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 improved, gears are commonly used to accomplish the required result. Gear “reduction” particularly refers to the swiftness of the rotary machine; the rotational quickness of the rotary machine is usually “reduced” by dividing it by a equipment ratio higher than 1:1. A gear ratio greater than 1:1 is certainly achieved whenever a smaller gear (decreased size) with fewer quantity of the teeth meshes and drives a more substantial gear with greater amount of teeth.
Gear reduction gets the opposite effect on torque. The rotary machine’s output torque is increased by multiplying the torque by the gear ratio, less some efficiency losses.
While in many applications gear decrease reduces speed and boosts torque, in various other applications gear decrease is used to increase rate 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 producing electricity. These applications make use of gearboxes that are assembled opposing of those in applications that decrease velocity and increase torque.
How is gear reduction achieved? Many reducer types can handle attaining gear decrease including, but not limited to, parallel shaft, planetary and right-position worm gearboxes. In parallel shaft gearboxes (or reducers), a pinion gear with a specific number of teeth meshes and drives a more substantial gear with a greater number of teeth. The “decrease” or equipment ratio can be calculated by dividing the amount of tooth on the large gear by the amount of teeth on the tiny gear. For example, if an electric motor drives a 13-tooth pinion gear that meshes with a 65-tooth equipment, a reduced amount of 5:1 is certainly achieved (65 / 13 = 5). If the electric motor speed is usually 3,450 rpm, the gearbox reduces this acceleration by five instances to 690 rpm. If the motor torque is 10 lb-in, the gearbox improves this torque by one 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 full total gear decrease (ratio) depends upon multiplying each individual equipment ratio from each equipment arranged 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). Inside our example above, the 3,450 rpm electric electric motor would have its swiftness decreased to 57.5 rpm by utilizing a 60:1 gearbox. The 10 lb-in electric motor torque would be risen 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 apparatus ratio is 1:1. The apparatus is named an idler and its principal function is to improve the path of rotation instead of decrease the speed or increase the torque.
Calculating the gear ratio in a planetary gear reducer is less intuitive as it is dependent on the amount of teeth of the sun and band gears. The earth gears become idlers and do not affect the apparatus ratio. The planetary gear ratio equals the sum of the number of teeth on the sun and ring gear divided by the number of teeth on sunlight 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 can 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 has 50 teeth, the resulting gear ratio is 25:1 (50 / 2 = 25).
When a rotary machine such as an engine or electric electric motor cannot supply the desired output quickness or torque, a gear reducer may provide a great choice. Parallel shaft, planetary, right-position worm drives are normal gearbox types for achieving gear reduction.