Coupling arrangement for perfecting lithograph press unit

Claim 1

In a perfecting type lithograph press unit, the combination comprising a press frame, a pair of blanket cylinders journaled in the frame and in running engagement with one another and having blankets of resilient material for printing on opposite sides of a web passing between them, each of the blanket cylinders having an associated plate cylinder, a common press drive shaft, a pair of individual gear trains both coupled to the press drive shaft for driving of the respective plate cylinders and their respectively associated blanket cylinders, phase adjusting means in the individual gear trains for changing the phase of the printed impression applied to the web, a pair of auxiliary closely fitted gears interposed between the blanket cylinders directly in mesh for directly coupling them together thereby to preclude momentary relative slippage of one of the blanket cylinders with respect to the web, as well as overdriving of one blanket cylinder by the other as a result of local variations in the radius and resilient characteristics of the portions of the blankets which are in engagement with one another, and means including a continuous type clutch interposed in series with the pair of gears, the clutch having provision for tight engagement during normal running of the press and provision for disengagement to permit operation of the phase adjusting means when the press is running as well as tight reengagement in any new adjusted phase position.