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Патент USA US2110874

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FOSTURE CHAIR
Filed 001;. 29, 1955
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PQSTURE CHAIR
Filed om. 29, 1955 ,
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Patented Mar. 15, 1938
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2,110,874
POSTURE CHAIR
Walter F. Herold, Bridgeport, Conn., assigner to
The Bassick Company, Bridgeport, Conn., a
corporation of Connecticut
Application October 29, 1935, Serial No. 47,253
9 Claims.
The present invention relates to an improve
ment in posture chairs, particularly of the type
in which the chair back is tiltably supported and
is adapted to be adjusted as to angularity, height
5 and tension, for the purpose of adapting the back
to the particular person using the chair.
An object of the invention is to provide a tilt
ingA structure upon which the `chair back is sup
ported and which is adapted to be tilted against
W spring pressure, the arrangement of the tilting
axis with respect to the spring and spring con~
nection. with the tilting structure being such
that substantial support is provided for the back
in the upright position, while, as the chair back
V is tilted rearwardly, ihe effort required to tilt
the same through a given number of degrees is
gradually diminished even though the spring
pressure is gradually built up, this eiiort being
represented during the initial tilting by rear
20 ward. pressure exerted by the occupant of the
chair
as the chair back
increasingly tilt
ed, by the rearwardly moving unbalanced Weight
of the person seated in the chair, so that through
out all but the initial range or" tilt there is an
¿"5 approximate balancing of the weight of the cc~
cupant oi"v the chair. In tilting back structures
heretofore in use there was no compensation for
this building 'up oi spring pressure, with the
result that, as the chair back was tilted towards
Si) its tilting limit, increasingly vgreater eiiort was
required to maintain it in tilted position as the
angle of tilt approached the limit position, while
the initial tilting from the upright position re
u quired relatively less e?lîort, and with the result
3^’ that either very little support was provided for
the back in the uprig--t position if relatively
easy tilting was permitted, or if adequate sup
port was provided .in the upright position rela
tively great effort was required to maintain the
‘5i-W back in tilted position.
A further object is to provide a ‘structure in
which a relatively short spring may be advan“
tageously used, and which lends itself to com
|_ pactness, light 'weight and cheapness.y
'
Another object is to provide improved adjust
ment means for adjusting the angle of the chair
back with respect to the tilting member, where
by the person seated in the chair may conven
P, iently adjust the handle with very little eiîort,
"" and also to provide the handle for operating the
angular adjustment means at a convenient loca
tion near the edge of the chair seat and at a
point forwardly of the chair structure so that
its operation will not necessitate a rearward shift
ing of the person’s weight against the chair
(Cl. 155-157)
back. Consequently the adjustment may be
made while the back
not under tension.
To
this end it is particularly proposed to provide
a universal joint connection between the handle
and the adjustment means, whereby the ad
justment axis is arranged longitudinally ofthe
tilting element while the axis ci the handle may
extend at any desired angle thereto, and par
ticularly forwardly and at one side of the swivel
post.
-
10
A further object is to provide height adjust~
ment means which enables the chair back to be
conveniently raised or lowered, and which may
be secured in adjusted relation without any pos
sibility of the same becoming accidentally displaced and at the same time without exerting
undue strain upon the parts, and further which
permits the adjustment and securing while the
user of the chair is seated therein in an upright
and natural position. It is also proposed to pro
vide such adjustment means whereby a very
secure connection may be produced between the
adjustable parts with very little effort on the
part of the person making the adjustment. An~
other object is to provide a back member which
may be readily removed for shipping purposes,
Without disassembly of any parts.
With the above and other objects in view em
bodiments of the invention are shown in the ac
companying drawings, and these embodiments n
will be hereinafter more fully described with
reference thereto, and the invention will be iinally
pointed out in the claims.
In the drawings:
Fig. l is a side elevation of a chair back tilting
mechanism, according tothe invention, the chair
base and the upper portion of the chair back be
ing broken away.
Fig. 2 is a longitudinal vertical sectional View.
Fig. 3 is a plan view, the seat being removed,
and portions of the spider arms being broken
away.
