A print media holder device has first and second grip members. Permanent magnets are attached to the first and second grip members. An electromagnet is disposed between the first and second grip members, where when the electromagnet is selectively energized the permanent magnets attached to the first and second grip members are repelled in a manner that increases the outer dimension of the print media holder device to grip a media core.

A print media holder device has first and second grip members. Permanent magnets are attached to the first and second grip members. An electromagnet is disposed between the first and second grip members, where when the electromagnet is selectively energized the permanent magnets attached to the first and second grip members are repelled in a manner that increases the outer dimension of the print media holder device to grip a media core.

A print media holder device has first and second grip members. Permanent magnets are attached to the first and second grip members. An electromagnet is disposed between the first and second grip members, where when the electromagnet is selectively energized the permanent magnets attached to the first and second grip members are repelled in a manner that increases the outer dimension of the print media holder device to grip a media core.

A sheet gripping mechanism includes a first sheet guide including a guide surface facing a sheet conveyance path along which a sheet is to be conveyed and a second sheet guide which faces the first sheet guide across the sheet conveyance path. The second sheet guide includes a protuberance extending toward the first sheet guide, to locations beyond the guide surface formed by the first sheet guide. When a sheet is located between the first sheet guide and the protuberance of the second sheet guide, the protuberance extends at least a portion of the sheet toward the first sheet guide to bring a part of a surface of the sheet into contact with the first sheet guide.

A sheet gripping mechanism includes a first sheet guide including a guide surface facing a sheet conveyance path along which a sheet is to be conveyed and a second sheet guide which faces the first sheet guide across the sheet conveyance path. The second sheet guide includes a protuberance extending toward the first sheet guide, to locations beyond the guide surface formed by the first sheet guide. When a sheet is located between the first sheet guide and the protuberance of the second sheet guide, the protuberance extends at least a portion of the sheet toward the first sheet guide to bring a part of a surface of the sheet into contact with the first sheet guide.

A print media holder device has first and second grip members. Permanent magnets are attached to the first and second grip members. An electromagnet is disposed between the first and second grip members, where when the electromagnet is selectively energized the permanent magnets attached to the first and second grip members are repelled in a manner that increases the outer dimension of the print media holder device to grip a media core.

A print media holder device has first and second grip members. Permanent magnets are attached to the first and second grip members. An electromagnet is disposed between the first and second grip members, where when the electromagnet is selectively energized the permanent magnets attached to the first and second grip members are repelled in a manner that increases the outer dimension of the print media holder device to grip a media core.

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.

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.

A print media holder device has first and second grip members. Permanent magnets are attached to the first and second grip members. An electromagnet is disposed between the first and second grip members, where when the electromagnet is selectively energized the permanent magnets attached to the first and second grip members are repelled in a manner that increases the outer dimension of the print media holder device to grip a media core.