On the surface, it may appear that gears are being “reduced” in quantity or size, which is partially true. When a rotary machine such as for example an engine or electrical motor needs the output speed reduced and/or torque improved, gears are commonly used to accomplish the desired result. Gear “reduction” specifically refers to the acceleration of the rotary machine; the rotational velocity of the rotary machine is usually “reduced” by dividing it by a gear ratio higher than 1:1. A gear ratio higher than 1:1 is achieved whenever a smaller equipment (decreased size) with fewer amount of tooth meshes and drives a more substantial gear with greater quantity of teeth.
Gear reduction has the opposite effect on torque. The rotary machine’s result torque is increased by multiplying the torque by the apparatus ratio, less some effectiveness losses.
While in lots of applications gear decrease reduces speed and improves torque, in other applications gear reduction is used to increase swiftness and reduce torque. Generators in wind generators use gear reduction in this manner 
to convert a relatively slow turbine blade swiftness to a higher speed capable of producing electricity. These applications make use of gearboxes that are assembled opposite of those in applications that reduce swiftness and increase torque.
How is gear decrease achieved? Many reducer types can handle attaining gear decrease including, but not limited by, parallel shaft, planetary and right-angle worm gearboxes. In parallel shaft gearboxes (or reducers), a pinion gear with a particular number of the teeth meshes and drives a larger gear with a greater number of teeth. The “reduction” or equipment ratio can be calculated by dividing the number of the teeth on the large gear by the number of teeth on the tiny gear. For instance, if an electric motor drives a 13-tooth pinion equipment that meshes with a 65-tooth equipment, a reduced amount of 5:1 can be achieved (65 / 13 = 5). If the electrical motor speed can be 3,450 rpm, the gearbox reduces this acceleration by five occasions to 690 rpm. If the motor torque can be 10 lb-in, the gearbox increases this torque by a factor of five to 50 lb-in (before subtracting out gearbox effectiveness losses).
Parallel shaft gearboxes many times contain multiple gear models thereby increasing the gear reduction. The total gear decrease (ratio) depends upon multiplying each individual equipment ratio from each gear established 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). In our example above, the 3,450 rpm electric motor would have its speed 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 efficiency losses).
If a pinion gear and its mating equipment have the same quantity of teeth, no reduction occurs and the gear ratio is 1:1. The apparatus is called an idler and its main function is to change the path of rotation instead of reduce the speed or raise the torque.
Calculating the apparatus ratio in a planetary equipment reducer is much less intuitive since it is dependent on the amount of teeth of sunlight and band gears. The earth gears become idlers , nor affect the gear ratio. The planetary equipment ratio equals the sum of the number of teeth on the sun and ring equipment divided by the amount 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 perform ratios from about 3:1 to about 11:1. If more equipment reduction is needed, additional planetary stages may be used.
The gear reduction in a right-angle worm drive is dependent 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 offers 50 the teeth, the resulting gear ratio is 25:1 (50 / 2 = 25).
Whenever a rotary machine such as for example an engine or electric electric motor cannot provide the desired output speed or torque, a equipment reducer may provide a great choice. Parallel shaft, planetary, right-angle worm drives are common gearbox types for achieving gear reduction.