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Table of Contents
Categories
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Adapter Sleeves (9)
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Ball Bearings (11)
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Ball Screw Bearings (2)
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Ceramic Bearings (28)
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Pillow Block Bearings (4)
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Plain Bearings (32)
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Roller Bearings (12)
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Slewing Bearings (43)
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Sliding Block (3)
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Stainless Steel Bearings (27)
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Super Precision Bearings (6)
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Thin Section Bearings (9)
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Track Rollers (4)
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Universal Joints (1)
Lee
1. Introduction
This handbook translates Chinese bearing code classifications into English, organizes prefix/suffix conventions, and maps China’s GB/T and JB/T standards to corresponding ISO standards (and thus to global catalogs like SKF, NSK, INA). It is meant as a quick-reference for engineers and technicians.
2. Bearing Type Classification
Rule: Read the first digit (or first two digits) of the basic bearing code (reading left to right) to identify the category. Below, Chinese digit/letter codes are translated, with the “class” number (as in the original Chinese) noted in parentheses for reference.
| Chinese Code | English Interpretation | Original “Class” |
|---|---|---|
| “6” | Single-row deep-groove ball bearing | (0-class) |
| “4” | Double-row deep-groove ball bearing | (0-class) |
| “2” or “1” | Self-aligning ball bearing (basic model has 4 digits) | (1-class) |
| “21”, “22”, “23”, “24” | Spherical (self-aligning) roller bearing | (3-class) |
| “N” | Cylindrical roller bearing (including short rollers & some long needle portions) | (2-class) |
| • “NU” | Cylindrical roller bearing, inner ring without flange | – |
| • “NJ” | Cylindrical roller bearing, inner ring one flange | – |
| • “NF” | Cylindrical roller bearing, outer ring one flange | – |
| • “N” (alone) | Cylindrical roller bearing, outer ring without flange | – |
| • “NN” | Double-row cylindrical roller, outer ring without flange | – |
| • “NNU” | Double-row cylindrical roller, inner ring without flange | – |
| “Needle rollers” | When roller length ≥ 5× diameter → needle roller bearing | (4-class) |
| • “NA” | Needle roller bearing with machined outer ring | – |
| • “NK” | Needle roller bearing with pressed outer shell | – |
| • “K” | Needle & cage assembly without inner/outer rings | – |
| “7” | Single-row angular-contact ball bearing | (6-class) |
| “3” | Tapered roller bearing (metric series) | (7-class) |
| “51”, “52”, “53” | Thrust radial ball bearing (basic model has 5 digits) | (8-class) |
| “81” | Thrust short cylindrical roller bearing | (9-class) |
| “29” | Thrust spherical (self-aligning) roller bearing | (9-class) |
Notes:
“Self-aligning ball bearings” typically have two rows of balls with a common sphered outer raceway, allowing misalignment.
Cylindrical roller bearings use suffix letters (NU, NJ, NF, etc.) to indicate flange arrangement.
Needle roller bearings: if roller length ≥5× diameter, they are treated as needle bearings; NA/NK/K denote types of outer ring or cage-only assembly.
Angular-contact ball bearings (“7xx” series) handle combined radial and axial loads; contact angle variations often shown by suffix (e.g. C/E/B in later section).
Tapered roller bearings (“3xx” series) handle combined loads; Chinese codes align with ISO metric tapered series.
Thrust bearings: ball or roller types indicated by initial digits (5xx for thrust ball, 81 for short roller thrust, 29 for thrust self-aligning rollers).
3. Prefix Codes
Placement: Directly before the basic bearing code; separated by a dot if multiple.
R: Bearing without separable inner or outer ring.
E.g.,
RNU207means NU207 without inner ring.
GS.: Thrust cylindrical roller bearing seat ring.
E.g.,
GS.81112.
K.: Roller & cage assembly.
E.g.,
K.81108denotes thrust cylindrical roller + cage assembly.
