US 3899801 A
A castor for use on a pile carpet can be constructed so as to include a plurality of separate, spaced bosses extending from the surface of a cylindrical wheel or roller used in the castor. In use such bosses distribute the weight transmitted to the carpet through the wheel unevenly in such a manner as to prevent any significant matting of the pile of the carpet.
Description (OCR text may contain errors)
United States Patent [191 Carrier CASTOR FOR USE WITH PILE CARPETv  Inventor: Vernon ,1. Carrier, 25830 Viana St.,
Lomita, Calif. 90717  Filed: Aug. 19, 1974  Appl. No.: 498,380
 US. Cl. 16/45  Int. Cl. A47B 91/00  Field of Search 16/45, 47, 46, 22
 References Cited UNITED STATES PATENTS 759,299 5/1904 Myers 16/45 1,305,535 6/1919 Grabowiecki 16/45 X 2,152,684 4/1939 Grange et al. 16/45 X 1 Aug. 19, 1975 2,403,812 7/1946 MacCallum 16/45 X 3,140,506 7/1964 Arenson 1. 3,492,016 1/1970 O'Connor et a1. 16/45 Primary Examiner-Alfred R. Guest Attorney, Agent, or Firm--Edward D. OBrian [5 7 ABSTRACT A castor for use on a pile carpet can be constructed so as to include a plurality of separate, spaced bosses extending from the surface of a cylindrical wheel or roller used in the castor. In use such bosses distribute the weight transmitted to the carpet through the wheel unevenly in such a manner as to prevent any significant matting of the pile of the carpet.
6 Claims, 5 Drawing Figures CASTOR FOR USE WITH PILE CARPET BACKGROUND OF THE INVENTION The invention set forth in this specification pertains to new and improved castors and more specifically to castors which are primarily intended to be utilized with pile carpet.
Because this term pile carpet is considered to be somewhat ambiguous it is considered necessary to indicate what is meant by this term in this specification. The word carpet as used in this specification designates a heavy fabric for use in covering a floor. The term pile as used herein in connection with the word carpet" is intended to designate surface fibers projecting from the surface of such a carpet. These pile fibers may be either cut or looped; normally they extend more or less perpendicular to the exposed surface of a carpet.
To a degree this latter is somewhat misleading. In certain types of pile carpet the pile fibers extend from the surface of the carpet so that they are substantially parallel to one another and are generally or nearly perpendicular to this surface. Frequently, however, the pile fibers used in pile carpets are either sufficiently flexible and/or sufficiently long and/or are inadequately supported by the carpet so as to extend in this manner. The fibers in carpets of the latter category will of course tend to bend so as to provide a pile surface in which the fibers may overlie one another to varying extents. Some carpets are constructed so as to utilize pile fibers which bend in this manner so as to achieve a desired aesthetic or similar effect while other carpets are constructed so that the pile fibers tend to remain perpendicular to a carpet surface.
It is considered that there is a problem in connection with the use of both types of pile carpet indicated in the preceding in conjunction with various items of furniture and the like which are normally located upon such carpet. This problem pertains to the matting of the pile fibers on a carpet if such pile fibers are subject to a concentrated load" consisting of the weight of an item such as a piece of furniture being directly applied to the pile fibers through a conventional castor for a prolonged period. Occasionally small cup-like members having flat bottoms are utilized underneath such legs or rollers in order to distribute the weight applied to the carpet over a comparatively large area of the carpet so as to minimize the amount the fibers of the carpet pile will be matted or compacted as much as conveniently possible.
Whenever such matting or compaction occurs there is the danger that a pile carpet will be deformed to an undesired extent so that such a carpet will not have its initial appearance after the weight has been removed from it. The degree in which a carpet pile can recover its initial appearance after weight has been removed from it will of course be dependent upon a number of factors. Such factors include the inherent nature of the fibers of the pile. They also include the construction of the carpet itself. Another factor which is important to such recovery is the amount of weight located on the carpet and the way in which such weight is distributed over the surface of the carpet. The time over which a load is applied is also significant.
Frequently it is possibleto restore matted pile fibers in a carpet to substantially an initial appearance by disadvantageous. relatively expensive steam treatment and/or other processes. The existence of this problem of the appearance of carpet being damaged as the result of matting and compacting of the pile fibers is relatively surprising in view of the rather extensive development work which has been devoted to the development of many different types of castors. Virtually everyone is familiar with the fact that normal castors are of either two different types-ball castors and roller castors. Such ball castors are constructed so as to utilize a socket which holds a rotatable ball. The balls in such sockets are normally of a spherical shape although on occasion their peripheries have been roughened to a degree not inconsistent with their ability to be rotatably mounted in a socket so as to increase surface adhesion.
