Fig 12Bevel gearsdrag to turn · click to pause16 and 24 teeth, shafts at 90°
PinionBevel gears connect shafts that meet, usually at 90°. Their pitch surfaces are cones that share an apex, and the teeth shrink toward it so they keep the right shape as the radius changes. The ratio is still the tooth count ratio. The cone angles are set by it: tan δ₁ = z₁/z₂. Spiral bevel gears curve the teeth for the same reason helical gears twist them.