Method of affixing a caster on a wooden or plastic furniture leg

A caster and leg assembly for supporting a piece of furniture on a floor. The assembly includes a caster affixed within a recessed area formed in the bottom of a wooden or plastic furniture leg to create a strong support for the furniture as well as create a good appearance. The caster has at least one spherical roller supported within the housing to allow the furniture to be readily movable omnidirectionally. With one spherical roller, the weight of the furniture acts at the center of the spherical roller. In one embodiment, there are three spherical rollers located equidistant from the vertical center line of the assembly to support the furniture weight equally by the spherical rollers. A glide can be readily attached and detached from the bottom of the caster and, when attached, the glide cup covers the spherical rollers and presents a flat, planar bottom surface.

BACKGROUND OF THE INVENTION

The present invention relates to a caster assembly for a use with furniture, and, more particularly, to a caster assembly adapted for use with a wooden or plastic leg of a piece of furniture.

In general, there are many types of furniture casters that are available and which are affixed or incorporated into the legs of such furniture to enable that particular piece of furniture to be readily rolled from one location to another.

Accordingly, the caster assemblies for furniture normally have rotatable rollers to facilitate the movement of the furniture. Such caster assemblies also generally have an elongated stem that interfits into the furniture. That stem has a central longitudinal axis along which is directed the weight of the furniture The roller itself is mounted to the assembly within a housing and the roller is rotatably mounted to that housing to roll about a central axis that is parallel to the plane of the floor. The housing is also pivotally mounted to the furniture leg so that the roller itself can not only rotate about its axis, but the housing, including the roller itself, can also pivot 360 degrees about the main longitudinal axis of the stem.

The swiveling action or movement is necessary to correctly align the roller for movement in the proper direction, however, such swiveling movement can be generally difficult to accomplish. For one reason it is apparent that all of the rollers supporting the furniture must be correctly aligned in order to easily move the furniture. In most instances, the rollers are positioned in various directions and it is therefore necessary to align all of the rollers at the initial movement of the furniture. With the weight of many pieces of furniture, there is considerable friction acting against the swiveling action of the caster assembly and the problem is aggravated by the need to align some 4-5 rollers in order to roll the furniture. Additionally, the roller is often embedded into an indentation in the carpet that lies along the surface of the roller and the roller must be moved out of the indentation to swivel. As such, therefore, while the swivel action is necessary to properly move the furniture, it can be somewhat difficult to get the swivel action to operate easily and thus the initial movement of the furniture is not easy to accomplish, particularly when the piece of furniture is on carpeting with padding.

The typical conventional caster for use with carpet is a cylindrical member that contacts the floor at a certain finite distance away from the longitudinal, vertical axis of the stem so that the roller can pivot to a position determined by the direction the furniture is being moved and then the roller rotates to make that movement easy to accomplish. A typical roller caster assembly used on a bed frame is shown and described in U.S. Pat. No. 4,007,502 of Mis. As can be seen in the Mis patent, the roller is offset with respect to the downward force that acts through a stem and, as will become clear, this typical caster of Mis suffers from certain inherent weaknesses.

Thus, since the contact point between the roller and the floor is located at an offset dimension from the longitudinal, vertical axis of the stem along which the weight of the furniture is directed, a bending moment is created based on the weight of the furniture acting downwardly on the stem and the distance between the location of that force along the longitudinal axis of the stem and the point where the roller contacts the floor to support the frame.

One of the difficulties with such casters, therefore, is that the bending moment created by that offset creates stress on the caster assembly and can cause a premature failure of the caster assembly or the furniture itself, thereby disabling the entire unit. The problem is aggravated, of course, with legs having increased degrees of weakness, and in particular, with the use of plastic legs as shown and described in U.S. Pat. No. 3,828,376 of Miller. Accordingly, it would be advantageous to have a caster assembly that has rollers that provide better support for the furniture and which do away with the offset that causes the bending moment and the premature fracture of essential components such as the leg of the furniture, thus avoid damaging the furniture. There are rollers that have ball bearings that may aid in the swiveling of the roller or aid in the rolling motion of the roller itself but most require the offset and the consequent swiveling action to operate in moving the furniture.

Other prior art furniture support assemblies have, in fact, utilized a plurality of elements that contact the floor and examples are illustrated in U.S. Pat. No. 1,060,076 of Glowacki and U.S. Pat. No. 1,282,396 of Friend. In the aforementioned patents, however, while a plurality of members contact the floor and thus allow the weight to be borne by a plurality of elements, there is a further problem with respect to the ease of moving such casters as the spherical members are clamped into the housing supporting the particular piece of furniture and the spherical contact members do not thus freely rotate to allow the ready movement of the furniture. Accordingly, in Glowacki, the balls that actually contact the floor are clamped tightly into a circular dome and thus are not movable with respect to the dome as the furniture is moved. Therefore, while the prior art did consider the support of the weight of a piece of furniture on a plurality of contact members, the moving of the furniture was not enhanced and only the idea of a strong support was considered and appreciated.

