The gear decrease in a right-angle worm drive is dependent on the number 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 offers 50 tooth, the resulting equipment ratio is 25:1 (50 / 2 = 25).
Calculating the apparatus ratio in a planetary equipment reducer is much less intuitive as it is dependent upon the amount of teeth of the sun and band gears. The earth gears become idlers , nor affect the apparatus ratio. The planetary equipment ratio equals the sum of the number of teeth on sunlight and ring gear divided by the number of teeth on sunlight gear. For instance, a planetary established with a Planetary Wheel Drive 12-tooth sun gear and 72-tooth ring gear includes a equipment 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 necessary, additional planetary stages may be used.
If a pinion equipment and its mating gear have the same quantity of teeth, no reduction occurs and the gear ratio is 1:1. The apparatus is named an idler and its own main function is to change the direction of rotation rather than decrease the speed or increase the torque.
Parallel shaft gearboxes often contain multiple gear units thereby increasing the apparatus reduction. The full total gear reduction (ratio) depends upon multiplying each individual gear ratio from each gear set stage. If a gearbox contains 3:1, 4:1 and 5:1 gear units, the full total ratio is 60:1 (3 x 4 x 5 = 60). In our example above, the 3,450 rpm electric motor would have its velocity reduced to 57.5 rpm by using a 60:1 gearbox. The 10 lb-in electric electric motor torque would be increased to 600 lb-in (before effectiveness losses).