{"data":{"fields":"term_definition","term_definition":"<div class=\"definition\">When the number of teeth in a gear is small, the tip of the mating gear tooth may interfere with the lower portion of the tooth profile. To prevent this, the generating process removes material at this point. This results in loss of a portion of the involute adjacent to the tooth base, reducing tooth contact and tooth strength. In a similar manner internal spur gear teeth may interfere when the pinion gear is too near the size of its mating internal gear . A condition in generated gear teeth when any part of the fillet curve lies inside a line drawn tangent to the working profile at its point of juncture with the fillet. When this happens, the tooth is weakened, and the lower end of the involute on involute teeth is slightly cut away, which decreases tooth action. Too much of the tooth profile becomes a fillet curve not used for contact. The corners of tools, cutters, and grinding wheels are likely to become dull or wear away too quickly. For these reasons, undercut is always objectionable. Undercut can be decreased or eliminated a) by increasing the pressure angle, thus making the base circle smaller, and b) by decreasing the dedendum, thus moving the root circle outward toward the base circle. This latter change is in effect moving the equivalent rack away from the center of the pinion.<\/div>"}}