ABSTRACT
The interaction of the basic rack and the gear is observed when the gears are cut on gear hobbers or gear shaping machines, or in generating grinding by means of a worm grinding wheel. The gear tooth form can be altered by shifting the datum line from the tangential position. The tooth form is affected by the addendum modification. The following characteristics of a generated tooth form are particularly significant for its load capacity. The profile angle, ϕt, because of the relationship between the mean radius of curvature of the tooth flanks and the contact load capacity. The tooth root thickness, because of the relationship between the modulus of the section and the bending strength at the root of the tooth. The fillet radius at the critical point for bending, as at this point, a rapid change in the cross-section results in stress concentration. The crest width, as excessive shear stress at the tip is undesirable, particularly in surface-hardened gears.
