Patent ID: 8070612

Claim:
A boot for a constant-velocity universal joint, the boot comprising: a major-diameter cylindrical portion; a minor-diameter cylindrical portion, separated from and concentric with the major-diameter cylinder portion, and having a smaller diameter than that of the major-diameter cylindrical portion; and an intermediate portion connecting the major-diameter cylindrical portion with the minor-diameter cylindrical portion, wherein said intermediate portion comprises: a stretchable bellows portion connected with said minor-diameter cylindrical portion integrally; and a rigidity-producing portion connected with the bellows portion and said major-diameter cylindrical portion integrally, wherein the rigidity-producing portion enlarges diametrically from said bellows portion toward said major-diameter cylindrical portion, and wherein a wall thickness of said boot at said rigidity-producing portion is enlarged as compared to a wall thickness of said boot at the bellows portion, whereby at least an outer peripheral surface of said rigidity-producing portion has a plurality of shoulders in a stepwise manner resulting from the enlarged wall thickness, wherein at least one of said shoulders comprises alternately repeated crests protruding in the diametrically outward direction of said shoulders, and roots denting in the diametrically inward direction of said shoulders, and said shoulders have a side surface that connects between said root and said crest in the substantially axial direction of said shoulders, and an end surface that connects between said crest and said root in the substantially diametrical direction, wherein the enlarged wall thickness is not provided at said root.