| 摘要 |
A bellows section (1) of a boot is adapted to be flexibly and repeatedly deformable without reduction in durability, thereby rotational resistance when a j oint angle is large is reduced. The boot has the bellows section (1) in which three or more circumferentially extending crests (11 1 -11 3 ) and roots (12 1 -12 2 ) between the crests are alternately formed; a large diameter installation section (2) formed at one end of the bellows section; and a small diameter installation section (3) formed at the other end. In the bellows section (1), a rising wall (1a) closest to the large diameter installation section (2) and a rising wall (1f) closest to the small diameter installation section (3) have smaller wall thickness than other portions of the bellows section (1) . The ratio (t 1 /t 2 ) of the thickness (t 1 ) of the rising walls (1a, 1f) to the thickness (t 2 ) of the other portions of the bellows section (1) is set to 0.6 ‰ t 1 /t 2 < 1.0. |
