IMPROVEMENTS IN ELEVATING CHAIRS
Year: 1878

page_text: LETTERS PATENT to Sydney Pitt, of Sutton, in the County of Surrey, for the
Invention of "IMPROVEMENTS IN ELEVATING CHAIRS." A communication
from abroad by Dr. Samuel Stockton White, of Philadelphia, United States of
America.
Sealed the 8th March 1878, and dated the 8th January 1878.
PROVISIONAL SPECIFICATION left by the said Sydney Pitt at the Office of
the Commissioners of Patents on the 8th January 1878.
SYDNEY PITT, of Sutton, in the County of Surrey. "IMPROVEMENTS IN ELEVATING
CHAIRS." [A communication from abroad by Dr. Samuel Stockton White, of Phila-
delphia, United States of America.]
The object of the Invention is to secure a wide range of vertical movement to
the chair frame while permitting it to be raised and lowered readily without shocks
or jars, and also at the same time allowing the chair frame to turn or swivel freely.
To attain these ends an accurately bored cylinder is supported by and swivels in
the chair base. A hollow or tubular piston, firmly secured at its upper end to the
chair frame or seat, works freely up and down in the cylinder. It is provided with
a closed bottom, and carries upon its lower end a suitable packing ring to ensure a
tight joint.
The bottom of the hollow piston is also provided with two valves, a larger and
smaller one, both opening outwards. The larger one is for the purpose of allowing
fluid to pass freely from the interior of the hollow piston to the cylinder when the
seat and piston are raised; the smaller one when held open is for the purpose of
allowing liquid to pass from the cylinder into the piston, so that the piston and seat
may descend. The end of this valve extends entirely through the bottom of the
piston, and projects a short distance above it, in order to be operated upon, and the
valve opened by a rod suspended over but just out of contact with it, which rod is
properly guided at its lower end by passing through a perforated disc secured in

page_text: :
the piston near its bottom, its upper end which extends to near the top of the
piston being pivotted to the inner end of a rocking lever projecting through a slot
in the side of the piston. The outer end of this lever extends to a point within
convenient reach of the operator's hand, and is provided with an aperture through
which a screw passes to limit the downward movement of the lever. A spiral spring
encircling this screw bears against the lever, and forces it down upon the head of
the screw, thereby keeping the rod suspended from the opposite end of the lever,
raised and out of contact with the small valve. A thumbscrew limits the upward
movement of the lever by coming in contact with a portion of the chair frame.
The tubular piston is provided with an enlargement above the top of the cylinder,
constituting a reservoir for the fluid to compensate the difference in area between
the piston and cylinder.
For stools and ordinary chairs, the raising and lowering may be done by hand,
but for heavy chairs, such as those used by barbers, dentists, and others, it is
preferred to employ a lifting device acting upon the side of the hollow piston.
This may consist of a rack formed in a recess in the side of the hollow piston,
directly opposite a vertical slot in the upper part of the wall of the cylinder, through
which slot works a pinion or spur wheel journalled in suitable lugs formed on the
cylinder, the teeth of which pinion mesh with those of the rack, and prevent axial
movement of the piston in the cylinder. The pinion is turned by means of a
bifurcated foot lever swinging on the shaft of the pinion, between the forks of which
lever is pivotted a gravity pawl, engaging the teeth of the pinion when the lever is
depressed. The lever carries a cross head, through which passes a rod pivõtted
between lugs formed on the cylinder, and encircling this rod is a compressed spiral
spring, which bears against the cross head, and the thrust of which tends to throw
the lever away from the cylinder, until its outward movement is checked by the
nut on the end of the rod.
A bevilled lug or projection is formed upon the cylinder immediately above the
slot through which the pinion works, and lies directly in the path of the pawl,
keeping it out of engagement with the teeth of the wheel when the lever is released
from the pressure of the foot of the operator, and thrown to its farthest outward
movement by the spring.
