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%.