In addition to caster assemblies, there are also glide assemblies that are mounted to the various pieces of furniture and have a generally flat, planar bottom contacting the floor. The glide assemblies are preferably used where the furniture is located on a hard or slippery surface such as a wood or tile floor and thus the flat bottom does not easily slip or cause damage to the floor itself. With such flooring surfaces, the user of a caster having a roller causes unnecessary sliding or rolling as contrasted to the intended use of a rug roller or caster on a carpeted surface where the friction with the carpet reduces the mobility of the roller or caster.

Glide assemblies are inherently stronger than caster assemblies since the weight of the bed frame using a glide acts along the longitudinal axis of the glide directly to the point of contact with the floor, and thus, there is no offset from that axis to the point of contact and, hence, no bending moment. In addition, of course, the glide planar surface allows more surface contact with the floor and thus carries the weight of the furniture over a wider area so as to provide a better distribution of that weight. As such, the glide assembly has enhanced strength and stability over the caster assembly.

A further alternative is with the use of a caster cup that is generally cup shaped that is slid underneath a roller of a caster assemble to aid in slowing the mobility of the caster and to stabilize the piece of furniture, particularly when used on a slippery flooring surface. The caster cups, however, are easily displaced from under the roller since they are not firmly locked to or attached to the caster assemblies and are thus difficult to maintain in place when the furniture is moved during the normal use of the furniture. Thus, over time, the caster cups become displaced with respect to the roller and no longer serve their intended purpose.

As a further problem with many of the aforedescribed caster assemblies, since the caster roller needs to pivot 360 degrees about its vertical axis, it is very difficult to build the caster assembly into a wooden or plastic leg of the furniture and, therefore, the caster for a wooden or plastic leg is simply screwed into the bottom of a leg by means of a threaded stem and, accordingly, creates a weak point as well as a less than pleasing appearance of the caster affixed to the bottom of a leg.

Accordingly, it would be advantageous to have a caster assembly that can be used with a wooden or plastic furniture leg that can be recessed into the leg so that the overall appearance is pleasing and the caster fits in with the exterior contour of the leg. It would also be advantageous to have a caster assembly for a wooden or plastic furniture leg wherein the caster assembly has a strong connection to the furniture leg and where there is no upstanding stem or other member that can introduce a weak point into the leg/caster combination. It would be still further advantageous to have a caster assembly for a wooden or plastic furniture leg where there is a glide that can be removably affixed to the bottom of the caster so that the user can readily convert the caster to a glide and vice versa.

SUMMARY OF THE INVENTION

Now, in accordance with the present invention, an improved caster and leg assembly is shown that overcomes the difficulties heretofore explained. In the present invention, the caster assembly is adapted for use with furniture having a wooden or plastic leg. The structure of the caster assembly comprises a housing that is attachable to the wooden or plastic leg of a piece of furniture by interfitting into a recessed area provided in the lower end of the furniture leg. By the interfitting of the caster into the bottom of a wooden or plastic leg, the combined caster and leg assembly can present an overall smooth, streamlined exterior surface as well as maintain the strength of the support for the furniture. As a further advantage, the present caster can be added or retrofitted to an existing furniture leg by an owner of the furniture or can be installed by the original manufacturer of the furniture.

The assembly has a generally vertical elongated axis or centerline such that the weight of the bed is transmitted to the housing of the caster and leg assembly generally along the centerline that is centrally located with respect to the housing. At the bottom of the caster there is at least one, and preferably three, spherical rollers that contact the floor and allow the piece of furniture roll with respect to the floor for the convenience of moving the furniture from one location to another location. The spherical rollers are mounted to a housing having a cavity and a plurality of small spherical balls are freely located between the housing and the spherical rollers such that each spherical roller or rollers freely rotate omni-directionally, that is, the roller or rollers are free to rotate about center points and thus can rotate in any direction. As such, therefore, the spherical roller(s) can rotate in any direction that the user pushes the piece of furniture in relocating that piece of furniture and no additional force is needed to commence the initial movement of the furniture.

In the preferred embodiment, there are at least three spherical rollers, more preferably three spherical rollers, so that the weight of the furniture and its supported components and weights are distributed at three contact points with the floor to better distribute the weight and prevent severe indentations in the floor. In addition, the location of the rollers is such that they are equidistant from the elongated, vertical central axis or centerline through which the weight of the furniture acts on the caster and leg assembly and thus, the single bending moment is eliminated and the structure has enhanced strength and stability. As stated, with the three rollers, each is still mounted to a housing such that the rollers move freely in any direction and do not need to be aligned to the direction of movement of the furniture by pivoting about a central axis or centerline. In effect, the need for a swiveling function is completely eliminated.

Accordingly, the caster assembly of the present invention has the strength of the prior art glide assemblies since the single offset has been eliminated and, of course, the assembly therefore does not need to swivel in order to allow the furniture or bed to be moved in any direction. With the offset and the need to swivel eliminated, the aforedescribed problems associated with those features are also eliminated.