The operation of the above apparatus is as follows:-Supposing the chair to be
at its lowest position, the piston and its reservoir and the small space in the cylinder
below the piston would be filled with any suitable fluid, preferably oil, and the large
valve having no pressure below it to overcome its gravity would fall and open.
When it is desired to elevate the chair, the operator presses his foot upon the
foot lever, swinging its lower end in towards the cylinder, and drawing the pawl
from its resting place on the inclined lug into engagement with the teeth of the
spur wheel, causing it to rotate and, through its engagement with the teeth of the
rack, to elevate the piston and chair frame or seat carried thereby. This causes
the fluid in the piston to pass through the valve openings and fill the increased
space in the cylinder, holding the valves open so long as the upward movement of
the piston is continued.
When the pressure of the foot is taken from the foot lever, the piston will begin
to lower or settle back, causing the fluid to flow back into the piston; but this
movement is very slight as the current acting on the valve carries it up against its.
seat on the packing ring, where it is firmly held by the pressure of the fluid.
As the limited movement of the foot lever will only partially rotate the pinion,
the operation of pressing in this lever with the foot must be repeated until the
chair is raised to the desired height.
When the foot lever is released by the foot it is pressed outward by the spring,
and the pawl thrown forward far enough to slide up on the inclined lug before
mentioned, and is so put out of engagement with the teeth of the pinion. This
leaves the piston cushioned on or held in suspension entirely by the fluid beneath it.
When it is desired to lower the chair, the operator simply presses open the
smaller valve by pressing upon its opening lever, as before explained. This allow

page_text: the fluid in the cylinder below the piston to flow back into the piston, but the
area of the valve opening is so small that the flow is limited, and the fall of the
piston so slow that when checked by the closing of the valve, no shock or jar would
be felt by a person in the chair.
In some cases the piston instead of being raised by a foot lever carrying a pawl,
as above described, it may be raised by fluid being forced beneath it into the
cylinder by a small plunger pump worked by a treadle. In this case the cylinder
is surrounded by a reservoir containing the supply of glycerine, oil, water, or other
equivalent liquid.
When the liquid in the reservoir is not subject to pressure, it may be covered by
a loose cap to prevent the entrance of dirt, but when subject to pressure the
reservoir of course must be tightly closed. The cap is provided with an annular
flange, and a cap on the upper end of the cylinder is provided with a similar flange,
and with a duct or channel leading from said flange to the outer surface of the
cylinder, so that any fluid which may escape between the piston and the upper part
of the cylinder may flow down the outside of the cylinder through the cap into the
reservoir.
A valve works in an opening leading from the reservoir to the pump cylinder,
in which a plunger provided with a suitable packing works. To adapt it to be
worked by the foot of the operator, the piston is pin-jointed to a foot lover pivotted
to the frame or base of the chair, or to a bracket projecting from the pump cylinder,
and provided with a spring, which tends to lift the piston when depressed by the
lever. By this mode of construction the operator can readily work the pump with
his foot by pressing down upon it, and is not required to work it both ways. The
fluid that enters the pump chamber passes outwards therefrom through a channel
provided with a suitable valve to the cylinder underneath the piston. Owing to
this mode of construction, if the chair seat were raised by hand or by any means
independent of the pump, the fluid in the reservoir would be drawn through the
valves above described into the cylinder, and would follow the sent supporting
piston in its ascent, and when this ascent ceases and the weight of the chair rests
upon the fluid in the piston, the valves automatically close by the back pressure,
and the chair will remain in its elevated position without strain on the elevating
mechanism.
To lower the chair it is only necessary to provide a suitable escape valve, which
will release the fluid in the chamber, and the weight upon the seat-suporting piston
will cause it gradually to descend to its lowest position, the rate of descent being
regulated by the area of the discharge opening, which may readily be varied by
well know means.
A valve opening inward against the pressure of the fluid may be used and be
connected with a suitable lever, so that the operator could with his hand or foot
open the valve against said pressure to permit of the escape of the fluid, such a
valve possessing the advantage of closing automatically the moment it is released by
the operator.
The reservoir may be a large cylinder closed at top, and with the lifting cylinder
and pump cylinder passing downwards into the reservoir through its closed top.
