Type classification of gear transmission device:
1) in agricultural machinery, construction machinery and simple mechanical equipment, there are some gear drives without dust cover or casing, and the gears are completely exposed outside, which is called open gear drive. This kind of transmission is not only easy to be invaded by foreign matters, but also poorly lubricated, so the working conditions are not good, and the teeth are easy to wear, so it is only suitable for low-speed transmission. Gear transmission is equipped with simple protective cover, and sometimes the big gear is partially immersed in the oil pool, which is called semi open gear transmission. Although its working conditions have been improved, it is still unable to prevent the invasion of foreign matters and the lubrication conditions are not included.
2) closed transmission: the gear transmission used in automobile, machine tool, aeroengine, etc. is installed in the box (Gearbox) which is precisely processed and tightly closed, which is called closed gear transmission (Gearbox). Compared with the open or semi open type, the lubrication and protection conditions * are mostly used in important occasions.
According to the hardness of tooth surface:
1) soft tooth surface gear: the hardness of tooth working surface is less than or equal to 350hbs or 38hrc;
2) hard tooth surface gear: the hardness of tooth working surface is greater than 350hbs or 38hrc.