As a further feature of the present caster assembly, a glide is readily attachable and detachable to convert the caster assembly from a roller caster to a glide function and vice versa. When attached, the glide alters the function of the caster assembly from a roller caster where the rollers are in contact with the floor to a glide function where the caster assembly is transformed into a glide. Accordingly, the bottom surface of the glide is a planar surface as in the case of most glides and the glide is attached and detached without the need for special tools or equipment. It should be noted, that the bottom surface of the glide is referred to as planar, however, typically it is an effective planar surface as there is normally a central portion of the bottom surface that is displaced upwardly and only a peripheral planar area is actually in contact with the floor. The attachment and detachment can be readily accomplished in the home by an installer that can determine at the time of installation whether or not the glide or roller function is applicable.

The resulting caster assembly therefore combines the strength of the glide assemblies with the mobility of a roller caster assembly and provides the user with the option of using the spherical rollers to contact the floor or easily transform the caster assembly to add a glide so that the assembly can be used on slippery surfaced floors.

In such situation, instead of changing the caster itself, the user only needs to attach the glide to the bottom of the caster housing whereupon the rollers are hidden and the lower surface of the caster assembly is a flat surface and therefore suitable for a hard wood or other slippery surface floors. The glide is locked on to the caster housing and does not become detached during the use or movement of the furniture.

In one embodiment the attaching and detaching of the glide is accomplished by an interfitting of the glide to a lower shroud that is positioned at the lower portion of the caster assemble. That lower shroud itself has a plurality of elongated openings generally formed as arcs of a circle with a larger opening portion and a smaller opening portion. The glide has a similar number of upwardly directed tabs that are adapted to fit into the larger post of the openings in the lower shroud. Each of the tabs has an upper lip that is dimensioned to fit through the larger opening portion of the elongated openings but which cannot fit through the smaller opening portions. A locking projection is formed on each of the elongated openings to securely lock the upwardly directed tabs to the lower shroud.

By simply rotating the glide, the tabs are rotated to a position where the tabs are moved into the smaller opening portions where the lips are captured by the lower shroud since the lips cannot pass through the smaller portion openings and the glide is securely retained in position affixed to the lower shroud. By such means, the glide is locked into position onto the lower shroud of the caster assembly and will not come apart while the furniture or bed is being used or even during movement thereof. Once affixed to the lower shroud, the glide thus converts the caster assembly to a glide function, however, even then, the weight is still distributed through the three spherical rollers that bear against the glide and carry the weight of the furniture.

Other features of the caster assembly will become more apparent in light of the following detailed description of a preferred embodiment thereof and as illustrated in the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring now toFIG. 1, there is shown a perspective view of a conventional bed frame with which the present invention can be applied. It should be noted, however, that while theFIG. 1embodiment of the present invention is initially shown and described specifically for use with a bed frame, the broader aspects of the invention make it applicable to any item of furniture with the same advantages and improvements.

Thus, inFIG. 1, the conventional bed frame is comprised of a pair of side rails10and cross members12. The number of cross members may vary depending upon the particular bed, and its size, that is, there may be one or more intermediate cross members that provide additional support to the box spring and mattress when assembled. The side rails10and cross members12are normally constructed of L-shaped angle iron. As shown, there are legs13that are normally located on the cross members12or the side rails10depending on the particular construction and, if any further cross members are used in the bed frame, there may also be one of more additional legs extending downward from those cross members. At the bottom of the legs13, there are affixed thereto casters14that are in contact with the floor.

Taking nowFIGS. 2 and 3, there is shown, respectively a side view of a typical caster14and a perspective view of a typical glide16. Either the caster14or the glide16can be used as a support for a bed frame and each is preferably used in differing circumstances. Taking first the caster14, as can be seen, the conventional caster comprises a roller18that is normally cylindrical and which rotates about an axis, indicated by the letter A, that is positioned parallel to the floor. The caster14includes a metal housing20having an upstanding stem22that extends upwardly and which is inserted into the leg or other support point on the piece of furniture.

The roller18thus rolls freely about its axis A in the direction at a right angle to that axis, however, the roller18obviously does not freely rotate to move the piece of furniture or bed frame if the user attempts to move that furniture in the direction along the axis of rotation of roller18. To accomplish moving the furniture in such direction, therefore, it is necessary for the housing20to swivel about the axis B of the upstanding stem so that the roller18becomes aligned with the proper path of travel. As will be later explained, in order for the housing20to swivel there is a necessary offset between the axis B and the point of contact of the roller18with the floor.

In the normal movement of the caster14, the swiveling movement takes place quite automatically as the furniture, such as a bed, is moved in the desired direction since the swivel effect takes place as the initial movement occurs and the roller18becomes aligned properly for that direction of movement. As explained, however, the swiveling action can be difficult to accomplish and the initial movement of the furniture therefore is not easily facilitated.

In addition to the swiveling problem, the normal caster, as shown inFIG. 2also suffers from an inherent weakness in that the weight of the furniture is directed downwardly along the axis B of the upstanding stem22whereas the contact with the floor and the support point for the furniture occurs at the point24at the bottom of the roller18. As can be seen, there is an offset or finite distance between the direction of the load imposed by the furniture along the axis B and the point at which that load is supported by the floor. That offset is necessary to accomplish the swiveling action, however, it also sets up a stress in the caster by creating a bending moment in the caster14that is always present and can lead to premature failure of the caster14and/or the connecting leg.

