In a section perpendicular to the tooth, the
following dimensions are defined The normal pres-
sure angle ¢, the normal diametral pitch P.. The
normal chordal thickness the normal tooth
space chordal width sn, and the backlash B. ¢, P..
and B are selected from the conventional values as
for a spur gear. In a section perpendicular to the
gear axis are defined the tangential pressure angle
¢ t, the diametral pitch P, and the tangential
backlash Bt. The following relations hold