The lower end of the pump cylinder in this case is secured to the top of an inner
chamber, which rises up from the bottom of the reservoir, and into which fluid can
pass freely from the reservoir. The chamber contains valves, one for allowing fluid
to pass into the lower end of the pump cylinder, the other for allowing fluid to pass
from the pump cylinder to the lifting cylinder.
The outlet valve for allowing fluid to escape from the bottom of the lifting
cylinder, whenever the seat of the chair is to be allowed to descend, may open into
the reservoir. The opening of the valve may be effected by a rod carried up through
the cover of the reservoir.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Sydney Pitt in the Great Seal Patent Office on the 8th July 1878.
SYDNEY PITT, of Sutton, in the County of Surrey. "IMPROVEMENTS IN ELEVATING
CHAIRS." A communication from abroad by Dr. Samuel Stockton White, of Phila-
delphia, United States of America.
The object of the Invention is to secure a wide range of vertical movement to
the chair frame while permitting it to be raised and lowered readily without
shocks or jars, and also at the same time allowing the chair frame to turn or swivel
freely. To attain these ends an accurately bored cylinder is supported by and
swivels in the chair base. A hollow or tubular piston firmly secured at its upper
end to the chair frame or seat works freely up and down in the cylinder. It is
provided with a closed bottom, and carries upon its lower end a suitable packing
ring to insure a tight joint.
The bottom of the hollow piston is also provided with two valves, a larger and
smaller one, both opening outwards. The larger one is for the purpose of allowing
fluid to pass freely from the interior of the hollow piston to the cylinder when the
seat and piston are raised; the smaller one when held open is for the purpose of
allowing liquid to pass from the cylinder into the piston, so that the piston and
seat may descend. The spindle of the smaller valve is encircled by a spiral spring
to facilitate the closing of the valve and to keep it normally pressed against its
seat, in addition to the pressure of the fluid beneath. The end of this valve
extends entirely through the bottom of the piston, and projects a short distance
above it in order to be operated upon, and the valve opened by a rod suspended
over but just out of contact with it, which rod is properly guided at its lower end
by passing through a perforated disc secured in the piston near its bottom, its
upper end, which extends to near the top of the piston, being pivotted to the inner
end of a rocking lever projecting through a slot in the side of the piston. The
outer end of this lever extends to a point within convenient reach of the operator's
hand, and is provided with an aperture, through which a screw passes to limit the
downward movement of the lever. A spiral spring encircling this screw bears
against the lever and forces it down upon the head of the screw, thereby keeping
the rod suspended from the opposite end of the lever raised, and out of contact with
the small valve. A thumbscrew limits the upward movement of the lever by
coming in contact with a portion of the chair frame.
The tubular piston is provided with an enlargement above the top of the
cylinder, constituting a reservoir for the fluid to compensate the difference in area
between the piston and cylinder.
For stools or ordinary chairs the raising and lowering may be done by hand, but
for heavy chairs, such as those used by barbers, dentists, and others, it is preferred
to employ a lifting device acting upon the side of the hollow piston. This may
consist of a rack formed in a recess in the side of the hollow piston directly
opposite a vertical slot in the upper part of the wall of the cylinder, through which
slot works a pinion or spur wheel journalled in suitable lugs formed on the
cylinder, the teeth of which pinion mesh with those of the rack, and prevent axial
movement of the piston in the cylinder. The pinion is turned by means of a
bifurcated foot lever swinging on the shaft of the pinion, between the forks of
which lever is pivotted a gravity pawl engaging the teeth of the pinion when the
lever is depressed. The lever carries a cross head, through which passes a rod
pivotted between lugs formed on the cylinder, and encircling this rod is a compressed
spiral spring, which bears against the cross head, and the thrust of which tends to
throw the lever away from the cylinder until its outward movement is checked by
the nut on the end of the rod.
