US3778014A

US3778014A - Chair base swivel arrangement

Info

Publication number: US3778014A
Application number: US00166099A
Authority: US
Inventors: D Beaver; R Driscoll; J Lannert
Original assignee: All Steel Equipment Inc
Current assignee: All Steel Equipment Inc
Priority date: 1971-07-26
Filing date: 1971-07-26
Publication date: 1973-12-11
Anticipated expiration: 1990-12-11

Abstract

A chair base swivel arrangement comprising a tubular member supported in upright position from a chair base and carrying at its upper end an axially split O-shaped bearing element of antifriction material that is engaged by a sintered swivel member on which the chair base nut or hand wheel rests. The bearing element seats of the tubular member and swivel member are of complemental semi-torus configuration relative to the bearing element peripheral surface, with the tubular member seat engaging the lower radially outer quadrant of the bearing element and the swivel member seat engaging the upper radially inner quadrant of the bearing element.

Description

Driscoll et al.

[45] Dec. 11, 1973 [54] CHAIR BASE SWIVEL ARRANGEMENT [75] Inventors: Richard P. Driscoll, Clarendon Hills; James W. Lannert, Oswego; Donald V. Beaver, Brookfield, all of Ill.

[73] Assignee: All-Steel Equipment Inc., Aurora,

Y lll,

[22] Filed: July 26, 1971 [2l] Appl. No.: 166,099

[52] U.S. Cl. 248/406, 308/230 [5l] Int. Cl. F16m 11/00, Fl6m 13/00 [58] Field of Search 248/405, 406, 415, 248/418, 425, 161; 308/230, DIG. 7; 10S/139 [56] i References Cited UNITED STATES PATENTS 674,912 5/'1901 Ellenbecker 248/405 2,999,665 9/1961 Ericson et al... 248/405 3,059,888 10/1962 Lie.' 248/415 3,086,826 4/1963 `Gunnell 30S/DIG. 7 3,148,855 9/1964 Hamilton 248/405 3,l67,366 l/l965 Freund 30S/DIG. 7 3,343,901 9/l967 Marcus 1087139 3,503,523 3/1970 Hamilton et al 24S/425 3,606,234 9/l97l Prescott 24S/406 Primary Examiner-Marion Parsons, Jr.

Attorney-Robert C. Brown, Jr. et al.

[57] ABSTRACT A chair base swivel arrangement comprising a tubular member supported in upright position from a chair base and carrying at its 4upper end an axially split O- shaped bearing element of antifriction material that is engaged by a sintered swivel member on which the chair base iiut or hand wheel rests. The bearing element seats of the tubular member and swivel member are of complementa] semi-torus configuration relative Ito the bearing element peripheral surface, with the tubular member seat engaging the lower radially outer quadrant of the bearing elementand the swivel member seat engaging the upper radially inner quadrant of the bearing element. v

8 Claims, 8 Drawing Figures CHAIR BASE SWIVEL ARRANGEMENT The present invention relates to a chair base swivel arrangement, and more particularly to a swiveling arrangement for swivel type chairs through which the chair seat is rotatably supported on its base.

The familiar swivel chair is an item of office furniture that is subject to extensive use in the office, and one of the parts of same that is subject to severe wear is the swivel mounting arrangement for swivelably supporting the chair seat on its base. The swivel arrangements involved require a special bearing arrangement that must furnish support for the chair seat, yet swing freely and still permit vertical adjustment for user comfort.

Conventional bearing arrangements for swivel chairs frequently involve a steel on steel approach that requires adequate lubrication to remain functional. Some attempt has been made to utilize plastic and ball bearing elements as part of the bearing arrangement to reduce lubrication requirements, but these arrangements have been subject to objections either because of high cost or inconsistent results.

The principal object of this invention is to provide a swivel arrangement for swivel chairs that brings into the chair swivel bearing the self-lubricating benefits available with selected plastic materials, while permitting a low cost, rugged design for mass production purposes.

Yet another principal object of the invention is to provide a swivel bearing arrangement for office chairs employing a simple plastic bearing element that consistently meets endurance test requirements without presenting undue lubrication needs or expensive preventative design.

