A couple of gear wheels for driving printing drum with means for mutual phase restoration

摘要

In a couple of axially engageable/disengageable gear wheels (12,14) for driving a printing drum, in which each gear wheel has a duplicate construction including a primary gear (12a,14a) for transmission of a power for driving the printing drum and an auxiliary gear (12b,14b) for suppressing a backlash, the primary gear and the auxiliary gear are shifted relative to one another in the phase, except a predetermined meshing area, so that the two duplicate gear wheels are allowed to disengage from and re-engage with one another only when the two gear wheels are rotationally positioned at a predetermined rotational relationship.