WS: Thrust cylindrical roller bearing shaft ring.
E.g.,
WS.81112.
International Catalogs: Manufacturers may have other prefixes (e.g., SKF uses suffix “K” for tapered bore, but Chinese GB/T codes embed bore size), so prefix usage beyond the above Chinese conventions depends on manufacturer.
4. Suffix Codes
Suffix letters/numbers follow the basic code; multiple suffixes appear in the order given by the Chinese bearing-code tables. Some have a separating dot before them.
4.1 Internal Structure Modifications
A, B, C, D, E: Changes in internal design (e.g., contact angle for angular-contact bearings).
Example:
7205C,7205E,7205B:C = 15° contact angle, E = 25°, B = 40° (angular-contact)
E: Enhanced (‘strengthened’) design for higher load capacity (e.g., cylindrical, spherical, thrust spherical bearings:
N309E,21309E,29412E).VH: Full-complement cylindrical roller bearing with roller self-locking (roller crown diameter differs from standard).
E.g.,
NJ2312VH.
4.2 Outer/External Structural Modifications
DA: Separable double-row angular-contact ball bearing with two half inner rings.
E.g.,
3306DA.
DZ: Roller bearing with cylindrical outer diameter (wheel bearings).
E.g.,
ST017DZ.
K / K30: Tapered bore (1:12 or 1:30).
E.g.,
2308K(1:12 taper),24040K30(1:30).
2LS: Double-row cylindrical roller bearing with two inner rings and seals on both sides.
E.g.,
NNF5026VC.2LS.Vindicates double-row, two inner rings, seals both sides, full-complement rollers.
N / NR / N2-: Snap-ring groove(s) on outer ring.
N: one groove (e.g.
6207N),NR: groove + snap ring (e.g.
6207NR),N2-: two grooves (e.g. four-point contact ball
QJ315N2).
S: Outer ring with lubrication groove and three oil holes (not marked on spherical roller bearings with D ≥ 320 mm).
E.g.
23040S.
X: Conforms to international standard dimensions.
E.g.,
32036X.
Z…: Special technical conditions, numbered from Z11 onward.
E.g.,
Z15= stainless-steel bearing variant (e.g. W-N01.3541).
ZZ: Roller bearing with two guiding flanges on outer rings.
4.3 Sealing / Shields / Dust Protection
RSR: One side with seal ring.
E.g.,
6207RSR.
.2RSR: Two-sided seal rings.
E.g.,
6207.2RSR.
ZR: One side dust cover.
E.g.,
6207ZR.
.2ZR: Both sides dust covers.
ZRN: One side dust cover, other side outer ring snap groove.
E.g.,
6207ZRN.
.2ZRN: Both sides dust covers + grooves.
4.4 Cage(Material) & Design
Solid cages (letter appears after cage code; A = guided by outer ring, B = guided by inner ring):
F: Steel solid cage, guided by rolling elements.
FA: Steel solid cage, outer-ring guided.
FAS: Steel solid cage, outer-ring guided, with lubrication groove.
FB: Steel solid cage, inner-ring guided.
FBS: Steel solid cage, inner-ring guided, with lubrication groove.
FH: Steel solid cage, carburized & quenched.
H, H1: Carburized & quenched cage.
FP/FPA/FPB: Steel window-type solid cage (outer-/inner-ring guided).
FV/FV1: Steel window-type, age/harden treated.
L: Light-metal solid cage, rolling-element guided.
LA/LAS/LB/LBS: Light-metal outer/inner guided, with or without lubrication groove.
LP/LPA/LPB: Light-metal window-type cages, guided accordingly.
M/M1: Brass solid cage.
MA/MAS/MB/MBS: Brass guided variations.
MP/MPA/MPB: Brass deep pocket cages (outer/inner guided).
T/TA/TB/THB/TP/TPA/TPB: Phenolic laminated fabric cages, various guided forms.