Other objects of the invention are to provide a swivel arrangement for office chairs and the like that is readily adaptable for application to existing chair bases, that does not compromise the desired adjustability in chair seat height, and that is economical of manufacture, convenient to install, and long lived in use.

In accordance with this invention, the swivel arrangement comprises an upright bearing tube and sintered swivel member arrangement cooperating with a bearing element of O-ring or torus shape formed from a suitable self-lubricating plastic material, in which the bearing tube and swivel member have bearing seats making the actual Contact with the bearing element which complement the shape of the bearing element and provide two available slip or wear surfaces about which the chair seat may swivel. The swivel member may be oil impregnated to reduce greasing requirements, and the bearing unit is enclosed for maximum protection against fouling.

Other objects, uses and advantages will be ovbious or become apparent from a consideration of the following detailed description and the application drawings in which like reference numerals indicate like parts throughout the several views.

In the drawings:

FIG. 1 is an elevational view of a swivel chair base arranged in accordance with the present invention, with parts shown in section and broken away to expose other parts;

FIG. 2 is an exploded side elevational view, on a smaller scale, of the principal components of the chair base swivel arrangement shown in FIG. l;

FIG. 3 is a top plan view of the swivel member that rests on the bearingelement of this invention, and that is keyed to the chair spindle to preclude relative rotational movement between the two;

FIG. 4 is a cross-sectional view substantially along line 4-4 of FIG. 3;

FIG. 5 is a sectional view through the hand wheel or nut employed in the chair swivel arrangement of FIGS. 1 and 2;

FIG. 6 is a bottom plan view of the hand wheel shown in FIG. 5, as viewed along line 6-6 of FIG. 5;

FIG. 7 is a plan view of the bearing element employed in accordance with this invention; and

FIG. 8 is a sectional view illustrating a modified form of swivel bearing arrangement in accordance with this invention.

However, it is to be understood that the specific drawing illustrations provided are supplied primarily to comply with the requirements of the Patent Law, and the invention has other embodiments which will be obvious to those skilled in the art, and which are intended to be covered by the appended claims.

GENERAL DESCRIPTION Reference numeral 10 of FIGS. 1 and 2 generally indicates one embodiment of the invention which comprises a bearing tube 12 supported by chair base 14 and defining at its upper end 16 a bearing retaining portion 18 in which is seated a bearing element 20 that is generally O-ring in shape and formed from a suitable selflubricating nylon type material.

The bearing tube 12 receives chair seat spindle 22 that is suitably threaded as at 24 for threaded cooperation with the nut or hand wheel 26 which is formed to receive, rest on, and be keyed to, swivel member 28 that engages the bearing element 20 in the manner indicated in FIG. 1.

The bearing retaining portion 18 of the bearing tube 12 defines a bearing seat 30 and the swivel member 28 defines a bearing seat 32 which are the means whereby the bearing element is supported and vertical loads supplied to the seat are transmitted to the bearing element, respectively. It is to be noted that the

bearing seats

30 and 32 are shaped to substantially complement the surface portions of the bearing element 20 that engage same. Bearing element 20, in accordance with this invention, is generally of the simplified O-ring or torus (sometimes called anchor ring) shape indicated in FIG. 7, except that it is split as at 34 whereby the bearing element has a self centering action with respect to the bearing seats that engage same under the loads applied against it to accommodate tolerance variations. Bearing element 20, retaining portion I8 of bearing tube l2, and swivel member 28 form a bearing unit 25.

Swivel member 28 is formed with lug 36 that is lodged in slot 38 of chair base spindle 22, and is shaped to define upwardly directed ridges or protuberances 40 adapted to seat in correspondingly located recesses or notches 42 formed in hand wheel or nut 26 (see FIGS. ,3, 4 and 6).

In the form shown, the bearing tube l2 is received within an inner shell 44 that is fixed at its lower end 46 to the conventional chair base legs 48, in a manner similar to that shown in Buhrmaster U.S. Pat. No. 3,186,669. The inner shell 44 carries at its upper end 50 a starred washer 52 on which rests a collar 54 against which the bearing tube upper end rests, and

which reinforces the upper end of the bearing tube 12.

