing mechanism is substantially such as shown in the before-
mentioned Patents, the lever of the tilting mechanism being, however, mounted
upon the supplementary elevating and lowering mechanism instead of being located
as in said Patents. This tilting mechanism comprises the lever G fulcrumed at g
upon the chair-body carrier E of the supplementary elevating and lowering
mechanism, and acted upon by the spring H, the tendency of which is to hold the
lever engaged with a detent rack h on the chair-body and thus lock the body in the
position to which it may be adjusted.
To facilitate the actuation of the supplementary elevating and lowering
mechanism the weight of the chair-body is approximately counterbalanced so that
the operator in raising and lowering the chair-body will have to exert but slight
force. The counterbalancing of the weight to be raised or lowered is effected by
means of coiled springs K K, one spring for each pair of the parallel arms. The
spring for either pair of arms is connected at its upper end adjacent to the inner
end of the upper arm of the pair and at its lower end connects with the lower arm
near its outer end. In this way the force of the springs is being always exerted
in a direction to aid in raising the supplementary elevating and lowering mechanism.
A bracket support L for a spittoon, tool tray, etc., is secured to an arm M of the
bracket D of the main elevating and lowering support.
From the above description it will be seen that a very wide range of vertical
adjustment of the chair body is provided for; and that the spring-counterbalanced
supplementary elevating and lowering mechanism may be quickly and easily
adjusted by the dentist before a patient enters the chair so that the chair-body

page_text: may be brought to approximately the height desired, thus requiring, after th
patient is seated, only such further vertical adjustment by way of the main
elevating and lowering support as may be found necessary to properly locate the
patient.
་ ་
As the raising of the chair-body after the patient's weight is added thereto is a
work frequently requiring considerable exertion on the part of the operator, it will
be seen that it is desirable to lessen as much as possible the work to be done in
lifting the chair body after the patient is seated.
My improvements may be modified in some respects without departing from
essential features of my invention; as for instance, as shown by Fig. 6, Sheet 4, in
which in place of the parallel-armed supplementary raising and lowering mechanism
there is shown mechanism as follows: Within the main elevating and lowering
support, which is made tubular, is a telescoping plunger N of the supplementary
elevating and lowering mechanism, having at top the carrier to which the chair-
body is jointed at n so as to be capable of tilting. A clamp screw P serves to lock
the plunger of the supplementary elevating and lowering mechanism to the main
elevating and lowering support in the desired position of adjustment. The plunger
N is tubular, and within it is a long coiled spring p bearing at its opposite ends
against the closed top of the plunger and the closed bottom of the main elevating
and lowering support, and acting with a tendency to lift the plunger and counter-
balance the weight of the chair-body which is only partly shown. The chair-body
carrier of the supplementary raising and lowering mechanism is adapted to
be engaged in suitable way, as by a pin o, with a detent segment R carried by
the chair-body and provided with a series of holes to receive the pin. In this way
when the chair is tilted about its jointed connection with its carrier it may be held
in its adjusted position.
The modification shown by Fig. 7 corresponds with that shown by Fig. 6 except
that the plunger N is provided with teeth s engaged by a pinion S to which motion
is imparted by a crank T, whilst in lieu of the clamp screw P a pawl U for
engaging the rack teeth serves as a detent to hold the supplementary raising and
lowering mechanism up to its adjusted position.
In the modifications shown by Figs. 8, 9 and 10, Sheets 5 and 6 of the drawings,
there is provided supporting mechanism for a vertically adjustable support (herein-
after termed the main elevating and lowering support) for the chair body A, said
support consisting of the plunger A¹ having vertically adjustable connection with
the base or pedestal A' of the supporting mechanism and actuated by means of the
jointed elevating lever A* and co-operating devices, the lever being jointed to the
cylinder B of the supporting mechanism, which cylinder is adapted to turn hori-
zontally in the pedestal and be locked therein by the locking lever B. The
vertically adjustable support A' has no horizontal or turning movement in the
non-elevating supporting cylinder B to which the elevating lever is attached, and
the manner of upholding and of lowering the support is as before.