Fig. 4 is a side elevation of a chair back tilting
mechanism, according to a modified form` of the
invention, a portion of one of the spider arms
being broken away.
Fig. 5 is a plan View, partially broken away.
Fig. 5 is a force diagram, according to the in
vention.
Fig. 7 is another force diagram, according to
the invention.
Fig. 8 is a force diagram, according to pre
viously known practice.
Fig. 9 is a perspective view of the tilting mem
35
2
2,110,874
ber employed in the embodiment illustrated in
lgs. l to 3.
Fig. l0 is a perspective View of the universal
joint means employed.
Cn
Similar reference characters indicate corre
spending parts throughout the several ñgures of
the drawings.
Referring to the drawings, and particularly to
Figs. l to 3, thereof, the chair seat I0 has se
cured to its under side a pair of angle-iron spider
arms lI-I I, between which there is disposed a
bearing member I2, the side portions I3--I3 of
which are secured to the respective sides of the
spider arms by means of rivets I4. The bearing
member I2 is provided with a cylindrical socket
I5 in which is engaged the usual post I6 mounted
upon the chair base, and upon which the chair
seat is thus mounted for swivelling movement.
A tilting bracket member l1 is mounted upon
the spider arms rearwardly of the bearing mem
ber I2 by means of a bolt I8 extending through
holes I9-I9 provided in the sides of the spider
arms and through apertured bearing portions
20-.-2û formed upon the sides of the bracket mem
loer i1, this bolt being provided at one end with
a head 2l, its other end being screw-threaded
and engaged by a nut 22. The tilting member I1
is adapted to have limited tilting movement, and
for this purpose stops 23-23 are formed upon
the outer sides of the bracket member l1 which
in the normal non-tilted position abut vertical
edge portions 2li-_24, especially formed upon the
sides of the spider arms for this purpose. Stops
25--25 are also formed upon the Outer sides of
the bracket member I1, their stop surfaces being
inclined forwardly and downwardly and adapted
in the limit position of rearward tilt to abut the
lower edges oi the sides of the angle irons.
A lateral base portion 26 is integrally formed
lo with and extends between the sides of the bracket
member l'i and is provided at its rearward end
with a downwardly extending flange 21. At the
upper side of the base 26 there is provided an
It will be observed that the point of engage
ment of the knife-edge bearing portions 30--30
with the spring bolt in the normal non-tilted
position is substantially to the rear of the per
pendicular distance line from the tilting axis of
the bracket member to the line of action oi the
spring force, and that the line of action of the
spring force intersects the curve through which
the spring connection with the bracket member
moves. This is clearly shown in the diagram,
Fig. 6, in which A represents the tilting axis, B
the point of the spring connection with the
bracket member, C the curve through which the
point B moves, P the line of action of the spring
force, and T the torque arm represented by the
perpendicular distance between the tilting axis
A and the line of spring action P.
By this arrangement the rate of increase of
the tension applied to the spring as the tilting
member is tilted rearwardly is gradually decreased
relatively to equal successive increments of the
rearward angular movement, the points B1, B“
and B3 representing such equal increments of
movement and the lines P1, P2 and P3 represent
ing the changes in the line of action of the spring.
It will be seen that as the tilting member ap
proaches its limit of tilt the additional tension
imparted to the spring for a given angular move
ment is less than the tension applied during the
same angular movement at the beginning of the ;
tilting action, and that the total distance the
spring is compressed, represented by the distance
B---B3 along the line P3, is substantially less than
the total angular movement of the bracket mem
ber, represented by the distance B---B3 along the ;~
line C. At the same time the torque arm T act
ing about the axis oi tilt A is gradually decreased,
as represented by the lines T1, T2 and T3. As
the moment of force is the product of P and T, it
will be seen that the successive increases in the
spring resistance gradually decrease as the tilt
upwardly extending wall 28, also integrally
ing member is tilted rearwardly through equal
successive increments of movement, in other
words the increase, represented by the difference
formed with and extending between the sides of
the bracket member I1, the upper end oi this
wall being provided with a slot 29 at each side
oi” which there are formed rearwardly projecting
between the product of Pl and T1 and the product 43
oi P and T, is greater than the increase repre
sented by the difference between the product of
P3 and T3 and the product of P2 and T2.
knife-edge bearing portions 30-30.