Received over the inner shell 44 is an outer decorative shell S6 having an outer diameter complementing that of the nut or hand wheel 26, and which is held centered with respect to the inner shell at the upper end of the bearing tube by the triangular flanges 58 of the washer 52. The lower end of the outer tube 56 is slotted as at 60, in a matter similar to that shown in said Buhrmaster patent, to receive the chair base legs 48.

Spindle 22 is suitably formed at its upper end 62 for securement to a chair seat (a portion of which is shown in dashed lines at 63), and carries a sleeve bearing 64 at its lower end 66 that is received within the bearing tube and has an outer diameter that substantially complements the inner diameter of the bearing tube.

lt will thus be seen that in normal operation, the weight of the chair seat and its load is transmitted to the chair base 14 through spindle 22, nut or hand wheel 26, swivel member 28, bearing element 20, and the bearing tube 12 from which the load is transmitted to the inner shell 44 and legs 48.

In normal use, when the chair seat is swiveled, the nut i and swivel member 28 rotate with spindle 22, relative to the bearing tube 12. The bearing arrangement illustrated provides two slip or wear surfaces at the respective bearing

seats

30 and 32 to accommodate this swiveling action. Under ordinary circumstances, bearing element 20 will remain stationary with respect to the bearing tube and the swivel member 28 will swivel with respect to the bearing element since the area of contact between seat 30 and the bearing element 28 exceeds the area of contact between the seat 32 and the bearing element. However, the alternate slip or wear surface represented by the engagement of bearing element 28 with seat 30 is available to accommodate swiveling movement of the chair seat in the event that the frictional relationships between the bearing element and seat 30 are such that the bearing element swivels with the swivel member 28.

It is to be noted that the bearing element 20 is substantially continuous about its circumference, except at the slit 34, which provides a substantially continuous and uninterrupted load supporting function about the

seats

30 and 32.

Seats

30 and 32 having configurations substantially complementing the external surface of the bearing element, and the bearing element 34 being split, results in a uniform load supporting action about the circumference of the spindle due to the self centering action on the bearing element. The bearing sleeve 64 resists lateral thrusts acting on spindle 62.

When one desires to adjust the elevation of the seat with regard to the chair base 14, the spindle 22 is held from rotation by grasping the chair seat 63 and the hand wheel 26 is rotated in 90 increments which are the result of the ridges 40 of swivel member 28 mating with notches 42 of the hand wheel 26. This action raises or lowers the spindle with respect to the hand wheel depending on the direction of rotation. Screw 70 acts as a retainer for the hand wheel 26 to keep the base assembled to the chair when the chair is lifted by its arms. In normal swivel action the retaining screw 70 is not functional.

In the embodiment 10A of FIG. 8, the seat 30A defined by the bearing tube 12A is formed in a hub assembly 80 in which the hub assembly 80 includes collar portion 54A that is integrally united with bearing retainer portion 18A. Hub assembly 80 is applied to the upper end 16A of the bearing tube.

The device 10A is otherwise the same as device l0.

SPECIFIC DESCRIPTION Referring back to device l0, the bearing tube 12 may be formed from any suitable metallic substance such as suitable tubing steel defining tubular member 82 that has the bearing portion 18 suitably formed in its upper end 16 to the configuration indicated in FIG. 1.

As indicated in FIG. 1, the external diameter of the shank portion of the bearing tube 12 is proportioned to substantially complement or fit closely inside the internal surface 84 of the inner shell 44, which is likewise made of any suitable metallic substance such as tubing steel. The lower end 91 of the bearing tube has applied thereto a hub cap 92 and both are suitably fixed to the inner shell 44, as by welding at 94. Preferably the joint between the cap 92 and the lower end of bearing tube 17 is made leak free to retain within the bearing tube l2 any lubricant that is applied to the bearing

units

25 and 64.

