The reducer is mainly composed of transmission components (gears or worms), shafts, bearings, housings, and their accessories. Its basic structure consists of three main parts:

1. The combination of gears, shafts, and bearings is made into a small gear and shaft, called a gear shaft. This structure is used when the diameter of the gear is not closely related to the diameter of the shaft. If the diameter of the shaft is d and the diameter of the gear root circle is df, then this structure should be adopted when df-d ≤ 6-7mn. When df-d>6-7mn, a structure is adopted where the gear and shaft are separated into two parts, such as a low-speed shaft and a large gear. At this point, the gear is connected to the shaft through a fixed flat key in the circumferential direction, and the parts on the shaft are fixed axially using the shaft shoulder, shaft sleeve, and bearing cover. Both shafts use deep groove ball bearings. This combination is used to withstand radial loads and small axial loads. When the axial load is large, a combination structure of angular contact ball bearings, tapered roller bearings, or deep groove ball bearings and thrust bearings should be used. Bearings use the thin oil splashed during gear rotation for lubrication. The lubricating oil in the oil pool of the box seat is splashed onto the inner wall of the box cover by the rotating gear, flows along the inner wall to the groove of the box surface, and then flows into the bearing through the oil guide groove. When the circumferential speed of the oil immersed gear is ≤ 2m/s, lubricating grease should be used to lubricate the bearing. To avoid the possibility of splashing thin oil washing away the lubricating grease, an oil blocking ring can be used to separate it. To prevent the loss of lubricating oil and the entry of external dust into the box, a sealing element is installed between the bearing end cover and the extended shaft.