The knife edge bearing portions Sli-3d engage
V-shape grooves 3I-3I in the head 32?. at one end
In Fig. 7 there is shown a force diagram similar
to that shown in Fig. 6, but on a reduced scale,
and showing in addition the reaction or" the per
oi the spring bolt 33, the side Surfaces oi the
bolt being preferably ilat adjacent the head, as
at 33a, where the bolt is engaged in the slot 29,
son’s unbalanced weight against the chair back
supported by the tilting member, W representing
the effort resulting from rearward pressure and
so that any tendency for the bolt to turn under
unbalanced weight oi the person and V represent
ing the perpendicular distance between the tilting l
axis A and the line of the pressure W. The prod
uct or" W and V will equal the product of P and T,
and at the rearward limit of tilt the product of
adjustment of the spring tension is prevented
through engagement of said ilat surfaces with
the sides of the slot. The bolt extends forwardly
in a downwardly inclined direction through an
opening 34 provided in a vertically disposed bear
ing wall portion 35 of the bearing member I2,
this portion being integrally formed with and ex
tending between the side portions I3-I3 of the
bearing member. At the forward side of the
,- bearing wall 35 there is formed an annular groove
Sii in which is seated one end of the spring 31,
the other end of the spring being engaged by a
washer 38 having an abutment portion 39 which
engages the extremity of the spring and forms
a seat thereof.
The forward end of the bolt 33
is threaded and projects loosely through the
washer 38 where it is engaged by an integrally
threaded hand wheel or nut :'iû, which upon being
turned moves the washer 38 toward or away from
the wall 35 and adjusts. the tension of the spring.
"W1 and Vl will equal the product of P3 and T3.
To consider the action in exemplary figures it
will be assumed that the initial spring resistance
represented by P is 250 pounds, that the radius
distance A-B is 2 inches, and the distance A-W
represented by the line ‘V l5 inches. The spring
is designed to have an increase in resistance of
i600 pounds per inch of compression. The limit
of tilt of the point B along the curve C repre
sented by the distance B---B3 is 1/2 inch. The
compression distance of the spring shown by the ”
longitudinal movement of the line of spring ac
tion from P to P3 is ¿è of an inch, so that if P
is 250 pounds the increase of P3 over P is 343%
pounds giving a total pressure of 593% pounds.
The torque arm T is 11/2 inches and the torque
12,110,874
3
arm T3 is 11A inches. The formula P><T=W><V
When reduced to ñgures will be
more than the unbalanced weight of the person
seated in the chair.
Thus in the example, according to the inven
This means that in the upright or non-tilted
pounds representing the increase in pressure re
quired between the non-tilted position and thel
tion, Fig. 7, the difference between 25 and 50
position the occupant of the chair will be sup
ported by the tilting arm under 25 pounds pres
sure. In the fully tilted position the formula
P3><T3=W1><V1 »when reduced to figures will be
10
Therefore ap-proximately 50 pounds is required in
the fully tilted vposition to establish a condition
of equilibrium `with the action. of the spring, and
15 as this force is represented bythe approximate
unbalanced weight of the «average person’s body
as it is -tilted rearwardly practically no effort is
‘required to maintain the back in tilted position.
The 25 pounds of >spring support in the non
20 tilted -position will provide .adequate support for
the back in the normal upright working posture,
due to the fact that the chair back will not respond
in this non-tilted position to the ordinary move
‘ments oft-he person in the chair. It will respond
25 however, to the voluntary effort of the person
to tilt the chair back rearwardly, and thereupon,
as the rearward tilting is increased, the unbal
anced weight gradually equalizes the spring pres
sure and no appreciable effort will be required
30 ’to maintain the-desired position of tilt.
