US2818676A

US2818676A - Spinning tops

Info

Publication number: US2818676A
Application number: US315700A
Authority: US
Inventors: Jonker Frederick
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-10-20
Filing date: 1952-10-20
Publication date: 1958-01-07
Anticipated expiration: 1975-01-07

Description

7; 5 F. JONKEl Q 2,818,676

' SPINNING TOPS Filed Oct 20, 1952 A; ORNEY SPENNHNG TOPS Frederick .l onker, Takoma Park, Md.

Application October 243, 1952, Serial No. 315,700

6 Claims. (Ci. 46-30) This invention pertains to spinning tops having in general the property of changing their axis of rotation when spun orginally about a certain axis referred to as the main axis. Such tops not only have amusement and entertainment value, but are also of value in demonstrating or teaching the mathematical and dynamic principles underlying their action.

Tops which automatically reverse their attitude when rotating are known. These tops provide a 180 degree change in axis of rotation, from a point on a curved surface to a stem.

The present invention however, provides for tops having less than 90 degree change of axis of rotation, tops which change their axis of rotation from a surface of smaller diameter to a surface of larger diameter, tops which end up spinning on an arbitrary point of a narrow rim instead of on a stem or surface, and tops which end up spinning on a predetermined point of a narrow rim as Well as tops which continue performing their reversing motions through automatically moving weights inside of these tops.

The improvements constituting the invention will be made clear in the following detailed specification of certain preferred and exemplary embodiments shown in the accompanying drawings, in which:

Fig. 1 is a side elevation, partially in section, of one form of top according to the invention, and including a showing of a suitable type of spinning aid,

Fig. 2 is a plan view of the top only of Fig. 1,

Fig. 3 is a view similar to Fig. l but of a modified form of top, and with a different type of spinning aid,

Fig. 4 is a plan view or the top only of Fig. 3,

Fig. 5 is a side elevation, partly broken away, of another form of top according to the invention,

Fig. 6 is a vertical sectional view of a different top, and

Fig. 7 is a similar view of still another modification.

Any of the tops of the invention can be spun by hand alone, but it is convenient to use a spinner such as shown in Fig. 1, in which numeral 10 denotes a handle having a projecting pin 12 adapted to enter a hole or socket 12 lying on the main axis of the top. A spool 14 loosely surrounds pin 12 and can be rotated by an unwinding cord 16, so that another pin 18 on the spool, which engages in an off-center socket such as 26 in the top, will rotate the top initially at fair speed. The spinner is then removed and the top continues to rotate. Spring devices for the same purpose are well known in the art.

The top 22 of Figs. 1 and 2 has a main axis A and is shaped so that all horizontal cross sect-ions thereof are circular or substantially so. The upper surface 24 and the lower surface 26 are defined by identical or nonidentical curves of such shape that the extension of the radius of curvature for every point of the curves crosses the main axis A in or beyond the center of gravity of the top, which may lie at 28. Two such extended radii are illustrated in Fig. 1 by arrows Sii'and 32.

2,818,676 Patented Jan. 7, 1958 A better way of defining the curves of

surfaces

24 and 26 is to say that the distance from the center of gravity to any point of the curve must increase as the angle x between the main axis and the line connecting the center of gravity with this point increases, when this angle is measured in such a manner that it is zero for the point where this distance is smallest. This definition will be referred to hereinafter as the curve definition. For example, the semi-circular or

semi-spherical curves

24 and 26 of Fig. 1 meet this definition, for their centers lie in each case beyond the center of gravity 28. Another shape meeting this requirement would be an elliptical cross-section where the short axes of the ellipses coincide with the main axis A, but many other geometrical shapes are possible.

In general all tops according to the present invention, as well as those mentioned above, meet this definition as any top changing its axis of rotation necessarily must.

However, the tops according to the present invention possess two different continuous surfaces meeting the curve definition and these surfaces are separated by a discontinuity.

