On a bearer-contact press used in offset lithography, preloading is the process of increasing and setting the pressure that the plate and blanket cylinder bearers exert on each other, the pressure exerted by the weight of the upper cylinder on the lower one not being sufficient for proper and effective operation. Proper bearer setting and pressure enables not only an accurate determination of plate and blanket packing, but also reduces wear on the gears driving the cylinders and provides a smoother driving of the cylinders. Although considered a factory operation, press operators may occasionally need to gauge and adjust the bearer pressure. See Plate Cylinder and Blanket Cylinder.
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