TN/TNH: Molded plastic cages (rolling-element guided / self-locking).
TV/TVH/TVP/TVP2/TVPB/TVPB1: Glass-fiber-reinforced nylon cages, various guided types for balls/rollers.
Pressed cages:
J: Stamped steel cage.
JN: Riveted cage for deep-groove ball bearings.
Modified cages: Numeric inserts in cage code denote transitional design changes, e.g.,
NU1008M1.
4.5 No-Cage Bearings
V: Full-complement bearing (filled with maximum number of rolling elements).
E.g.,
NU207V.
VT: Full-complement with separators between rolling elements.
E.g.,
51120VT.
4.6 Tolerance Classes (Dimensional & Running Accuracy)
Follows ISO 492 & ISO 15312 for tolerance and running accuracy. Chinese suffix conventions:
P0: ISO standard class 0 (omitted in code).
P6: ISO class 6 (normal).
P6X: ISO class 6 for tapered roller bearings.
P5: ISO class 5 (higher precision).
P4: ISO class 4 (even higher).
P2: ISO class 2 (very high; not for tapered rollers).
SP: Equivalent to dimension tolerance of P5, running accuracy of P4 (double-row cylindrical).
UP: Dim tolerance P4, running accuracy higher than P4 (double-row cylindrical).
HG: Dim tolerance P4, running accuracy between P4 and P2 (spindle bearings).
Catalog equivalents:
ABEC/ISO: ABEC 1 ≈ ISO P6; ABEC 5 ≈ ISO P4; ABEC 7 ≈ ISO P2. Some catalogs use codes like PA5 (~ISO P4) or PA7 (~ISO P2).
4.7 Internal Clearance
Follows ISO 5753:
C0: Normal clearance (omitted).
C1: Less than normal.
C2: Less than C0.
C3: Greater than normal.
C4: Greater than C3.
C5: Greater than C4.
Combined: When both tolerance and clearance appear: e.g., P6 + C3 → “P63”; P5 + C2 → “P52”.
Non-standard clearance: Denoted by letter “R” (radial) or “A” (axial) followed by clearance limits in μm separated by dots.
E.g.,
6210.R10.20= 6210 bearing with radial clearance 10–20 μm.
6212.A120.160= axial clearance 120–160 μm.
4.8 Noise Testing
F3: Low-noise bearing (mainly cylindrical rollers & deep-groove balls with bore > 60 mm).
E.g.,
6213.F3.
G: Low-noise bearing (deep-groove balls with bore ≤ 60 mm).
E.g.,
6207.G.
Decoding DIN
Deutsches Institut für Normung (DIN) standards bring German engineering precision to bearings. Understand the tolerances, dimensions, and how DIN compares with ABEC and ISO. DIN standards, renowned for their precision and efficiency, offer a unique perspective on bearing manufacturing. As FHD Bearings operates in a competitive landscape, incorporating DIN standards into their production processes enhances the quality of their offerings, reinforcing their position as a reliable B2B partner for machine manufacturers and distributors.
4.9 Heat Treatment
Suffixes indicating ring heat treatment for high-temperature service:
S0: Rings tempered to allow service up to 150 °C.
S1: Up to 200 °C.
S2: Up to 250 °C.
S3: Up to 300 °C.
S4: Up to 350 °C.
4.10 Special Technical Conditions
F…: Sequential manufacturing-tech conditions (e.g., F80 = compressed ring tolerances & clearance).
K…: Sequential inspection-tech conditions (e.g., K5 = compressed ring tolerances).
.ZB: For cylindrical rollers >80 mm with increased crown.
E.g.,
NU364.ZB.
.ZB2: Needle end crown > usual requirement (e.g.,
K18×26×20F.ZB2).ZW: Double-row needle & cage assembly (e.g.,
K20×25×40FZW)..700…: Special sequential numbering starting with 700000.
