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Publication numberUS3667716 A
Publication typeGrant
Publication dateJun 6, 1972
Filing dateAug 31, 1970
Priority dateAug 31, 1970
Also published asCA946725A1
Publication numberUS 3667716 A, US 3667716A, US-A-3667716, US3667716 A, US3667716A
InventorsFries Bernard J
Original AssigneeSteelcase Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Telescoping chair base
US 3667716 A
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Description  (OCR text may contain errors)

June 6, 1972 B. J. FRIES 3,667,716

TELESCOPING CHAIR BASE Filed Aug. 31, 1970 2 Sheets-Sheet 1 INVENTOR. 5EAJ40 J FEAQS June 6, 1972 B. J. FRIES TELESCOPING CHAIR BASE Filed Aug. 31, 1970 2 Sheets-Sheet 2 INVENTOR,

35611420 u. FF/S BY f,

United States Tatent O1 ce US. Cl. 248-405 11 Claims ABSTRACT OF THE DISCLOSURE A threaded chair spindle is threadably carried by a nut which is rotatably supported by a hub tube such that the lower bearing surface of the spindle extends within the hub tube. A spindle cover tube is longitudinally fixed with respect to said spindle and encloses the threaded portion of the spindle but can be rotated with respect to the spindle. An elongated, vertical rib projects in wardly from the inside surface of the spindle cover tube and mates with a vertical groove in the side of the nut so that the spindle and the spindle cover tube can be raised or lowered by rotating the spindle cover tube with respect to the spindle.

BACKGROUND This invention relates to height adjustable, rotatable chair bases. One problem which exists with respect to such bases is that the threads of the spindle are exposed as the chair is raised and the spindle is threaded out of its bell nut and hub tube. Because the spindle must rotate freely within the hub tube and because it must thread smoothly in its bell nut, the spindle and hub tube assembly must be lubricated. As the spindle threads become exposed, the lubrication on the spindle also becomes exposed and can readily pick up dust and dirt. This reduces the efficiency of operation of the hub tube and spindle assembly and may ultimately decrease the useful life of one or more components thereof. Also, when the spindle is threaded upwardly out of the hub tube, the person using the chair becomes exposed to the lubrication on the spindle and may get lubricant spots on his clothing.

Various types of telescoping bases have been provided in the art in an attempt to eliminate the aforesaid undesirable features of a height adjustable, rotatable chair base. However, the solutions offered by these bases are not entirely satisfactory, generally because they utilize complicated mechanisms. One problem in particular is created by the fact that these systems generally require the use of a special connection between the spindle and the chair base. For example, rather than the spindle being connected directly to the chair iron or chair control in a conventional manner, the chair control will frequently be constructed so as to rotate directly on the spindle.

The present invention provides a spindle cover tube for at least partially enclosing a spindle. -A nut is threaded onto the spindle and means are provided for slidably engaging the spindle cover tube with the nut such that rotation of the tube with respect to the spindle causes the spindle to thread in the nut moving the spindle and the longitudinally fixed tube vertically with respect to the nut.

Thus in this invention, the spindle threads and the adjusting nut for the spindle are hidden from view. The lubricated portions of the hub tube and spindle assembly are always enclosed such that dust and dirt are prevented from interfering with the efiiciency of operation of the chair base. Similarly, oil stains on clothing and the like are prevented. Finally, it is significant that in this 3,667,716 Patented June 6, 1972 invention, it is not necessary to use a special construc tional type of construction between the chair spindle and the chair control can be utilized.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and advantages of the invention can be seen by reference to the specification and to the appended drawings wherein:

FIG. 1 is a perspective view of the chair base;

FIG. 2 is a cutaway-cross-sectional view of the chair base with the spindle being threaded to its uppermost position;

FIG. 3 is a cutaway-cross-sectional view of the chair base with the spindle being threaded to its lower most position;

FIG. 4 is a perspective view of the top portion of the chair base with the spindle cover tube removed; and

FIG. 5 is a plan view of the chair base without legs and with a portion of the top of the spindle cover tube being cutaway.

