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Concepts and Terminology in Rolling Bearing Assembly

 

1. Contact Angle: The angle between a plane perpendicular to the bearing axis (radial plane) and the line of action of the resultant force transmitted to the rolling elements through the bearing rings or washers (nominal line of action).

 

2. Inner (Outer Diameter) of the Ball Assembly: The diameter of the inscribed cylinder of the inner (outer) row of balls in the bearing.

 

3. Inner (Outer) Diameter of the Roller Assembly: The diameter of the inscribed cylinder of the inner (outer) row of rollers in a radial contact roller bearing.

 

4. Nominal Width of the Bearing: The distance between the two theoretical end faces of the bearing rings (back face of the washers). Used to define the width of radial bearings (height of thrust bearings).

 

5. Actual Width of the Bearing: The distance between the intersection points of the axis of the radial bearing and the two tangential planes of the actual end faces of the bearing rings that define the bearing width. The bearing width is defined by the inner and outer ring end faces.

 

6. Actual Width Deviation of the Bearing: The difference between the actual width and the nominal width of the bearing. 7. Radial runout of the inner ring of a complete bearing: Kia - The difference between the maximum and minimum radial distances between the inner bore surface and a fixed point on the outer ring at different angular positions. At this angular position, or on either side of it, the rolling elements should be in contact with the inner and outer ring raceways or the inner ring back flange (for tapered roller bearings), i.e., the bearing components are in their normal relative positions.

 

8. Radial runout of the outer ring of a complete bearing: Kea - The difference between the maximum and minimum radial distances between the outer diameter surface and a fixed point on the inner ring at different angular positions. At this angular position, or on either side of it, the rolling elements should be in contact with the inner and outer ring raceways or the inner ring back flange (for tapered roller bearings), i.e., the bearing components are in their normal relative positions.

 

9. Runout of the inner ring end face to the raceway of a complete bearing: Sia - The difference between the maximum and minimum axial distances between the inner ring reference end face and a fixed point on the outer ring at a radial distance from the inner ring axis equal to half the inner ring raceway contact diameter at different angular positions. Both the inner and outer raceways should be in contact with all rolling elements.

 

10. Runout of the outer ring end face to the raceway (Sea): At different angular positions of the outer ring, the difference between the maximum and minimum axial distance between the outer ring reference end face and a fixed point relative to the inner ring at a radial distance from the outer ring axis equal to half the outer ring raceway contact diameter. Both the inner and outer raceways should be in contact with all rolling elements.

 

11. Runout of the end face to the inner bore (Sd): The difference between the maximum and minimum axial distance between a plane perpendicular to the ring axis and the ring reference end face at a radial distance from the inner ring axis equal to half its raceway contact diameter.