Service Manual 2-19Drum Maintenance SystemThe drum maintenance system creates a thin intermediate liquid transfer surface, alayer of silicone oil, on the surface of the drum prior to printing. The oil keeps the inkfrom sticking to the drum’s surface and facilitates its transfer to the sheet of paper ortransparency film. The oil is contained in a porous foam roller.Prior to each print, a cam, driven by the process motor, raises the pivot plate, whichraises the oil roller against the rotating drum. A compliant wiper blade, also raised bythe same cam, assures that the oil film is smooth and even across the drum’s surface.The process drive rotates in one direction, which rotates the drum maintenancecamshaft, and raises the drum maintenance system to the drum. The process driverotates in the opposite direction to lower the drum maintenance system. The bladeremoves oil that is drained back into the maintenance kit drawer, through a felt filter,to the oil roller for reuse. As the drum completes one rotation, the rotating cam lowersthe oil roller and then a moment later, lowers the blade.The drum has a floating deadband, which is the narrow section of the drum containingexcess oil and other debris. The oil bar is left on the drum surface when the blade isremoved from the drum. This oil bar location is controlled to keep it outside of theprint area.An EEPROM chip, built-in to the maintenance kit, stores the number of oiling cyclesperformed by the drum maintenance system. The EEPROM stores the number ofprints remaining to track consumable life. At printer startup, four oiling cycles areperformed to condition the drum.s8400-121DrumMaintenance rollerDrum maintenancepivot plateDrum maintenancecamshaftBladeOil on drum
