In motors/pumps generally following bearings are used (ref: https://www.nke.at/en/bearings-applications/applications/electrical-motors):

  1. Deep groove ball bearings
  2. Cylindrical roller bearings
  3. Angular contact ball bearings

All these bearings are designated with bearing number for example: Deep groove ball bearings: 6205.

Form this bearing no. we can easily have the information about its outer dimensions as given here:https://www.skf.com/in/products/rolling-bearings/ball-bearings/deep-groove-ball-bearings/productid-6205 OR from its catalogue.

Based on these outer dimensions, is there any way out to calculate the following specifications/dimensions:

  1. Pitch diameter
  2. Ball diameter
  3. Number of balls in the bearing
  4. Contact angle of the balls

Can somebody please let me know how can we go about this ?

  • $\begingroup$ Calculate? Use a lookup table... $\endgroup$
    – Solar Mike
    Jan 4, 2021 at 6:42
  • $\begingroup$ @SolarMike, could you please provide some reference/links for the lookup tables ? I tried finding but couldn't get any, $\endgroup$
    – Ranjan Pal
    Jan 6, 2021 at 13:38

1 Answer 1


The trade numbers typically give you the envelope dimensions (inner and outer diameters, thickness). Everything else is at the discretion of the manufacturer - pitch diameter, rolling element size, quantity and contact diameter. This is why for the same trade number bearing you might see several different manufacturers, all with different load ratings.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.