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 an engine or electrical motor needs the result speed decreased and/or torque increased, gears are commonly utilized to accomplish the desired result. Gear “reduction” specifically refers to the quickness of the rotary machine; the rotational acceleration of the rotary machine is certainly “decreased” by dividing it by a equipment ratio greater than 1:1. A gear ratio higher than 1:1 is certainly achieved whenever a smaller gear (reduced size) with fewer quantity of the teeth meshes and drives a larger gear with greater number 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 efficiency losses.
While in many applications gear decrease reduces speed and improves torque, in other applications gear reduction is used to improve rate and reduce torque. Generators in wind turbines use gear decrease in this manner to convert a relatively slow turbine blade velocity to a high speed capable of generating electricity. These applications use gearboxes that are assembled opposing of these in applications that reduce acceleration and increase torque.
How is gear decrease achieved? Many reducer types can handle attaining gear reduction including, but not limited to, 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 more substantial gear with a greater number of teeth. The “reduction” or gear ratio is definitely calculated by dividing the number of teeth on the large gear by the number of teeth on the small gear. For example, if a power motor drives a 13-tooth pinion equipment that meshes with a 65-tooth gear, a reduction of 5:1 can be achieved (65 / 13 = 5). If the electric motor speed can be 3,450 rpm, the gearbox reduces this velocity by five moments to 690 rpm. If the motor torque is definitely 10 lb-in, the gearbox increases this torque by a factor of five to 50 lb-in (before subtracting out gearbox efficiency losses).
Parallel shaft gearboxes many times contain multiple gear sets thereby increasing the apparatus reduction. The total gear reduction (ratio) depends upon multiplying each individual equipment ratio from each equipment set stage. If a gearbox consists of 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 motor would have its speed decreased to 57.5 rpm by utilizing a 60:1 gearbox. The 10 lb-in electric motor torque would be increased to 600 lb-in (before performance losses).
If a pinion equipment and its mating equipment have the same quantity of teeth, no reduction occurs and the gear ratio is 1:1. The gear is called an idler and its primary function is to change the path of rotation rather than decrease the speed or boost the torque.
Calculating the gear ratio in a planetary gear reducer is less intuitive since it is dependent on the amount of teeth of sunlight and ring gears. The planet gears become idlers and don’t affect the gear ratio. The planetary gear ratio equals the sum of the amount of teeth on the sun and ring gear divided by the number of teeth on the sun gear. For instance, a planetary established 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 needed, additional planetary stages may be used.
The gear reduction 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 provides 50 tooth, the resulting equipment ratio is 25:1 (50 / 2 = 25).
Whenever a rotary machine such as for example an engine or electric motor cannot provide the desired output rate 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.