Supplementary elevating and lowering mechanism interposed between the chair
body, which it carries, and the main elevating and lowering support A¹, is provided
as follows: Two pairs or sets of parallel arms C C and CC, a pair at each side
of the main elevating and lowering support, have jointed connection with the upper
end of this support by way of a bracket-like attachment D thereof removably and
adjustably secured to the support. The pair of arms C C are pivotally connected,
one above the other, with the bracket D at one side of the main elevating and
lowering support at dd, and the pair of arms C¹ C have similar pivotal connection
with the bracket at the opposite side of the support, the lower arm of each pair o.
parallel arms being pivoted to a downwardly projecting portion or hanger d¹ of the
bracket D. At their forward or outer ends the parallel arms are jointed to a chair
body carrier E, the pair of arms C C being pivoted to this carrier at e e, and the
pair of arms C1 C' similarly pivoted thereto.
The chair-body carrier É constitutes a part of the supplementary elevating and
lowering mechanism, and the chair body has suitable supporting connection with

page_text: it, whilst provision is made for tilting the chair body upon the carrier and for
locking it in any position to which it may be adjusted by vertically tilting it: as
above explained.
To provide, in accordance with my improvements, for actuating the supplementary.
elevating and lowering, mechanism by the main elevating and lowering support by
which said mechanism is carried, suitable controlling connection is made between
the supplementary elevating and lowering mechanism and a part of the supporting
mechanism to which no vertical movement is imparted, so that when upward or
downward movement is imparted to the main elevating and lowering support the
parallel arms partake of such movement and also are caused to rock by means of
their controlling connection and thus quickly raise or lower the chair body to which
a wide range of vertical movement may be imparted.
As shown a rearward extension I of the supplementary raising and lowering
mechanism is provided by extending the lower arms of the two pairs of parallel
arms rearwardly from their pivotal supporting connections with the main elevating
and lowering support. The rear ends of these arms incline rearwardly or converge
toward each other, and have jointed connection with a bracket or arm J rigid with
the cylinder B of the supporting mechanism of the main elevating and lowering
support. The parallel arms controlling connection thus made between the bracket J
and rearward extension of the supplementary elevating and lowering mechanism, as
shown, consists of a link K jointed by being pivoted at its opposite ends to the
said bracket and the rearward extension of the supplementary elevating and
lowering mechanism. In lieu of this link of the controlling connection an
equivalent may be employed; and instead of forming the rearward extension of
the supplementary raising and lowering mechanism by prolongations of the lower
arms of the two pairs of parallel arms, such rearward extension may be formed by
backward prolongations of the upper arms of the two pairs of parallel arms; or but
a single arm or an attachment to one or more of the arms might be prolonged
rearwardly to constitute the rearward extension of the supplementary elevating and
lowering mechanism which has connection with a non-elevating portion (in this
instance the cylinder B) of the supporting mechanism of the main elevating and
lowering support.
From the above description of Figs. 8, 9 and 10 it will be seen that.vertical
movement, of the main elevating and lowering support, to either raise or lower
it, imparts similar movement to the supplementary raising and lowering mechanism,
but to an increased extent, and that consequently the chair body may be quickly
raised or lowered and has a wide range of vertical adjustment. The extent to
which the movement imparted to the chair body may be increased over that
imparted to the main elevating and lowering support depends, as will readily be
understood, upon the relative lengths of the rearward extension of the supple-
mentary raising and lowering mechanism and the parallel arms. or those portions
thereof in advance of their jointed connection with the main elevating and
lowering support.
!
As shown by Fig. 11 a counterbalancing spring, L connects the upper and
lower parallel arms CC, the spring being connected with the upper arm near
its inner end and with the lower arm near its outer end. A spring may similarly
connect the arms C'C'. It will be seen that the counterbalancing spring (or
springs) tends to rock the parallel arms upward to elevate their outer ends; and so,
according to the strength of the spring (or springs), counterbalances more or less
of the weight carried by these arms, thus reducing the work to be done by means
of the elevating lever..
Fig. 12 shows a modification of the controlling connection between the parallel
arms and the supporting mechanism for causing the arms to rock about their pivotal
connection with the main raising and lowering, support. In this modification the
rearward extension I of the parallel arms carries a roller and bears upward against
the inclined or curved, under surface of a projection M. of the cylinder B of the
supporting mechanism. In Fig. 13 a slotted projection. N on the cylinder of the

page_text: supporting mechanism is engaged by a roller carried by the extension of the parallel!
arms as will be understood although the arms and their extension are omitted in,
this view.
