An articulated multi-swivel chair operable for access to stations disposed within a 360 degree circular range about the chair, includes a mechanism composed of at least two friction loadable pivots each supporting a corresponding link and, in combination, acting to support, with universal motion in two lateral axes, a chair body. Each of the pivots are preferably formed utilizing a tapered roller bearing or thrust bearing or bushing which are adjustable to provide a predetermined level of pivot friction by tightening an adjustment device such as an adjusting nut associated with each bearing. The first or lowest pivot is supported in a base which is of appropriate design to prevent tipping or which may be bolted or otherwise secured to the floor. To prevent pivot lock-up and provide shock absorbtion when the links are fully extended, repulsion devices are provided in the links. These are preferably in the form of magnets being so located in the links as to have two magnet disposed in proximity to each other with like poles facing, i.e. when adjacent links are aligned.

BACKGROUND OF THE INVENTION 
Articulated chairs operable to transport a user to portions disposed in a 
360 degree circular range about the chair, utilizing a mechanism having 
two pivots, have been available for some time. Basically, these prior 
devices include a base portion having a pivot within which is supported a 
first link. The first link in turn includes a pivot in which a second 
link, including a support bushing for the chair body, is supported. The 
device utilizes ball bearings, which are non-adjustable bearing devices, 
in order to provide pivots with a minimum of friction. The resulting 
articulated chair device imparts a "floating feeling" to a person sitting 
in the chair body and is operable to transport the person anywhere within 
a 360 degree circular range defined by the extent of the mechanism. 
The prior articulated chair permitted rapid and easy access to various 
"stations" or devices located within the 360 degree extent of its 
operating range. Because the prior mechanism was designed to provide 
apparently effortless motion, the "free floating" sensation which resulted 
from its use has been found "too free floating" by users whose need to 
move rapidly from station to station is limited. Attempts to add friction 
providing or loading devices to the prior chair have been unsuccessful 
mainly because the resulting mechanism will tend to "lock-up" when motion 
in certain directions is attempted. This occurs especially when the links 
are fully extended or are completely superimposed (aligned one above the 
other). The friction in the pivots tends to keep the links aligned, 
thereby causing radial thrust applied by the user to be ineffective to 
cause link rotation about the pivots. A noticable and annoying amount of 
movement or shifting about by the user of the device is required to 
"unlock" the mechanism and commence the relatively "free floating" action 
of the articulated chair. 
A second, and related, disadvantage of the prior device is that, because 
only minimal friction is generated by the pivots, the device tends to be 
biased in a particular position when the total mechanism is not completely 
leveled. Thus, in the absence of a correcting or leveling device applied 
by the user, the chair will float to an equilibrium position. To overcome 
this requires that a technician familiar with the leveling mechanism spend 
time properly leveling the chair once it is placed in its final position. 
Further, moving the chair from the position for which it has been leveled 
may require a releveling operation if the floor is differently sloped. 
It is therefore an object of the present invention to provide an 
articulated chair of the multi-swivel or multi-linkage type which provides 
an acceptable, and to some extent adjustable, "feel" or degree of friction 
with respect to the floating action of the chair. 
It is a related object to provide a chair which, in general, can be 
delivered and set up without special leveling operations for most 
applications. 
It is a still further object of the invention to avoid or substantially 
reduce the probability of "locking up" of the linkages, especially when 
they are fully extended or completely superimposed, in response to a 
radial thrust applied by the user of the chair. 
BRIEF DESCRIPTION 
The objects are accomplished by utilizing at least two pivots, one for each 
link, each of which pivot being supported in an adjustably loaded tapered 
roller or thrust bearing. Additionally, each pair of links carry facing 
repulsion magnets whereby when the pair of links are aligned, repulsion 
forces are generated therebetween which tend to bias the links out of 
alignment. 
