Helical Gear

A gear used to drive printing press rollers or cylinders in which the teeth are cut at an angle to the surface of the cylinder. Helical gears, found on newer presses, by design reduce play, the unimpeded (and undesirable) movement between gears. The older spur gear, on which the teeth are cut parallel to the surface of the cylinder, generally requires a backlash gear to reduce play. Cylinders in which the bearers (metal rings attached to the ends of the cylinder) of the plate cylinder run in contact with those of the blanket cylinder commonly use spur gears, while those that run out of contact use helical gears to reduce play and provide a smoother drive. (See Plate Cylinder, Blanket Cylinder and Spur Gear.)

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