At the upper end 16 of the bearing tube l2, the starred washer 52 includes a rounded rim portion 96 that rests on the upper end 50 of the inner shell and deflnes a bore 98 through which the bearing tube l2 projects. The pointed or triangular flanges 58 are four in number and are spaced equidistant about the circumference of the washer 52 so that opposed flanges 58 are 180 degrees apart. The flanges 58 are deflected downwardly, as indicated in FIG. l, such that when the outer shell 56 is applied thereto, the flanges 58 are deflected radially inwardly somewhat so that their respective edge corners 100 bear firmly against the inner surface 102 of the outer shell 56 for firm centering purposes.

The inner shell 44, the washer 52, and the collar 54 are joined by welding as at 104 between flanges 58 in at least two places apart or preferably at four places between each adjacent pair of flanges 58.

The collar 54 has internal and external diameters substantially identical to those of the inner shell 44, and is proportioned axially of the inner shell to space the bearing element 20 as desired above the floor on which the chair is to rest. In applying the bearing tube l2 to the inner shell, the bearing tube 12 is moved downwardly of the inner shell until its retainer portion 18 rests against the end 106 of the collar, with the other end 108 of the collar resting on washer 52.

As already indicated, the inner shell 44 is suitably welded to the chair base legs 48, and the welds are substantially covered by the outer shell 56.

Spindle 22 is formed from any suitable metallic material such as mild steel. Upper end 62 is suitably formed for application to a chair seat 63 in any conventional manner, and threading 24 may be of any suitable type best adapted for purposes of this invention. Slot 38 extends longitudinally of the spindle through the threading 24 and is proportioned to receive lug 36 of the swivel member 28 for sliding adjustment of member 28 longitudinally on the spindle 22.

The sleeve bearing 64 may be of any suitable type, for instance nylon or polyethylene, and made in the form of a tube 111 press fitted onto spindle 22. Alternately, the sleeve bearing may be moulded directly on the spindle 22. The exterior surface 112 of the bearing 64 should be lightly greased before application into bearing tube 12. The surface 112 should have a diameter substantially complementing the internal diameter of the bearing tube shank 90 for close fitting relation thereto.

The nut or hand wheel 26 is formed from any suitable material, it comprising a zinc die cast structure in the illustrated embodiment, having its outer surface 120 suitably chrome plated. Hand wheel 26 defines a body 122 having a bore 124 internally threaded as at 126 for threaded cooperation with the threading 24 of spindle 22. Thebody includes a depending skirt 128 that masks the bearing unit 25 in the assembled relation of same. Screw 70 is suitably applied to threaded opening 130 in the skirt 28.

The body 122 and its skirt 128 define a socket 132 in which the bearing unit 25 is received. Socket 132 is defined by the internal side wall 134 of skirt 128 and a base wall 136 which is suitably indented to define notches or recesses 42 that are proportioned to receive the ridges 40 of swivel member 28. The notches 42 each have on either side of same angled surfaces 140 (see FIG. 6) that serve to guide the respective ridges 40 into the respective recesses 42.

The swivel member 28 in the form shown comprises an annular sintered member 150 formed from a material suitable for this purpose. In one commercial embodiment, member 150 is ASTM B426-68 type III grade l oil impregnated sintered copper steel having a hardness on the order of Rockwell B 65.

Body 150 is shaped to define lug 36, ridges 40, and define a bore 152 that closely receives the threading 24 of spindle 22 (see FIG. l). Body 150 is formed with annular internal shoulder 154 that defines bearing seat 32 and end portion or extension 156 which is received within the bearing element 20.

The bearing element is preferably formed from a suitable self lubricating type material (for instance, nylon type products, such as that sold under the trademark DELRIN by E. I. Du Pont De Nemours Company, Wilmington, Del. [Delfin 100 being employed in a commercial embodiment of the invention]). Bearing element 20 is preferably of the simplified torus or anchor ring configuration that is illustrated and thus has the circular transverse cross-sectional configuration that is shown in FIG. 1, which bearing

seats

30 and 32 substantially complement. Bearing element 20 is in the form of O-ring 160, which in the form illustrated, is split axially thereof, as at 34 (see FIG. 7) to define

end portions

164 and 166 that are separated but in closely spaced relation.

