The gear decrease in a right-angle worm drive is dependent on the number of threads or “starts” on the worm and the number of teeth on the mating worm wheel. If the worm has two begins and the mating worm wheel has 50 teeth, the resulting gear 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 ring gears. The planet gears act as idlers , nor affect the apparatus ratio. The planetary gear ratio equals the sum of the number of teeth on sunlight and ring gear divided by the number of teeth on sunlight gear. For example, a planetary established with a 12-tooth sun gear and 72-tooth ring gear includes a equipment ratio of 7:1 ([12 + 72]/12 = 7). Planetary gear pieces can perform ratios from about 3:1 to about 11:1. If more equipment reduction is necessary, additional planetary stages may be used.

If a pinion gear and its mating equipment have the same number of teeth, no reduction occurs and the gear ratio is 1:1. The gear is called an idler and its main function is to improve the direction of rotation instead of reduce the speed or raise the torque.

Parallel shaft gearboxes often contain multiple gear models thereby increasing the apparatus reduction. The full total gear decrease (ratio) depends upon multiplying each Planetary Wheel Drive individual gear ratio from each equipment established stage. If a gearbox consists of 3:1, 4:1 and 5:1 gear sets, the full total ratio is 60:1 (3 x 4 x 5 = 60). In our example above, the 3,450 rpm electric engine would have its swiftness reduced to 57.5 rpm by utilizing a 60:1 gearbox. The 10 lb-in electric engine torque would be increased to 600 lb-in (before performance losses).