1. Bearing axis

The theoretical rotation axis line of rolling bearing, the axial bearing is the inner ring axis line, and the thrust bearing is the axis line of the shaft ring. 

2. The inner ring is a shaft washer axis

The axis line of a cylindrical or conical cylinder or conical body with a basic cylindrical or conical hole in the inner ring. 

3. Outer ring (washer)axis

If the outer surface of the outer ring is cylindrical, the axis line of the outer surface connected with the cylinder is the axis line of the outer ring. If the surface is basically spherical, the line perpendicular to the reference end face of the outer ring is the axis line of the outer ring. 

4. Cone (cup)axis of the inner ring (outer ring)

The axis line of the inner ring (outer ring) of tapered roller bearing. 

5. Radial plane

A plane perpendicular to the axis line and parallel to the cut surface of the base end face of the ring or the back of the washer may be considered a radial plane. 

6. Radial direction

The direction in which the axis passes in the radial plane. 

7. Axial plane

The plane within the line of the axis of containment. 

8. Axial direction

Parallel to the bearing axis.The direction perpendicular to the base end face of the ring or the cut face on the back of the washer may be considered axial. 

9. The radial (axial) distance from the radial (axial) distance

The distance measured in the radial direction. 

10. Contact Angle (nominal contact Angle)

The Angle between the plane perpendicular to the bearing axis line (radial plane) and the resultant action line (nominal action line) passed to the rolling body by the bearing ring or washer. 

11. Nominal contact point

The point of contact between the rolling body and the raceway surface when the bearing parts are in normal relative position. 

Reference face of a ring (a washer)

The end face of the ring (washer) designated by the bearing manufacturer as the reference level may be used as the reference for measurement.