Z52JN.790144: High-temperature low-speed bearing with special heat treatment, stamped-steel cage, large clearance, phosphated, grease-lubricated—service > 270 °C.
KDA: Split inner ring.
K / K30: Tapered bore 1:12 / 1:30 (not Chinese GB/T but manufacturer convention).
N: Outer ring snap ring groove.
S: Lubrication groove & holes on outer ring (now standard on new E1 series).
W03B: Stainless-steel bearing.
N2: Two retaining grooves on outer ring for snap ring.
4.11 Paired Bearings & Spindle Bearings
K1, K2, K3, K4… K11: Paired installation conditions under “K” technical conditions.
K1: Two deep-groove bearings paired for unidirectional axial load.
K2: Two deep-groove for bidirectional axial.
K3: Back-to-back with zero clearance (“O” arrangement).
K4: Face-to-face with zero clearance (“X” arrangement).
K6–K8: Similar for angular-contact bearings.
K9–K11: Similar for tapered rollers with spacers and paired arrangements.
General paired types:
.UA: Small axial clearance in paired faces/back arrangement.
.UO: Zero clearance.
.UL: Light interference fit in paired arrangement.
E.g.,
B7004C.TPA.P4.K5.UL: Spindle angular-contact ball bearing 15° contact, phenolic cage inner guided, ISO P4 tolerance, compressed tolerance K5, universal paired type with slight interference.
Spindle bearings often use suffixes like TPA.HG.K5.UL (phenolic cage, outer guided, HG precision, compressed tolerance, paired with interference).
Contact angle codes: C = 15°, D = 25° (in spindle bearing context).
Tolerance class P4S for spindle bearings.
5. Chinese National Standards & ISO Equivalents
Below are the listed GB/T and JB/T standards, their English titles (if available), and the known ISO equivalents. Where a Chinese standard has been updated or replaced, the latest Chinese version and ISO adoption year are noted.
Caveat: Chinese national standards frequently “adopt” or “equate to” relevant ISO standards. Where explicit mapping is known from official listings, it is cited. In some JB/T (industry) standards, direct ISO equivalents may not be publicly documented; general functional alignment (e.g., measurement methods aligned with ISO test methods) is noted without specific ISO number if unavailable.
5.1 GB/T Standards
GB/T 305-1998: Rolling bearings—Snap ring groove and snap ring on outer ring—Dimensions and tolerances
Chinese title: 滚动轴承 外圈上的止动槽和止动环 尺寸和公差
English title: Rolling bearings—Snap ring groove and snap ring on outer ring—Dimensions and tolerances
Status: Withdrawn (replaced by newer edition adopting ISO)
ISO equivalent: Adopted ISO standard (likely ISO 464 / parts in ISO 15 series for snap ring grooves)
GB/T 308-2002: Rolling bearings—Steel balls
Chinese title: 滚动轴承钢球
English: Rolling bearings—Steel balls
ISO equivalent: ISO 3290:1998 (Dimensions and tolerances for bearing balls)
GB/T 309-2000 (replaced): Rolling bearings—Needle rollers
Chinese: 滚动轴承滚针
Latest: GB/T 309-2021 replaced GB/T 309-2000.
ISO equivalent: ISO 3096:2018 Rolling bearings—Needle rollers—Boundary dimensions, GPS and tolerance values
GB/T 4661-2002: Rolling bearings—Cylindrical rollers
Chinese: 滚动轴承 圆柱滚子
English: Rolling bearings—Cylindrical rollers
ISO equivalent: Adopted ISO for cylindrical rollers (e.g., ISO 303 series for cylindrical rollers boundary dimensions).
GB/T 4662-2003: Rolling bearings—Rated static load
Chinese: 滚动轴承 额定静载荷
English: Rolling bearings—Static load ratings
ISO equivalent: ISO 76:2006.
