Abstract: A torsional vibration damper with a housing defining an annular space. A cover is mounted on the housing. The cover and the housing define an annular working chamber. A first mass inertia ring is disposed inside and configured to rotated relative to the annular working chamber. A second mass inertia ring is disposed inside the annular working chamber. The second inertia mass ring is configured to rotate inside the annular working chamber independently with respect to the first inertia mass ring. A viscous damping media is disposed inside the annular working chamber. A hub is configured to extend from the housing in an axial direction.

Abstract: A viscous torsional vibration damper of the kind operating on the shear film principle has an annular shaped housing providing an annular working chamber within which is mounted an annular complementary inertia mass ring and a viscous damping fluid substantially fills shear film spaces between the working surfaces of the inertia ring and confronting working surfaces of the housing within the chamber. The cover has one or more lugs extending from the outside of an axially extending wall that engage with lugs inside the housing near the bottom wall. Rotation of the cover relative to the housing causes an axial force through the lugs that forces the cover into sealing engagement with the housing.

Abstract: A viscous torsional vibration damper comprising a housing adapted to be connected to a rotary member to be damped, the housing comprising an annular chamber having an inner cylindrical surface and an outer cylindrical surface elongated about a central axis, an inertial mass within the chamber and having an inner cylindrical surface and an outer cylindrical surface elongated about an axis of rotation, the inertial mass and the chamber configured such that the inertial mass is rotatable in the chamber relative to the housing, a first annular centering element and a second annular centering element between the opposed inner cylindrical surfaces of the chamber and the inertial mass or the opposed outer cylindrical surfaces of the chamber and the inertial mass, the annular centering elements configured and arranged to bias the axis of rotation of the inertial mass towards alignment with the central axis of the chamber, a clearance gap between the housing and the inertial mass, the clearance gap having a first port