ABSTRACT
Speed Reduction The rotary motion created by most motors occurs at speeds too high to be applied directly to moving scenery. The speed of a motor’s shaft must be reduced to usable levels, generally by a gearbox, although V-belts and toothed belts are also occasionally used. Regardless of how speed is reduced:
Where Pin, Pout = power put into, and power received out of the speed reducer (ftlb/sec, watts)
Efficiency = the decimal value of the percentage of power passed through the speed reducer (if reducer is 72% efficient, use 0.72)
Tin, Tout = torque at input shaft, and torque at output shaft (ft-lb, Nm) in, out = angular speed at input shaft, and output shaft (radians/sec)
Manufactured speed reducers rarely list efficiency directly, but instead they provide a sample set of input and output power values or input power and output speed and torque. Efficiency can be calculated in both cases using the formulas above if needed.1
