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If you know the Bearing nomenclature procedure and its simple calculations, you can easily identify and decode Bearing details by its Bearing number.

A Bearing number contains many hidden information about the bearing in itself. The bearing no (pattern number) provide us enough details about the bearing silently. In this post, we will discuss about How to Identify Bearings by Bearing Number.

Let us take an example to understand the bearing nomenclature more easily. Suppose, we have a bearing whose patt no is 6305ZZ. Let us divide it in sub components. Here ‘6‘ indicate bearing type. There are few companies which use their separate identifying nomenclature. However, most of them follow a common standard for bearing nomenclature.

Bearing Number Nomenclature

Fig. 1 – Bearing Number Nomenclature

Types of Bearings and Their Code in Bearing Number

Decode bearing Number- Type code Fig. 2 – Types of Bearings and their Codes

Thus, we can easily identify now that in case of bearing 6305ZZ, the first digit ‘6 means the bearing type is ‘Single row deep groove ball bearing’.

In case of Inch bearings, the bearing’s first digit will be ‘R’. After ‘R’, the size of the bearing will be given in 1/16th of an inch. To understand it better, Lets take an example of Inch bearing. Suppose, we have R4-3RS bearing. Here, R4 means, it is an inch bearing whose bore size is 4/16th or you can say 1/4th of an inch.

Bearing Series and Their Code in Bearing Number

The second digit of a bearing patter number indicates the bearing series. Series of a bearing denotes the toughness of the bearing. They are:

Decode bearing Number- Series of bearing Fig. 3 – Series (Toughness) of Bearing

Thus, we can identify now that in case of bearing 6305ZZ, the second digit ‘3 means the bearing is of medium toughness.

Bore size of Bearing

The third and fourth digit of bearing patter number indicates the bore size of bearing. It is the inner diameter of the bearing and measured in millimeters. In general, the bore size is equal to five times the third and forth digit of bearing’s patter number. However, from ‘0’ to ‘3’, this formula does not imply. The bore size indicated by ‘0’ to ‘3’ are :

Decode bearing Number- details of bore Size Fig. 4 – Bore size of bearing

Note : In case there is no fourth digit, then the 3rd digit indicates the bore size in mm. For example: in case of bearing 636, the bore size of the bearing will be 6mm.

Thus, we can identify now that in case of bearing 6305ZZ, the third and fourth digit ‘05’ means the bearing’s bore size is 25 mm.

Shielding/Sealing/Specialty of Bearing in Bearing Number

The last letters of the bearing indicates the availability/unavailability/type of shielding or sealing and other specialty in the bearing. The various types of indications are:

Decode bearing Number- Special Fig. 5 – Sealing/Shielding/Any other details of Bearing

Thus, we can identify now that in case of bearing 6305ZZ, the last letters ‘ZZ’ means the bearing is shielded from both sides.

Coming to the conclusion, we can now easily decode bearing number of most of the bearings. Here, Bearing 6305ZZ means “it is a Single row deep groove ball bearing having medium toughness, with a bore size of 25 mm and is shielded from both sides.

Interesting???? Isnt it? Its fun to decode bearing number. Try some more bearings pattern no and check how accurate you are.

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Comments ( 17 )

  1. Excellent and useful information . I never knew about this even though I was using this bearing in my day to day maintenance work.

    • Thanks for your appreciation. These appreciations are very motivating for us. Keep following Many more interesting articles are coming ahead.

  2. Very informative and interesting too, illustrated well. All the while I knew only the id part ie Multiply by 5 part.

  3. Thanks for your support. Our upcoming articles will be even more interesting and informative. We are keen to provide short and crisp information for the technician inside you. Keep following.


  4. Its very Useful for me.
    Thank you for such a Brilliant work.

  5. Dharma Naik Banoth
    January 7, 2021 at 7:13 PM

    Very happy to visit this site
    I am using this method in Mechanical Maintenance work every day in my Duty

  6. thanks,its very useful technical information for all technicians

  7. Thanks for information im a mechenical engineer student i study your information.

    • Hi Ali,
      The different engineering streams are all interrelated and comply each other. We are happy that we could provide you enough data to keep you interested.
      Keep following us.
      Team Electricalfundablog

  8. Dear my friend
    please send me the relation between ball diameter and ball bearings number

  9. some information like you shared maybe not correct, like as RS mean one side sealed and 2Rs both side Sealed, i think Rs for Rubber seal and 2RS mean both side of bearing seald with rubber seal.

    • Hi Shafiq,
      Thanks for reaching us out. We will verify the information and correct it if found wrong.
      Appreciate your effort in notifying us. We are always committed to provided our users right and crisp information with no extra and irrelevant content.
      Keep following us. You are an important member of this team.
      Team Electricalfundablog.

  10. How can we find out a bearing outside diameter?
    Plz help me

  11. ok thanks

  12. That’s special thank you

  13. It’s just amazing.

  14. Good Information for learning.

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