Accordingly, while the caster14is certainly helpful in providing mobility to the piece of furniture, there are inherent weaknesses that can lead to a failure of the caster or the leg of the bed frame itself that are always present due to the basic design of the caster and can lead to the possibility of damage to the caster or other structural components of the bed frame.

Turning toFIG. 3, a glide16is shown and which is also used with furniture as a support, particularly where the piece of furniture is located on a hardwood or tile floor. Again, the glide16includes an upstanding stem26that is adapted to be inserted into the leg or other support point of the furniture. The glide16has a flat bottom surface28and is thus preferred on the aforementioned floors and, unlike the caster14, is exceptionally strong since the weight of the furniture acting downwardly along the main axis of the upstanding stem26is directly supported by the contact with the floor and there is therefore no offset to that force that can cause stress. The glide is typically used on a bed rail assembly and can be used on carpeted floor for strength, however the added friction between the bottom of the glide and the carpeted floor make the potential of damage to the bed structure more likely.

On the other hand, of course, with the use of glide16, the mobility of the furniture is sacrificed. Not only is the mobility of the furniture sacrificed, but there is an additional weakness in the glide16if the furniture is attempted to be moved since the glide16does not move readily along a carpet, for example, and any attempt to slide the furniture along that type of flooring can cause the glide to get caught on the material and cause the glide to snap off from the upstanding stem26or worse, to break off a leg or other part of the furniture. This is particular true where the glide is positioned at the center of a bed frame affixed to a cross member since that location is already a relatively weak structure and is subject to bending and breaking.

Therefore, since the present caster assembly30does not need to swivel in order to allow the piece of furniture to be moved, as was the case with the prior art rollers, the present caster assembly30can be affixed to the piece of furniture in a wider variety of ways, such as being attached offset to the side of the furniture as the center of the caster assembly30need not be the particular point of the caster assembly that is actually affixed to the furniture. With the prior art swivel casters, particularly those screwed into the furniture, such versatility was not present and the means and location of attachment to the furniture was limited.

Turning now toFIG. 4, there is shown an exploded view of a caster assembly30constructed in accordance with the present invention. In the Figure, the caster assembly30includes an upstanding stem32that again, is adapted to enter and be secured to the particular piece of furniture to which the caster assembly30is attached. As noted, the stem32will be described that interfits with a leg of a bed frame assembly, however, the stem32may have a flat flange at its upper point with suitable holes so that the caster assembly can be secured to a piece of furniture by means of wood screws or other securing means. A housing34is provided and from which the upstanding stem32extends and within which is positioned a plurality of spherical rollers36. In the preferred embodiment, and as is shown inFIG. 4, three spherical rollers are utilized. Each of the spherical rollers36extend downwardly external of the housing34and, as such, contact the floor when in position supporting a piece of furniture.

In this embodiment, the spherical rollers36can be formed of plastic material, particularly a plastic having good lubricity and a good memory, one example of which is available commercially from the DuPont Company under the trademark DELRIN. That same material can be used for other components of the caster assembly30such as the housing34. A glide cup38is also provided that is readily attached and detached from the housing34so that the contact with the floor can be by means of the spherical rollers36or, at the option of the user, by contact with the flat, planar bottom40of the glide cup38. The glide cup38can also be made of the same plastic material as previously described.

In order to allow the glide cup38to be readily attached and detached to the housing34, there is provided at the lower perimeter of the housing34, at least one projection42that extends outwardly from the lower perimeter. Again, in this embodiment, there are a plurality of such projections42extending from the housing34. Glide cup38has an upstanding flange44having formed therein, an internally facing ridge46with a plurality of recesses48that dimensionally coincide with the projections42on the housing34. Thus when the glide cup38is to be attached to the housing34, the glide cup38is positioned over the lower periphery of the housing34and the projections42fit through the recesses48so that the glide cup38can be fully moved over the lower periphery of the housing34.

The projections42thus pass through and clear the internally facing ridge46after passing through the recesses48such that the glide cup38can be simply rotated a predetermined amount and lock the projections42behind the internally facing ridge46so that the glide cup38is securely attached to the housing. In the position with the glide cup38attached to the housing, the caster assembly30acts as a glide and the spherical rollers36are contained within the glide cup38. As is obvious, therefore, the glide cup38can, by another predetermined rotation, be just as easily detached from the housing34so that the spherical rollers36can contact the floor.

When the glide cup38is installed, the spherical rollers36touch and actual bear on the upper surface of the glide so that, in use, the weight of the bed or other furniture is distributed through the spherical rollers36to the glide cup38such that the weight of the furniture is well distributed to the glide cup38and there is no weight acting on any of the projections42or other likely breakable components.

The spherical rollers36, as can be seen, preferably have centers of rotation and thus are free to rotate omni-directionally, that is, in any direction about their center point of the spherical shape. In addition, in the preferred embodiment, the centers of the spherical rollers36are positioned equidistant from the main axis of the upstanding stem32so that the weight of the furniture that acts along the main axis of the upstanding stem32is equally distributed among the spherical rollers36in their contact with the floor. With the weight distribution equally divided, the overall weight is borne by the main axis of the caster assembly30and thus through the strength of the assembly. Accordingly, the present caster assembly30provides the mobility of the prior art casters while having the strength and structural integrity of the prior art glides. In addition, with the addition of the glide cup38the caster assembly30can also have the non-marring flat planar surface to contact the floor whenever desired and without difficulty.

