1) Bearing classification based on the type of load carried
a) Radial bearings
In radial bearings, the load acts perpendicular to the direction of motion of the moving element.
b) Thrust or axial bearings
A thrust bearing is a particular type of rotary rolling-element bearing. Like other bearings, they permit rotation between parts, but they are designed to support a predominately axial load
2) Bearing classification based on the thickness of lubrication
a) Thick-film bearings
The thick film bearings are those in which the working surfaces are completely separated from each other by the lubricant. Such type of bearings is also called as hydrodynamic lubricated bearings.
b) Thin film bearings
The thin film bearings are those in which, although lubricant is present, the working surfaces partially contact each other at least part of the time. Such type of bearings is also called boundary lubricated bearings.
c) Zero film bearings
The zero film bearings are those which operate without any lubricant present.
3) Bearing classification based on the angle of contact
When the angle of contact of the bearing with the journal is 360°, then the bearing is called a full journal bearing. This type of bearing is commonly used in industrial machinery to accommodate bearing loads in any radial direction.
When the angle of contact of the bearing with the journal is 120°, then the bearing is said to be a partial journal bearing. This type of bearing has less friction than full journal bearing, but it can be used only where the load is always in one direction.
The most common application of the partial journal bearings is found in railroad car axles.
When a partial journal bearing has no clearance i.e. the diameters of the journal and bearing is equal, then the bearing is called a fitted bearing.