A bevilled lug or projection is formed upon the cylinder immediately above the
slot, through which the pinion works, and lies directly in the path of the pawl,

page_text: keeping it out of engagement with the teeth of the wheel when the lever is released
from the pressure of the foot of the operator, and thrown to its farthest outward
movement by the spring.
The operation of the above apparatus is as follows:-Supposing the chair to be
at its lowest position, the piston and its reservoir and the small space in the
cylinder below the piston would be filled with any suitable fluid, preferably oil,.
and the large valve having no pressure below it to overcome its gravity would fall
and open.
When it is desired to elevate the chair the operator presses his foot upon the foot
lever, swinging its lower end in towards the cylinder, and drawing the pawl from
its resting place on the inclined lug into engagement with the teeth of the spur
wheel, causing it to rotate, and through its engagement with the teeth of the rack
to elevate the piston and chair frame or seat carried thereby. This causes the fluid
in the piston to pass through the valve openings and fill the increased space in
the cylinder, holding the valves open so long as the upward movement of the
piston is continued.
When the pressure of the foot is taken from the foot lever the piston will begin
to lower or settle back, causing the fluid to flow back into the piston, but this
movement is very slight, as the current acting on the valve carries it up against
its seat on the packing ring, where it is firmly held by the pressure of the
fluid.
As the limited movement of the foot lever will only partially rotate the pinion,
the operation of pressing in this lever with the foot must be repeated until the
chair is raised to the desired height.
When the foot lever is released by the foot it is pressed outward by the spring,
and the pawl thrown forward far enough to slide up on the inclined lug before
mentioned, and is so put out of engagement with the teeth of the pinion. This
leaves the piston cushioned on or held in suspension entirely by the fluid
beneath it.
When it is desired to lower the chair, the operator simply presses open the
smaller valve by pressing upon its opening lever as before explained. This allows
the fluid in the cylinder below the piston to flow back into the piston, but the area
of the valve opening is so small that the flow is limited, and the fall of the piston
so slow that when checked by the closing of the valve no shock or jar would be
felt by a person in the chair.
In some cases the piston instead of being raised by a foot lever or treadle
carrying a pawl, as above described, may be raised by a treadle caused to force
fluid by a small plunger pump beneath it into the cylinder. In this case the
cylinder is surrounded by a reservoir containing the supply of glycerine, oil, water,
or other equivalent liquid.
When the liquid in the reservoir is not subject to pressure, it may be covered by
a loose cap to prevent the entrance of dirt, but when subject to pressure the
reservoir of course must be tightly closed. The cap is provided with an annular
flange, and a cap on the upper end of the cylinder is provided with a similar flange,
and with a duct or channel leading from said flange to the outer surface of the
cylinder, so that any fluid which may escape between the piston and the upper
part of the cylinder may flow down the outside of the cylinder through the cap
into the reservoir.
A valve works in an opening leading from the reservoir to the pump cylinder,
in which a plunger provided with a suitable packing works. To adapt it to be
worked by the foot of the operator the plunger is pin-jointed to a foot lever
pivoted to the frame or base of the chair, or to a bracket projecting from the pump
cylinder, and provided with a spring, which tends to lift the plunger when
depressed by the lever. By this mode of construction the operator can readily
work the pump with his foot by pressing down upon it, and is not required to
work it both ways. The fluid that enters the pump chamber passes outwards
therefrom through a channel provided with a suitable valve to the cylinder under-

page_text: neath the piston. Owing to this mode of construction, if the chair seat were
raised by hand or by any means independent of the pump the fluid in the reservoir
would be drawn through the valves above described into the cylinder, and would
follow the seat-supporting piston in its ascent, and when this ascent ceases, and the
weight of the chair rests upon the fluid in the cylinder, the valves automatically
close by the back pressure, and the chair will remain in its elevated position with-
*out strain on the elevating mechanism.
To lower the chair it is only necessary to provide a suitable escape valve, which
will release the fluid in the cylinder, and the weight upon the seat supporting
piston will cause it gradually to descend to its lowest position, the rate of descent
being regulated by the area of the discharge opening, which may readily be varied
by well-known means.