It is considered that the number of different types of roller castors is far greater than the number of different types of ball castors. Such roller castors have normally been constructed so as to include a wheel or roller rotatably mounted about an axle which in turn is mounted in such a manner that the roller or wheel can rotate about a horizontal axis and about a vertically extending axis as the castor is used. When the surfaces of such wheels or rollers are of a cylindrical or spherical shape they tend to mat or compact pile fibers on pile carpet in the same manner as the balls in ball castors. This is of course a result of the concentration of the load placed upon the carpet in a comparatively small region or area of the carpet.
It has been proposed to avoid matting or compacting through the use of specialized rollers having a plurality of flanges spaced from one another by ribs. Expedients of this type are considered disadvantageous because with them there is still a concentration of weight upon pile fibers in localized areas contacted by the flanges on the rollers. In theory such flanges can be utilized to fit between these fibers as they are attached to a carpet. As a practical matter this is not considered to be satisfactory since most pile fibers are located relatively close to one another and since the user of a castor will normally not be able to locate the castor so that such flanges hit precisely between tufts of the pile fibers.
SUMMARY OF THE INVENTION It is believed that it will be apparent from the preceding discussion that there is a need for new and improved castors for use with pile carpet. A broad object of the present invention is to fulfill this need. Other objects of the invention are to provide castors as described: which can be constructed at a comparatively nominal cost; which are easily and conveniently used; and which effectively avoid any significant matting or permanent compacting of carpet pile fibers. The invention is also intended to provide castors which are specifically constructed in such a manner as to avoid any reasonable chance of damaging such pile fibers as by cutting them or the like.
In accordance with this invention these and various other objectives of the invention as will be apparent from a detailed consideration of the remainder of this specification and the accompanying drawing are achieved by providing a castor for use on pile carpet, this castor having a cylindrical castor wheel and means for mounting the wheel so that the wheel can rotate about its axis in which the improvement comprises: a plurality of separate bosses located on the surface of the wheel so as to extend therefrom, these bosses being spaced from one another and being the only 'projec tions from the surface of the wheel capable of contact ing the carpet, these bosses being shaped so as to have non-pointed ends remote from the wheel and being shaped so that these ends are smaller than the portions of the bosses at the periphery of the wheel.
BRIEF DESCRIPTION OF THE DRAWING Since a summary such as the preceding is intended to be a brief compendium of salient facts relative to this invention it cannot be expected to fully and completely indicate many aspects and features of the invention. It is considered that the invention is best more fully explained with reference to the accompanying drawing in which:
FIG. 1 is an end elevational view of a presently preferred embodiment or form of a castor in accordance with this invention;
FIG. 2 is a cross sectional view taken at line 2-2 of FIG. 1;
FIG. 3 is a fragmentary cross sectional view corresponding to a part of FIG. 2;
FIG. 4 is a lineal projection illustrating the periphery of the wheel employed in the castor illustrated in the preceding figure; and
FIG. 5 is a side elevational, partially in section, view illustrating a cap capable of being employed with the castor shown in the preceding figures.
The precise castor illustrated embodies certain essentially intangible concepts as are set forth and defined in the appended claims. These concepts can be utilized within a number of somewhat differently appearing castors through the use or exercise of routine engineering skill.
DETAILED DESCRIPTION In the drawing there isshown a castor of the present invention which includes a generally cylindrical castor wheel 12. This wheel 12 is provided with a centrally located opening 14 into which there is fitted a conventional bearing sleeve 16. This sleeve 16 carries a conventional axle 18 so that the wheel 12 is positioned between conventional washers 20 on the axle 18. A conventional head 22 on one end of the axle 18 is used for preventing the wheel 12 from coming off of this axle 18. The end of the axle 18 remote from the head 22 is provided with a conventional bent shank 24 terminating in a top portion 26.
This top portion 26 is located generally perpendicular to the axis of the wheel l2 in a conventional manner. This top portion 26 is also shaped in a conventional manner so as to be capable of being retained in a conventional mounting member (not shown) used to support the castor 10 in such a manner that the castor 10 can be turned about a vertical axis when in use while the axis of the wheel 12 remains in a horizontal position. If desired for aesthetic reasons a small end cap 28 may be located in an annular groove 30 in the wheel 12 so as to cover the head 22 and one of the washers 20.