PREFERRED EMBODIMENT Referring to FIG. 1, the visible portions of the chair base include the top portion of spindle 10, spindle cover tube 20, hub cover tube 50 and legs 60. Referring to FIGS. 2 and 3, it can be seen that spindle 10 is threaded in nut 30 which is carried on hub tube 40 such that spindle 10 extends thereinto. Cover tube 20 is longitudinally supported by or fixed to spindle 10 but is free to rotate with respect thereto. It encloses the threaded portion of spindle 20 and it slidably engages nut 30 by means of rib 22 mating groove 31 *(FIG. 5) such that rotation of spindle cover tube 20 causes both it and spindle 10 to move vertically. Spindle cover tube 20 moves vertically within hub cover tube 50 and is always at least partially within hub cover tube 50 regardless of the relative vertical position of spindle 10. Legs 60 extend through hub cover tube 50 and are secured to hub tube 40 such that a support for the base is provided.

Spindle 10 is a conventional member having a threaded portion 11 for threading in nut 30. It includes a bearing surface 12 to facilitate rotation within hub tube 40. Finally, it includes a tapered head 13 to facilitate its assembly with a chair control in a conventional manner.

Spindle cover tube 20 at least partially encloses spindle 10 to the extent of enclosing threaded portion 11. It has a top 21 with a hole therein such that it fits down over tapered head 13 of spindle 10. Top 21 rests on the uppermost thread of threaded portion 11, but it is not rigidly secured to spindle 10. Thus spindle cover tube 20 is rotatable with respect to spindle 10 even though it is designed to be longitudinally fixed thereto for simultaneous vertical movement therewith.

Spindle cover tube 20 also includes an elongated, generally vertical rib 22 on its inside surface (FIGS. 2 and 3). This can be formed by welding a rod to the inner surface of spindle cover tube 20 (FIG. 5). Rib 22 should extend for a distance at least equal to the height of threaded portion 11 of spindle 10. Usually, this will be equal to the height of spindle cover tube 20 but need not necessarily be so.

Nut 30 is threaded onto threaded portion 11 of spindle 10. It includes a generally vertical groove 31 in its outside circumferential surface which extends the height of nut 30 (FIG. 4). Groove 31 is provided for mating engagement with rib 22 on spindle cover tube 20. Nut 30 also includes a downwardly depending skirt 32 having a small setscrew 33 therein, both of which facilitate the mounting of nut 30 and spindle 10 in hub tube 40. A separate washer 34 is provided for the same purpose.

Hub tube 40 is of a conventional tubular construction and is provided with a separate tubular bushing member 41 which is usually constructed of nylon. Bushing 41 thus provides a self-lubricating bearing surface for spindle 10, particularly the bearing portion 12 thereof. Bushing 41 is locked to hub tube 40 by means of key members 43 protruding through apertures in hub tube 40. Bushing 41 also includes a flanged top 42 which provides a bearing surface for Washer 34 and which also acts as an engaging lip for setscrew 33.

Hub tube 40 is enclosed by hub cover tube 50. The bottom 51 thereof has a hole which fits over hub tube 40 and hub cover tube 50 is welded to hub tube 40 at the circumference of that hole. Hub cover tube 50 includes a plurality of apertures or slots which allow legs 60 to extend through hub cover tube 50 and be welded to hub tube 40. Thus in the preferred embodiment, hub cover tube 50 is included mainly for decorative purposes rather than structural purposes. A plurality of legs 60 are welded to hub tube 40 and extend laterally therefrom to provide the support for the base.

In assembling the various components, legs 60 are first welded to hub tube 40. Hub cover tube 50 is slipped over hub tube 40 at the bottom. Bushing 41 is inserted into hub tube 40 until projections 43 snap into place and flange 42 rests on the top of hub tube 40.

Washer 34 is placed on top of flange 42. Nut 30 is threaded onto spindle and spindle 12 is then inserted into hub tube 40 and is forced downwardly until nut 30 comes to rest atop washer 34. Skirt 32 then shrouds washer 34 and flange 42, thus holding washer 34 in place. Setscrew 33 is threaded inwardly such that it extends under flange 42, thus allowing spindle 10 to rotate in hub tube 40 but preventing it from being separated therefrom.

Finally, spindle cover tube is slipped over spindle 10 and a chair control is then rigidly secured to tapered head 13. Thus, while spindle cover tube 20 is free to rotate with respect to spindle 10, it is maintained against any substantial vertical movement with respect thereto by the top of threaded porion 11 below, and the chair control above.

