On the surface, it could 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 electric motor needs the output speed decreased and/or torque increased, gears are commonly used to accomplish the required result. Gear “reduction” specifically refers to the acceleration of the rotary machine; the rotational velocity of the rotary machine is usually “decreased” by dividing it by a gear ratio higher than 1:1. A gear ratio higher than 1:1 is certainly achieved whenever a smaller gear (decreased size) with fewer number of the teeth meshes and drives a more substantial gear with greater number of teeth.

Gear reduction has the opposite influence on torque. The rotary machine’s output torque is improved by multiplying the torque by the gear ratio, less some effectiveness losses.

While in many applications gear reduction reduces speed and increases torque, in various other applications gear reduction is used to increase velocity and reduce torque. Generators in wind turbines use gear decrease in this fashion to convert a comparatively slow turbine blade quickness to a higher speed capable of generating electricity. These applications make use of gearboxes that are assembled opposing of those in applications that decrease acceleration 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 equipment with a particular number of teeth meshes and drives a more substantial gear with a lot more teeth. The “reduction” or equipment ratio is certainly calculated by dividing the number of teeth on the large equipment by the amount of teeth on the small gear. For example, if a power motor drives a 13-tooth pinion gear that meshes with a 65-tooth gear, a reduced amount of 5:1 is usually achieved (65 / 13 = 5). If the electrical motor speed is usually 3,450 rpm, the gearbox reduces this swiftness by five occasions to 690 rpm. If the electric motor torque is certainly 10 lb-in, the gearbox improves this torque by a factor of five to 50 lb-in (before subtracting out gearbox performance losses).

Parallel shaft gearboxes many times contain multiple gear pieces thereby increasing the gear reduction. The total gear reduction (ratio) is determined by multiplying each individual equipment 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). Inside our example above, the 3,450 rpm electric motor would have its rate decreased to 57.5 rpm by using a 60:1 gearbox. The 10 lb-in electric engine torque would be risen to 600 lb-in (before effectiveness losses).

If a pinion gear and its mating equipment have the same amount of teeth, no decrease 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 reduce the speed or raise the torque.

Calculating the apparatus ratio in a planetary gear reducer is much less intuitive as it is dependent on the number of teeth of sunlight and ring gears. The planet gears become idlers and do not affect the gear ratio. The planetary gear ratio equals the sum of the number of teeth on sunlight and ring equipment divided by the number of teeth on the sun gear. For instance, a planetary set with a 12-tooth sun gear and 72-tooth ring gear includes 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 gear reduction is needed, additional planetary stages may be used.

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 starts and the mating worm wheel offers 50 tooth, the resulting equipment ratio is 25:1 (50 / 2 = 25).

Whenever a rotary machine such as an engine or electric motor cannot supply the desired output acceleration or torque, a equipment reducer may provide a good solution. Parallel shaft, planetary, right-position worm drives are common gearbox types for attaining gear reduction.