While the invention contemplates that unsplit O- rings ofthe type indicated may be employed, the split ring type is preferred so that tolerance variations in making the parts that define bearing

seats

30 and 32 are accommodated, the general shape of the

seats

30 and 32, when the bearing is assembled, tending to cam the ring into properly centered relation with respect to the cam surfaces and 32.

It is preferable, however, that the ring 160 be substantially continuous about the circumferences of

seats

30 and 32, and for this reason the split 34 should be of small dimension (circumferentially of ring 160) that is limited to be adequate to insure the lateral adjustability that is desired. In a commercial embodiment, the ends 160 and 164 are separated by a space of three thirtyseconds inch, in a ring 160 having an internal diameter of 1.182 inches, and an external diameter of l l 1/l6ths inches and a cross section of 1//4 inch diameter.

Bearing seat 30 is defined by the retainer portion 18 of the bearing tube 12, which has the cupped configuration shown in FIG. 1 defined by an internal shoulder and saucer shaped rim portion 172 that is shaped to substantially complement the configuration of the external surface 165 of ring 160 (excluding split 34). Rim portion 172 terminates in an edge portion 174 that projects axially from the bearing tube somewhat above the center line 176 of the bearing element (see FIG. 1), approximately to the extent that the extension 156 of the swivel member 28 projects below the center line 176 of the bearing element.

The portions of the bearing

seats

30 and 32 which contact the surface 165 of the bearing element 20 may be considered to be semi-torus or anchor ring shaped in cross-sectional configuration in view of the manner that they lap around a substantial portion of the surface 165 of the bearing element. It is to be noted that the seat 30 engages the lower one quarter or quadrant surface on the outer side of the bearing element while the seat 32 engages the upper one quarter or quadrant surface on the inner side of the bearing element.

In the device 10A, the bearing tube 12A is a two part structure including the combination retainer portion and collar assembly or member 80, which is shouldered as at 180 to rest on the end 182 of the bearing tube 12A. Member 80 is formed from any suitable mild steel and is machined to the shape indicated, it thereby defining a socket 184 in which the upper end 16A of the bearing tube is received.

Member 80 is of cup shaped configuration defining a base wall 186 that is bored as at 188 to receive the spindle threading 24, wall 186 being suitably relieved as at 190. Wall 186 includes an axially extending rim portion 192 shaped to define seat 30A and an axially extending flange portion 194 which forms the collar 54A.

Member 80 after being applied to tube 12A in the manner indicated in FIG. 8, on top of starred washer 52, is suitably spot welded to the bearing tube, and member 80, the washer and the bearing tube are welded together at the same locations as in the device 10 (see weld 104).

The device 10A is otherwise the same as device 10.

It will therefore be seen that the invention provides a chair base swivel arrangement for swivel chairs of highly simplified construction requiring a bearing element of minimum size and simplified nature. The complementary nature of the bearing element20 and the

seats

30 and 32 which engage same, together with the self adjusting nature of the bearing element provided by its split 162, insures a continuous area of contact about the circumference of the bearing between its split ends 164 and 166 along the opposed quadrant areas of the bearing ring circumferential surface that have been indicated. Only nominal lubrication is required for this invention as the material from which the bearing element is formed is self lubricating in nature. However, it is preferred that when the parts are assembled that the bearing seat 30 be lightly greased to insure that the two possible slip or wear surfaces contemplated by this invention are available. Also, swivel member 28 may be oil impregnated, if desired. As already indicated, since the area of contact between the bearing element 20 and seat 32 is of less area than the area of contact between the bearing element and bearing seat 30, normally the bearing element 20 will remain stationary on swiveling of the chair seat, and the parts that are fixed to same for rotation therewith, which includes the spindle 22, the swivel member 28, and the nut or hand wheel 26 when it is resting in interlocked relation with the swivel member 28. Having a slip or wear surface at the seat 30 makes for a more readily swivelable chair seat.

However, the slip or wear surface at the bearing seat 30 is always available in the event that the bearing element 20 becomes adhered to the seat 32 sufficiently so that slippage occurs at the seat 30 rather than at the seat 32.

lt should also be noted that both slip surfaces provided by

seats

30 and 32 are greater than what would be available if the bearing surface between the spindle and its support was at the outer surfaces 195 of the spindle threading 24. Furthermore, bearing element 20 is not only well spaced from the spindle threading, but is protected from it by swivel member end portion 156, which avoids undesirable contact between the bearing element and the spindle threads that could result in shaving of the bearing element or other premature wear.

