| 摘要 |
PROBLEM TO BE SOLVED: To reduce abrasion in a thrust dynamic pressure bearing part by easily generating a sufficient dynamic pressure needed in the thrust dynamic pressure bearing part. SOLUTION: A depth of a dynamic pressure generating groove in a thrust bearing part SBb having a smaller bearing gap than that of the other thrust bearing part SBa out of the two thrust bearing parts SBa and SBb is formed smaller than a depth of a dynamic pressure generating groove in the other thrust bearing part SBa. A second opposing member 16 is made of a material harder than a material forming a first opposing member 13, and a predetermined urging means which urges a thrust plate 23 so as to always float from the second thrust bearing part SBb. |