Turning now toFIG. 5, there is shown a bottom plan view of the caster assembly30constructed in accordance with the present invention and with the glide cup38not attached thereto. In this Figure, the physical layout of the spherical rollers36can be further explained. In particular, the main, longitudinal axis of the upstanding stem (not shown inFIG. 5) is at the center point50of the caster assembly30and the weight of the furniture is therefore concentrated along that axis and therefore acting downwardly at about the center point50. Also shown are the center points52of the spherical rollers36. Thus, it can be seen that the center points52of the spherical rollers36, in the preferred embodiment, are all equidistant from the main longitudinal axis of the upstanding stem so that the weight of the furniture is equally distributed among the three spherical rollers36and along the center and the structural strength of the caster assembly30.

Turning next toFIGS. 6 and 7, there is shown, respectively, a side cross sectional view of the caster assembly30without the glide cup38attached and a side cross sectional view with the glide cup38attached. The spherical rollers36may be provided in commercially available self-contained cartridges54that can be inserted into suitably shaped holes56formed in housing34. In order to allow the spherical rollers36to freely rotate about their center points52, a plurality of small spherical balls58are freely position within the cartridges54and freely movable within an annular recess59and which allow the spherical rollers36to be able to rotate in any direction readily and with a minimum of friction. While a annular recess59is shown, the same omni-rotation of the spherical rollers36can be accomplished, albeit less efficiently, without the use of the annular recess59such that the small spherical balls58are simply located at the upper surface of the spherical rollers36. In a still further less efficient construction, the small spherical balls58can be eliminated altogether. Such mechanisms are readily available commercially including the spherical rollers contained within a housing with small spherical balls freely floating intermediate the housing and the spherical rollers36to allow the spherical rollers36to freely rotate about their center points in any direction, that is, omni-directionally.

InFIG. 7, the addition of the glide cup38can be seen with the internally facing ridge46locked in position behind the projections42so that the glide cup38is securely affixed to the housing34and the spherical rollers36are covered by the glide cup38and out of operational use.

Turning now toFIG. 8, there is shown a perspective, exploded view of the preferred embodiment of the caster assembly70of the present invention and in view of a later more detailed description of the individual components, a brief description of those components will be initially discussed and new designation numbers assigned even though many components are the same as or similar to the components used in the prior embodiments.

Accordingly, as shown inFIG. 8, there is a spindle72that, as explained, is used to affix the caster assembly70to the particular piece of furniture. Atop of the spindle72is positioned a bushing74that is preferably of a plastic material such as polypropylene. The bushing74enables the caster assembly70to be inserted into the female opening normally provided in furniture, including bed frames and the structural members that make up beds in general. The bushing74is pressed onto the spindle72and is thus held thereto by an interference fit. By convention, the components will also be referred to as upper and lower throughout and such reference shall be intended to denote the upper direction as toward the piece of furniture and the lower direction to be towards the floor on which the furniture is supported. By that convention, therefore, the bushing74is positioned on the upper portion of the spindle72and the lower portion of the spindle72extends through an upper shroud76through an opening78.

The lower portion of the spindle72, when assembled, further passes through a central bore80formed in a stem housing82. As will be seen, the spindle72is in an interference fit in the central bore80such that the stem housing82is pressed on to the spindle72to affix the spindle72firmly to the stem housing82. The spindle72continues with its lower end fitted, again, in an interference fit, into the bore84of a ball cup86. A plurality of spherical rollers88are fitted within the ball cup86by a snap fit as will be explained and a plurality of smaller balls90are located atop of the spherical rollers88to aid in the omni-directional rotation of those spherical rollers88.

Beneath the spherical rollers88, there is positioned a lower shroud92and which is affixed to the upper shroud76by means such as drive screws94. Finally, as shown in the FIG., there is a glide cap96that is removably affixed to the lower shroud92so as to be easily attached and detached from the lower shroud92.

Turning now toFIG. 9, taken along withFIG. 8, there is shown a bottom perspective view of the upper shroud76and which has in its interior a plurality of locating ribs98and bosses100that extend downwardly to receive the drive screws94when the lower shroud92is affixed to the upper shroud76. In addition, as can be seen, there is an annular flange102that extends downwardly into the interior of the upper shroud76and which has a plurality of slots104formed therein. In the preferred embodiment, the upper shroud76is formed of a molded plastic material such as polypropylene.

With reference toFIG. 10, taken along withFIG. 8, there is shown a side cross sectional view of the stem housing82. In that Fig. the central bore80can be seen through which the lower portion of the spindle72passes in an interference fit in affixing the spindle72to the stem housing82. As also can be seen, the is a spherical indentation106formed in the lower surface of the stem housing82having a predetermined radius and center point and an annular recess108extending upwardly from the lower surface of the stem housing82and surrounding the spherical indentation106. As shown, of course, there are preferably three spherical indentations106that conform to the preferred number of spherical rollers88employed in the preferred embodiment. In addition, there is formed in the stem housing82, a plurality of upwardly directed bosses110, having internal bores112, the purpose of which will be later explained.

