US3805320A

US3805320A - Article of manufacture

Info

Publication number: US3805320A
Application number: US00319768A
Authority: US
Inventors: K Bocksch; W Hensel
Original assignee: Mauser KG
Current assignee: Mauser KG
Priority date: 1972-01-03
Filing date: 1972-12-29
Publication date: 1974-04-23
Anticipated expiration: 1991-04-23
Also published as: IT972878B; FR2166366A1; FR2166366B3; JPS4877551A; BE793143A; BR7300053D0

Abstract

A caster for chairs has a circular hub through which an axle extends centrally with end portions projecting beyond opposite axial sides thereof. A pair of rollers are each journalled on one of these end portions and the hub is provided with a socket by means of which it can be mounted for pivoting movement about an upright axis which is laterally offset from and extends normal to the axle. A nose projects from the outer circumferential face of the hub below the socket and is bounded by two outer surfaces which extend from the outer circumferential face substantially parallel to and circumferentially normal to the axis, respectively.

Description

United States Patent [191 Bocksch et al.

ARTICLE OF MANUFACTURE Inventors: Karl Bocksch, Arolsen; Willi Hensel,

Willingen, both of Germany Mauser Kommanditgesellschaft, Koeln, Germany Filed: Dec. 29, 1972 Appl. No.: 319,768

Assignee:

Foreign Application Priority Data Jan. 3, 1972 Germany 2200062 References Cited UNITED STATES PATENTS 11/1933 Wilson ..16/18 A 12/1950 Schultz 16/18 GG [111 3,805,320 [451 Apr. 23, 1974 3,719,370 3/1973 Gintick 16/18GG 2,423,659 7/1947 Rabe 297/310 Primary Examiner-Bobby R. Gay Assistant Examiner-Doris L. Troutman Attorney, Agent, or FirmMichael S. Striker [57] ABSTRACT A caster for chairs has a circular hub through which an axle extends centrally with end portions projecting beyond opposite axial sides thereof. A pair of rollers are each journalled on one of these end portions and the hub is provided with a socket by means of which it can be mounted for pivoting movement about an upright axis which is laterally offset from and extends normal to the axle. A nose projects from the outer circumferential face of the hub below the socket and is bounded by two outer surfaces which extend from the outer circumferential face substantially parallel to and circumferentially normal to the axis, respectively.

6 Claims, 4 Drawing Figures PATENTEU APR 23 I974,

ARTICLE OF MANUFACTURE BACKGROUND OF THE INVENTION The present invention relates generally to articles of manufacture, and more particularly to a caster for chairs and the like.

Casters are already well known in many different types and uses. The present invention is particularly concerned with casters which are employed on chairs and similar seating-type furniture and wherein a circular hub is provided with an axially extending axle on opposite end portions of which are journalled rollers for rotation relative to the hub. The hub itself is provided with a socket in which a pin mounted on the piece of furniture can be received, so that the hub can pivot about an axis which is laterally offset from and extends normal to the axle on which the rollers rotate. Usually, chairs and similar types of furniture which are provided with casters have bases of usually cruciform-shaped configuration. The three or more arms or projections of such bases are each provided with a caster. The difficulty with the prior art is that with the particular type of casters with which the present invention is concerned, even a small tilting of the piece of furniture while load is applied to it tends to cause the piece of furniture to roll rearwardly and to fall over forwardly. It is very common in chairs using casters, particularly office chairs, to provide bases having only three legs, or having legs which are relatively short. On the one hand the shortness of the legs in particular is desirable, because it is space saving and reduces the danger that someone walking past the piece of furniture might get his or her feet hooked underneath the base and become tripped. On the other hand, however, this type of base brings with it a particular danger that the chair or furniture might overturn under the conditions outlined above, and the possibility of trouble is further enhanced if the person resting on the chair or piece of furniture places weight upon the region as to the front of the seat and thus shifts the center of gravity too far forwardly.

It has been observed that in the stability or instability of such furniture the position of the rollers of the casters in the regions where the caster pivots about the upright pivot axis thereof, is particularly important. If the caster is so positioned that its axle about which its rollers rotate, extends in direction outwardly towards the end of the base projection on which the caster is mounted, then the danger that the chair might tilt over under the above-outlined circumstances is reduced or eliminated, because this in effect causes an increase in the critical rolling-inclination angle that leads to tiltingover. If, however, the axle is oriented in the direction towards the center of the base, then the chair will tip forwardly about the axle, and will then slide rearwardly on the forwardly located casters until a sufficient shifting in the center of gravity has taken place for the chair to tilt over in forward direction. The same is true in the reverse case, if the chair is tilted rearwardly.

Investigations have indicated that this particular problem is found quite frequently in chairs having casters, particularly office chairs, and that it rather often leads to physical injuries which may range from light all the way to quite severe.

SUMMARY OF THE INVENTION It is, accordingly, a general object of the present invention to provide an improved caster for chairs and the like, which is not possessed of the aforementioned disadvantages of the prior art.

More particularly it is an object of the present invention to provide such an improved caster which will provide for automatic blocking in the critical tilting range of the casters, so as to prevent a rearward rolling of the casters in the event of a tilting-over movement of the piece of furniture and an unfavorable distribution of the weight of the user on the seat.

An additional object of the invention is to provide such a caster which should be uncomplicated in its construction and simple to produce.