As the bearing element 20 is not keyed to the spindle 22 in any way, its shape may be the simple O-ring or torus configuration that is indicated.

Tests of the swivel arrangement illustrated indicates that it satisfactorily withstands torture tests of the type applying a 250 pound load six inches off the center of the center line of the spindle, with the spindle being rotated relative to the base at approximately 30 rpm for 120,000 cycles.

The foregoing description and the drawings are given merely to explain and illustrate the invention and the invention is not to be limited thereto, except insofar as the appended claims are so limited, since those skilled in the art who have the disclosure before them will be able to make modifications and variations therein without departing from the scope of the inention.

We claim:

1. A chair base swivel arrangement comprising:

a base structure including an upright tubular member carrying an annular bearing seat at its upper end,

a one piece bearing element of anchor ring configuration and formed from antifriction material seated on said seat in substantial concentric relation therewith,

a swivel member seated on said bearing element and including a bearing seat engaging said bearing element,

said seats and said element lying in substantially parallel planes that are substantially normal to the axes thereof,

a chair seat having a threaded spindle received in said tubular member,

a nut removably seated on said swivel member and threadedly engaged with said spindle,

means for keying said swivel member against rotational movement relative to said spindle,

and means for releasably keying said nut to said swivel member,

said bearing seats defining substantially continuous and uninterrupted bearing surfaces for engaging said bearing element that substntially complement the surface portions thereof that are engaged thereby,

said tubular member seat engaging the lower outer quadrant of said bearing element surface.

and said swivel member seat engaging the inner upper quadrant of said bearing element surface,

said bearing element being interrupted to define two end portions in closely spaced relation whereby when said bearing element is engaged by said bearing seats said bearing element is biased into conformity therewith,

a post structure in which said tubular member is received and a plurality of leg elements fixed to and extending laterally of said post structure,

said post structure comprising:

an inner shell to which said leg elements are fixed,

an outer shell received over said inner shell in substantial concentric relation therewith and receiving said leg elements,

said tubular member extending through said inner shell at either end of the latter,

a cap closing off said tubular member at the lower end of same,

and means for fixing said tubular member to said inner shell at the lower end of same,

a starred washer applied to the upper end of said inner shell and within said outer shell,

said washer including triangular projections of equal radial lengths spaced thereabout engaging said outer shell,

and a collar applied between said tubular member seat and said washer for supporting said tubular member seat on the upper end of said inner shell.

2. The swivel arrangement set forth in claim l wherein:

said tubular member bearing seat is integral there with. 3. The swivel arrangement set forth in claim 1 wherein:

said tubular member seat comprises:

a hub member received on the upper end of said tubular member,

said hub member including said collar and being formed to define said tubular member seat.

4. The swivel arrangement set forth in claim 1 wherein:

said nut includes a skirt depending therefrom disposed in masking relation about said tubular member bearing seat and said collar,

said nut skirt and said outer shell being of substantially equal diameters and being in coaxial relation.

5. A chair base swivel arrangement comprising:

a chair seat having a threaded spindle received in said tubular member,

and means for releasably keying said nut to said swivel member,

said bearing seats defining substantially continuous and uninterrupted bearing surfaces for engaging said bearing element that substantially complement the surface portions thereof that are engaged thereby,

said tubular member seat engaging the lower outer quadrant of said bearing element surface,

a post structure in which said tubular membber is received and a plurality of leg elements fixed to and extending laterally of said post structure,

said post structure comprising:

an inner lshell to which said leg elements are fixed,

an outer shell received over said inner shell in sub stantial concentric relation therewithrand receiving said leg elements,

said washer including projections of equal radial lengths spaced thereabout said outer shell,

and an annular support applied between said tubular member seat and said washer for supporting said tubular member seat on the upper end of said inner shell.

