Swivel chair

Sept. 21, 1965

3,207,464

G. HRACH

SWIVEL CHAIR

Filed April 23, 1964

<img file="US3207464A_D0001.tif" />

United States Patent Office

3,207,464

Patented Sept. 21, 1965

3,207,464 SWIVEL CHAIR

Gordon Hrach, Bedford, Ohio, assignor to B, L. Marble Furniture, Inc., Bedford, Ohio, a corporation of Ohio

Filed Apr. 23,1964, Ser. No. 362,055

Claims. (Cl. 248—417)

This invention relates to chairs and, more particularly, to means for returning a swivel chair seat to a predetermined position.

Conventional swivel chairs, such as are provided at lunch counters, for example, have a base which is attached to the floor. A pedestal extends upright from the base and supports a seat for turning movement about the central axis of the pedestal. The chair, which usually has an upright back, may be turned to face away from the counter to facilitate getting into and out of the chair. A series of chairs are usually provided along the front of a counter and, since the chairs customarily are placed close together, it is necessary to turn the chair around to face in the direction away from the counter while getting into or out of the chair.

Where a row of chairs is provided along the front of a counter, it is desirable to provide some means for returning the chairs to a position facing toward the counter, when they are unoccupied. Otherwise, the empty chairs would be turned in a haphazard arrangement and they would give the counter a disorderly appearance.

Various devices have been suggested for urging swivel chairs toward a predetermined direction. In one form of self return swivel chair, for example, springs urge the chair toward a predetermined position when it is turned away from that position. The spring return type of swivel chair is objectionable because it urges the seat toward a front-facing position with a force which is proportional to the angular displacement of the seat. If the seat is given a relatively small angular displacement, the springs are ineffective and the seat may remain slightly turned from the desired position. The cam type swivel chair is also unsatisfactory because the occupant of the seat senses the vertical displacement of the seat as it rides up or down on the cam. This vertical movement causes the chair to appear to be unstable.

Another type of swivel chair includes a cam which urges the chair to return to a front facing position as soon as it is turned away from that position.

Many self-return swivel chairs are not capable of turning a full 360°. If the angular displacement of the chair is limited, it is more difficult to get in and out of the seat. Furthermore, the design and the shape of the chair back and arms is restricted, since there must be sufficient space between the chairs for a person to slide into and out of the seat. If the chair is capable of turning a full 360°, the arms and back of the chair do not hinder a person getting into and out of the seat.

A swivel type counter chair is subjected to severe wear and abuse and therefore it must be rugged in construction and capable of withstanding the wear over a long period of time. Since a large number of chairs usually are provided along the front of a counter, the swivel chair should be as inexpensive as possible. A slight cost saving in one self return chair therefore is multiplied many times in providing chairs for an entire counter. Heretofore, self return swivel chairs for counter seats have had relatively complicated and expensive self return devices.

In view of the defects of the prior self return swivel chairs it is an object of this invention to provide an improved self return swivel chair.

It is a further object of this invention to provide in a chair a self return swivel mechanism having a minimum number of components.

It is a still further object of this invention to provide a self return swivel chair which allows the seat to turn 360°.

These objects are accomplished in accordance with the preferred embodiment of the invention by a pedestal g tube which is fastened at its lower end to a base. A cam surface is formed on the upper end of the pedestal tube. A plurality of bushings are supported within the central bore of the pedestal tube and a spindle is mounted in telescoping relation in the pedestal to and is journalled 10 for rotation in the bushings. A chair seat is mounted on the upper end of the spindle and a roller is mounted on an axle extending radially outward from the spindle. The roller is supported on the cam surface for positioning the spindle longitudinally relative to the pedestal tube.

The bushings in the pedestal tube form a low friction bearing which allows both rotational and longitudinal movement of the spindle relative to the tube. The lower portion of the spindle has a wide radial groove formed therein and a set screw extends through the pedestal tube 20 and into the groove, but the end of the screw is spaced from the bottom of the groove. The groove is also substantially wider than the screw, which allows the spindle to rotate and to move axially relative to the pedestal tube as the roller rides over the cam. The set screw, 25 however, engages the side of the groove to prevent the spindle from being pulled out of the pedestal.

The pedestal tube is oriented so that the low portion of the cam surfaces faces the counter and the slope of the cam surface is sufficient to cause the seat which is 30 mounted on the spindle, to turn by its own weight to a position facing the counter. The roller has a low friction bearing and in combination with the bearing inserts in the pedestal tube, there is a minimum of frictional resistance to the turning of the seat.

