Gear Reducing Formulas
Output torque, speed and horsepower with gears.
Gear Output Torque
Mo = Mi r μ (1)
where
Mo = output torque (Nm, lbf ft)
Mi = input torque (Nm, lbf ft)
μ = gear efficiency (%)
Example - Geear Output Torque
The output torque from a transmission with input torque 500 Nm, gear transmission ratio 3.8 and gear efficiency 0.9 - can be calculated as
Mo = (500 Nm) (3.8) (0.9)
= 1710 Nm
Gear Output Speed
So = Si / r (2)
where
So = output speed (rad/s, rpm)
Si = input speed (rad/s, rpm)
Example - Gear Output Speed
The output speed of a transmission with input speed 2000 rpm and transmission ratio 3.8 can be calculated as
So = (2000 rpm) / (3.8)
= 526 rpm
Gear Output Horsepower
Po = Pi μ (3)
where
Po = output horsepower (W, hp)
Pi = input horsepower (W, hp)
Example - Gear Output Power
The output power from a transmission with input power 300 kW and efficiency 0.9 can be calculated as
Po = (300 kW) (0.9)
= 270 kW
