Simply speaking, is the use of gear deceleration at all levels to achieve the purpose. Reducer　is composed by a gear pair at various levels, such as drive pinion gear reducer can achieve a certain goal, then this multi-level structure can greatly reduce the speed.

Reducer is generally used for low speed high torque transmission equipment,, the motor internal combustion engine or other high speed power input shaft through the gear teeth of the small gear of the output shaft of the gear reducer to achieve the purpose, Common reducer on the same principle will also have a few gears to achieve the desired reduction effect than the size of the gear teeth, is the transmission ratio.

Reducer is a power transmission mechanism, the use of the speed change gear, the rotation speed of the motor will be decelerated to the desired number of revolutions, and with a larger torque mechanism.

The role of the gear unit
1, deceleration while increasing the output torque, the motor output torque multiplied by the ratio of the gear ratio, but be careful not to exceed the rated torque reducer.

2, while reducing the deceleration of the load inertia, reducing the inertia of the gear ratio squared. We can look at General Electric has an inertia value. General types of gear reducer has a helical gear reducer (including parallel shaft helical gear reducer, worm gear reducer, bevel gear reducer, etc.), the planetary gear reducer, cycloid reducer, worm reducer and so on.