A valve opening inward against the pressure of the fluid may be used and be
connected with a suitable lever, so that the operator could with his hand or foot
open the valve against said pressure to permit of the escape of the fluid, such a
valve possessing the advantage of closing automatically the moment it is released
by the operator.
The reservoir may be a large cylinder closed at top, and with the lifting cylinder
and pump cylinder passing downwards into the reservoir through its closed top.
The lower end of the pump cylinder in this case is secured to the top of an inner
chamber, which rises up from the bottom of the reservoir, and into which fluid
can pass freely from the reservoir. The chamber contains valves, one for allowing
fluid to pass into the lower end of the pump cylinder, the other for allowing fluid
to pass from the pump cylinder to the lifting cylinder.
The outlet valve for allowing fluid to escape from the bottom of the lifting
cylinder whenever the seat of the chair is to be allowed to descend, may open into
the reservoir.
The opening of the valve may be effected by a rod carried up through the cover
of the reservoir.
Having thus described the nature of the Invention, I will proceed to describe
more fully the manner of performing the same.
The accompanying Drawings represent the improvements as embodied in the
best way now known to me, but some of the improvements obviously may be used
without the others, and the details of construction may obviously be modified in
various ways without departing from the spirit of the Invention.
Figure 1 represents a vertical central section of part of an elevating chair, in
which a cylinder is supported by and swivels in the chair base, and in which the
chair seat is supported on a hollow piston or plunger, which can work up and down
in the cylinder.
The piston is closed at bottom and forms a fluid reservoir, and there are two
valves, a larger and smaller one, at the bottom to control the passage of liquid into
and out of the reservoir.
The piston or plunger is also capable of being raised by a lifting device acting
upon it at its sides, and the lifting device is worked by a treadle, whereby the
operator is enabled to raise the chair seat by the use of his foot, leaving his hands
disengaged, and avoiding the necessity of his stooping to work the lifting device.
Figure 2 is a side elevation thereof; Figure 3, a horizontal section on the line 2, 2,
of Figure 1; Figure 4, a vertical central section on an enlarged scale through the
lower end of the piston, showing the details of construction of the valves and
packing ring; Figure 5, a horizontal section on the line 3, 3, of Figure 4, with 6
some of the parts broken away to show more clearly the portions lying beneath
them; and Figure 6 is a bottom plan view of the under side of the piston in section
on the line 4, 4, of Figure 4.
An accurately bored cylinder A is shown as supported by and swivelling in the
chair base A¹. A hollow or tubular piston B firmly secured at its upper end to 5
the chair frame or seat, works freely up and down in the cylinder A, which is
provided with a closed bottom, and carries upon its lower end a suitable packing

page_text: ring to insure a tight joint. This packing ring in the present instance lies in an
annular recess formed around the bottom edge of the piston, and is held firmly
in place by a perforated plate b¹ secured upon the end of the piston by suitable
ineans.
The bottom of the hollow piston is also provided with a circular recess C³, and
with a conical valve opening leading to the interior of the piston, A valve C
closes this opening, and consists in the present instance of a conical portion, the
base of which is a flat disc, and a spindle C¹ projecting from the back of the disc
through a guide opening in the plate 6', between which plate and a suitable packing
ring clet into a groove in the face of the recessed portion 0%, the flat disc portion
of the valve works, being held to its seat upon the packing when at rest, and when
the piston is moving downward by the pressure of the fluid in the cylinder
beneath.
A second valve c, somewhat similar in construction, but of smaller area than the
valve C, and opening outward as does that valve, is also provided in the bottom of
the piston, its spindle working through a guide opening in the plate b¹, and being
encircled by a spiral spring to facilitate the closing of the valve, and to keep it
normally pressed against its seat in addition to the pressure of the fluid beneath.