In keeping with these objects, and others which will become apparent hereafter, one feature of the inven tion resides, as a novel article of manufacture, in a caster for chairs and the like which, briefly stated, comprises a circular hub having an outer circumferential face, and an axle extending centrally through this hub and having end portions projecting beyond opposite axial sides thereof. A pair of rollers is located at the opposite axial sides of the hub and each of these is turnably journalled on one of the end portions. Mounting means is provided for mounting the hub turnably about an upright pivot axis which is laterally offset from it extends normal 'to the axle, and a nose projects from the outer circumferential face of the hub below the mounting means and is bounded by two outer surfaces which extend from the outer circumferential face substantially parallel to and substantially normal to the axis, respectively.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a section taken on line I-l of FIG. 4;

FIG. 2 is a side view illustrating the hub of the embodiment shown in FIGS. 1 and 41;

FIG. 3 is a view of the hub in FIG. 2, as seen in the direction of the arrow III shown in FIG. 4; and

FIG. 4 is a side view of the embodiment of the caster in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing the embodiment in FIGS. 14 it will be noted that FIGS. 1 and 4 illustrate the complete caster whereas FIGS. 2 and 3 are views of the hub of the caster. .With this in mind it is pointed out that the hub itself is completely circular in outline and is identified with reference numeral 1. Secured in it, as by casting the huh 1 around it, isan axle 2 opposite axial ends of which project beyond the opposite axial sides of the hub 1.

Also located at the opposite axial sides of the hub l are two rollers 4 which are of cupped configuration as shown, their open sides facing inwardly towards the hub 1. The rollers 4 are each journalled on one of the projecting end portions of the axle 2, for which purpose the rollers 4 are provided with bores or recesses accommodating journal sleeves 8 in which the end portions of the shaft 2 are received. Outwardly springy circlips 3 (that is circumferentially incomplete spring-metal rings which, when radially inwardly defected, tend to resume their large-diameter original dimensions) secure the rollers 4 on the end portions of the axle 2 in known manner. Usually this is done by having corresponding grooves in the outer surface of the respective end portion and in the inner surface of the respective journalled sleeve 8, with the circlips being received in part in the respective groove.

The rollers 4 in the illustrated embodiment have outer circular flanges 10 the outer surface of which contact the support surface for the casters, for instance a floor. The inner surfaces of these flanges 10 are slightly spaced from the outer circumferential face bounding the circular hub 1, and they extend partly in axial direction over this outer circumferential face. However, the flanges 10 define with one another an axial circumferentially extending gap, that is they do not contact one another.

The hub 1 is provided with mounting means for mounting it turnably about an upright pivot axis which is laterally offset from and extends normal to the axle 2. In the illustrated embodiment this mounting means is in form of a bore or socket 9 which can receive a downwardly projecting pin provided in the piece of furniture to which the caster is to be secured. Of course, it is conceivable that the pin might form a part of the hub itself, rather than be an extraneous component which is receivable in the socket 9. In any case, how- .ever, the axis about which the hub 1 will thus be pivotable will be laterally spaced from the axle 2 (see FIG. 2), will have an upright orientation and will extend normal to the axle 2.

FIGS. 2-4 indicate particularly clearly that there is located. beneath the socket 9 a nose 5 bounded by a surface 6 which extends in substantial parallelism with the pivot axis passing longitudinally through the center of the socket 9, and by a second surface 7 which extends normal to this pivot axis, that is in substantial parallelism with the surface on which the caster is to be supported. In the illustrated embodiment the two surfaces 6 and 7 include with one another an obtuse angle and each of the surfaces merges tangentially into the outer circumferential face of the hub 1. Of course, it is conceivable to have the surfaces 6 and 7 include a different angle, for instance they could include a right angle with one another.

Because the flanges 10 partly overlap the circumferential face of the hub 1 in the illustrated embodiment, the axial thickness of the nose 5 is less than the axial length of the outer circumferential face, and in particular it is less than the axial width of the gap defined between the juxtaposed edges of the flanges 10 (compare FIGS. 1 and 3).

With a caster constructed as disclosed herein, the problem which is so objectionable in the prior art has been overcome. If in the critical pivotal position of the caster on the chair the latter tilts, then the nose of the respective caster will contact the ground and will prevent the rearward rolling-away of the chair.

If, as has been shown in the illustrated embodiment, the flanges l0 partially overlap the outer circumferential face of the circular hub l in the illustrated manner,

then the entry of contaminants, particularly of carpet threads which might have become severed from the carpet, into the interior of the caster and to the axle 2 thereof, is at least made more difficult which of course is beneficial in terms of continued maintenance-free and reliable operation.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a caster for chairs and the like, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. As a novel article of manufacture, a caster for chairs and the like, comprising a circular hub having an outer circumferential face; an axle extending centrally through said hub and having end portions projecting beyond opposite axial sides thereof; a pair of rollers located at said opposite axial sides of said hub and each being turnably journalled on one of said end portions; mounting means for mounting said hub turnably about an upright pivot axis which is laterally offset from and extends normal to said axle; and a nose projecting from the outer circumferential face of said hub below said mounting means and being bounded by two outer surfaces which extend from said outer circumferential face substantially parallel to and substantially normal to said axis, respectively.

2. An article of manufacture as defined in claim 1, wherein said surfaces include with one another an acute angle.

3. An article of manufacture as defined in claim 1, wherein the diameter of said rollers is greater than that of said hub.

4. An article of manufacture as defined in claim 1, wherein said rollers have respective outer circumferential circular flanges which slightly overlap said outer circumferential face in direction axially of said hub but are radially outwardly spaced from said circumferential face, the flanges of said rollers defining between themselves a gap extending circumferentially of said face; and wherein said nose has a thickness in axial direction of said hub and said gap which is smaller than the axial dimension of said gap.

5. An article of manufacture as defined in claim 1, wherein said hub and nose are of one piece with one another.

6. An article of manufacture as defined in claim 1, wherein said mounting means comprises an elongated socket whose central longitudinal axis coincides with

Claims

6. An article of manufacture as defined in claim 1, wherein said mounting means comprises an elongated socket whose central longitudinal axis coincides with said pivot axis.