A break in the circumference of an offset press plate cylinder, blanket cylinder, impression cylinder, or transfer cylinder in which is typically housed the various clamps or reels that hold the plate or blanket to the cylinder or, in the case of an impression and transfer cylinder, the grippers that carry the paper (or other substrate) through the press. The cylinder gap on many offset presses is about 20% of the circumference of the cylinder. The cylinder gap on the plate cylinder also allows the inking system to renew itself between printed sheets. On some plate cylinders, the cylinder gap provides a inclined "ramp" back up to the surface of the cylinder, allowing the form rollers to smoothly return to the plate without producing streaks or bumps. (See Offset Lithography: Printing Unit and Inking System: Offset Lithography.)
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