The end of this valve extends entirely through the bottom of the piston, and
projects a short distance above it, in order to be operated upon, and the valve
opened by a rod f suspended over but just out of contact with it, which rod is
properly guided at its lower end by passing through a perforated disc B secured in the
cylinder near its bottom, its upper end, which extends to near the top of the piston,
being pivoted to the inner end of a rocking lever F projecting through a slot in
the side of the piston. The outer end of this lever extends to a point within con-
venient reach of the operator's hand, and is provided with an aperture through
which a screw F¹ passes, to limit the downward movement of the lever. A spiral
spring f¹ encircling this screw bears against the lever, and forces it down upon the
head of the screw, thereby keeping the rod f suspended from the opposite end of
the lever raised, and out of contact with the valve c. A thumb screw F2 limits
the upward movement of the lever by coming in contact with a portion of the
chair frame.
Other arrangements than that above described may be adopted for opening the
smaller valve. The arrangement described is, however, well suited for the
purpose.
The tubular piston, if desired, may be provided with an enlargement B¹, con-
stituting a reservoir for the fluid to compensate the difference in area between the
piston and cylinder.
For stools or ordinary chairs the raising and lowering may be done by hand,
but for heavy chairs, such as those used by barbers, dentists, and others, I prefer to
employ a lifting device. This may consist of a rack d formed in a recess in the
hollow piston directly opposite a vertical slot in the wall of cylinder A, through
which slot works a pinion or spur wheel D journalled in suitable lugs formed on
the cylinder, the teeth of which pinion mesh with those of the rack and prevent
axial movement of the piston in the cylinder. The pinion is turned by means of a
bifurcated foot lever E swinging on the shaft e of the pinion, between the forks of
which is pivoted a gravity pawl e¹ engaging the teeth of the pinion when the
lever is depressed. The lever carries a cross head e², through which passes a rod
G pivoted at g between lugs g₁ formed on the cylinder, and encircling this rod is a
compressed spiral spring g², which bears against the cross head e, and the thrust of
which tends to throw the lever away from the cylinder, until its outward movement
is checked by the nut on the end of the rod.
A bevilled lug or projection H is formed upon the cylinder immediately above
the slot, through which the pinion D works, and lies directly in the path of the
pawl e', keeping it out of engagement with the teeth of the wheel when the lever E
is released from the pressure of the foot of the operator, and thrown to its farthest
outward movement by the spring g³.

page_text: The operation of this device is as follows:-Supposing the chair to be at its
lowest position, the piston and its reservoir and the small space in the cylinder
below the piston would be filled with any suitable fluid, preferably oil, and the
large valve C having no pressure below it to overcome its gravity, would fall
against the plate b¹ and open. When it is desired to clevate the chair the operator
presses his foot upon the lever E, swinging its lower end in towards the cylinder,
and drawing the pawl from its resting place on the inclined lug into engagement
with the teeth of the wheel D, causing it to rotate, and through its engagement
with the teeth of the rack to elevate the piston and chair frame or seat carried
thereby. This causes the fluid in the piston to pass through the valve openings
and fill the increased space in the cylinder, holding the valves open so long as the
upward movement of the piston is continued. When the pressure of the foot is
taken from the lever E the piston will begin to lower or settle back, causing the
fluid to flow back into the piston, but this movement is very slight, as the current
acting on the valve C carries it up against its seat on the packing ring, where it is
firmly held by the pressure of the fluid.
As the limited movement of the lever will only partially rotate the pinion D, the
operation of pressing in this lever with the foot must be repeated until the chair
is raised to the desired height. When the lever is released by the foot it is pressed
outward by the spring, and the pawl e' thrown forward far enough to slide upon
the inclined lug H, and out of engagement with the teeth of the pinion D.
This leaves the piston cushioned on or held in suspension entirely by the fluid
beneath it.
When it is desired to lower the chair the operator simply presses up the outer
end of the lever F, which lowers the inner end and brings the end of the rod f in
contact with the valve c, which is so small as to be easily opened against the
pressure of the fluid below it. This allows the fluid in the cylinder below the
piston to flow back into the piston, but the area of tho valve opening is so small
that the flow is limited, and the fall of the piston so slow that when checked
by the closing of the valve, no shock or jar would be felt by a person in the
chair.
