\"Comprehensive Bearing Number Guide\"

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Classification of bearings: The first digit, counted from the left, or the sum of the first and second digits – “6” denotes deep groove ball bearings (category 0); “4” denotes double row deep groove ball bearings (category 0). “2” or “1” denotes self-aligning ball bearings (the basic model consists of four digits) (category 1). “21”, “22”, “23”, “24” denote self-aligning roller bearings. (Type 3) “N” denotes cylindrical roller bearings (including a subset of short cylindrical rollers and slender needle rollers). (Type 2) “NU” indicates that the inner ring has no flanges. “NJ” single rib on the inner ring. “NF: Outer ring with a single flange. “The outer ring of N has no flange. “NN” double-row cylindrical roller, with no flange on the outer ring. “NNU” double-row cylindrical roller, with no rib on the inner ring. The roller length is at least 5 times the diameter; such bearings are known as needle bearings (type 4). “NA” refers to needle bearings with the outer ring turned, “NK” to those with the outer ring stamped, and “K” to needle and cage assemblies without inner or outer rings. ““7” indicates angular contact ball bearings (Type 6); “3” indicates tapered roller bearings (metric series) (Type 7). “51”, “52”, and “53” denote thrust ball bearings (there are five basic model numbers in total for this type; Type 8). “81” refers to thrust cylindrical roller bearings (Type 9), while “29” denotes thrust spherical roller bearings (Type 9).

**Standards:**
GB/T 305-1998 – Grooves and retaining ring dimensions and tolerances on the outer rings of rolling bearings
GB/T 308-2002 – Steel balls for rolling bearings
GB/T 309-2000 – Needles for rolling bearings
GB/T 4661-2002 – Cylindrical rollers for rolling bearings
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 – Oil-sealed and rust-proof packaging of rolling bearings
JB/T 3573-2004 – Method for measuring radial clearance of rolling bearings
JB/T 6639-2004 – Technical specifications for nitrile rubber seals used in rolling bearing components
JB/T 6641-2007 – Residual magnetism in rolling bearings and methods for its evaluation
JB/T 6642-2004 – Methods for measuring and evaluating roundness and waviness errors in rolling bearing components
JB/T 7048-2002 – Engineering plastic cages for rolling bearing components
JB/T 7050-2005 – Method for evaluating the cleanliness of rolling bearings
JB/T 7051-2006 – Methods for measuring and evaluating surface roughness of rolling bearing components
JB/T 7361-2007 – Hardness testing methods for rolling bearing components
JB/T 7752-2005 – Technical specifications for sealed deep groove ball bearings
JB/T 8196-1996 – Residual magnetism in rolling elements and methods for its evaluation
JB/T 8571-1997 – Test procedures for dust resistance, grease leakage prevention, and temperature rise characteristics of sealed deep groove ball bearings
JB/T 8921-1999 – Inspection rules for rolling bearings and their components
JB/T 10336-2002 – Supplementary technical specifications for rolling bearings and their components
JB/T 50013-2000 – Test procedures for the life and reliability of rolling bearings
JB/T 50093-1997 – Evaluation methods for the life and reliability of rolling bearings.

**Prefix codes:** The prefix code “R” is placed directly before the basic bearing code; all other codes are separated from the basic code by a small dot. GS. — Thrust cylindrical roller bearing rings. Example: GS.81112. K. — Assembly of rolling elements and cage. Example: Thrust cylindrical roller and cage assembly K.81108 R – a bearing without a separable inner or outer ring. Example: RNU207 — NU207 bearing without an inner ring. WS — Thrust cylindrical roller bearing ring. Example: WS.81112. —— Internal design —— Dimensions and deformation design —— Sealing —— Retainer —— Tolerances —— Clearance —— Heat treatment —— Special designs —— Machine tool spindle bearings —— Low-noise bearings ——Suffixes. Suffixes are placed after the basic code. When there are multiple sets of suffix codes, they should be arranged from left to right in the order specified in the bearing code table. Some suffix codes are separated from the basic code by a dot. Suffix codes – internal structures A, B, C, D, E – represent variations in the internal structure. Example: Angular contact ball bearings 7205C, 7205E, 7205B; C corresponds to a contact angle of 15°, E to 25°, and B to 40°. Examples: Cylindrical roller, self-aligning roller, and thrust self-aligning roller bearings N309E, 21309E, 29412E – enhanced design with increased bearing load capacity. VH — Full roller cylindrical roller bearing with roller self-locking (the radius of the rollers is different from that of standard bearings of the same type). Example: NJ2312VH. Suffix codes – Bearing dimensions and external structure: DA – Separable double-row angular contact ball bearing with two half inner rings. Example: 3306DA. DZ — Roller bearing with a cylindrical outer diameter. Example: ST017DZ. K— Tapered bore bearing, taper 1:12. Example: 2308K. K30 – Tapered bore bearing, taper 1:30. Example: 24040 K30. 