It may be stated that this is almost the oppo
site effect from that obtained in ordinary pos
ture chairs, where the line of action of the spring
is tangent at the -approximate center of the tilt
35 ing range to the curve through which the spring
connection with the tilting member moves. In
this case there is practically no decrease in the
rate of increas-e‘of tension applied to the spring,
the distance of the spring compression is approxi
mately the same as the «angle of tilt, and there
is no »appreciable decrease in the torque arm as
the tilting member is tilted rearwardly. This is
clearly shown by the comparative diagram Fig. 8.
It will’be assumed that the radius of the curve
45 C represented by the line A--B is 2 inches, that
the length of the Yline V is l5 inch-es and the
pressure W .at the back in the non-tilted position
`is 25 pounds, these figures being thesame as in
the'diagram Fig. 7. The torque lines T and T3
are each approximately 2 inches vand the dis
tance of compression of the spring repre
sented by the longitudinal movement of the
line of action of the spring from P `to P3 is 1/2
fully tilted position is only 100 per cent, while
in the example shown in Fig. 8 the difference,
represented by the increase from 25 to 91 pounds,
is approximately 26S per cent. Consequently, in
these previous structures it has been necessary
in order to permit the chair back to be tilted
rearwardly with a reasonable amount of ease to
sacrifice any substantial support by the spring
in the vertical position, so that the ordinary
movements of the person seated in the normal
upright working position in the chair would cause
the chair back to respond by moving rearwardly
and the beneficial support that should be ,afforded
by the chair back was lost.
'20
A yoke shaped angle adjustment member com
prising side portions fil-M and a connecting
portion 41a is pivotally mounted between the rear
ward end portions of the sides of the tilting
bracket member ll by means of a cross pin 42
which extends through .apertures 43-43 in the
sides and through apertured ears ¿iQ-44 formed
upon the upper ends of the side portions :tI-4l.
The connecting portion @la
provided in its
lower edge with a rectangular cut-out ¿i5 in which -30
is engaged a block 636 having pockets 4l in its
ends in which the vertical edges of the cut-out
45 are engaged, the edges of the pockets 4'! being
divergent from the center line of the block
whereby the portion 4W may have limited tilt 35
ing movement with respect to the block. A
threaded hole 43 is provided through the block
which is engaged by a screw shaft 49 journaled
in a cylindrical passage 5S provided in the ñange
portion 2l of the tilting member, said shaft being 40
provided at its inner end beneath the lateral base
portion 26 with a U-shaped bracket 5I. A nut
52 is engaged upon the threaded shaft '49 adja
cent the outer side of the flange 2l to retain the
shaft against relative longitudinal movement. It
will be seen that upon rotation of the shaft 49
in one or the other directions the block member
46 is moved either toward or away from the flange
2l and in turn imparts swinging movement to
the angle adjustment member about the pin 42. .»
The sides of the bracket 5l (see Fig. 10) are
provided with holes 53-53, which are engaged
by lugs 54 provided upon the vertical sides of a
inch, this distance beingl equal to the angular
rectangular plate 55, provided upon its horizontal
distance B-B3 along the curve C. If the spring
has an vincrease in resistance of 1000 pounds 'to
one inch of compression, as in the diagram Fig.
'7, then the increase of resistance for ’M2 inch of
sides with lugs 56-56, which engage holes 51-51 . >
compression will be 500 pounds.
The formula
60 W><`V=P><T when reduced to figures will be
W(25) XV(15) =375=P('1871/2) XT(2)
This-means that to provide 25 pounds support in
the upright or non-tilted position the spring will
~ be adjusted to have an 'initial pressure of 1871/2
pounds. When compressed M2 inch the increase
in spring pressure of 500'pounds will make a total
pressure of 6871/2 pounds. Thus in the fully
tilted position the‘formula W1><V1=P3><T3 when
70 reduced to figures will be
Therefore approximately‘QZ pounds pressure is
required in the ‘fully tilted »position to maintain
the back >-in this position, »which is considerably
of a U-shape bracket member 58 secured upon
the end of a shaft 59, journaled in a U-shaped
bracket 60 secured upon the base portion 26 by
means of a bolt 5i and a nut 62. The axis of
the shaft 59 is at an angle of 45° to the axis 60
of the shaft t9, although it may be at any de
sired angle, and through the universal joint con
nection between the shaft 59 and the shaft 49,
provided by means of brackets 58 and 5I and
the plate 55, rotation of the shaft 59 imparts 65
rotation to the shaft 49. This arrangement per
mits the shaft 59 to extend at one side of and
forwardly of the bearing post I2, so that the
handle 63 upon the end of the shaft may be
located at a convenient point where it may be 70
readily reached by the occupant of the chair for
the purpose of adjusting the angle of the back.
