| 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 joint angle is large is reduced. The boot has the bellows section (1) in which three or more circumferentially extending crests (11<SUB>1</SUB>-11<SUB>3</SUB>) and roots (12<SUB>1</SUB>-12<SUB>2</SUB>) between the crests are repeatedly 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<SUB>1</SUB>/t<SUB>2</SUB>) of the thickness (t<SUB>1</SUB>) of the rising walls (1a, 1f) to the thickness (t<SUB>2</SUB>) of the other portions of the bellows section (1) is set to 0.6 = t<SUB>1</SUB>/t<SUB>2</SUB> < 1.0. |
