| 摘要 |
A bearing member has: a recess (51c) which has one end open and which has a bottom section (51b) located on the side opposite the opening and having a curved surface expanding along a sphere, the recess (51c) containing the sphere; and at least two rocking grooves (52) which are provided in the side surface of the recess and into which the ends of a rotational force transmission pin are inserted. At least part of each of the rocking grooves is provided with a portion which is parallel to the axis of the bearing member, and is also provided with a portion (52a) which curves so as to approach the axis. When the recess is viewed in the axial direction of the bearing member from the side of the recess which is open, the recess is formed in such a manner that the recess has no undercut section, and that the distance between the two rocking grooves which is measured on the open side of the recess in the direction perpendicular to the axial direction is, when a shaft member is mounted to the bearing member and even if the shaft member is in the most tilted position, less than the distance between the opposite ends of the rotational force transmission pin measured in the direction perpendicular to the axis of the bearing member. |