Other arrangements for effecting the lifting of the chair seat by the action of the
treadle may be adopted.
Figures 7 to 20 show another chair, in which the lifting is effected by a treadle
actuating the plunger of a small plunger pump, and in which other of the improve-
ments are also embodied.
Figure 7 represents a plan or top view of the chair, portions of the upholstering
of the seat being removed to show the parts beneath; Figure 8, a view in elevation
of one side of the chair; Figure 9, a rear elevation thereof; Figure 10, a rear
elevation of the foot support; Figure 11, a rear elevation of the elevating appa-
ratus, partly in section on the line 1, 1, of Figure 13; Figure 12, a vertical section
through the same on the line 2, of Figure 13; Figure 13, a plan or top view of
the elevating mechanism, with a portion of the foot lever and of the cap of the
reservoir broken away; Figure 14 is a horizontal transverse section therethrough
on the line 3, 3, of Figures 11, 12, 15, and 17, looking upwards, showing the fluid
passages and valve connections; Figure 15 represents a vertical section on the
line 4, 4, of Figure 13; and Figure 16, a similar section on the line 5, 5, of said
Figure; Figure 17 represents a sectional elevation on the line 6, 6, of Figure 19;
Figure 18, a vertical section on the line 7, 7, of said Figure; and Figure 19, a
horizontal transverse section on the line 8, 8, of Figures 17 and 18.
The three Figures last named represent a modified form of lifting apparatus.
The above Drawings show the improvements as adapted to the well-known
"Harris chair," but it is obviously applicable to other well-known forms of chair
bases or chair bodies.
In Figures 7 to 16 inclusive a cylinder A is shown as secured to or forming a
part of the base of a chair, with a piston or plunger B (capable of turning and
moving freely endwise in said cylinder) secured upon or forming a part of a seat

page_text: frame: B', the piston being provided with suitable packing b. The cylinder is
surrounded by a reservoir C containing glycerine, oil, water, or other well-known
equivalent liquid, which cylinder has a cover or cap C' to prevent the entrance of
dirt. The cap C₁ is provided with an annular flange c, and a cup C on the upper
end of the cylinder is provided with a similar flange c¹, and with a duct or
channel c² leading from said flange to the outer surface of the cylinder, so that any
fluid which may escape between the piston and the upper part of the cylinder may
flow down the outside of the cylinder through the cap C₁ into the reservoir. A
valve d of any suitable well-known construction (in this instance an ordinary
puppet valve) works in an opening leading from the reservoir C to a cylinder D, in
In this instance to
which a plunger E provided with a suitable packing e works.
adapt it to be worked by the foot of the operator the piston is pin jointed at f to a
foot lever F pivoted to the frame or base of the chair, or to a bracket f¹ projecting
from the pump cylinder and provided with a spring F¹, which tends to lift the
piston when depressed by the lever. By this mode of construction the operator
can readily work the pump with his foot by pressing down upon it, and is not
required to work it both ways. The fluid that enters the pump chamber passes
outwards therefrom through a channel G, provided with a suitable valve g to the
cylinder A underneath the piston B, and carries the chair seat.
To lower the chair seat a suitable escape valve is provided to release the fluid
in the chamber A, and allow the weight upon the seat-supporting piston B to cause
it gradually to descend to its lowest position, the rate of descent being regulated by
the area of the discharge opening, which may readily be varied by well-known
.means. In this instance the discharge opening his shown as leading from the
cylinder to the reservoir C, the opening being closed by a cone-valve H operated by
a screw, the shank of which extends within easy reach of the operator.
A valve opening inward against the pressure of the fluid might be used and be
connected with a suitable lever, so that the operator could, with his hand or foot,
open the valve against said pressure to permit of the escape of the fluid, such a
valve possessing the advantage of closing automatically the moment it is released
.by the operator.