6. In a swivel arrangement for chair bases of the type supporting a chair seat spindle, having a threaded portion, from a base structure, in which the swivel arrangement includes a tubular member receiving the spindle, means supporting said tubular member in upright position from said base structure, said tubular member having an upwardly facing annular bearing seat at its upper end, a bearing means seated on said bearing seat in substantial concentric relation therewith, a swivel member seated on said bearing means and including a downwardly facing annular bearing seat engaging said bearing means, a nut removably seated on said swivel member and including internal threading for threaded connection with the spindle threaded portion for supporting the latter on said tubular member, means for releasably keying said nut to said swivel member, and means for keying said swivel member against rotational movement relative to the spindle, the improvement wherein: said bearing means comprises a one piece torus shaped element formed from antifriction material and having a torus shaped'external surface,

with said bearing element'being free of keying connection to said spindle and to said seats,

said bearing seats each being of concave semitorus configuration substantially complementing the configuration of the surface portions of said bearing element they engage and each being proportioned to engage approximately an annular quadrant of said external surface of said bearing element, said bearing seats and said bearing element being spaced laterally of and about said spindle,

and said swivel member seat engaging the inner upper quadrant of said bearing element surface and being shaped to shield said bearing element from said spindle threaded portion,

wherebyv said swivel member seat and said bearing element define a first normally operative slip surface therebetween and said bearing element and said tubular member seat define a second contingency slip surface therebetween of greater area than said first slip surface,

and whereby said seats and said bearing element are in vertical and radial thrust transmitting relation.

7. The improvement set forth in claim 6 wherein:

said bearing element is split axially thereof to define two opposed end portions in closely spaced relation,

said bearing element being free to flex laterally thereof whereby said seats cam said element into centered relation therewith to accommodate tolerance variations.

8. The improvement set forth in claim 6 wherein said base structure comprises:

said post structure comprising:

an inner shell to which said leg elements are fixed,

an outer shell received over said inner'shell in substantial concentric relation therewith and receiving said leg elements,

said washer including projections of equal radial lengths spaced thereabout engaging said outer shell,

Claims

1. A chair base swivel arrangement comprising: a base structure incLuding an upright tubular member carrying an annular bearing seat at its upper end, a one piece bearing element of anchor ring configuration and formed from antifriction material seated on said seat in substantial concentric relation therewith, a swivel member seated on said bearing element and including a bearing seat engaging said bearing element, said seats and said element lying in substantially parallel planes that are substantially normal to the axes thereof, a chair seat having a threaded spindle received in said tubular member, a nut removably seated on said swivel member and threadedly engaged with said spindle, means for keying said swivel member against rotational movement relative to said spindle, and means for releasably keying said nut to said swivel member, said bearing seats defining substantially continuous and uninterrupted bearing surfaces for engaging said bearing element that substntially complement the surface portions thereof that are engaged thereby, said tubular member seat engaging the lower outer quadrant of said bearing element surface, and said swivel member seat engaging the inner upper quadrant of said bearing element surface, said bearing element being interrupted to define two end portions in closely spaced relation whereby when said bearing element is engaged by said bearing seats said bearing element is biased into conformity therewith, a post structure in which said tubular member is received and a plurality of leg elements fixed to and extending laterally of said post structure, said post structure comprising: an inner shell to which said leg elements are fixed, an outer shell received over said inner shell in substantial concentric relation therewith and receiving said leg elements, said tubular member extending through said inner shell at either end of the latter, a cap closing off said tubular member at the lower end of same, and means for fixing said tubular member to said inner shell at the lower end of same, a starred washer applied to the upper end of said inner shell and within said outer shell, said washer including triangular projections of equal radial lengths spaced thereabout engaging said outer shell, and a collar applied between said tubular member seat and said washer for supporting said tubular member seat on the upper end of said inner shell.

2. The swivel arrangement set forth in claim 1 wherein: said tubular member bearing seat is integral therewith.

3. The swivel arrangement set forth in claim 1 wherein: said tubular member seat comprises: a hub member received on the upper end of said tubular member, said hub member including said collar and being formed to define said tubular member seat.

4. The swivel arrangement set forth in claim 1 wherein: said nut includes a skirt depending therefrom disposed in masking relation about said tubular member bearing seat and said collar, said nut skirt and said outer shell being of substantially equal diameters and being in coaxial relation.

