| 摘要 |
A joint boot, wherein sealing performance of a large-diameter attachment part to an outer casing is enhanced, includes a larger-diameter attachment part 2, a small-diameter attachment part 4 and a bellows part 5. The large-diameter attachment part 2 is provided on its inner periphery with plural convex portions 7 and constructed to be capable of externally fitting in plural recessed portions 8 formed on the outer periphery of the outer casting 1. The large-diameter attachment part 2 and the bellows part are formed in separate bodies, and a fit cylinder part 6 is extended at one extremity of the bellows part 5. The convex portions 7 include each an inner wall portion 12 jutting radially inwardly in a curved form, an outer wall portion 11 in an arc form constituting part of the outer periphery surface of the large-diameter attachment part, a central strut wall 13 A connecting both in the circumferential middles of both, and a pair of lateral strut walls 13 B, 13 B connecting the inner and outer wall portions on both sides of the central strut wall, thereby forming four relief holes 21 A, 22 A, 23 A, 24 A, circumferentially juxtaposed on the convex portions.
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