2LS — A double-row cylindrical roller bearing with dust covers on both sides of the inner rings. Example: NNF5026VC.2LS.V — Double inner rings, dust covers on both sides, full-roller double-row cylindrical roller bearing with internal structure changes. N — Bearing with a retaining groove on the outer ring. Example: 6207N. NR — Bearings with a stop groove and a stop ring on the outer ring. Example: 6207 NR. N2-—— A four-point contact ball bearing with two stop grooves on the outer ring. Example: QJ315N2. S — Bearing with lubrication grooves on the outer ring and three lubrication holes. Example: 23040 S. For spherical roller bearings with an outer diameter D ≥ 320 mm, S is not marked. X — The external dimensions comply with international standard specifications. Example: 32036X Z••—— Technical specifications for special structures. Arranged in sequence downward starting from Z11. Example: Z15 — Stainless steel bearing (W-N01.3541). ZZ— Roller bearing with two retaining rings for guiding the outer rings. Suffix code — Sealing and dust protection. RSR — The bearing has a seal on one side. Example: 6207 RSR .2RSR — Bearings with seals on both sides. Example: 6207.2RSR. ZR — The bearing has a dust cover on one side. Example: 6207 ZR .2ZR bearings have dust covers on both sides. Example: 6207.2ZR ZRN — One side of the bearing has a dust cover; the outer ring on the other side has a snap-ring groove. Example: 6207 ZRN. .2ZRN — Bearings with dust covers on both sides, and a stop groove on the outer ring. Example: 6207.2ZRN. Post-code — Retainer and its material 1 Solid retainer. A or B is placed after the cage code: A indicates that the cage is guided by the outer ring, while B indicates that it is guided by the inner ring. F— Steel solid cage, roller guidance. FA — Steel solid cage, outer ring guidance. FAS — Steel solid cage, outer ring guidance, with lubrication grooves. FB – Steel solid cage, inner ring guidance. FBS — Steel solid cage, inner ring guidance, with lubrication grooves. FH — Steel solid cage, carburized and quenched. H, H1 — Carburized and quenched retainer. FP — Steel solid window-type retainer. FPA — Steel solid window-type retainer, with outer ring guidance. FPB — Steel solid window-type retainer, with inner ring guidance. FV, FV1 — Steel solid window cage, aged and quenched/tempered. L — Solid retainer made of light metal, for guiding the rolling elements. LA — Solid retainer made of lightweight metal, with outer ring guidance. LAS — Solid cage made of lightweight metal, outer ring guidance, with lubrication grooves. LB – Solid retainer made of light metal, with inner ring guidance. LBS – Solid cage made of lightweight metal, with inner ring guidance and lubrication grooves. LP — Solid window-type retainer made of light metal. LPA — Solid light-metal window-type retainer with outer-ring guidance. LPB — Solid window-type retainer made of light metals, with inner ring guidance (axial guidance for thrust roller bearings). M, M1 – Brass solid cage. MA — Brass solid cage, outer ring guidance. MAS – Brass solid cage, outer ring guidance, with lubrication grooves. MB — Brass solid cage, inner ring guidance (thrust self-aligning roller bearings use the shaft ring for guidance). MBS — Brass solid cage, inner ring guidance, with lubrication grooves. MP— Brass solid straight-pocket cage. MPA— Solid brass straight-flute cage with retainer; outer ring guided. MPB — Brass solid straight-pocketed retainer with inner ring guidance. T — Phenolic laminate tube solid retainer, ball guide. TA — Phenolic laminate tube solid retainer, with outer ring guidance. TB — Phenolic laminated fabric tube solid retainer, with inner ring guidance. THB — Phenolic laminated cloth tube pocket-type retainer, with inner ring guidance. TP — Phenolic layer fabric tube straight pocket hole retainer. TPA — Phenolic laminate tube direct pocket retainer, with outer ring guidance. TPB — Phenolic laminated cloth tube direct pocket retainer, with inner ring guidance. TN — Engineering plastic injection-molded cage, with rolling elements for guidance; different materials are indicated by additional numbers. TNH — Self-locking pocket-type retainer for engineering plastics. TV — Glass fiber reinforced polyamide solid retainer, steel ball guidance. TVH — Glass fiber reinforced polyamide self-locking pocket-type solid retainer, with steel ball guidance. TVP – Glass fiber reinforced polyamide window-type solid retainer, with steel ball guidance. TVP2 – Glass fiber reinforced polyamide solid retainer, with roller guidance. TVPB — Glass fiber reinforced polyamide solid retainer, inner ring guidance (thrust roller bearings use shaft guidance). TVPB1 — Glass fiber reinforced polyamide solid window-type retainer, shaft guidance (thrust roller bearing). Stamped retainer J – Steel plate stamped retainer. JN — Riveted retainer for deep groove ball bearings. A change in the cage is indicated by a number added after