In the tops according to the present invention, the surface forming said discontinuity becomes the location of the final spinning point of the top if the distnace from the center of gravity to this surface is a maximum at this surface. This is the case for the tops shown in Figs. 1, 2, 3 and 4.

However, if the distance from the center of gravity to this surface is not a maximum at this surface but changes its value, the point of rotation will pass the surface when the top is changing its axis of rotation. This is the case with the top of Fig. 5.

When not spinning, the top 22 of Figs. 1 and 2 will assume such an attitute that the contact point with the ground or other surface is formed by that point where the distance from this point to the center of gravity 28 is smallest. When spun around the main axis A, by means of the spinner shown or otherwise, the top will gradually change position and commence spinning on a point such that the distance to the center of gravity 28 is greatest. For the top 22 of Fig. 1, this will be an arbitrary point of the circumference of the interface of the two halves. The

curves

24 and 26 may meet on a circle which is the equator of the top, but it is convenient in some cases to provide an equatorial groove 34 as shown in Fig. 1, to receive a spinning cord in lieu of the use of the mechanical spinner, or in connection with a simpler form of spinner to be described in connection with Fig. 3.

The preferred location of the center of gravity 28 is on the main axis A and close to the middle or equatorial plane, but it can also be displaced laterally from axis A as indicated at 28. Such a top will, when spun on the main axis A, change its axis as before until it is spinning upon a point on the equator, but instead of this being an arbitrary point, it will be point 36 of Fig. 2, such that when spinning on point 36 the center of gravity 28 will be at the greatest possible distance from the horizontal surface on which the top is spinning.

Figs. 3 and 4 show a modified form of this same top, and also a simpler form of spinner 38, comprising a simple end pin loosely received in the center socket of the top 40. The top 40 again has a main axis A, and upper and lower

curved surfaces

42 and 44 separated by an annular concentric rim 47 lying in the middle plane of the top. Cord grooves such as 46, 48 may be provided adjacent this rim. If the center of gravity is at point 50 on axis A, the top will erect itself during rotation until it is spinning on an arbitrary point on rim 47, while if the center 3 of gravity is displaced as to point 50', it will spin upon point 52 of Fig. 4.

Further variations can be obtained by giving the upper and lower halves of. the top diifarent diameters at their interface. Fig. 5 shows such avariation with two hemisphericai surfaces 5.4 56 separated by the groove 58 for the spinning cord. It the center of gravity lies on axis nd t n e c at e twah l es c h o he final spinning point will be an arbitrary point on the periphery of the middle plane or edge of the upper hemisphere, while it it is displaced as. to point. 6 the final spinning point will be one of. two points on that edge in thesame manner asbefore. Many other shapes than the emis h 23p? shown. P9 $ibl 7 Referring again to Fig. 5, if the center of gravity is located on axis A but suificiently below the middle plane, as at point 62, the top can be made to invert itself completely when spun around axis A with the center of gravity at the lowest point. This will be the casewhen the distance from the center of gravity 62 to any point of the circumference of the top iilcreases as the angle x between the axis A and the line connecting 62 with this point on the circumference increases. The angle should be measured as shown in Fig. 5, starting atthe point Where the angle is smallest; it runs from 0 to 180.

Still another form of top involves the use of a movable center of gravity. Fig. 6 showssuch a top 64 having an internal cavity 66 in which is slidable a weight 68. The outer shell or surface of the top may be spherical or of any other shape meeting the curve definition stated above. When this top is spun around axis A, it will invert itself, whereupon the weight 68 will drop down and the top will invert itself again, this cycle continuing so long as sufficient speed is maintained.

