Abstract: An inking mechanism for a rotary offset printing machine in which ink is taken from an ink reservoir in metered quantities and distributed by inking rollers to form an ink film which is adapted to be applied to a printing plate mounted on a plate cylinder, at least one of said inking rollers being a distributing roller mounted for rotational and axial reciprocating displacement. A distributing drive is provided which includes a releasable shift coupling operable for interrupting axial movement of the distributing roller upon a printing stoppage even though the printing machine continues to operate. Upon resumption of printing, the shift coupling is actuatable by a releasing mechanism so that the distributing rollers resume axial reciprocating movement. The illustrated shift coupling is shown as a pair of gear plates arranged between two drive wheels, and alternatively, a friction closure coupling can be used, either of which can be electromagnetically, pneumatically, or hydraulically actuated.