Formula and example
How it is calculated
i = Z₂/Z₁; n₂ = n₁/i; M₂ = M₁ × i for a lossless transmission
Worked example
A 20-tooth gear drives a 60-tooth gear: i = 3, so 900 rpm becomes 300 rpm and 10 N·m ideally becomes 30 N·m.
Things to check
- Two externally meshing gears rotate in opposite directions.
- Friction reduces the transmitted torque. For multiple stages, multiply the individual gear ratios.