This drive consists of a small gear (in pink) and a big one (in green) but its velocity ratio is 1. Screw gear causes this paradox. Normal module mn = 2 mm

Pink gear:

- Helix angle B1 = 0 deg.,

- Face module ms2 = mn = 2 mm

- Tooth number Z1 = 18

- Pitch circle dia. D1 = 36.0 mm Green gear:

- Helix angle B2 = 45 deg., right hand

- Face module ms2 = 2.83

- Tooth number Z2 = 18

- Pitch circle dia. D2 = 50.91 mm

Angle between gear axles E = B1 + B2 = 45 deg. Velocity ratio: i = Z2/Z1 = 1 (not D2/D1 = 1.41)