or inserted between the cage code, showing that the cage structure has been modified. These numbers are only for the transitional period, e.g., NU 1008M 1. Suffix codes – Bearing without a cage: V – Bearing with fully loaded rolling elements. Example: NU 207V. VT — Full-load rolling-element bearing with an isolation ball or roller. Example: 51120VT. Postfix code – Tolerance grade (dimensional accuracy and rotational accuracy). P0 – The tolerance grade corresponds to grade 0 as specified by the international ISO standard; this grade is not indicated in the code. P6 — The tolerance grade conforms to Grade 6 as specified in the international standard ISO. P6X —— A tapered roller bearing whose tolerance class meets the level 6 specifications defined by the international standard ISO. P5 — The tolerance grade corresponds to level 5 as specified by the international standard ISO. P4 — The tolerance grade corresponds to level 4 as specified by the international standard ISO. P2 —— The tolerance grade corresponds to level 2 as specified by the international standard ISO (excluding tapered roller bearings). SP — The dimensional accuracy is equivalent to grade 5, and the rotational accuracy is equivalent to grade 4 (double-row cylindrical roller bearings). UP — The dimensional accuracy is equivalent to grade 4, and the rotational accuracy is higher than grade 4 (double-row cylindrical roller bearings). HG — The dimensional accuracy is equivalent to grade 4, while the rotational accuracy is higher than grade 4 but lower than grade 2 (for the spindle bearings). Post-code — Clearance C1 — The clearance falls within Group 1 as specified by the standards, and is less than Group 2. C2 —— 2 groups whose clearance meets the standard requirements, and 0 groups that are below the standard. C0 – The clearance falls within Group 0 as specified by the standards; this group is omitted from the code and not indicated. C3 — The clearance falls into the 3rd group as specified by the standard; it is greater than the 0th group. C4 —— 4 groups of clearances that meet the standard requirements, with more than 3 groups. C5 —— 5 groups of clearances meet the standard requirements, which is more than 4 groups. When both the tolerance grade code and the clearance grade code need to be indicated, the tolerance grade code (P0 grade is not indicated) is used together with the clearance group code (group 0 is not indicated). Example: P63=P6+C3 indicates a bearing tolerance grade of P6 with a radial clearance of group 3. P52=P5+C2, which indicates a bearing tolerance grade of P5 with a radial clearance of group 2. For non-standard clearances, in cases where special radial and axial clearances are required, the relevant limit values shall be indicated as a numerical value in μm after the letter R (radial clearance) or A (axial clearance), with a decimal point separating the digits. Example: 6210.R10.20 —— 6210 bearing, radial clearance of 10 μm to 20 μm. 6212.A120.160——6212 bearings, with an axial clearance of 120 μm to 160 μm. Post-code — Bearing with test noise F3 — Low-noise bearing. It mainly refers to cylindrical roller bearings and deep groove ball bearings with an inner diameter of d > 60 mm. Example: 6213.F3. G — Low-noise bearing. It mainly refers to deep groove ball bearings with an inner diameter d ≤ 60mm. Example: 6207.G – suffix code; Heat treatment: S0 – The bearing rings have undergone high-temperature tempering, allowing them to operate at temperatures up to 150 ℃. S1 — The bearing rings have undergone high-temperature tempering, allowing them to operate at temperatures up to 200 ℃. S2 —— The bearing rings have undergone high-temperature tempering, allowing them to operate at temperatures up to 250 ℃. S3 — The bearing rings undergo high-temperature tempering; the operating temperature can reach 300 °C. S4 — The bearing rings have undergone high-temperature tempering, allowing them to operate at temperatures up to 350 ℃. Post-code — Special technical conditions F••—— Sequentially numbered manufacturing technical conditions. Example: F80 — Tolerances for the inner and outer diameters of the bearing and compression of the radial play. K••—— Inspection technical specifications for sequential numbering. Example K5 — Reduction of tolerances on the inner and outer diameters of bearings. .ZB — Convex cylindrical rollers with a diameter of over 80 mm. Example: NU 364.ZB. .ZB2 — The convexity at both ends of the roller exceeds the standard technical requirements. Example: K18 × 26 × 20F .ZB2. ZW — Double-row needle and retainer assembly. Example: K20 × 25 × 40FZW. .700•••—— Technical specifications for sequentially numbered values starting with 700000. Z52JN.790144 – This bearing is suitable for high-temperature and low-speed applications. It undergoes special heat treatment; its cage is made by stamping and riveting steel plates. It has a large clearance, is phosphated, and pre-lubricated with grease. Its operating temperature can exceed 270 °C. Suffix codes — Special technical conditions: KDA—Split inner ring; Split-type inner ring. K—Tapered bore, taper ratio 1:12. K30—Tapered bore, taper ratio 1:30. N—Circular groove in the outer ring for a snap ring. S—Lubrication grooves and holes in the outer ring. The “S” suffix has been completely eliminated in the new E1 series! The outer ring oil filling groove and oil holes are now standard features. W03B Stainless steel bearing N2, two retaining grooves for fixing the outer ring; two stop grooves used to hold the outer ring in place. Postcode – Paired bearings and machine tool spindle bearings. 