Device for guiding sheets in a processing machine

A print machine has a paper sheet rotary guide with a detachable drum cap. The cap (7,8) has especially an ink repellent coating (15) of chrome, iron, titanium, nickel, cobalt, tungsten or molybdenum, covered by a an ink-repellent seal. A pneumatically operated paper sheet guide (10) is located in the sheet transfer zone under the cylinder (6).