Abstract: A suction system for a printing press having a cycled suction-requiring element serviced by a suction line in a dusty environment. The line includes a suction valve having an operator coupled to the press drive and which is cyclically opened and closed to define active suction intervals separated by idle intervals. A source of pressurized air is connected, via a pressure valve, to the suction line. A pressure valve operator, also coupled to the press drive, opens the pressure valve momentarily during an idle interval following each predetermined number of operations of the suction valve, so that the suction line is cyclically cleaned by reverse shot of pressurized air without interfering with the function performed by the suction. In the preferred embodiment the suction valve operator is coupled to the pressure valve operator through an integral step down driving connection.