Classification of bearings

Counting from left to right, adding the first or the first and second digits together

6 "represents deep groove ball bearings (Class 0)

4 "represents double row deep groove ball bearings (Class 0)

2 "or" 1 "represents self-aligning ball bearings (basic model with four digits) (Class 1)

21, 22, 23, and 24 represent self-aligning roller bearings. (Category 3)

N "represents cylindrical roller bearings (including a portion of short cylindrical rollers and slender needle rollers) (Class 2)

The inner circle of 'NU' has no blocking edge.

NJ "inner circle single gear edge.

NF "outer ring single gear edge.

The outer ring of 'N' has no blocking edge.

NN "double row cylindrical roller with no outer edge.

NNU "double row cylindrical roller with no inner edge.

The roller length is at least 5 times the diameter size, which is called needle roller bearing (Class 4)

NA "spiral cutting outer ring needle roller bearing

NK stamped shell needle roller bearing

K "needle roller and holder assembly, without inner and outer rings.

7 "represents angular contact ball bearings (Class 6)

3 "represents tapered roller bearings (metric) (Class 7)

51, 52, and 53 represent radial thrust ball bearings (basic model with five digits) (Class 8)

81 "represents thrust short cylindrical roller bearings (Class 9)

29 "represents thrust self-aligning roller bearings (Class 9)

National standard for bearings

GB-T 305-1998 Dimensions and tolerances of stop grooves and stop rings on the outer ring of rolling bearings

GB-T 308-2002 Rolling Bearing Steel Balls

GB-T 309-2000 Rolling Bearing Needle Roller

GB-T 4661-2002 Rolling Bearings Cylindrical Rollers

GB-T 4662-2003 Rated static load of rolling bearings

GB-T 6391-2003 Rated dynamic load and rated life of rolling bearings

JB-T 3034-1993 Rolling Bearing Oil Seal Anti rust Packaging

JB-T 3573-2004 Measurement Method for Radial Clearance of Rolling Bearings

JB-T 6639-2004 Technical Conditions for Skeleton Nitrile Rubber Sealing Rings of Rolling Bearing Parts

JB-T 6641-2007 Residual Magnetic Field and Evaluation Method for Rolling Bearings

JB-T 6642-2004 Measurement and Evaluation Method for Roundness and Waviness Errors of Rolling Bearing Parts

JB-T 7048-2002 Rolling Bearing Parts Engineering Plastic Retainers

JB-T 7050-2005 Cleanliness Evaluation Method for Rolling Bearings

JB-T 7051-2006 Measurement and Evaluation Method for Surface Roughness of Rolling Bearing Parts

JB-T 7361-2007 Test Method for Hardness of Rolling Bearing Parts

JB-T 7752-2005 Technical Conditions for Sealed Deep Groove Ball Bearings of Rolling Bearings

JB-T 8196-1996 Residual Magnetic Field and Evaluation Method of Rolling Elements in Rolling Bearings

JB-T 8571-1997 Rolling Bearing Sealing Deep Groove Ball Bearing Dust Prevention, Leakage, and Temperature Rise Performance Test Procedure

JB-T 8921-1999 Rolling Bearings and Their Parts