1. Classification of bearings
The first number from left to right or the first and second numbers added together: "6" means deep groove ball bearing (category 0), "4" means double row deep groove ball bearing (category 0), " 2" or "1" means spherical ball bearings (the basic model has four numbers in total) (category 1), "21", "22", "23" and "24" means spherical roller bearings. (Category 3), "N" means cylindrical roller bearings (including short cylindrical rollers and part of slender needle rollers) (Category 2), "NU" inner ring without ribs, "NJ" inner ring with single ribs, "NF" has a single outer ring, "N" has no ribs in the outer ring, "NN" has double row cylindrical rollers and has no ribs in the outer ring, and "NNU" has double row cylindrical rollers and has no ribs in the inner ring. The roller length is at least 5 times the diameter, which is called a needle roller bearing (category 4), "NA" turned outer ring needle roller bearing, "NK" stamped shell needle roller bearing, K" needle roller and cage assembly , without inner and outer rings. “7” represents angular contact ball bearings (category 6), “3” represents tapered roller bearings (metric) (category 7), “51”, “52” and “53” represent radial thrust ball bearings (category 7). The basic model has five numbers) (category 8), "81" indicates thrust short cylindrical roller bearing (category 9), "29" indicates thrust spherical roller bearing (category 9)
2. National standards 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 Rolling bearings static load rating
GB-T 6391-2003 Rolling bearings dynamic load rating and rated life
JB-T 3034-1993 rolling bearing oil seal rust-proof packaging
JB-T 3573-2004 Rolling bearings - Measurement method of radial clearance
JB-T 6639-2004 Rolling bearing parts Skeleton nitrile rubber sealing ring technical conditions
JB-T 6641-2007 Rolling bearings residual magnetism and its evaluation method
JB-T 6642-2004 Rolling bearing parts - Measurement and evaluation method of roundness and waviness errors
JB-T 7048-2002 Rolling bearing parts Engineering plastic cage
JB-T 7050-2005 Rolling bearing cleanliness assessment method
JB-T 7051-2006 Rolling bearing parts Surface roughness measurement and evaluation methods
JB-T 7361-2007 Rolling bearing parts hardness test method
JB-T 7752-2005 Rolling bearing sealed deep groove ball bearing technical conditions
JB-T 8196-1996 Rolling bearings Rolling element residual magnetism and its evaluation method
JB-T 8571-1997 Rolling bearings, sealed deep groove ball bearings, dustproof, grease leakage, temperature rise performance test procedures
JB-T 8921-1999 Inspection rules for rolling bearings and their parts
JB-T 10336-2002 Supplementary technical conditions for rolling bearings and their parts
JB-T 50013-2000 Rolling bearing life and reliability test procedures
JB-T 50093-1997 Rolling bearing life and reliability test evaluation method