Turning now toFIGS. 11 and 12, taken along withFIG. 8, there is shown, respectively, a top perspective view, a bottom perspective view and a bottom plan view of the stem housing82. InFIG. 11, there can be seen, a plurality of ribs114extending outwardly from the central bore80and which preferably comprise three ribs114wherein the upper edges116of such ribs114fit into the slots104(FIG. 9) of the upper shroud76when the overall caster assembly70is assembled into a completed unit. As further shown inFIG. 11, the upwardly directed bosses110comprise three bosses110and the internal bores112of those bosses110are dimensioned so as to receive the bosses100of the upper shroud76(FIG. 8), again, when the overall caster assembly70is assembled. Further enlarged bores118are formed in the stem housing82along the internal bores112in the lower surface of the stem housing82(FIGS. 10 and 12) and are also utilized to allow the overall caster assembly70to be compactly and sturdily assembled together into the completed unit.

Turning now toFIGS. 13 and 14, taken along withFIG. 8, there is shown, a top perspective view and a bottom perspective view, respectively, of the ball cup86of the present invention. There is thus shown, the bore84within which the lower end of the spindle72terminates in an interference fit upon assembly. Surrounding the bore84are openings120that, as will be seen, contribute to the overall compactness of the completed assembly. Three circular flanges122extend downwardly from the ball cup86and contain the spherical rollers88. The internal cavity124of those circular flanges122is formed in a generally spherical configuration and includes a circular ridge126that is used to contain those spherical rollers88in a snap fit. As seen, with reference toFIG. 13, the upper peripheral surface128surrounding each of the internal cavities124is slightly chamfered inwardly in a gently sloping surface leading into the internal cavities124. Slightly raised flanges130partially surround the upper periphery of the internal cavities124.

Turning toFIG. 15, there is shown a side cross sectional view of the ball cup86such that one of the internal cavities124can be seen with the internal spherical configurations. As will be seen, the configuration and the dimensions of the spherical internal cavity124as such that the spherical rollers88can simply be snapped into those internal cavities124and retained in that position where the spherical rollers88are contained but can freely rotate in any direction, that is, omni-directionally. In the preferred embodiment, the spherical rollers88are comprised of an acetal plastic material.

Next, inFIG. 16, taken withFIG. 8, there is shown a top perspective view of the lower shroud92and which has its external peripheral surface mate with the external peripheral surface of the upper shroud76to contain the components of the completed caster assembly70. In this FIG., the lower shroud92includes three bosses132that extend upwardly and, when the caster assembly70is assembled, the bosses132extend through the openings130of the ball cup86(FIGS. 13 and 14) to contact and fit into the enlarged bores118of the stem housing82(FIGS. 11 and 12). The lower shroud92also includes a plurality, (preferably three) of openings134having circular flanges136that extend upwardly and through which the circular flanges122of the ball cup86pass (FIG. 14) in the assembly of the overall caster assembly70.

In the lower surface138of the lower shroud92, there is formed a series (three) of elongated slots140having a longitudinal axis forming a circular arc. As can be seen, the elongated slots140comprise a larger width portion142and a smaller width portion144about that arced configuration. In addition, there are small projections145formed at the entrance to the smaller width portions144that extend slightly into the elongated slots. The purpose for the elongated slots140will become apparent from a discussion of the next Figures.

Thus, turning toFIGS. 17 and 18, taken along withFIG. 8, there is shown a top perspective view and a side view of the glide cap96that is used with the present invention. As explained, the glide cap96is designed to be easily affixed to and removed from the overall caster assembly70to convert the caster assembly70between its different functions of action as a roller assembly and a glide assembly.

Thus, inFIGS. 17 and 18, there is a lower surface146that is generally planar and is adapted to contact the floor when the glide cap96is installed with the caster assembly70. A plurality of tabs148are molded into the glide cap96and which, itself is preferably a plastic molded polypropylene material. Again, the preferred number of tabs148, as shown, is three. At the upper end of the tabs148, three are formed lips150that are directed outwardly with respect to the center of the glide cap96.

Thus, returning toFIG. 16, taken along withFIGS. 17 and 18, the interaction of the tabs148and the elongated slots140can be explained. In affixing the glide cup96to the lower shroud92, the tabs148align with the larger width portions142of the elongated slots140in the lower surface138of the lower shroud92such that the glide cup96can be positioned to insert those tabs148through the larger width portions142. Thereafter, by merely rotating the glide cup96, the tabs148can enter the smaller width portion144where the lips150are captured by the lower surface138of the lower shroud92. The smaller width portions144prevent the passage of the lips150therethrough and thus the glide cup96is readily and easily retained to the lower shroud92so that the caster assembly70acts as a glide. As the tabs148pass by the small projections145, the tabs148are effective locked into position and do not readily become detached by normal use of the bed or movement thereof. Obviously, the removal of the glide cup96is just as easily accomplished by a reversal of the process, that is, the glide cup96is rotated to the position where the tabs148are in alignment with the larger width portions142so that the lips150can pass through the elongated slots140and the glide cup96removed.

