A sheet guide unit for a sheet-fed press which will prevent the sheet from flapping or fluttering, and allow sheets of thinner paper to be conveyed smoothly even when using a skeleton cylinder, The sheet guide unit is provided under an intermediate cylinder or a delivery cylinder, and has a curved sheet guide surface with which the lower surface of the cylinder creates a small sheet guide space, the space through which an air stream is directed. An air supply chamber and a pair of air aspiration chambers are provided for directing air through the sheet guide space. An air guide fin which is an outer extended portion of the curved sheet guide surface directs the air from the sheet guide into the aspiration chambers.

A method of adjusting an air guide system having various actuators, in a sheet-fed printing machine, includes the method steps of providing characteristic curves containing conveying parameters which are critical for sheet conveyance, plotted against a printing machine-specific parameter, and which are optimal for sheet-specific parameters; storing the characteristic curves in a memory; feeding the actual sheet-specific and printing machine-specific data of a print job to a CPU; accessing by the CPU the characteristic curve which is optimal for the actual data from the memory; outputting the appropriate commands to the individual actuators; and, if necessary, providing operator intervention; and a device for performing the method.

An air cushion guide for sheet or web-formed material includes at least one guide member formed with nozzle openings through which air is blown between the guide member and the guided material for supporting the guide material on a supporting air cushion located above the guide member, at least one of two variables consisting of volumetric air flow emerging from the nozzles and flow speed between the guide member and the guided material being adjustable independently of one another so that a proportionality between the two variables is nullified or neutralized; and a method of adjusting a flotation height.

An air assisted sheet guide device in a printing machine which is operable during either positive pressure (blast) air operation as well as suction air operation to permit reliable and stable sheet guidance with reduced air flow turbulence. The sheet guide device includes at least one module that defines a guide surface having air flow openings therein and an air flow channel, and a pneumatic system for creating either a positive or suction pressure generated air flow in the flow channel. One or more plate-like air directional elements are mounted within the air flow channel which create a uniform pressure distribution on the guide surface during positive (blast) air operation and which more uniformly direct air to the pneumatic system during suction pressure operation.

An air cushion guide for sheet or web-formed material that includes at least one guide member having a chamber and a surface formed with nozzle openings that may communicate with the chamber, through which air is blown between the guide member and the guided material for supporting the guided material on a supporting air cushion located above the guide member. Each of the nozzle openings has a cross sectional area. At least one moveable element is constructed to vary a volumetric flow of air emitted from the nozzle openings to form the air cushion guide. The moveable element is selected from the group consisting of a component having a movement which changes a number of the nozzle openings formed in the surface that are supplied with blown air, and at least one component having a movement that changes the cross sectional area of at least one of the nozzle openings formed in the surface. A control unit is provided for controlling a movement of the at least one moveable element.