Compared with ordinary gear reducer, the planetary gear transmission and the small teeth difference planetary transmission have the advantages of compact structure, small size, light weight and so on. If the planetary gear transmission and the planetary gear transmission with small tooth difference are compared, the planetary transmission of the planetary gear transmission has the following advantages:
    1.Turning arm bearing load is only about 60% of the involute profile, the life of about 5 times. Because the turning arm bearing is a tooth differenced planetary transmission of weak links, so this is a very  important advantages.
    2.Almost half of cycloid gear and pin gear tooth contact, at the same time and cycloid tooth and needle tooth grinding, can be so smooth running, low noise.
    3.Needle teeth pin can be added to the sleeve, make contact with the cycloid gear rolling friction, prolong the service life of cycloid gear is an important part.
    4.The efficiency is higher, the first level transmission can reach 90%~95%, and the efficiency of the involute gear transmission with a tooth difference is only 85%~90%.

    Cycloidal reducer is less tooth differenced involute profile by development of planetary gear reducer, the difference is its planetary gear is used cycloidal tooth, teeth and internal gear using needle.Cycloid pin gear planetary transmission belongs to a tooth differenced planetary transmission, the gear teeth within the Zb and the difference between the planet wheel gear Zb to 1.The input shaft and output shaft is less tooth differenced planetary gear transmission, and at this time, the speed of the input shaft Nx and output shaft speed Ny the ratio between the I = Nx/Ny = - Zc.Therefore, the transmission ratio of planetary gear reducer is equal to the number of gear teeth, the input shaft and the output shaft turn to the opposite direction. The involute gear reducer has the advantages of simple structure and small velocity ratio, and the common speed ratio is 3,4,5,6,8,10. The commonly used single stage speed ratio of the gear reducer is 9,11,17,23,29,35,43,59,71,87.