| 摘要 |
<p>A dental handpiece (10) has a rotor (15) and a ball bearing assembly (13, 14) supporting the rotor (15). At least one of the ball bearing assemblies (13, 14) has a ball (20) and a retainer (21). The retainer (21) has at least one grease retaining groove (30, 50) or void (51) therein.</p> |
