A metal ring attached to both ends of a plate cylinder, blanket cylinder and impression cylinder in the printing unit of an offset printing press. On the plate and blanket cylinders, the diameter of the bearers is the true diameter of the cylinder, the main body of the cylinder being undercut, or possessing a shorter diameter than the bearers, so as to allow varying degrees of cylinder packing. In some presses (called bearer-contact presses), the bearers of the plate and blanket cylinders are in direct contact with each other, the advantages being easy alignment of the cylinders and reduced gear damage. In other presses (called non-bearer-contact presses), the bearers are not in contact, but the manufacturer's recommended gap between plate and blanket cylinder bearers can be used to determine proper cylinder settings. (See Plate Cylinder and Blanket Cylinder.) On the impression cylinder, it is the bearers that are undercut, the body of the cylinder itself being the essential measure of the cylinder diameter. (See Impression Cylinder.) The diameter of cylinder bearers is also equal to the diameter of the gears running the cylinder.
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