what does gear reduction actually mean

On the surface, it could seem 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 decreased and/or torque improved, gears are commonly utilized to accomplish the required result. Gear “reduction” specifically refers to the acceleration of the rotary machine; the rotational acceleration of the rotary machine is definitely “decreased” by dividing it by a gear ratio greater than 1:1. A gear ratio greater than 1:1 is certainly achieved when a smaller gear (reduced size) with fewer quantity of tooth meshes and drives a larger gear with greater amount of teeth.

Gear reduction has the opposite effect on torque. The rotary machine’s result torque is increased by multiplying the torque by the gear ratio, less some performance losses.

While in many applications gear reduction reduces speed and improves torque, in various other applications gear reduction is used to improve speed and reduce torque. Generators in wind turbines use gear decrease in this fashion to convert a relatively slow turbine blade acceleration to a higher speed capable of producing electricity. These applications use gearboxes that are assembled reverse of these in applications that reduce acceleration and increase torque.

How is gear reduction achieved? Many reducer types can handle attaining gear reduction including, but not limited by, parallel shaft, planetary and right-position worm gearboxes. In parallel shaft gearboxes (or reducers), a pinion equipment with a specific number of the teeth meshes and drives a larger gear with a greater number of teeth. The “decrease” or equipment ratio is certainly calculated by dividing the number of tooth on the large gear by the amount of teeth on the small gear. For instance, if a power motor drives a 13-tooth pinion gear that meshes with a 65-tooth gear, a reduction 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 moments to 690 rpm. If the engine torque is definitely 10 lb-in, the gearbox boosts this torque by one factor of five to 50 lb-in (before subtracting out gearbox effectiveness losses).

Parallel shaft gearboxes many times contain multiple gear pieces thereby increasing the apparatus reduction. The full total gear reduction (ratio) depends upon multiplying each individual equipment ratio from each gear set stage. If a gearbox includes 3:1, 4:1 and 5:1 gear models, the full total ratio is 60:1 (3 x 4 x 5 = 60). Inside 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 electric motor torque would be increased to 600 lb-in (before effectiveness losses).

If a pinion equipment and its mating gear have the same quantity of teeth, no decrease occurs and the gear ratio is 1:1. The apparatus is called an idler and its own principal function is to improve the path of rotation instead of reduce the speed or raise the torque.

Calculating the gear ratio in a planetary equipment reducer is less intuitive as it is dependent on the number of teeth of sunlight and band gears. The planet gears act as idlers and don’t affect the apparatus ratio. The planetary gear ratio equals the sum of the number of teeth on the sun and ring equipment divided by the number of teeth on the sun gear. For instance, a planetary arranged with a 12-tooth sun gear and 72-tooth ring gear has 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.

The gear decrease 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 provides 50 the teeth, the resulting equipment ratio is 25:1 (50 / 2 = 25).

When a rotary machine such as for example an engine or electric engine cannot provide the desired output speed or torque, a equipment reducer may provide a good solution. Parallel shaft, planetary, right-angle worm drives are normal gearbox types for achieving gear reduction.


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