There are two types of bearings: plain bearings and rolling bearings. 

Sliding bearings: according to the load received: centripetal bearings, thrust bearings, according to the sliding surface lubrication state is divided into: liquid lubricated bearings, incomplete liquid lubricated bearings, non-lubricated bearings. 

Rolling bearings: aligning ball bearings, aligning roller bearings, tapered roller bearings, double row deep groove ball bearings, thrust ball bearings, deep groove ball bearings, angular contact ball bearings, cylindrical roller bearings, needle bearings. 

According to the different forms of friction when the journal is working in the bearing, the bearing is divided into sliding bearing and rolling bearing. 

I. plain bearing

According to the direction of load on the bearings, the sliding bearings are divided into three categories:

Radial bearing -- to bear radial load, the direction of load is perpendicular to the center line of the shaft; 

(2) thrust bearing - bearing axial load, load direction and axis center line parallel; 

Radial - thrust bearings - both radial and axial loads. 

According to the friction state, the sliding bearings are divided into two categories: non-liquid friction sliding bearings and liquid friction sliding bearings.The former is in the state of dry friction or boundary friction, while the latter is in the state of liquid friction. 

Two, rolling bearing

(1) according to the load direction borne by the rolling bearing, it can be divided into:

Centripetal bearing, mainly under radial load. 

Thrust bearing, mainly under axial load. 

(2) according to the shape of the rolling body can be divided into: ball bearings and roller bearings.The rolling body in the bearing has single column and double column. 

(3) according to the load direction or nominal contact Angle, rolling body types are divided into:

1. Deep groove ball bearing. 

2. Cylindrical roller bearing. 

3. Needle roller bearing. 

4. Adjustable ball bearing. 

5. Angular contact ball bearing. 

6. Adjustable roller bearing. 

7. Tapered roller bearing. 

8. Thrust Angle contact ball bearing. 

9. Thrust centering roller bearing. 

10. Thrust taper roller bearing. 

11. Thrust ball bearing. 

12. Thrust cylindrical roller bearing. 

13. Thrust needle roller bearing. 

14. Combination bearing. 

In a rolling bearing, there is point or line contact between the rolling body and the raceway, and the friction between them is rolling friction.The service life of rolling bearing decreases sharply when rotating speed is high.When the load is large and the impact is large, the rolling bearing point or line contact. 

In plain bearings, the journal and the bearing are in contact with each other, and the contact surfaces are sliding friction.Sliding bearing structure is the journal with a bearing bush;The principle of selection is to choose rolling bearings, special cases with sliding bearings.Plain bearing surface contact;Special structure requirements are large structure, sliding bearing cost is low.