OPERATION In operation, a chair control of a chair seat is rigidly secured to tapered head 13 of spindle 10. When a person rotates the chair, spindle '10, spindle cover tube 20, and nut will rotate on Washer 34 which in turn rotates on flange 42 of bushing 41. If a person desires to elevate the chair, he merely rotates the chair and spindle 10 while grasping spindle cover tube 20 to hold it against rotation. Because rib 22 on spindle cover tube 20 mates with groove 31 or nut 30, nut 30 is also held against rotation with respect to spindle 10 and spindle 10 thereby threads either upwardly or downwardly in nut 30. Because spindle cover tube 20 is supported by the uppermost thread of spindle 10, and because it is prevented from moving upwardly with respect to spindle 10 by the presence of the chair control on tapered head 13, it must also move upwardly or downwardly with respect to nut 30. This movement is facilitated by the fact that rib 22 on spindle cover tube 20 slidably engages groove 31 and thereby allows spindle cover tube 20 to slide upwardly or downwardly with respect to nut 30. Thus, by holding spindle cover tube 29 against rotation with respect to spindle 10, one can cause both spindle 10 and spindle cover tube 20 to move vertically with respect to nut 30'.

As spindle 10 and spindle cover tube 20 are adjusted vertically, spindle cover tube 20 telescopes within hub cover tube 50. Hub cover tube 50 is just slightly larger in diameter than spindle cover tube 20 such that this telescoping action is facilitated. The relative heights of spindle cover tube 20 and hub cover tube 50 are such that spindle cover tube 20 is always at least partially within hub cover tube 50, even when spindle 10 is threaded to its uppermost position as shown in FIG. 2.

More specifically, the height of spindle cover tube 20 is such that it closes the entire threaded portion 11 of spindle 10. This causes threaded portion 11 to be enclosed regardless of its relative vertical position and eliminates the necessity of using an excessively long hub cover tube 50. Additionally, it facilitates the mating action of rib 22 and groove 31 since, by extending the height of spindle cover tube 20, rib 22 will be sufficiently long that it can never be elevated out of engagement with groove 31 in nut 30. If it were desired to utilize a longer spindle cover tube 20, rib 22 would only need to be as long as the height of threaded portion 11 of spindle 10 in order that the same end would be accomplished.

If for any reason it were desired to remove spindle 10, spindle cover tube 20 and nut 30 from the rest of the base, a small aperture is provided in spindle cover tube 20 such that setscrew 33 would be accessible merely by adjusting spindle 10 to its uppermost position. .In the alternative, one could first remove the chair control from tapered head 13 and then remove spindle cover tube 20 in order to permit access to setscrew 33. By turning setscrew 33 outwardly, the entire upper assembly of spindle 10, spindle cover tube 20 and nut 30 can be disengaged from the lower assembly of hub tube 40, hub cover tube 50 and legs 60. This will facilitate lubrication, repair, etc.

In light of the above disclosure, it can be seen that this invention provides a unique telescoping base assembly wherein the threads and adjusting nut are always hidden from view. This prevents exposure of the lubricated parts of the chair base assembly from dust and dirt and similarly protects the clothing of the chair user from becoming spotted with grease. Furthermore, these goals are accomplished with a mechanism which requires no special connection between the chair control and the chair spindle. Rather, a conventional assembly therebetween is facilitated.

It is understood that the above is merely a preferred embodiment of the invention and that a number of changes and alterations can be made thereof Without departing from the spirit and broader aspects of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

1. A chair base comprising: a threaded spindle for connection to a chair; a spindle cover tube longitudinally fixed with respect to said spindle, at least partially enclosing said spindle, and being rotatable with respect thereto; a nut threaded onto said spindle; means for slidably engaging said spindle cover tube with said nut such that rotation of said spindle cover tube with respect to said spindle causes said spindle to thread in said nut thereby moving said spindle and said spindle cover tube vertically with respect to said nut.

2. The chair base of claim 1 comprising: a hube tube rotatably supporting said nut with said spindle extending into said hub tube; said spindle cover tube enclosing at least that portion of said spindle which is threaded such that said nut is also enclosed by said spindle cover tube even when said spindle is threaded to its uppermost position.

3. The chair base of claim 1 comprising: a hub tube rotatably supporting said nut with said spindle extending into said hub tube; a hub cover tube at least partially enclosing said hub tube and having a diameter larger than that of said spindle cover tube such that said spindle cover tube can move vertically within said hub cover tube; the respective lengths of said spindle cover tube and said hub cover tube being such that said spindle cover tube is within said hub cover tube even when said spindle is threaded to its uppermost position.

4. The chair base of claim 3 comprising: said spindle cover tube being of sufficient length to enclose the threaded portion of said spindle.

