{"data":{"fields":"term_definition","term_definition":"
When gears are produced by a generating process, the datum line of the basic rack profile need not necessarily form a tangent to the reference circle. The tooth form can be altered by shifting the datum line from the tangential position. The involute shape of the tooth profile is retained, the effect is merely to use parts further from or nearer to the origin of the same involute. The radial displacement from the tangential position is termed addendum modification. The displacement is considered positive when in the direction away from the center of the gear (applies to internal spur and helical gears). The effect of addendum modification on the tooth form is shown in the figures below. The load carrying capacity of the teeth without addendum modification shown in Figure A can be improved by the positve addendum modification shown in Figure B. An extremely large addendum modification results in an unsuitable tooth form with pointed teeth, as shown in Figure C.<\/div>
\"ED-3a\"<\/div>
\"ED-3b\"<\/div>
\"ED-3c\"<\/div>"}}