Provided in a sheet-fed printing machine is a sheet transport drum, including a first comb segment and a second comb segment, the second comb segment being mounted so as to be rotatable relative to the first comb segment for providing an adjustment to a format length corresponding with that of a printing-material sheet, the comb segments being formed of prongs having interspaces therebetween, and at least one covering provided for covering the interspaces between the prongs.