Internationally, transmission gear transmissions have evolved along the trend of miniaturization, high speed, and standardization. The application of special gears, the development of planetary gears and the low noise gearing are some of the characteristics of gear design.
In order to achieve miniaturization of the gear unit, the bearing thrust of the existing involute gear can be improved. Hard tooth surface technology is generally used in various countries to increase the hardness and reduce the size of the equipment; it can also be used to indicate the special gear tooth shape. With the trend of medium-speed diesel engine power generation, high-power planetary gears are effective in large-scale ships; now large-scale transmissions such as metallurgy, mines, cement, rolling mills, etc., with small volume, good coaxiality and high efficiency of planetary gears , more and more applications.