Abstract: An object of the invention is to provide a dust cover for a ball joint which can suppress generation of a so-called mouth opening phenomenon in a small-diameter opening portion even under a low-temperature atmosphere, can effectively inhibit a seal performance from being lowered in the small-diameter opening portion and inhibit the sedimentation or the garbage from entering into a dust cover from an external portion, and has a good sealing performance. For this purpose, in a dust cover for a ball joint having a spherical head portion, a shaft, one end large-diameter opening portion, the other end small-diameter portion, and a film portion, concavo-concave engagement is formed between an inner peripheral surface of the rigid ring and an outer peripheral surface of a retainer having a cylindrical portion which is fitted and retained to an outer peripheral surface of the shaft.

Abstract: A dust cover for a ball joint is structured such that a spherical head portion formed in one end of a ball stud is retained within a socket, a shaft in the other end of the ball stud is fastened and fixed to a knuckle, a one end large-diameter opening portion having an embedded reinforcing ring is fixed and retained to an outer peripheral surface of the socket, the other end small-diameter opening portion having an embedded reinforcing ring is retained to the shaft, a film portion connecting the large-diameter opening portion and the small-diameter opening portion is provided, and the dust cover is made of an elastic material. A maximum inner diameter of the film portion is larger than an inner diameter of the reinforcing ring which is embedded in the one end large-diameter opening portion. Therefore, a functional advantage and an assembling advantage can be provided.

Abstract: An object of the invention is to provide a dust cover for a ball joint which can suppress generation of a so-called mouth opening phenomenon in a small-diameter opening portion even under a low-temperature atmosphere, can effectively inhibit a seal performance from being lowered in the small-diameter opening portion and inhibit the sedimentation or the garbage from entering into a dust cover from an external portion, and has a good sealing performance. For this purpose, in a dust cover for a ball joint having a spherical head portion, a shaft, one end large-diameter opening portion, the other end small-diameter portion, and a film portion, concavo-concave engagement is formed between an inner peripheral surface of the rigid ring and an outer peripheral surface of a retainer having a cylindrical portion which is fitted and retained to an outer peripheral surface of the shaft.