Figures 17, 18, and 19 show a modified form of the Invention, in which C repre-
sents a large cylindrical reservoir; A, a cylinder enclosed therein; and B, a seat
supporting piston or plunger. The fluid passes from the reservoir into the pump
chamber D provided with a plunger E through a spring valve d, and is expelled
through a channel G and spring valve g into the cylinder A, the cylinder being
provided with a discharge valve H opening inwardly, operated by a link and bell-
crank lever, and automatically closed by the pressure of the fluid, as herein-before
alluded to.
The operation of the Invention will readily be understood from the foregoing
description.
As before explained, the chair seat may be lifted by hand, but for heavy chairs,
such as used by dentists, mechanical means are by preference employed.
When the operator works the pump with his foot the liquid is forced from the
reservoir through the pump into the cylinder, and elevates the chair as above
described.
It will be noted that as the seat-supporting piston B is capable of turning freely
as well as moving endwise relatively to the cylinder A, the chair can readily be
revolved, and it may be of course provided with all the other usual well-known
O adjustments.
For economy's sake I have shown the fluid as passing from the cylinder A back
into the reservoir; but it is obvious that where liquid such as water is employed
that it may be connected with a water main, so as to allow the liquid escaping from
the cylinder to flow into the drain instead of passing back into the reservoir.
In the foregoing description I have described the cylinder and plunger as
cylindrical in shape for convenience of turning; it is obvious that a cylinder and
plunger of polygonal shape could be employed when it is desired not to turn the

page_text: apparatus, or that the cylinder and plunger could be prevented from turning
relatively to each other by the usual spline and feather or their well-known
equivalents, and that the chair could be made to rotate upon the seat support, or
the piston and cylinder might be made to rotate together in the chair base,
as herein-before described. The foot lever may also be connected with the seat
support.
Having thus described the nature of the Invention, and the manner of performing
the same, I would have it understood that what is claimed is,―
First. The combination, substantially as herein-before set forth, of a cylinder
mounted and swivelling upon the base of a chair, a piston secured to the frame or
seat of the chair, a fluid reservoir, and communicating valves between the reservoir
and piston, whereby as the chair is raised or lowered the fluid is transferred from
the reservoir to the cylinder, and vice versa.
Second. The combination, substantially as herein-before described, of a cylinder
mounted upon the base of a chair, a piston secured to the seat of the chair and
working up and down in the cylinder, and mechanism for raising the piston in the
cylinder by the action of a treadle.
Third. The combination, substantially as herein-before described, of a cylinder
mounted upon the base of a chair, a piston secured to the seat of the chair and
working up and down in the cylinder, and a lifting device acting upon the side of
the piston.
Fourth. Mounting the hydraulic cylinder used for upholding the chair seat in
such a way that it can swivel freely in the chair base.
Fifth. The combination, substantially as herein-before set forth, of the cylinder
mounted upon the base of the chair, the tubular piston closed at bottom and secured
to the seat or frame of the chair, and constituting a fluid reservoir, the automatically
operated outlet valve in the piston, and the inlet or lowering valve operated by
suitable tripping mechanism, whereby the fluid is transferred from the piston to the
reservoir as the chair is raised, and returns thereto as the inlet valve is opened by
the tripping mechanism, and the chair lowered.
Sixth. The combination, substantially as herein-before set forth, of the cylinder
mounted upon the base of the chair, the tubular piston secured to the seat of the
chair, its lifting rack, the gear wheel mounted on the cylinder, and the ratchet lever
operating upon the gear wheel.
Seventh. The combination in an elevating chair, substantially as herein-before
set forth, of a fluid reservoir, a cylinder arranged within the reservoir, and a seat-
supporting piston movable endwise therein.
Eighth. The combination, substantially as berein-before set forth, of a cylinder
mounted upon a base or support, a seat-supporting piston, a fluid reservoir, exterior
of the cylinder, and communicating valves between the reservoir and cylinder,
whereby as the chair is raised or lowered the fluid is transferred from the reservoir
to the cylinder, and vice versa.
In witness whereof, I, the said Sydney Pitt, have hereunto set my hand and
seal, this Fifth day of July, in the year of our Lord One thousand eight
hundred and seventy-eight.