5. A chair base swivel arrangement comprising: a base structure including an upright tubular member carrying an annular bearing seat at its upper end, a one piece bearing element of anchor ring configuration and formed from antifriction material seated on said seat in substantial concentric relation therewith, a swivel member seated on said bearing element and including a bearing seat engaging said bearing element, said seats and said element lying in substantially parallel planes that are substantially normal to the axes thereof, a chair seat having a threaded spindle received in said tubular member, a nut removably seated on said swivel member and threadedly engaged with said spindle, means for keying said swivel member against rotational movement relative to said spindle, and means for releasably keying said nut to said swivel member, said bearing seats defining substantially continuous and uninterrupted bearing surfaces for engaging said bearing element that substantially complement the surface portions thereof that are engaged thereby, said tubular member seat engaging the lower outer quadrant of said bearing element surface, and said swivel member seat engaging the inner upper quadrant of said bearing element surface, a post structure in which said tubular membber is received and a plurality of leg elements fixed to and extending laterally of said post structure, said post structure comprising: an inner shell to which said leg elements are fixed, an outer shell received over said inner shell in substantial concentric relation therewith and receiving said leg elements, said tubular member extending through said inner shell at either end of the latter, and means for fixing said tubular member to said inner shell at the lower end of same, a starred washer applied to the upper end of said inner shell and within said outer shell, said washer including projections of equal radial lengths spaced thereabout said outer shell, and an annular support applied between said tubular member seat and said washer for supporting said tubular member seat on the upper end of said inner shell.

6. In a swivel arrangement for chair bases of the type supporting a chair seat spindle, having a threaded portion, from a base structure, in which the swivel arrangement includes a tubular member receiving the spindle, means supporting said tubular member in upright position from said base structure, said tubular member having an upwardly facing annular bearing seat at its upper end, a bearing means seated on said bearing seat in substantial concentric relation therewith, a swivel member seated on said bearing means and including a downwardly facing annular bearing seat engaging said bearing means, a nut removably seated on said swivel member and including internal threading for threaded connection with the spindle threaded portion for supporting the latter on said tubular member, means for releasably keying said nut to said swivel member, and means for keying said swivel member against rotational movement relative to the spindle, the improvement wherein: said bearing means comprises a one piece torus shaped element formed from antifriction material and having a torus shaped external surface, with said bearing element being free of keying connection to said spindle and to said seats, said bearing seats each being of concave semitorus configuration substantially complementing the configuration of the surface portions of said bearing element they engage and each being proportioned to engage approximately an annular quadrant of said external surface of said bearing element, said bearing seats and said bearing element being spaced laterally of and about said spindle, said tubular member seat engaging the lower outer quadrant of said bearing element surface, and said swivel member seat engaging the inner upper quadrant of said bearing element surface and being shaped to shield said bearing element from said spindle threaded portion, whereby said swivel member seat and said bearing element define a first normally operative slip surface therebetween and said bearing element and said tubular member seat define a second contingency slip surface therebetween of greater area than said first slip surface, and whereby said seats and said bearing element are in vertical and radial thrust transmitting relation.

7. The improvement set forth in claim 6 wherein: said bearing element is split axially thereof to define two opposed end portions in closely spaced relation, said bearing element being free to flex laterally thereof whereby said seats cam said element into centered relation therewith to accommodate tolerance variations.

8. The improvement set forth in claim 6 wherein said base structure comprises: a post structure in which said tubular member is received and a plurality of leg elements fixed to and extending laterally of said post structure, said post structure comprising: an inner shell to which said leg elements are fixed, an outer shell received over said inner shell in substantial concentric relation therewith and receiving said leg elements, said tubular member extending through said inner shell at either end of the latter, and means for fixing said tubular member to said inner shell at the lower end of same, a starred washer applied to the upper end of said inner shell and within said outer shell, said washer including projections of equal radial lengths spaced thereabout engaging said outer shell, and an annular support applied between said tubular member seat and said washer for supporting said tubular member seat on the upper end of said inner shell.