Abstract: A sheet-transporting drum includes sheet-supporting areas each being formed of a first comb segment and a second comb segment having segment teeth. At least one of the comb segments is rotatable for adaptation to a sheet format. A mechanical leading-edge gripper is provided on the first comb segment and a pneumatic trailing-edge gripper is provided on the second comb segment. A mechanical trailing-edge gripper is additionally disposed on the second comb segment and is deactivatable in particular by format adjustments. This advantageously allows either the trailing edge of a sheet to be securely held down mechanically or a full-bleed print to be applied to the sheet when the trailing edge of the sheet is held down pneumatically. A sheet-fed printing machine is also provided.

Abstract: A sheet-transport drum includes at least two sheet-supporting surfaces with suction openings. Each respective sheet-supporting surface is formed of first and second comb segments with segment teeth. Suction grooves are provided in the segment teeth and a trailing-edge suction groove is provided in the sheet-supporting surface of each respective second comb segment. A rotary valve is provided for a timed supply of suction air. A plurality of vacuum sources is provided and a trailing-edge suction groove is assigned to each respective vacuum source by the rotary valve. This ensures that the vacuum provided by a respective trailing-edge suction groove at the trailing edge of a respective sheet is reliably maintained even if a previous or following sheet is missing. A sheet-fed printing machine with the sheet-transport drum is also provided.

Abstract: A sheet-transport drum includes at least two sheet-supporting surfaces with suction openings. Each respective sheet-supporting surface is formed of first and second comb segments with segment teeth. Suction grooves are provided in the segment teeth and a trailing-edge suction groove is provided in the sheet-supporting surface of each respective second comb segment. A rotary valve is provided for a timed supply of suction air. A plurality of vacuum sources is provided and a trailing-edge suction groove is assigned to each respective vacuum source by the rotary valve. This ensures that the vacuum provided by a respective trailing-edge suction groove at the trailing edge of a respective sheet is reliably maintained even if a previous or following sheet is missing. A sheet-fed printing machine with the sheet-transport drum is also provided.

Abstract: A sheet-transporting drum includes sheet-supporting areas each being formed of a first comb segment and a second comb segment having segment teeth. At least one of the comb segments is rotatable for adaptation to a sheet format. A mechanical leading-edge gripper is provided on the first comb segment and a pneumatic trailing-edge gripper is provided on the second comb segment. A mechanical trailing-edge gripper is additionally disposed on the second comb segment and is deactivatable in particular by format adjustments. This advantageously allows either the trailing edge of a sheet to be securely held down mechanically or a full-bleed print to be applied to the sheet when the trailing edge of the sheet is held down pneumatically. A sheet-fed printing machine is also provided.

Abstract: A machine processing printing-material sheets contains a first sheet transport drum and a second sheet transport drum disposed immediately after the first sheet transport drum in a sheet transport direction. The first sheet transport drum has gripper systems which describe a gripper flight circle during its rotation and a drum profile deviating substantially from a circular shape with outer contour regions running between the gripper systems and set back from the gripper flight circle. The second sheet transport drum has a sheet support surface with pneumatic grooves formed therein. The sheet support surface is composed of a first and second comb segments each with segment prongs. The pneumatic grooves are introduced into the segment prongs of at least one of the comb segments. The pneumatic grooves are preferably introduced both into the segment prongs of the first comb segment and into the segment prongs of the second comb segment.

Abstract: A reversing or turning assembly of a sheet-processing machine includes an impression cylinder having a circumferential surface for transporting sheets thereon for printing the sheets in a printing nip associated with the impression cylinder. Gripper devices are provided for gripping the printed sheets at a respective trailing edge thereof and for lifting the gripped sheets off the impression cylinder for reversing the gripped sheets. The circumferential surface of the impression cylinder is formed with recesses in a region thereof occupied by the trailing edge of the sheets, for permitting the gripper devices to penetrate or dip into the recesses to grip the sheet trailing edge. The recesses have a position being variable in circumferential direction of the circumferential surface of the impression cylinder for adapting to different sheet formats.

Abstract: A device for transferring a sheet via a peripheral region of a cylinder includes an airflow-generating device for applying at least one air flow to the peripheral region of the cylinder, with which the sheet is associated, the airflow being directed in a direction of rotation of the cylinder; and a method of operating the device for transferring a sheet via a peripheral region of a cylinder.