Gearboxes are generally used for low-speed and high torque transmission equipment. They reduce the speed of electric motors, internal combustion engines, or other high-speed power by meshing the gears with fewer teeth on the input shaft of the gearbox with the large gears on the output shaft. Ordinary gearboxes also have several pairs of gears with the same principle to achieve the desired reduction effect. The ratio of the number of teeth between the large and small gears is the transmission ratio