Cylindrical gear reducer is a kind of power transmission mechanism, using the speed converter of gears to decelerate the number of rotations of the motor to the desired number of rotations and to get a larger torque. Cylindrical gear reducer is generally used for low-speed and high-torque transmission equipment, and it is used to decelerate the power of the electric motor, the internal-combustion engine, or other high-speed power through the gears with fewer teeth on the input shaft of the gear reducer mesh with the large gears on the output shaft to reach the deceleration purpose. Ordinary cylindrical gear reducer will also have several pairs of the same principle gears to achieve the desired deceleration effect, the ratio of the number of teeth of large and small gears is the transmission ratio.
A gear transmission in which the axis of one or more gears rotates around the fixed axis of another gear is the principle of a planetary speed reducer. Planetary gear reducers, cycloid reducers, worm gear reducers, planetary friction type mechanical stepless speed changers and so on.