PURPOSE: To combine a cover member with a body member strongly by journal- connecting a cover hub to a clutch hub and engaging so that a rollover part is gnaws into the recessed part of a cover member by rolling.

CONSTITUTION: The radial inner end of a cover hub 45 extending to the annular axial direction of a cover member 29 is journal-connected to the surface of a clutch hub 57. In the outside peripheral edge 41 of the cover member 29, plural diameter shrinkage recessed parts are formed mutually at some intervals across the entire priphery of the outer surface and the rollover part 69 of the outside peripheral edge 33 of the body member 27 is rollovered and engaged tightly and while the torque is transmitted from a fluid joint 11 to a shaft means 13, the rotary motion of the cover member 29 for the body member 27 is obstructed. Thus, the high torque transmission of a viscous joint 11 can be ensured.