1. The nominal noninal bore diameter (outside diameter)

Enveloping basic cylindrical inner hole (cylindrical outer surface) the diameter of a cylinder on a theoretical surface.The diameter of a cone that encloses the theoretical surface of a cone hole in a specified radial plane.The spherical diameter of the theoretical surface that envelops the basic spherical surface.

Note: for the nominal inner diameter of rolling bearing, the nominal outer diameter is generally the reference value of the deviation between the actual inner hole and the outer surface.

2. Nominal ring width

The distance between the theoretical ends of a bearing ring.It is generally the reference value (base size) of the actual width deviation.

3. Nominal bearing width (bearing height) bearing width

The distance between the theoretical ends of the ring (the back of the washer) to define the radial bearing width (thrust bearing height).Generally is the bearing actual width or bearing actual height deviation of the reference value (basic size). 

4. Actual bearing width

The distance between the axis line of a centripetal bearing and the intersection point of the two tangent planes of the actual end face of a ring of limited bearing width.Limit the bearing width with the inner ring end face and the outer ring end face.

Note: for single row tapered roller bearings, is the distance between the bearing axis line and the intersection point of the following two planes: one plane is tangent to the actual back of the inner ring, the other is tangent to the actual back of the outer ring.At this time, the inner, outer raceway and the inner side of the inner raceway are in contact with all the rollers.

5. Actual bearing height

The distance between the axial line of the thrust bearing and the intersection of the two actual backsides of the tangent plane of the washer that defines the bearing height. 

6. The deviation of the actual bearing height

The difference between the actual and nominal height of thrust bearing.

7. Nominal chamfer dimensions

Chamfer size as reference.

8. Radial single chamfer dimension

The distance between the imaginary cusp of a ring or washer and the intersection of the chamfered surface and the end face of the ring or washer in a single axial plane.

9. Axial single chamfer dimension

The distance between the imaginary cusp to chamfer surface of a ring or washer and the intersections of the inner bore or triangular belt surface of the ring or washer in a single axial plane.

10. The maximum allowable single chamfer size largest permissible single chamfer dimension

Maximum allowable radial or axial single chamfer size.

Nominal ball diameter

Generally used to identify the diameter of the ball size.

The single diameter of a ball

The distance between two parallel planes tangent to the actual surface of the ball.

The diameter of a ball is the diameter of a ball

The arithmetic mean of the largest and smallest single diameters of a sphere.

Ball diameter variation

The difference between the largest and smallest single diameters of a ball.

15. A lot of balls

Suppose a certain number of balls are made under the same conditions and are considered a whole.

Ball grade

A particular combination of ball size, shape, surface roughness, and gauge difference. 

17. Ball gauge

The small difference between the average diameter of a batch and the nominal diameter of a ball.

18. Ball subgauge

The quantity of a specified series that is the true deviation of the ball gauge closest to the ball batch.

Nominal diameter of a roller

Generally used to identify the diameter of the roller diameter value.

For symmetric rollers, it refers to the theoretical diameter in the radial plane passing through the middle of the length of the roller. For asymmetric rollers, it is the largest theoretical diameter (that is, in the radial plane including the imaginary sharp Angle of the big end of the cone roller).

A single diameter of a roller

The distance between two lines that are tangent and parallel to the actual surface of the roller in a plane (radial plane) perpendicular to the axis of the roller.

Nomnial length of a roller

Length value commonly used to identify the length of the roller.

The actual length of a roller

The distance between two radial planes including exactly the actual end of the roller.

23. Roller gauge

Within the same radial plane, the average diameter of a single plane of the roller deviates from the diameter deviation range defined by the upper and lower deviations of the nominal diameter of the roller.For cylindrical rollers and needles the plane passes through the middle of its length.

24. Roller grade

Specific combination of roller diameter and shape tolerances.

25. The deviation from circular from

The minimum radial distance between two concentric circles of the measured contour is the roundness error. 

26. The cylindricity error deviation from cylindrical form

The minimum radial distance between two coaxial cylinders of measured contour is the error of cylindricity.

27. Spherical error (of basically spherical surface) from spherical form

The maximum radial distance in any equatorial plane between an inscribed sphere on the contour surface (inner surface) or an external sphere surrounding the contour surface (outer surface) and any point on the contour surface.

28 sets of bearings (centripetal bearing inner ring radial runout of radial runout of assembled bearing inner ring

The difference between the maximum and minimum radial distance between the inner hole surface and a fixed point relative to the outer ring when the inner ring is in different angular positions.The rolling body at the angular position of the above point or at the nearby two sides shall be in contact with the inner surface of the inner ring, outer ring raceway or the rear side of the inner ring (tapered roller bearing), that is, the bearing parts are in a normal relative position.

29. The complete set of bearing outer ring (centripetal bearing) radial runout radial runout of assembled bearing outer ring

The difference between the maximum and minimum radial distance between the outer diameter surface and a fixed point relative to the inner ring when the outer ring is in different angular positions.The rolling body at the angular position of the above point or on both sides of it shall be in contact with the inner surface of the inner ring, outer ring raceway or the rear side of the inner ring (tapered roller bearing), that is, the bearing parts are in the normal relative position.

30. Radial internal clearance (bearing that can bear pure radial load, not in tight condition

When there is no external load, the arithmetic mean of the radial distance from a radial eccentricity limit position to the opposite limit position of one ring relative to another in different angles.The mean includes the mutual displacements of the ring or washer at different angular positions and the displacements relative to the ring or washer at different angular positions of the rolling body group.

31. Theoretical radial clearance (radial contact bearing

Outer raceway contact diameter minus inner raceway contact diameter minus twice the diameter of the rolling body.

32. Axial internal clearance (bearing that can bear axial load in two directions and is not under tight state

The arithmetic mean of the axial distance of a ring or washer from one axial limit position to the opposite limit position with respect to another ring or washer in the absence of external load.The mean includes the mutual displacements of the ring or washer at different angular positions and the displacements of the rolling body group relative to the ring or washer at different angular positions.