This preferred embodiment of the invention is illustrated in the accompanying drawings in which:

FIG. 1 is a side elevational schematic view of the self return swivel chair of this invention;

FIG. 2 is an enlarged front elevational view of the 40 chair pedestal assembly of this invention;

FIG. 3 is an enlarged side elevation view, partially in section, of the chair pedestal assembly;

FIG. 4 is a cross sectional view of the pedstal assembly along the line 4—4 in FIG. 3; and

FIG. 5 is a schematic view of the cam surface profile.

Referring to FIG. 1, a counter 2 is shown schematically. Typically, the counter 2 would be provided with a plurality of swivel chairs which are arranged at spaced intervals along the front of the counter, although only 50 one chair 4 is shown in FIG. 1. Each of the counter chairs 4 includes a base 6 which is secured to the floor, an upright pedestal tube 8, and a spindle 10 which is telescoped in the tube 8. A seat 12 is mounted on the upper end of the spindle 10 and a back 14 is supported 55 by the seat 12.

As shown in the enlarged views of FIGS. 2 and 3, the pedestal tube 8 has a central bore 16 of a relatively large diameter and a bore 18 of a smaller diameter, with a shoulder 20 between the bores 16 and 18. The pedestal 60 tube 8 is secured to the base 6 by a bolt, not shown, which extends through a threaded hole 22 and into a corresponding hole in the base 6. A plurality of cylindrical bushings 24 are inserted in the bore 16 in the tube 8 and the lowermost bushing 24 is supported on the shoulder 65 20. The bushings are preferably formed of bronze and have substantially the same dimensions.

The pedestal tube 8 has a cam surface 26 formed on the upper end thereof. The spindle 10 is telescoped in the tube 8 and an axle 28 is secured in the spindle 10 and ex1° tends radially outward from the spindle. As shown in FIGS. 2 and 3, a roller 30 is mounted for rotation on the

3,207,464 radial axle 28 and the roller 30 rests on the cam surface 26.

At its lower end, the spindle 10 has a wide radial groove 32 formed therein. A screw 34 extends radially through the wall of the pedestal tube 8 and into the groove 32. The end of the screw 34, however, is spaced from the bottom of the groove 32, so that the screw does not interfere with the rotation of the spindle. Axial movement of the spindle 10 also is restricted except when the spindle 10 has been displaced to such an extent that the screw 34 engages the side wall of the groove 32. As the spindle 10 rotates, the roller 30 rides on the cam 26 and the groove 32 is sufficiently wide to allow the spindle 10 to move axially upward as the roller rides over the high portion of the cam surface 26. The profile of the cam 26 is shown schematically in FIG. 5. As the spindle 10 turns through 360°, the roller 30 lifts the spindle 10 upwardly relative to the pedestal tube 10.

As shown in FIG. 1, the seat 12 is mounted on the spindle 10 with the front of the seat facing toward the counter 2 and with the roller 30 oriented at the lowermost portion of the cam surface 26. When the chair 4 is assembled as shown in FIG. 1, the seat 12 may be turned by the occupant away from the counter 2 while getting into and out of the seat. As the seat 12 is turned relative to the pedestal 8, the roller 30 rides up on the sloping portion of the cam 26 and when the seat 12 is released, the force of gravity on the seat 12 urges the roller 30 toward the lowest portion of the cam 26. Accordingly, the seat 12 is returned to the position facing the center. Since the cam surface is substantially sinusoidal, as shown in FIG. 5, the maximum force urging the seat 12 toward a front facing position is applied when the seat is turned substantially 90° from the position facing the counter, where the slope of the cam surface 26 is a maximum. At the lowermost position of the roller 30 on the cam surface 26, the slope of the cam surface 26 is relatively small, thereby permitting a slight turning of the seat by the occupant with only a minimal restoring force urging the seat toward a position facing the counter.

Since the roller 30 rides freely on the cam surface 26, and the bushings 24 minimize the friction between the pedestal 8 and the spindle 10, the slope of the cam and the total rise of the spindle on the cam 26 are small. A benefit due to the low frictional resistance is that the cam surface has only a slight vertical rise and as the seat turns, the vertical displacement of the seat relative to the pedestal is almost imperceptible to a person sitting on the seat. The restoring force due to the weight of the seat on the cam is sufficient, however, to return the seat to a position facing the counter when the seat is unoccupied. Accordingly, the seat is more comfortable to get into and out of and it is more stable. The swivel mechanism of this invention may be easily replaced or repaired simply by unscrewing the screw 34 and lifting the spindle 10 out of the tube 8. When the spindle 10 has been removed, the bushing 24 may be inspected and replaced, if necessary.

While this invention has been illustrated and described in one embodiment, it is recognized that variations and changes may be made therein without departing from the invention as set forth in the claims.