Thus, the use of adjustable thrust or tapered roller bearings permits 
introduction of a predetermined amount of friction at each pivot; while 
the use of repulsion magnets reduces the problem of "locking up" of the 
mechanism by biasing the links out of the configuration in which 
"locking-up" occurs.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As shown in FIG. 1, the general construction of the articulated 
multi-swivel and multi-link chair 10 of this invention includes a base 12 
which rests on the floor and which supports a multi-link chair support 
mechanism 14 which, in turn, supports the seat body 16. The multi-link 
chair support mechanism 14 has at least two links, a lower link 18, and an 
upper link 20. The position of the chair 10 shown in FIG. 1 is one in 
which the chair body 16 is furthest removed from the central vertical axis 
of the base 12. This position is referred to herein as the extended 
position. In the extended position the links 18, 20, of the multi-link 
chair support mechanism 14, have the relationship shown in FIGS. 1 and 2. 
As shown in FIG. 2, each link carrys a magnet 22. The inboard end of lower 
link 18, and the center of upper link 20 carry a downwardly extending 
spindle 24 which is threaded at its end to mate with a nut 28. Each 
spindle 24 is supported in upper and lower tapered roller bearings 26A and 
26B. The nut 28 is threaded on the spindle 24. As the nut 28 is tightened, 
it bears against the inner race of the lower roller bearing 26B causing 
the rollers to ride inwardly slightly as they re-adjust between the inner 
and outer race. This increases the radial load of thrust, thereby 
increasing the amount of pivot friction. This tapered roller bearing, 
sometimes called a thrust bearing, thus provides a pivot mechanism 38 
having an adjustably predetermined amount of pivot friction produced by 
tightening or loosening the adjustable nut 28. 
In this fashion the inboard end of each link pivots in the link below it, 
with the lowest link 18 pivoting on the central axis of the base 12. 
Furthermore, each link supports the link above it with the base 12 
supporting the lowest link 18 and the upper link 20 supporting the seat 
body 16. 
More specifically, the outboard end of the upper link 20 carries a bushing 
30 which receives a chair seat spindle mechanism 32 to support the seat 
body 16. The combination bushing 30 and seat spindle mechanism 32 may be 
any one of known types normally employed with business-type desk chairs 
and may include a height adjustment mechanism such as the combination of 
the adjusting member 34 carried by the bushing 30 and the threaded portion 
36 of the seat spindle 32. This well-known combination allows the seat to 
be adjusted for height as well as to be rotatable about the axis of its 
support spindle 32. 
The pivot 40 of FIG. 3 is generally similar in construction to the pivot 38 
of FIG. 2 with some details of construction changed for ease of assembly. 
Thus, with reference to FIG. 3, each lower tapered roller bearing 26B is 
supported on a felt or similar material washer 42 which retains excess 
lubrication that might otherwise fall from the device. The felt washer 42 
is, in turn, supported on a retaining washer 44, usually of metal or 
similar stiff material, which in turn is supported on a lock washer 46. 
This assembly is inserted over spindle 24, up against shoulder or lip 47 
and secured in place by lock nut 28. The lock washer 46 restrains 
unintended or accidental rotation of the adjusting or loading nut 28. 
A spacer washer 48, which can compress to allow the inner portions of the 
split roller bearing device 26A, 26B to be driven together by rotation of 
adjusting or loading nut 28, is provided between the portions 26A, 26B. 
The upper roller bearing 26A is separately inserted from the top, and is 
supported on top of lip 47. 
FIG. 4 shows a three link chair support mechanism composed of a lower link 
18, an intermediate link 18A, and an upper link 20. The additional link 
18A reduces the tendency of the multi-link chair support mechanism to 
"lock-up." Any number of additional links 18A can be inserted between the 
lower link 18 and the upper link 20, as desired. 