TakingFIG. 19, there is shown a side cross sectional a view of the completed and assembled caster assembly70. In the FIG., therefore, it can be seen that the spherical rollers88are fitted into the ball cup86and are freely rotatable therein omni-directionally and the plurality of smaller balls90freely move within the annular recess108to allow the movement of the spherical rollers88. Those smaller balls90move over the upper surface of the spherical rollers and are contained within the area between the spherical rollers88and the spherical indentations106in the stem housing82. In the assembled form, as shown in this FIG., therefore the drive screws94affix the lower shroud92to the upper shroud76to encase all of the components in the overall caster assembly70in accordance with the present invention. Alternatively, of course, in the place of drive screws94, other means could be used, such as self tapping, thread cutting screws.

Turning now toFIG. 20, there is shown a perspective view of bed rails60connecting between a headboard62and a footboard64and showing a cross member66. As can be seen, with the use of bed rails60, the vertical height of the bed rails60above the floor is not a standard dimension and depends on the height of the legs of the headboard62and the footboard64. Accordingly the cross member66must have a support that is adjustable as to height. In such case, a caster assembly30is provided that supports the center of the cross member66and is adjustable in height but still has the advantages as previously explained with respect to mobility and strength of the caster assembly30. The cross member66may also be of the type that is universally adapted for use with bed rails and is further disclosed in a U.S. patent application filed on the same day as the present application and entitled UNIVERSAL TENSION SPRING SUPPORT MEMBER FOR BED RAILS OR BED FRAME, and the disclosure of that application is incorporated herein by reference.

Thus, turning toFIG. 21, there is shown a perspective view of a caster assembly30that is adjustably affixed to the leg extending downwardly from the cross member66so as to contact the floor and provide support to the overall completed bed. Thus, in this embodiment, the upstanding stem32is threaded at68and is screwed into a corresponding internally threaded opening in the leg of the cross member66. This embodiment is not, however, the preferred embodiment. The preferred embodiment is to affix the caster assembly to the furniture by means of a plastic bushing shown inFIG. 8that is press fitted into the suitable opening in the piece of furniture. As stated, since the caster has considerable strength, it can be used in place of a conventional glide that is normally used with such cross members and yet the caster assembly30is also mobile and can readily be moved along a bare wood floor or a carpeted floor without suffering the breakage problems associated with the use of a normal glide.

Turning now toFIG. 22, there is shown a perspective view of a piece of furniture, namely a couch152, that is supported by caster assemblies154of the present invention. As can be seen, the weight of the couch152is directed downwardly upon the caster assemblies154to be supported on the floor and, as has now been explained, the couch152can thereof be rolled in any direction without the need to align any offset rollers and thus the rollability of the couch152is greatly improved over the prior art casters used with such furniture. As also should be noted, the overall appearance of the couch152is pleasing with respect to the caster assemblies154since they blend in both functionally as well as esthetically with the appearance of the couch152since, as will be later described, the caster assemblies154are actually fitted into wooden or plastic legs that support the couch152.

Next, inFIG. 23, there is a cross sectional view of a combined caster and leg assembly156constructed in accordance with the present invention. As can be seen, the caster and leg assembly156comprises a leg158and which is constructed out of wood or a plastic material. At the top surface or upper end160of the leg158there is a threaded stem162for securing the caster and leg assembly156to a piece of furniture, such as the couch152ofFIG. 22, in order to affix the caster and leg assembly156thereto for supporting the piece of furniture on a floor. At the lower end164of the leg158, there is formed a recessed area166that is cut or molded in the lower end164.

Within the recessed area166there is located the caster168and which, as has been explained, includes a caster housing170that is fitted up into the recessed area166so as to not detract from the external appearance of the leg158as well as to provide a strong support for the piece of furniture. The caster housing170can be affixed within the recessed area166by means such as screws172whereby the caster168is contained substantially within the recessed area166with the spherical rollers174(three spherical rollers174are used) extending downwardly from the recessed area166in order to contact the flat planar surface of the floor176. There is also a longitudinal, vertical centerline CL shown inFIG. 23that centers the weight imposed by the furniture directly through the caster and leg assembly156since the centerline CL is centered with respect to the center points of the spherical rollers174, thereby avoiding the offset and misaligned effect of the distribution of weight with normal casters used with furniture.

The small spherical balls178are also shown to be located within the annular, upwardly extending cup shaped recess180formed in the caster housing170so that the spherical balls178are free to move in and out of the chamber182intermediate the spherical rollers174and the upper surface184formed in the caster housing170. That upper surface184has the same curvature or a slightly more shallow curvature than the exterior surface of the spherical rollers174in order to allow the free movement of the spherical balls178into and out of the chamber182.

Accordingly, as can now be appreciated, the caster and leg assembly156provides a very strong support for the furniture since the weight of the furniture acts directly through the caster and leg assembly156without any offset between the direction of the weight and the contact with the floor and yet the caster168can be embedded into the wooden or plastic leg used for the furniture.

