| 摘要 |
PROBLEM TO BE SOLVED: To reduce spin loss.SOLUTION: A facing 121 is provided on a surface forming a contact part with at least one of a primary disc and a secondary disc (center disc 12a). In the facing 121, a plurality of grooves 122 is provided in a disc circumferential direction so that a width in a disc radial direction of the facing 121 sectioned by the plurality of grooves 122 in the disc circumferential direction is made narrower than a width in the disc radial direction of the contact part.SELECTED DRAWING: Figure 8 |
