The gear decrease in a right-angle worm drive would depend on the amount of threads or “starts” on the worm and the amount of teeth on the mating worm wheel. If the worm has two begins and the mating worm wheel has 50 the teeth, the resulting equipment ratio is 25:1 (50 / 2 = 25).

Calculating the apparatus ratio in a planetary gear reducer is less intuitive as it is dependent on the amount of teeth of sunlight and band gears. The planet gears act as idlers and do not affect the apparatus ratio. The planetary gear ratio equals the sum of the Planetary Wheel Drive number of teeth on the sun and ring gear divided by the number of teeth on the sun gear. For instance, a planetary established with a 12-tooth sun gear and 72-tooth ring gear has a gear ratio of 7:1 ([12 + 72]/12 = 7). Planetary gear models can achieve ratios from about 3:1 to about 11:1. If more equipment reduction is needed, additional planetary stages may be used.

If a pinion gear and its mating gear have the same number of teeth, no reduction occurs and the gear ratio is 1:1. The apparatus is named an idler and its main function is to improve the path of rotation rather than decrease the speed or increase the torque.

Parallel shaft gearboxes many times contain multiple gear units thereby increasing the apparatus reduction. The full total gear reduction (ratio) is determined by multiplying each individual gear ratio from each equipment set stage. If a gearbox includes 3:1, 4:1 and 5:1 gear sets, the full total ratio is 60:1 (3 x 4 x 5 = 60). Inside our example above, the 3,450 rpm electric motor would have its rate reduced to 57.5 rpm by utilizing a 60:1 gearbox. The 10 lb-in electric electric motor torque would be risen to 600 lb-in (before performance losses).