Image Number 4 for United States Patent #6896414.
The ball roller according to the present invention has a unique shape so that it can be handled just as easily as a conventional ball while being endurable against high load as is a roller. The ball roller comprises a rolling portion having an arcuate surface, and two spherical end portions spherically protruding from both ends of the rolling portion. The rolling portion has a radius of curvature larger than that of each of the spherical end portions, curvature centers of the spherical end portions are located on the rotational axis of the rolling portion. In another embodiment of the present invention, a ratio between the maximum diameter d of the rolling portion and the distance W between the two apexes of the spherical end portions falls within a rage of approximately 80%.+-.17%.