Tight Mesh Center Distance

Inv = Involute function

z = number of teeth, first gear

z1 = number of teeth, second gear

d = ref diameter of first gear

d1 = ref diameter of second gear

at = pressure angle

atw = working pressure angle

aw = working center distance

st = transverse tooth thickness of gear 1 at d

st1 = transverse tooth thickness of gear 2 at d1

inv aw = ((z1(st + st1) – pi*d1) / (d1(z + z1)) + inv at

aw = ((d + d1) / 2) * (cos at / cos atw)