By placing this handle forwardly, the occupant
of the chair, in making the adjustment, will nat
urally lean forwardly, and therefore rear-ward
2,110,874
pressure upon the back will be relieved and the
angular adjustment may be made with great
ease.
In chairs heretofore in use, where the
means for angularly adjusting the back Was ar
sult of this is that in the adjusted position there
is a tight engagement established between the
ñanges of the angular adjustment member and
the flanges of the height adjustment member
ranged rearwardly of the chair structure, it was
along the entire surfaces of the flanges of the
'customary to lean backwardly in making the
angular adjustment member, and therefore an
absolutely rigid relation is established, and this
adjustment and pressure would therefore be eX
erted upon the back.
The sides 4I-iiI of the angle adjustment
member are provided at their rearward marginal
portions with V-shape bends (i4-64, which are
engaged by the forwardly and inwardly bent
flanges 65 fiii provided upon a height adjust
ment member et. A strap member 61 is riveted
to the member 66 and extends at each side
thereof where it is provi-ded upon its ends with
the vertical posts 68--58 upon the upper ends of
which there is supported the back member 69, a
portion of which is shown in Fig. 3. In one of
20 the side portions di there is provided a threaded
bearing hole 1S, the axis of which is at an in
clined angle to the piane of said portion 4|, the
metal about the bearing being embossed, as at
'I I, to bring said axis into this relation.
A threaded shaft 12 is engaged in the bearing
hole lil, and at its inner end is provided with a
tapered wedge portion 13, which engages in the
acute angle corner formed by the outer flange of
the V-shape portion '64, at the opposed side of the
30 angle adjustment member from the bearing por
tion 1i), and the inner surface of the height ad
justment member 56. A handle 14 is provided
upon the end of the shaft 12 which is disposed
in a convenient location where it may be con
veniently turned by the person occupying the
chair. The wedge portion 'I3 has bearing in an
apertured bracket member 15 secured to the side
portion 4I.
The height adjustment member is
provided near its upper and lower ends with stop
40 lugs 16 and 'i1 in the path of the wedge portion
I3, and which limit the extent to which the
height adjustment member may be adjusted and
at the same time prevent its accidental removal.
The bracket 15 supports the inner end of the
shaft 12 against any tendency to bend, in the
event that the height adjustment member is a1
lowed to drop, bringing the stop lug 16 forcibly
against the inner end of the shaft, and such as
might occur when the shaft 12 is turned out
wardly to loosen the connection of the height
adjustment member with the angle a-djustment
member.
The angle adjustment member is preferably
formed of sheet metal, so that the sides thereof
are slightly springy, and, when the shaft 12 is
turned outwardly to withdraw the tapered wedge
end 13 from wedging engagement between the
angle adjustment member and the height ad
justment member, the sides ¿il-4i contract
slightly with respect to the flanges ‘E5-65 so that
they are relatively loose with respect to the
latter. The strap member ‘51 may thereupon be
grasped at each side and easily raised or lowered
as desired to adjust the height of the back.
l Thereupon the adjustment is fixed by turning
shaft 'i2 inwardly causing the tapered wedge
portion 13 to tightly wedge between the flange
of the V-shape portion S4 at one side and the
inner surface of the height adjustment member
Bâ. At the same time the flange of the V-shape
portion ‘54 at the other side is tightly pressed
against the flange t5 of the height adjustment
member through the outward spreading pressure
exerted upon the side portion 4I as the tapered
wedge portion 13 is forced into place. The re
with very little effort required in the turning of
the shaft 12 to establish this relation. In order
to remove the back, for shipping purposes, it is
only necessary to Withdraw the shaft 12 to a
point where the tapered wedge end 13 is out
of the path of the stops 16-16, whereupon the
height adjustment member 66 may be slipped off
the angle adjustment member.
