US3390421A

US3390421A - Chair base

Info

Publication number: US3390421A
Application number: US518710A
Authority: US
Inventors: William H Sullivan
Original assignee: B L MARBLE FURNITURE Inc
Current assignee: B L MARBLE FURNITURE Inc
Priority date: 1966-01-04
Filing date: 1966-01-04
Publication date: 1968-07-02
Anticipated expiration: 1985-07-02

Description

July 2, 1968 w. H. SULLIVAN CHAIR BASE Filed Jan. 4, 1966 INVENTOR 14/14/41 swan/4A4 B P A ATTORNEY$ United States Patent 3,390,421 CHAIR BASE William H. Sullivan, Shaker Heights, Ohio, assignor to The B. L. Marble Furniture, Inc, Bedford, 01:10, a corporation of Ohio Filed (Ian. 4, 1966, Ser. No. 518,710 12 Claims. (Cl. 16-30) ABSTRACT OF THE DISCLOSURE A caster assembly for a chair base of the type having outwardly extending legs. The caster assembly includes a scuff plate positioned on top of the leg and a caster assembly positioned under the bottom of the leg. The scuff plate has a screw socket for receiving a threaded screw which is secured at its base to the chair caster and extends through the leg where it is threadedly engaged in the socket. The threaded connection permits opposed bearing surfaces on the scuff plate and on the caster assembly to be clamped rigidly against the chair leg.

This invention relates to chairs and more particularly to swivel chair bases.

Chairs of the typical office type have four legs extending outward from the center of the base. The seat is mounted on an upright post that is received in a socket in the center of the base, and the chair seat swivels relative to the base. Casters support the outer ends of the legs for rolling the chair over the floor.

Usually, the chair casters have stems and sockets are drilled in the wood legs of the base for receiving the caster stems. The caster stems are held in the sockets by friction. After the chair has been in use for a period of time, the lateral force exerted by the roller on the stem causes the stem to enlarge the socket, so that the caster drops out. Another method of mounting a caster stem in a chair is to .drive the stem of the caster directly into the wood. In this type of mounting the stem is serrated to prevent turning relative to the leg and is glued in the socket. Even this type of rigid mounting ultimately allows the caster to work free and to drop out of the socket.

Another difficulty encountered with chair casters is that the stems of the casters may be bent during shipping. When this occurs, the socket becomes enlarged and the caster drops out. Usually, the only remedy when the socket becomes enlarged is to replace the entire wood chair base, which is expensive. Attempts to fix a wood base having an enlarged caster stem socket have been found to be generally unsatisfactory.

Accordingly, it is an object of this invention to provide an improved wood chair base of the type having casters on the legs.

It is another object of this invention to provide a caster mounting for a wood chair base that securely maintains the caster stem in the base.

It is a further object of this invention to provide an improved wood chair base having a scuff plate and a caster securely mounted on each leg.

These objects are accomplished in accordance with a preferred embodiment of the invention by a chair base in which the casters under each leg are supported by a stem which extends through a hole in the leg. A scuff plate is applied to the top of each leg and each scuff plate has a socket that is aligned with the hole in the leg. The end of the caster stem is secured in the scuff plate socket and the stem does not turn relative to the chair leg.

This preferred embodiment is illustrated in the accompanying drawings in which FIG. 1 is a perspective view of a chair base having the caster mounting of this invention;

FIG. 2 is a side elevational view of one of the legs, partially in cross section;

FIG. 3 is a cross sectional view of the leg along the line 3-3 in FIG. 2; and

FIG. 4 is a cross sectional view of the leg along the line 4--4 in FIG. 2.

As shown in FIG. 1, a chair base 2 has a center portion 4 which supports an upright seat post (not shown). The base also includes outwardly extending legs 6. Each of the legs is provided with a caster assembly 8. At the top of each leg 6 there is a scuff plate 10. The scuff plates .10 are at the outer ends of the legs to protect the base from becoming marred and to protect the shoes of the chairs occupant. Preferably, the scuff plates 10 are formed of a plastic material.

As shown in FIG. 2, the leg 6 has a recess 12 t0 accommodate the scuff plate, so that the upper surface of the plate is substantially in alignment with the top surface of the leg 6. The edges of the scuff plate adjacent the leg 6 have recessed

shoulders

14 and 16. The scuff plate 10 has a rounded end portion and rounded longitudinal edges and is reinforced by a rib 18 which extends longitudinally through the scuff plate. A boss 20 is formed integrally in the scuff plate and projects into a socket 22 that is formed in the leg 6. A tubular insert 24 is secured in the boss 20 and has a flange 26 which abuts against the bottom of the socket 22. The insert 24 is secured in the boss 22 by a rib 28 which engages a corresponding groove 30 in the insert 24. Preferably, the scuff plate 10 is molded around the insert 24, so that the insert is rigidly secured in the scuff plate. The frictional engagement between the insert and the boss and between the flange 26 and the socket 22 resists turning of the insert relative to the leg 6.

A bore 32 of a substantially smaller diameter than the socket 22 extends through the leg 6 in alignment with the socket 22. A stem 34 on the caster assembly 8 extends through the bore 32. The diameter of the bore 32 is only slightly larger than that of the stem 34 so that the bore 32 fits closely around the stem to resist bending of the stem. External threads 36 on the stem 34 engage internal threads 38 in the insert 24. At the base of the stem 34 there is a circular plate 40 which fits in the recess 42 in the leg 6. As shown in FIG. 2, the bottom of the recess 42 extends substantially at right angles to the axis of the stem 34. Preferably, the plate 40 has radial grooves in its upper surface which bite into the wood at the bottom of the recess 42 to resist turning of the plate relative to the leg 6.