It is to be understood that the structure described up to this point in this section of the specification is considered to be conventional. Obviously various different known bearing structures may be utilized to mount the wheel 12. Similarly various different types of means may be utilized to mount the castor 10 so that the axis of the wheel 12 is in a horizontal plane and so that the castor 10 may be rotated about a vertical axis relative to a piece of furniture or the like (not shown) on which the castor I0 is mounted.
In accordance with the present invention the surface of the castor I0 is provided with a plurality of identical bosses 32. These bosses 32 are preferably located as close to one another as reasonable possible in order to achieve a comparatively effective weight distribution when the castor 10 is used. These bosses 32 are spaced from one another for the same reason. Each of these bosses in the preferred embodiment of the castor 10 has the shape of a frustum of a right circular cone.
It is preferred to form the bosses 32 in such a conical shape since bosses of this shape will tend to fit between pile fiber and will only compact or mat such fibers to a restricted degree. Further, when the bosses 32 are of this shape and are oriented on the wheel 12 so that their axis intercept the axis of the wheel 12 these bosses 32 are symetrically located in such a manner that the wheel 12 may be rotated in either direction about its axis with equal facility. If the bosses 32 should be projections of a uniform cross sectional configuration or if they should be canted around the periphery of the wheel 12 so that their axes would not intercept the axis of the wheel 12 there is a reasonable possibility of a carpet being damaged when the castor I0 is used and- /or of this castor 10 not performing in a desired manner.
Indeed in order to minimize such damage the bosses 32 are provided with non-pointed ends 34 which extend transverse to the axes of these bosses 32 and these ends 34 are preferably provided with slightly rounded edges 36. The use of such slightly rounded edges 36 is considered preferable so as to minimize the chances of a pile fiber being cut or damaged. In order to equalize the pressure exerted on a pile carpet the bosses 32 are preferably located as close to one another as reasonably possible and are preferably equally spaced from one another around the periphery of the wheel 12. As a consequence of such spacing around the periphery of the wheel 12 the castor 10 will exert the same action with respect to a carpet regardless of the position of the wheel 12 relative to such carpet.
Such action involves a weight distribution between adjacent pile fibers in such a manner that the bosses 32 extend generally between some of such fibers so as to tend to exert weight where such fibers are attached to a carpet proper. The tapered shapes of these bosses 32 leading from the ends 34 to the portions 38 of the bosses 32 at the periphery of the wheel 12 operate so as to tend to push carpet pile fibers together as such fibers extend more or less vertically. This makes it possible for such fibers themselves to carry a certain amount of weight as they are compacted together. As a consequence of this type of action there is substantially no danger of damage to a pile carpet resulting from matting or compacting when the castor 10 is used on such a carpet.
On occasion, however, it will be desired to utilize a castor such as the castor 10 on other than pile carpet. Preferably the bosses 32 are located in rows as indicated in FIG. 4 of the drawing in such a manner that a cap 40 having internal threads 42 may be threaded over the wheel 12 and the bosses 32. These threads 42 are of such dimension as to fit over'and around the ends 34 of the bosses 32. Normally friction between the ends 34 of the bosses 32 and the threads 42 will be adequate to hold the cap 40 in place as the castor is used on other than a pile carpet.
I. A castor for use on a pile carpet, said castor having a cylindrical wheel and means for mounting said wheel so that said wheel can rotate about its axis in which the improvement comprises:
a plurality of separate bosses located on the surface of said wheel so as to extend therefrom, said bosses being spaced from one another and being located adjacent to one another, said bosses being the only projections from the surface of said wheel capable of contacting a carpet, said bosses being shaped so as to have ends remote from said wheel of a nonpointed configuration and being shaped so that said ends are of smaller dimensions than the portions of said bosses at the periphery of said wheel.
2. A castor as claimed in claim 1 wherein:
each of said bosses gradually decreases in cross sectional configuration as it extends away from the surface of said wheel.
3. A castor as claimed in claim 1 wherein:
none of said bosses has any sharp edge capable of cutting pile on a carpet.
4. A castor as claimed in claim 1 wherein:
each of said bosses has a shape of a frustum of of a right circular cone.
5. A castor as claimed in claim 1 wherein:
each of said bosses has the shape of a frustum of a right circular cone and is located so that its axis intercepts the axis of said wheel,
each of said bosses also having its largest extremity adjacent to the periphery of said wheel and having a rounded edge remote from said wheel,
said bosses being located on said wheel at a pattern such that a threaded cap may be threaded over said bosses.
6. A castor as claimed in claim 5 including:
a cap having internal threads located therein threaded on said bosses.