In Figs. 4 and 5, I have illustrated a modified
form of the invention, in which the tilting mem
ber is formed of sheet metal and is mounted for
tilting movement upon the bearing post I2, in
stead of upon the sides of the spider arms, as 20
in the first embodiment. The sheet metal tilt
ing bracket member comprises an upper trans
verse portion 8D and side portions 8I-8I bent
downwardly at right angles therefrom, the side
portions being provided at their rearward upper
corners with apertured portions 82--82 in which
the pivot pin 42 pivotally mounting the angle
adjustment member is engaged.
The tilting member is mounted for tilting move
ment at the forward lower corners of the side
portions by means of a bolt 83 engaged through
apertured bearing lugs 84--84 formed upon the
bearing post I2, the sides 8I-8I being dis
posed between these bearing lugs 84-84 and the
side portions I3-I3 of the bearing post, which
are secured to the angle iron spider arms Il-II
by means of rivets I4. The sides 8I--8l of the
tilting member are provided with lanced and out
wardly embossed stop portions 85 and 86 be
tween which are disposed the inner head ends of 40
the rearwardly disposed rivets I4-I4, and which
hea-d ends act as limit stops for determining the
degree of tilting movement of the tilting member,
the stop portions 86 being engaged with the rivet
heads in the non-tilted position and the stop
portions 85-85 engaging the rivet heads in the
fully tilted position.
In the transverse top portion 80 there is pro
vided toward its forward edge a cross-shaped
opening 81, having lugs 88 bent upwardly from
its transverse portion and disposed at each side
of its longitudinal portion, the rearward surfaces
of these lugs forming with the upper surface of
the top portion 80 V-shaped pockets in which
are engaged the knife edge portions 89-89 of
the head 90 provided upon the end of the spring
bolt 33, which bolt extends through the longi
tudinal portion of the opening 81.
A sheet metal plate 9I is disposed within the
lower portion of the tilting member between the (30
sides 8I-8I, and is secured to said sides by
means of lugs 92 formed upon its side edges and
engaged »and staked into apertures 93 formed
in the sides 8I-8I, this plate being provided at
its rearward end with a downwardly bent aper
tured flange 94 in which is supported the angle
adjusting screw shaft 49. The shaft 59 for op
erating the screw shaft 49 is mounted at the
under side of the plate 9| in a similar manner
to the mounting of the operating shaft 59 upon
the under side of the base portion 26 in the iîrst
embodiment. Inasmuch as the angle adjusting
and height adjusting parts are substantially iden
tical to those of the first embodiment a further
description of these is not deemed necessary.
75
2,110,874
I have illustrated and described preferred and
satisfactory embodiments of the invention, but
it will be understood that changes may be made
therein, within the spirit and scope thereof, as
defined in the appended claims.
Having thus described my invention what I
claim and desire to secure by Letters Patent is:
1. In a back support for use in a chair, a chair
back supporting member having a pair of spaced
10 side portions, a vertically adjustabie chair back
member having a pair of spaced flanges engaged
for vertical sliding movement with the outer
sides of said side portions, and a screw shaft
mounted in one of said members having a wedge
end adapted to engage between one of said side
portions and said back member to press said
side portion tightly against one of said ñanges.
2, In a back support for use in a chair, a chair
5
other side portion and said back member to press
said flange tightly against the adjacent flange
of said back portion, the flange of the other side
portion adapted through said threaded engage
ment of said screw shaft therewith to be tightly
pressed against said other flange of said back
portion.
6. In a back support for use in a chair, a chair
back supporting member, a chair back member
engaged with said supporting member for ver 10
tical sliding movement, a screw shaft mounted in
one of said members having a locking end ar
ranged to engage between said members to secure
the back member in adjusted position, a pair of .
vertically spaced stop means on another of said
members normally in the path of the locking end
of said screw shaft to limit the relative vertical
movement of said back member, said back mem
outer sides of said side portions, and a screw
shaft having threaded engagement in one of said
ber adapted to be removed from said supporting
member upon retraction of said screw shaft to 20
remove said locking end out of the path of said
stop means.