The plate 40 forms the upper race of a ball bearing assembly 44. A wheel 46 is mounted on a bracket 48 and the bracket 48 is journaled on the stem 34 for turning movement relative to the leg 6. The stem 34 extends through the ball bearing assembly 44 and through the bracket 48. A head 50 is formed on the end of the stem 34, preferably by cold working after the parts are assembled on the stem. Of course, any other suitable arrangement for mounting the bracket 48 on the stem 34 which permits the bracket 48 to turn relative to the stem could be substituted for the assembly shown in FIGS. 2 and 3.

The caster assembly of this invention is mounted in a chair leg 6 in which the recess 12, the socket 22, the bore 32 and the recess 42 have been formed. The caster assembly' 8 is preferably assembled as a unitary structure with the bracket 48, and the ball bearing assembly 44 secured on the stem 34 by the head 50. The stem 34 is inserted through the bore 32 until the plate 40 is positioned against the bottom of the recess 42, as shown in FIGS. 2 and 3. The scuff plate 10 is then assembled on the leg 6 by inserting the boss 20 into the socket 22 until the internal threads 38 in the insert 24 engage the threads 36 on the end of the stem 34. The plate 40 is then rotated relative to the scuff plate .10 until the stem 34 has been threaded into the insert 24 to such an extent that the scuff plate is rigidly secured in the recess 12 and the plate 40 is pressed tightly against the bottom of the recess 42. In this manner, the stem 34 is tightly secured in the leg 6.

The outer surface of the boss has a substantially larger diameter than the stem 34. Therefore, the boss otters resistance to transverse forces tending to enlarge the socket 22 and the bore 32. Accordingly, the caster assembly 8 remains tightly affixed to the base 6 and provides a long service life for the chair base.

If the caster assembly should become worn, or for some other reason needs to 'be replaced, the caster assembly can be removed from a chair leg 6, by unscrewing the stem 34 from the insert 24. Then, a new caster assembly may be installed in the leg 6.

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.

I claim:

1. A caster assembly for a chair base having an outwardly extending leg comprising a scuff plate, a caster said scuif plate and said caster each having opposed bearing surfaces, and means for securing together said plate and said caster said securing means including means for adjusting the distance between said opposed surfaces, whereby the scuff plate and the caster may be clamped against opposite sides of said chair leg,

2. The caster assembly according to claim 1 wherein said securing means includes a stem extending between said caster and said scuff plate, said securing means including screw thread means for adjusting the distance between said caster and said scuff plate.

3. The caster assembly for a chair base having an outwardly extending leg comprising: a scuff plate on one side of said leg, a caster on the opposite side of said leg, and means for securing together said plate and said caster, said scuff plate having a boss projecting toward said caster and said securing mean including a stem on said caster, said stern threadedly engaging said boss.

4. The caster assembly according to claim 1 wherein said caster has a bearing plate in position to engage said leg and said securing means includes a stem fastened to said bearing plate.

5. The caster assembly for a chair base having an outwardly extending leg comprising a scuff plate on one side of said leg, a caster on the opposite side of said leg, and means for securing together said plate and said caster, said caster having a bearing plate in position to engage said leg, said securing means including a stern fastened to said bearing plate, said stem being threaded at the end opposite said bearing plate and said scuff plate being threadedly secured to said stern opposite end.

6. The caster assembly for a chair base having an outwardly extending leg comprising: a scuff plate on one side of said leg, at caster on the opposite side of said leg, and means for securing together said plate and said caster, said scuff plate having a boss, said boss having a threaded socket therein, and said securing means including a stem on said caster, said stem having threads on the end opposite said caster, said stem threads engaging the threads in said socket.

7. The caster assembly according to claim 6 wherein said boss has an insert therein, said insert including said socket and being metallic, and said boss being plastic.

8. The caster assembly according to claim 6 wherein said boss includes an insert, said insert including said socket and having a flange extending across the end of said boss, and flange having a substantially larger diameter than said stem.

9. The caster assembly according to claim 3 wherein said scuff plate has ribs supporting said boss.

10. A caster mounting assembly comprising a chair leg having upper and lower sides, said leg sides being in opposed relation, a scuff plate at said upper side, a caster at lower side, said leg having a bore extending between said upper and lower sides, said caster having a bearing surface engaging said lower side, said scutf plate having a bearing surface engaging said upper side, a stem extending through said bore, means securing one end of said stem to said caster and the opposite end to said scuff plate, said securing means including screw threads for adjusting the distance between said scuff plate and said caster.

11. The caster mounting assembly according to claim 10 wherein said leg has a recess at said upper side, said recess and said scuff plate cooperating to resist turning of said scuff. plate relative to said leg.

12. A caster mounting assembly according to claim 10 wherein said scuff plate has a boss aligned with said leg 'bore, said screw threads are on said stem opposite end and on said boss, whereby said stem and boss are adjustably secured together.

References Cited UNITED STATES PATENTS 2,217,754 10/1940 Johnson 248-3451 2,292,445 8/1942 Hilldring 248-3451 2,587,886 3/1952 Penchoen 248188.7 2,954,637 10/1960 Scherer 248-3451 2,992,803 7/1961 Good 248188.7 3,148,855 9/1964 Hamilton 248-l88.7

BOBBY R. GAY, Primary Examiner. MARVIN A. CHAMPION, Examiner. D. TROUTMAN, Assistant Examiner.