5. The chair base of claim 1 in which said means for slidably engaging comprises: one of said nut and said spindle cover tube having a groove, the other having an elongated rib in mating engagement with said groove; said groove or said rib in said nut extending generally vertically the height thereof; said groove or said rib in said spindle cover tube extending generally vertically therein and being of a length equal at least to the length of the threaded portion of said spindle.

6. The chair base of claim 2 in which said means for slidably engaging comprises: one of said nut and said spindle cover tube having a groove, the other having an elongated rib in mating engagement with said groove; said groove or said rib in said nut extending generally vertically the height thereof; said groove or said rib in said spindle cover tube extending generally vertically therein and being of a length equal at least to the length of the threaded portion of said spindle.

7. The chair base of claim 3 in which said means for slidably engaging comprises: one of said nut and said spindle cover tube having a groove, the other having an elongated rib in mating engagement with said groove; said groove or said rib in said nut extending generally vertically the height thereof; said groove or said rib in said spindle cover tube extending generally vertically therein and being of a length equal at least to the length of the threaded portion of said spindle.

8. The chair base of claim 4 in which said means for slidably engaging comprises: one of said nut and said spindle cover tube having a groove, the other having an elongated rib in mating engagement with said groove; said groove or said rib in said nut extending generally vertically the height thereof; said groove or said rib in said spindle cover tube extending generally vertically therein and being of a length equal at least to the length of the threaded portion of said spindle.

9. A chair base comprising: a threaded spindle for rigid connection to a chair control; a nut threaded onto said spindle; a spindle cover tube enclosing at least the threaded portion of said spindle and being maintained in fixed vertical relationship with respect to said spindle; a hube tube rotatably supporting said nut with said spindle extending into said hub tube; means for holding said nut against rotation with respect to said spindle whereby said spindle cover tube and said spindle can be moved vertically with respect to said nut.

10. The chair base of claim 9 comprising: a hub cover tube at least partially enclosing said hub tube and having a diameter larger than that of said spindle cover tube such that said spindle cover tube can move vertically within said hub cover tube; the respective length of said spindle and hub cover tubes being such that said spindle cover tube is within said hub cover tube even when said spindle is threaded to its uppermost position.

11. The chair base of claim 10 in which said means for holding said nut against rotation with respect to said spindle comprises: means for slidably engaging said spindle cover tube with said nut such that rotation of said spindle cover tube with respect to said spindle causes said spindle to thread in said nut thereby moving said spindle and said tube vertically with respect to said nut.

References Cited UNITED STATES PATENTS 2,219,844 10/1940 Lotter et a1. 248--l57 2,590,382 3/1952 Danielson 248-157 2,999,665 9/1961 Ericson 248-405 3,218,021 11/v965 Michalshi 248-405 X 3,439,893 4/1969 Haquette 248-405 J. FRANKLIN FOSS, Primary Examiner US. Cl. X.R.

2 3 5 UNITED STATES PATENT eFFicE QERTIFICATE OF GGRRECTWN Patent No. 3 667 '716 Dated June 6, 1972 Inventofl B. J. Fries It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 2, lines 1, 2 and 3;

After "special" insert construction for securing the chair spindle to the chair.

Rather, a conventional Col. 4, line 2;

"closes" should be -enc1oses- C01. 4, line 55;

"hube" should be hub Col. 6, line 4;

"hube" should be hub Signed and sealed this 28th day of November 1972.

(SEAL) Attest:

EDWARD M.FLET(?HER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3727871 *Apr 14, 1972Apr 17, 1973Harper HSeat-height adjustment device
US4308863 *Oct 18, 1979Jan 5, 1982Ace Orthopedic Manufacturing, Inc.External fixation device
US4598892 *Jul 27, 1984Jul 8, 1986Haworth, Inc.Mechanical chair-height control mechanism
US5116004 *May 10, 1991May 26, 1992New Focus, Inc.Vertically adjustable mounting post for optical element
US5385323 *Oct 14, 1993Jan 31, 1995Garelick; Richard J.Telescoped tubular support members
US6550728Aug 2, 2002Apr 22, 2003Heidt Products Inc.Height adjustable table
WO1986000974A1 *Jul 23, 1985Feb 13, 1986Haworth IncMechanical chair-height control mechanism
WO1992020953A1 *May 8, 1992Nov 26, 1992New Focus IncVertically adjustable mounting post for optical element
Classifications
U.S. Classification248/405, 108/147, 248/188.4
International ClassificationA47C3/20, A47C3/24
Cooperative ClassificationA47C3/24
European ClassificationA47C3/24