Instead of providing for a movable center of gravity which moves in only one direction, it can be arranged to move in two or three directions. Such a top is shown in Fig. 7, and denoted by numeral 70. The top 70 is shown as spherical, but it could also be. elliptical or of other shape. Inside the topis a cavity 72, which may be cylindrical, spherical or of other suitable shape, its wall having a number of shallow depressions 74 therein to receive a movable weight 76 such as a sphere, for example. The top is spun in the. position shown, with the weight 76 at the. bottom. Then A will be the main axis, and the shape of the top and the position of the center of gravity of the combined top and wegiht 76 will have to meet the requirements of the curve definition as stated earlier. When the top begins to invert itself, the weight 76 will drop out of its initial depression and lodge in another, and soon. The depths of these other depressions and the shape of the top. will of course also have to meet the curve definition, when considering the main axis as the axis going through the geometric center of the top and the center of weight '7 6.

All of the tops will be finished in patterns of bright contrasting colors in order that the different positions may be observed. It will be observed that it is a common characteristic of the tops described herein, that they will operate as tops regardless of whether they are initially spun upon one end or the other. That is, there is no unique position in which the tops must initially be placed. A top as shown in certain of the figures will move from an initial spinning condition on one end or the other to a condition in which it is spinning on the edge, or even to a preferred point on the edge, the recognition of this fact in either case being made easy by the appropriate coloring. The top of Fig. 4 will spin on either end initially, and from one end it will turn completely over, while from the other it will not turn. Again, the coloring is to be chosen to make this apparent to the observer. In the forms of Figs. 6 and 7, of course, the turning from 4 one end to the other, during spin, is automatic-ally repeated.

I claim:

1. A spinning top adapted to change its axis of rotation automatically, said top having a substantially circular cross-section in planes perpendicular to its main axis, and a middle plane perpendicular to said main axis and dividing the top into two halves; these two halves each hav ing a continuous curved surface having such a shape that the distance from a point of said surface to the intersection of said main axis with a plane which is parallel to said middle plane and containing the center of gravity of the top, changes its value continuously as the angle between said main axis and the line connecting said intersection and said point of said surface increases, when said angle is measured in such a manner that it is zero when said distance reaches its extreme value; driving means for said top, and means for detachably coupling said driving means to said top to initiate its spin; the lastnamed means defining an initial axis of spin for the top which is aligned with said main axis.

2. A top in accordance with claim 1, in which the said halves of the top are not identical, and the top has at said middle plane a diameter equal to that of the larger half; said change in value for the larger half being a decrease of said distance and said extreme value for the larger half being the largest possible distance; and said change in value for the smaller half being an increase of said distance and said extreme value for the smaller half being the smallest possible distance.

3. A top in accordance with claim 1, said two halves of the top being substantially identical, and the top having at said middle plane a diameter substantially equal to the intersection of said halves; and in which said continuous change in value is an increase in said distance and said extreme value is the smallest possible value of said distance.

4. A top in accordance with claim 3, having at said middle plane a disc of larger diameter than the diameter of either of the halves.

5. A top in accordance with claim 1, said two halves of the top being substantially identical, and the top having at said middle plane a diameter substantially equal to the intersection of said halves; a hollow elongated chamber inside said top concentric with said main axis, and a weight in said chamber adapted to move back and forth along the direction of said main axis under the influence of gravity.

6. A top in accordance with claim 1, said two halves of the top being substantially identical hemispheres, and the top having at said middle plane the same diameter as said hemispheres; a substantially spherical hollow chamber inside said top substantially concentric with said hemispheres, a number of depressions in the wall of said chamber, at least one depression lying on said main axis, and a movable weight Within the chamber sized to fit loosely in said depressions.

References Cited in the file of this patent UNITED ST TES PATENTS 643,311 Verniaud Feb. 13, 1900 973,595 Wahlin Oct. 25, 1910 1,575,264 Henry Mar. 2, 1926 1,610,530 Monson Dec. 14, 1926 2,015,649 Amell Oct. 1, 1935 2,058,692 Humphrey Oct. 27, 1936 2,332,507 Dailey Oct. 26, 1943 2,700,346 Ostberg Ian. 25, 1955 FOREIGN PATENTS 130,596 Germany May 9, 1902