Having now particularly described and ascertained the nature of my said inven--
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The combination of the pedestal or base, the main elevating and lowering
support carried thereby, the supplementary elevating and lowering mechanism.
carried by said main support and vertically adjustable independently thereof,.
and the chair body carried by and jointed to tilt upon said supplementary
mechanism, substantially as set forth.
2. The combination of the pedestal or base, the horizontally turning main
elevating and lowering support carried thereby, the supplementary elevating and.
lowering mechanism carried by said main support, partaking of its up and down.
and horizontal turning movements and vertically adjustable independently thereof,.
the chair body carried by and having jointed supporting connection with said.
supplementary mechanism, and means by which to tilt the chair-body upon the
supplementary elevating and lowering mechanism and secure it in its tilted position,.
substantially as set forth.
3. The combination of the pedestal or base, the main elevating and lowering.
support carried thereby, the spring-counterbalanced supplementary elevating and
lowering mechanism carried by said main support and vertically adjustable
independently thereof, means for maintaining said supplementary mechanism in its.
position of adjustment, and the chair body carried by and jointed to tilt upon said
supplementary mechanism, substantially as set forth."
4. The combination of the main elevating and lowering support, means for
vertically adjusting it, the parallel arms having jointed connection at their inner
ends with the said support, the chair-body carrier to which said arms are jointed at.
their outer ends, means carried by the parallel arms and chair body carrier for
maintaining the parallel arms in their position of adjustment, and the chair-body
having supporting connection with said carrier, substantially as set forth.
5. The combination of the main elevating and lowering support, means for
vertically adjusting it, the parallel arms having jointed connection at their inner
ends with said support, the chair-body carrier to which said arms are jointed at
their outer ends, means for maintaining the parallel arms in their position of adjust-
ment, the chair-body having supporting connection with said carrier, and the
counterbalancing springs connected at their opposite ends with the upper and lower
parallel arms, substantially as set forth.
6. The combination of the main elevating and lowering support, means for
vertically adjusting it, the parallel arms having jointed connection at their inuer
ends with said support, the chair-body carrier to which said arms are jointed at.
their outer ends, means carried by the parallel arms and chair body carrier for
maintaining the parallel arms in their position of adjustment, the chair body having
jointed supporting connection with said carrier and tilting thereon, and means for
maintaining the chair-body in the position to which it may be tilted, substantially
as set forth.
7. The combination of the pedestal or base, the main elevating and lowering-
support, the bracket rigid with the upper end of the support, the parallel arms
having jointed connection at their inner ends with the support by way of said
bracket, the chair-body carrier to which said arms are jointed at their outer ends,.
means for maintaining the parallel arms in their position of adjustment, the chair-
body having jointed supporting connection with said carrier, and means for tilting
the chair body upon its carrier and for securing it in its tilted position, substantially
as set forth.
8. The combination, in a dental chair, of the main elevating and lowering
support, its supporting mechanism, the supplementary elevating and lowering

page_text: mechanism comprising the chair body carrier and the parallel arms pivoted thereto
and carried by the main elevating and lowering support with which they have
jointed supporting connection, and the controlling connection between said arms
and the supporting mechanism, whereby the arms partake of the vertical movements
of the main support as well as rock about their jointed connection therewith,.
substantially as set forth.
9. The combination of the main elevating and lowering support, its supporting
mechanism, the supplementary elevating and lowering mechanism, carried by the
main elevating and lowering support and consisting of the chair body carrier and
the parallel arms pivoted thereto and having jointed supporting connection with
the main elevating and lowering support and controlling connection with the
supporting mechanism, and means for elevating and lowering said support and
simultaneously actuating the supplementary elevating and lowering mechanism,
substantially as set forth.
10. The combination of the main elevating and lowering support, its supporting
mechanism, the supplementary elevating and lowering mechanism comprising the
parallel arms having jointed connection with the main elevating and lowering
support and provided with the rearward extension having connection with said
supporting mechanism, and the chair body carried by the supplementary elevating
and lowering mechanism, substantially as set forth.
11. The combination of the main elevating and lowering support, its supporting
mechanism, the bracket at the upper end of said support provided with the hangers,
the supplementary elevating and lowering mechanism comprising the parallel arms
having jointed connection with said bracket and provided with the rearward
extension, the connection between said extension and said supporting mechanism,
and the chair body carried by the supplementary elevating and lowering mechanism,
substantially as set forth.
Dated this 1st day of May 1894.