7. In a chair, a post having spaced side por~
tions, spider arms at the outer sides of said spaced
side portions and having a wedge end adapted
side portions, headed rivets engaged through 25
to engage between the other side portion and
said back member to press said other side por
together, the> rivet heads projecting inwardly
tion tightly against the adjacent flange, the
other side portion adapted through said threaded
from the inner surfaces of said side portions to
form stop abutments, bearing means on said
back supporting member having a pair of spaced
side portions, a vertically adjustable chair back
member having a pair of spaced flanges en
gaged for vertical sliding movement with the
30 engagement of said screw shaft therewith to be
tightly pressed against said other flange.
3. In a back support for use in a chair, a sub
stantially U-shaped chair back supporting mem
ber having a transverse portion and a pair of
spaced rearwardly extending side portions, a ver
tically adjustable chair back member rearwardly
of said supporting member having a pair of
spaced flanges engaged for vertical sliding move
ment with the outer sides of said side portions,
a screw shaft having threaded engagement in
one of said side portions and having a Wedge end
adapted to engage between the other side por
tion and said back member to press said side
portion tightly against one of said flanges, the
other side portion adapted through said threaded
engagement of said screw shaft therewith to be
tightly pressed against said other flange.
and securing said side portions and spider arms
post, a tilting chair back supporting member 30
mounted on said bearing means for tilting move
ment about a horizontal axis and comprising side
portions inwardly- spaced from said side portions
of said post in opposed relation to said rivet
heads, a pair of outwardly projecting stop por 35
tions on each of said side portions of said tilting
member respectively disposed forwardly and
rearwardly in the path of said rivet heads and
adapted to engage said rivet heads' respectively
in the tilted and non-tilted positions of said tilt
ing member, and spring means acting between
said post and said tilting member to normally
maintain said tilting member in non-tilted posi
tion.
8. In a tilting chair back support for use in a
chair having a seat element, a bracket member
mounted upon said seat element, a chair back
4. In a back support for use in a chair, a chair , supporting angle adjusting member hingedly con
back supporting member having a pair of spaced
side portions, a vertically adjustable chair back
50
member having a pair of spaced flanges engaged
for vertical sliding movement with the outer sides
of said side portions, one of said side portions
having an inclined inner surface adjacent the
Ul Eil inner surface of said back member, a screw shaft
having threaded engagement in the other of said
side portions and having a wedge end adapted
to engage between said inclined inner surface
and the inner surface of said back member to
60 vpress said first side portion tightly against one
of said ñanges, the other side portion adapted
through said threaded engagement of said screw
shaft therewith to be tightly pressed against
said other ñange.
5. In a back support for use in a chair, a chair
back supporting member having a pair of spaced
side portions having outwardly diverging ñanges
nected to said bracket member having a trans
verse portion having a vertically sided slot open 50
at one end, a rotatable screw carried by said
bracket member, a nut engaged upon said screw,
slot means in the sides of said nut pivotally en
gaging the vertical sides of said slot of said angle
adjusting member whereby rotation of said screw i -
imparts swinging movement to said angle ad
justing member relatively to said bracket mem
ber, and means for rotating said screw.
9. In a tilting chair back support for use in
a chair having a seat element, a bracket member 60
mounted upon said seat element, a chair back
supporting angle adjusting member hingedly con
nected to said bracket member having a trans
verse portion having a vertically sided slot open
at one end, a block member having slot means
in its sides pivotally engaging the vertical sides
of said slot of said angle adjusting member,
at their rearward edges, a chair back member
means connected to said bracket member engag
having a pair of spaced inwardly converging
flanges engaged with the outer sides of said di
ing said block member and operative to adjust
ably move said block member whereby swinging
movement is imparted to said angle adjusting
member relatively to said bracket member.
70 verging flanges of said side portions, a screw
shaft having threaded engagement in one of said
side portions and having a wedge end adapted
to engage between the diverging flange of the
WALTER F. HEROLD.
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