Even with the three-link chair support mechanism arrangement, it has been 
found that some locking-up of the multi-link chair support mechanism 
occurs. In order to reduce the tendency of the mechanism to lock up, 
repulsion magnets are carried in each link. As can be seen in FIG. 2, the 
magnets 22 are carried near the extreme ends of each link in order to 
maximize the moment generated around the associated pivot 38. Magnets 22 
in adjacent links are so disposed that at least one magnet in each link 
will be disposed adjacent to at least one magnet in an adjacent link when 
the links are aligned. The magnets are disposed with the same poles facing 
outwardly so that a repulsive force will be generated between adjacent 
magnets 22. 
The links 18, 20 are preferably made of aluminum or non-magnetic steel, in 
order that they do not interfere with the repulsive effect of adjacent 
magnets. In practise, No. 5 ceramic magnets available in a standard size 
of one inch long by seven eights inches in diameter, have been found to 
generate sufficient repulsive forces, when one eighth inch or less 
clearance is used therebetween in adjacent links, to substantially prevent 
any lock-up in a two or three link multi-link chair support mechanism. 
Although other magnets, such as magnets formed of Alnico, can be used, 
ceramic magnets have been found to have greater life and present no 
corrosion problems. In addition they are lighter in weight. However, if it 
is desired to use other magnets, or less powerful magnets, they may be 
employed although it may be found necessary to utilize larger magnets 
and/or more than one repulsive pair to obtain the desired effect. 
The repulsive forces generated between adjacent magnets 22, also act as a 
shock absorbing means when the chair is forced outwardly, causing the 
multi-link chair support mechanism to be fully extended. 
FIG. 4 shows a preferred arrangement of magnets when three links 18, 18A, 
20 are employed. As would be obvious, the arrangement of links can be 
reversed so that the lowest link is long and the upper link is short and 
carries the chair support mechanism 16. The arrangement shown in FIG. 4 is 
preferred only in that it results in a more attractive looking chair 
device. Similarly, the links 18, 20 of FIG. 2, can be revised, with a 
shorted upper link carrying the chair and a longer lower link pivotably 
supported on the base 12. 
OPERATION 
To use an articulated multi-swivel chair in accordance with the present 
invention, one need only sit in the chair and move in the direction that 
it is desired to be transported by the chair. This will cause the chair 
body 16 apparently to float in the desired direction. 
To control the "feel" or (drag) friction of the floating motion, adjusting 
or loading nuts 28 may be tightened or loosened thereby increasing or 
decreasing the amount of additional frictional forces generated in each 
pivot 38. These frictional forces increase the amount of effort necessary 
to change the position of the chair and thereby restrain any tendency of 
the chair to "float" to one position or another, when it is not otherwise 
held, due to a slightly sloping floor condition. Special leveling is 
thereby eliminated in usual applications. 
Although two links 18, 20 are shown in the preferred embodiment of the 
drawings, any additional number of middle links 18A, as shown in FIG. 4, 
can be added simply by inserting them in an analogous manner to that shown 
in FIG. 4. Of course, if a non-secured base is used, such as the base 12 
shown in the drawings, it will have to be properly dimensioned to avoid 
tipping of the chair by compensating for the additional range of travel 
due to additional links. 
The preferred pivot arrangement shown in FIG. 3 can be substituted for the 
pivots shown in FIGS. 2 or 4. 
The use of a lock washer 46, as shown in FIG. 3, helps restrain changes in 
adjustment by preventing accidental rotation of nut 28. It can, of course, 
be used in the pivot 38 of FIG. 2 just as effectively. This is also true 
of the lubrication retaining felt or cloth washer 42, the retainer washer 
44, and the spacer washer 48. 
Each of the pivots or pivot mechanisms must incorporate the friction adding 
features, as otherwise the chair will freely swivel about the low friction 
pivot mechanism thereby partially defeating the objects of the invention. 
The repulsive magnets 22 bias the links 18, 20 out of alignment, thereby 
reducing or eliminating any lock-up in the multi-link chair support 
mechanism. These magnets are particularly important when the pivots have 
been friction loaded. 
While preferred embodiments have been shown and described herein, it will 
be realized that this is for the purposes of illustration, and the 
invention should not be considered as limited except in accordance with 
the appended claims.