Viscous rotary damper

A rotary damper comprising a driven gear having a rear surface, an axis of rotation and a cylindrical annular projection projecting from said rear surface coaxially with said gear axis, a case with a transverse bottom and having an axially extending cylindrical annular groove coaxial with said gear axis, the cylindrical annular projection being received in the cylindrical annular groove, there being a gap defined between the cylindrical annular projection and the cylindrical annular groove, grease filling said groove, an outer wall of the case defining the cylindrical annular groove having an inner periphery and a distal end opposite said bottom and being formed on said inner periphery and adjacent to said distal end with an axially extending annular depression having a greater outer diameter than the diameter of said inner periphery, said gear including a portion substantially covering said annular depression and the grease being partly forced out into the annular depression.