Turning now toFIG. 24, there is a cross sectional view of a further embodiment of the present invention where the wooden or plastic furniture leg186has its upper end188affixed to the frame of the furniture and is part of the furniture such that the recessed area190formed in the lower end192of the furniture leg186has been cut into the furniture leg186. Thus, in this embodiment, the recessed area190can be pre-formed by the manufacturer of the furniture and the leg installed by that manufacturer or, alternatively, the present invention may be incorporated into the normal leg of a piece of furniture by cutting or shaping the recessed area190in order to retrofit the caster168of the present invention into an already constructed piece of furniture. Thus, a user already having the piece of furniture with a wooden or plastic leg can add the present caster168to upgrade that furniture and attain the advantages of strength and better appearance by adding the caster168of this invention to the leg186of the furniture.

Accordingly, the normal furniture leg186again holds the caster168to produce the caster and leg assembly192illustrated inFIG. 24. As with the prior embodiment, the longitudinal, vertical axis or centerline CL again is the direction and location of the acting weight of the furniture since it is equidistant from the center points of the spherical rollers174and therefore the weight of the furniture is not offset to cause harmful moment arms in the caster and leg assembly194.

InFIG. 25there is a cross sectional view of a still further embodiment of the present invention and where there is only one spherical roller174that is positioned in the caster168so as to have its center point along the longitudinal, vertical centerline CL of the furniture leg196so that, as with the prior embodiments, the weight of the piece of furniture acts downwardly along the centerline CL directly, without offset, to the floor176. In this embodiment, the upper end198of the furniture leg196may also be directly affixed to the frame of the particular piece of furniture and the lower end200has formed therein a more narrow recessed area202. Within that recessed area202, there is provided a socket204that is affixed therein and which receives a stem206to affix the caster housing208to the furniture leg196.

Again, the centerline CL of the caster and leg assembly208passes through the center point of the spherical roller174to insure that the weight of the furniture acts directly through the spherical roller174and not offset as with the conventional offset casters.

Therefore, with the use of the leg and caster assembly of the present invention, the support through the leg contacting the floor is strengthened and yet the overall appearance is enhanced by locating the caster contiguous to the smooth continual exterior surface of the lower portion of the furniture leg. In any of the embodiments ofFIGS. 23-25, a glide can be attached to the caster housing in the manner shown and described with respect toFIGS. 4 and 7hereof.

Turning now toFIG. 26, there is shown a perspective, cutaway view of a box spring210that has a caster212affixed thereto in accordance with the present invention. As can be seen, the box spring210is constructed of a angle iron lower edge214that extends around the perimeter of the box spring210forming an inwardly directed ledge that supports the wooden cross beams216of the box spring210. The wooden cross beams216are also supported by metal T-shape cross supports218and a generally rigid wire structure220both stabilizes the inner stuffing222and supports the outer covering224.

At each corner of the box spring210there is provided a plastic corner226that supports the upper wire228of the, rigid wire structure220and which also rounds off the angle iron lower edges214to provide an overall rounded and pleasing appearance of the box spring210. At the bottom of the plastic corner226, there is a threaded hole (not shown). As alternative embodiments, the plastic corner226may be constructed of wood, metal or other suitable materials and instead of a threaded hole, there may be a pilot hole or no hole at all as will be later explained.

Turning toFIG. 27, taken along withFIG. 26, there is a side view of the caster212used with theFIG. 26embodiment and where the caster212can be of the construction previously disclosed and discussed and which has a threaded stud230extending upwardly therefrom. Therefore, in order to affix the caster212to the bottom of the box spring210, the threaded stud230is simply screwed into the threaded hole in the bottom of the plastic corner226.

In the alternative embodiment, if the corner of the box spring210is wood, the threaded stud230can have wood screw threads and be screwed to the wooden corner by the aid of a small pilot hole or directly into the wood if there is no hole present at all. In any event, the caster212is screwed directly to the bottom of the box spring210.

Turning finally toFIGS. 28 and 29, there is shown, respectively, a perspective view of a box spring232illustrating a further method of affixing a caster234to a box spring232and a perspective view of the caster234itself. As such, there is a female receptacle236formed in the bottom of the box spring232and, as shown, is in the configuration of a chevron, or L-shaped, that is, two straight portions238joined at an angle. The receptacle236can be provided as an insert embedded into the bottom of the box spring232or by other means, including, cutting the receptacle236therein. The internal, outer edges240can be tapered inwardly as the height of the receptacle236increases upwardly.

InFIG. 29, the male wedge member242is shown affixed to the caster234and which is generally L-shaped and dimensioned to interfit into the female receptacle236. Thus, the external edges244of the male wedge member242are tapered outwardly toward the caster236in a complementary way to the inwardly tapered inner edges of the receptacle236. Therefore, the caster234is affixed to the box spring232by simply pushing the male wedge member242up into the female receptacle236in the direction shown by the arrow W so that the male wedge member242is jammed into the female receptacle236to retain the caster234to the box spring232in a manner to be removable retained thereto. The affixation or junction between the caster234and the box spring232is further enhanced by the weight of the mattress and other covers that are placed atop of the box spring232since that weight further pushes the male wedge member242strongly into the female receptacle236.

While the present invention has been set forth in terms of a specific embodiment or embodiments, it will be understood that the caster assembly herein disclosed may be modified or altered by those skilled in the art to other configurations. Accordingly, the invention is to be broadly construed and limited only by the scope and spirit of the claims appended hereto.