1) Paired bearings that meet the K technical specifications; the following special technical requirements apply to paired bearings: K1 – Two sets of deep groove ball bearings installed in pairs to withstand unidirectional axial loads. K2 — Two sets of deep groove ball bearings are installed in pairs to withstand bidirectional axial loads. K3 — Two sets of deep-groove ball bearings are installed back to back with no play (O-type installation). K4 — Two sets of deep groove ball bearings mounted face-to-face with no play (X-type mounting). K6 — Two sets of angular contact ball bearings are installed in pairs to withstand unidirectional axial loads. K7 — Two sets of angular contact ball bearings mounted back to back with no play (O-type mounting). K8 – Two sets of angular contact ball bearings mounted face to face without play (X-type installation). K9 – Two sets of tapered roller bearings with spacers between the inner and outer rings, mounted in pairs to withstand unidirectional axial loads. K10 — Two sets of tapered roller bearings with spacers between the inner and outer rings are mounted back-to-back without any clearance (O-type mounting). K11 — Two sets of tapered roller bearings with spacers between the outer rings are mounted face-to-face without any clearance (X-type mounting). Bearings that are configured in pairs or groups need to be delivered packaged together, or indicated as belonging to a pair. Bearings from different groups are not interchangeable. When installing bearings that belong to the same group, they should be installed according to the marks and positioning lines. If the individual paired bearings are arranged with a certain axial or radial clearance, such clearance shall be specified after the K technical conditions, as indicated in item 1, 2) of point (7). For example, 31314A .K11.A100.140 denotes two sets of 31314A single-row tapered roller bearings mounted face to face, with a spacer ring between their outer rings; the axial clearance is between 100 μm and 140 μm before assembly, while it is zero after assembly. Universal mating bearings can be installed in any configuration (in series, face-to-face, or back-to-back), with the suffix codes UA, UO, and UL. .UA — Allows for a small axial play when bearings are mounted face-to-face or back-to-back. .UO—— No play when bearings are mounted face-to-face or back-to-back. .UL — Slight pre-load when bearings are mounted face-to-face or back-to-back. For example, B 7004C.TPA.P4.K5.UL denotes an angular contact ball bearing for spindles, with a contact angle of 15°; it features a solid retainer made of phenolic laminated fabric, outer ring guidance, a bearing tolerance class of 4, reduced tolerances for the inner and outer diameters, and a universal design that allows for paired installation. The bearing exhibits slight preloading when installed back-to-back or face-to-face. The suffix — indicates that it is a machine spindle bearing of type KTPA.HG, with a fabric-retained solid retainer, outer ring guidance, and a precision class of HG. TPA.HG.K5.UL: Solid retainer with cloth inserts and holes for securing the components; outer ring provides guidance. Precision grade is HG. The tolerances for the outer and inner diameters of the bearing are reduced. It features a unitary design suitable for paired installation, with the bearings being mounted face-to-face or back-to-back with a slight preload. TPA.P2.K5.UL: Solid retainer with cloth inserts and holes for holding the components; outer ring provides guidance. Precision grade is HG. The tolerances for the outer and inner diameters of the bearing are reduced. It features a unitary structure designed for paired installation, with the bearings being installed face-to-face or back-to-back with a slight pre-interference. TPA.P2 UL – cloth-covered solid retainer with holes for securing the components; outer ring provides guidance; precision grade HG. The tolerances for the bearing’s outer and inner diameters are reduced. It features a tandem design, and the bearings are installed face to face or back to back with a slight pre-interference. Post-code – Machine tool spindle bearing TPA.P2.K5.UL: solid retainer with fabric insert and through-hole design; outer ring provides guidance; precision grade HG; universal design for paired installation; the bearings are installed face to face or back to back with a slight pre-interference. C contact angle / contact angle: 15″C. Contact angle / Winkel des Kontakts: 25 ‰C. P4S tolerance class P4S.