Screw Gear Drive

Normal module mn = 2 mm
+ Pinion:
- Helix angle B1 = 30 deg., left hand
- Tooth number Z1 = 15
- Pitch circle dia. D1 = 34.64 mm
+ Wheels:
- Helix angle B2 = 30 deg., left hand
- Tooth number Z2 = 30
- Pitch circle dia. D2 = 69.28 mm
Velocity ratio: i = Z2/Z1 = D2/D1 = 2
Angle between gear axles E = B1 + B2 = 60 deg.
The wheels axles are not parallel even if the wheels engage with the pinion at its opposite sides.