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

Calculating the apparatus ratio in a planetary equipment reducer is less intuitive since it is dependent on the number of teeth of sunlight and band gears. The planet gears become idlers and don’t affect the apparatus ratio. The planetary gear ratio equals the sum of the amount of teeth on sunlight and ring equipment divided by the amount of teeth on the sun gear. For example, a planetary arranged with a 12-tooth sun gear and 72-tooth ring gear has a gear ratio of 7:1 ([12 + 72]/12 = 7). Planetary gear pieces 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 equipment and its mating equipment have the same amount of teeth, no decrease occurs and the apparatus ratio is 1:1. The gear is named an idler and its own principal function is to improve the path of rotation instead of decrease the speed or raise the torque.

Parallel shaft gearboxes often contain multiple gear sets thereby increasing the gear reduction. The total gear decrease (ratio) depends upon multiplying each individual gear ratio from each gear established stage. If a gearbox contains 3:1, 4:1 and 5:1 gear models, the total ratio is 60:1 (3 x 4 x 5 = 60). In our example above, the 3,450 rpm electric electric motor would have its quickness decreased to 57.5 rpm by utilizing a 60:1 gearbox. The 10 lb-in electric motor torque would be risen to 600 lb-in (before effectiveness losses).