Abstract: An eccentric gear comprises first and second gear rings (7,10) of which the one (7) has internal, straight cogs and the other (10) a smaller number of external cogs. At least one gear ring has a conical form with a large end (A--A) and a small end (B--B), the other gear ring (10) having a smaller pitch diameter than the first one (7) and being eccentrically mounted in bearings relative to the first one. Axes of symmetry (24,25) of the respective gear rings form an angle (.alpha.) with each other. The contact points or the locations of engagement between the flanks of the cogs in the one gear ring and the opposed flanks of the cogs in the other gear ring are substantially located along a helical line which extends in axial direction between said large and small ends.

Abstract: A roller device such as is used, e.g. as a distribution roller in an off-set printing machine, include an outer cylinder mounted in bearing units at opposed ends and is rotatable around and axis. At least one of the bearing units includes an inner cylinder, a casing built into the inner cylinder, which casing is rotatable via a gear by a rotation speed that differs from the rotation speed of the inner cylinder. A mechanism is provided which operates between the casing and the inner cylinder, for the purpose of converting the relative rotational movement between the casing and the inner cylinder into an axial reciprocal motion of the inner cylinder and thus also of the outer cylinder.