Compound Gear Train Ratio
Compound Gear Train Ratio
A compound gear train multiplies the ratios of its stages, achieving large reductions in a compact space.
The overall ratio is GR = (N_2/N_1)·(N_4/N_3). where N_1…N_4 are the tooth counts of the four gears.
Inputs
N_1 := 15=15
N_2 := 45=45
N_3 := 18=18
N_4 := 54=54
Multiply the two stage ratios.
GR := (N_2/N_1)·(N_4/N_3)=9
Results
Two 3:1 stages give a 9:1 overall reduction — output torque is multiplied ninefold and speed divided by nine.
Assumptions & limitations
- Ideal gears (no losses).
- Tooth counts as given.
- Two compound stages.