US 3503523 A
Description (OCR text may contain errors)
March 31 l970 w. F. HAMILTON E rAL 3,503,523
BEARING CONSTRUCTION FOR ROTATABLE TRYS Filed Jan. 17. 1968 Y 1f will /J E UnitedStates Patent 3,503,523 BEARING CONSTRUCTIOI FOR ROTATABLE TRAY William F. Hamilton and Stuart R. Scheyer, Mundelein, Ill., assignors to Decorel Corporation, Mundelein, Ill., a corporation of Illinois Filed Jan. 17, 1968, Ser. No. 698,486 Int. Cl. A47g 23/08; A47f 5/03, 5/04, 5/16 U.S. Cl. 211-163 9 Claims ABSTRACT F THE DISCLOSURE A rotatable serving tray or Lazy Susan is described in which a ceramic compartmented tray is pivoted for rotation about a ceramic base and in which a spoked bearing ring of anti-friction plastic is interposed between the rotatable elements and is positioned by a central pivot shaft.
The present invention relates to rotatable trays, and in particular to an improved bearing construction for such trays.
The well-known Lazy Susan rotatable tray is a common fixture in almost every household. Such trays generally comprise a base, a central shaft, and a rotatable serving tray overhanging the base and mounted thereupon for rotation. Variations of this design are found in rotatable trays intended for other uses, such as for storing small parts in a workshop or for displaying merchandise in a store.
A principal object of the present invention is to provide an improved bearing construction for rotatable trays in which the tray is mounted for free rotation while being held secure against tipping or rocking. The improved construction of the invention is intended to embody the foregoing features while being of simple and inexpensive construction and requiring no complex or finely machined parts such as ball bearings. In more detail, it is intended that the bearing construction be compatible with rotatable tray elements made of a ceramic material without the need for additional parts such as inserts, bearing races, and the like.
Other objects and advantages of the invention will become apparent upon reference to the drawings, in which:
FIGURE 1 is a perspective of an improved rotatable serving tray exemplifying the present invention;
FIG. 2 is an enlarged sectional elevation of the serving tray of FIG. l, taken through the axis of tray rotation; and
FIG. 3 is a detail of the anti-friction bearing member used in the tray of the foregoing gures.
While the invention will be described in connection with a particular exemplary embodiment, it will be understood that it is not intended to so limit the invention, but it is instead intended to cover all alternative and equivalent constructions as may be included within the spirit and scope of the invention as defined by the appended claims.
In the drawings, there is shown in FIG. 1 a Lazy Susan serving tray exemplifying the present invention. The tray includes a base 11 and a rotatable tray platform 12 which is surmounted by a decorative pedestal 13 carrying a handle 15 at its upper end. The tray platform 12 has a plurality of individual compartments 16 formed by the intersection of a central upraised ring 17 and a plurality of dividers 1S.
Pursuant to a principal feature of the invention, an improved bearing construction is provided which gives the rotatable platform 12 a high degree of stability while still allowing it to rotate freely. This is accomplished by the provision of a ring-shaped bearing member 20 3,503,523 Patented Mar. 31, 1970 made of anti-friction plastic which is interposed between the relatively rotatable elements 11, 12. To receive the bearing member 20, the underside of the rotatable platform 12 is provided with a saucer-like depression 21, and a like depression 22 is provided in the base 11. The bearing element 20 itself consists of an outer ring 23 and an inner ring 25 which are linked by connecting means which in the exemplary embodiment comprise a plurality of interconnecting spokes 26. Within the inner ring 25 is a spacer flange 27 having an aperture 28 adapted to receive a central shaft 30 which attaches the platform 12 to the base 11 for rotation.
A significant feature of the invention is that the use of the bearing element 20 as described herein allows the relatively rotating elements 11, 12 to be made of materials not otherwise suited for relative rotation with respect to one another. For instance, a successful rotatable tray has been constructed using ceramic material for both base 11 and platform 12 with the interposed bearing element 20 being made of an anti-friction plastic material. Preferably, the bearing element 20 is made of injection molded plastic which may be nylon, polytetrafluoroethylene, or any other polymeric material having similar anti-friction properties.
As another feature of the invention, the platform 12 is adapted to receive and be positioned by the central shaft 30 in a manner which minimizes rocking and tipping. This is done by providing a frusto-conical upraised central member 31 at the center of the platform 12 where the shaft 30 is received. An opening 32 allows the shaft 30 to protrude through the platform 12 and engage the pedestal 13. According to the invention, the opening 32 at the uppermost portion of the upraised cone structure 31 is spaced substantially above the level of the bearing element 20 by a distance generally on the order of the radius of the outer ring 23 of the bearing element 20. In this way the attachment of the platform 12 to the base 11 is achieved principally at two points: along a circular line of contact corresponding to the outer ring 23 of the bearing element 20, and by the pivoting of the central shaft 30 within the opening 32.
As a further feature of the invention, the bearing element 20 is retained in proper position by the central flange 27. The flange 27 is sized to slip over the central shaft 30 in a close but freely rotating fit. The bearing element 20 is thus retained in substantial concentric alignment with the saucer-like depressions 21, 22 in the platform 1 Zand base 11 respectively.
The central shaft 30 is preferably threaded at each end as shown in FIG. 2, and washers 33, 34 are provided at each end by which the relatively rotating elements 11, 12 are retained. At the lower end, inside the hollow within the base 11, is provided an elastic stop nut 36 which threads to the threaded end of the shaft 30 so that the degree of tightness of the assembled parts may be easily adjusted. At the upper end, the central shaft 30 is simply screwed into a corresponding threaded opening in the pedestal 14 to complete the assembly.
The following is claimed as invention:
1. In a rotatable serving tray, the combination com prising, a base having an upper surface with a circular saucer-like depression forming a bearing surface on its upper end, a platform having a lower surface with a circular saucer-like depression forming a bearing surface on the under side thereof, shaft means concentric with said depressed bearing surfaces and joining said base and said platform for relative rotation therebetween, and a bearing member interposed between said depressed bearing surfaces of said base and platform, said bearing member being made of anti-friction plastic material and comprising an outer ring and an inner ring of diameter smaller than said outer ring joined by a plurality of interconnecting spokes, the inner ring having a central flange defining a aperture adapted to receive the shaft concentric therewith for retaining the bearing member in substantial concentric alignment with the respective saucer-like depressed bearing surfaces of said base and platform.
2. A rotatable tray as defined in claim 1 in which said plastic material consists of molded nylon.
3. A rotatable tray as defined in claim 1 in which said plastic material consists of polytetrauoroethylene.
4. The combination defined in claim 1 in which the bearing surfaces of said base and said platform are of ceramic material.
5. The combination defined in claim 1 in which said base and said platform are substantially and entirely made of ceramic material.
6. The combination dened in claim 1 in which said platform includes an upstanding truncated frusto-conical section concentric with said shaft and engaging said shaft at a point spaced substantially above the level of engagement with said bearing element.
7. The combination defined in claim 6 in which said shaft includes an upper flange engageable with the upper surface of said platform and a lower flange engageable with the underside of said base.
8. The combination defined in claim 7 in which the lower portion of said shaft is threaded and in which said lower flange comprises an elastic stop nut threaded to said shaft.
9. The combination defined in claim 7 having a handle carried by said shaft above said upper ange.
References Cited UNITED STATES PATENTS FRANCIS K. ZUGEL, Primary Examiner U.S. Cl. X.R.