Replaced by GB/T 4662-2012 (still equivalent to ISO 76:2006)
GB/T 6391-2003: Rolling bearings—Rated dynamic load and rated life
Chinese: 滚动轴承 额定动载荷和额定寿命
English: Rolling bearings—Dynamic load ratings and rating life
ISO equivalent: Latest GB/T 6391-2010 aligns with ISO 281:2007 (commonly used for dynamic load/life calculation).
Other GB/T: Beyond those listed, Chinese standards for deep-groove, angular-contact, tapered, spherical, thrust bearings adopt corresponding ISO dimensions (e.g., GB/T 276 for deep-groove ≈ ISO 15; GB/T 297 for tapered ≈ ISO 355; GB/T 288 for spherical ≈ ISO 15 series; etc.). Engineers reference ISO catalogs from SKF/NSK/INA interchangeably with GB/T dimensions.
5.2 JB/T Standards
JB/T are China’s machinery industry standards; some align with ISO test/method standards or supplement GB/T where special conditions apply.
JB/T 3034-1993: Rolling bearings—Sealing, rust-prevention packaging
Chinese: 滚动轴承 油封防锈包装
Applies to cleaning, rust prevention, and packing of bearings, balls, rollers, needles, and parts.
ISO alignment: General packaging/rust-protection methods align with ISO 15243 (bearing failure analysis) and ISO cleanliness concepts, but no direct ISO number found.
JB/T 3573-2004: Rolling bearings—Methods for measurement of radial internal clearance
Chinese: 滚动轴承 径向游隙的测量方法
ISO equivalent: ISO 11341 / ISO 199 for clearance measurement methods; Chinese method aligns with ISO 5753 clearance definitions.
JB/T 6639-2004: Bearing parts—Technical conditions for nitrile rubber seal rings (skeleton type)
Chinese: 滚动轴承零件 骨架式丁腈橡胶密封圈技术条件
ISO alignment: Sealing standards often reference ISO 6194 series for seals; exact mapping not publicly listed.
JB/T 6641-2007: Rolling bearings—Residual magnetism and evaluation method
Chinese: 滚动轴承 残磁及其评定方法
ISO alignment: ISO 15243 mentions residual magnetism aspects; detailed method likely aligns with ISO magnetic testing methods.
JB/T 6642-2004: Bearing parts—Roundness and waviness measurement and evaluation method
Chinese: 滚动轴承零件 圆度和波纹度误差测量及评定方法
ISO alignment: ISO 492/ISO 4287 for surface texture; ISO 25178 series for waviness; method aligns with general geometric tolerancing standards.
JB/T 7048-2002: Bearing parts—Engineering plastic cages
Chinese: 滚动轴承零件 工程塑料保持架
ISO alignment: Cage material standards reference ISO 5753/ISO 281 for polymer cages; specific ISO for cage dimensions depends on bearing type.
JB/T 7050-2005: Rolling bearings—Cleanliness evaluation method
Chinese: 滚动轴承 清洁度评定方法
ISO alignment: ISO 4406 (hydraulic fluid contamination) principles often applied; ISO cleanliness codes used in bearing manufacturing though direct ISO for bearing cleanliness not fixed.
JB/T 7051-2006: Bearing parts—Surface roughness measurement and evaluation
Chinese: 滚动轴承零件 表面粗糙度测量和评定方法
ISO alignment: ISO 4287/4288 for surface roughness; bearing surfaces follow such ISO.
JB/T 7361-2007: Bearing parts—Hardness test methods
Chinese: 滚动轴承 零件硬度试验方法
ISO alignment: ISO 281 for hardness requirements; ISO 6508 (Rockwell), ISO 6507 (Vickers) for hardness testing methods.
JB/T 7752-2005: Sealed deep-groove ball bearing technical conditions
Chinese: 滚动轴承密封深沟球轴承技术条件
ISO alignment: Specifications align with ISO for sealed bearings (e.g., ISO 15243 for sealing tests, ISO temperature rise tests).
JB/T 8196-1996: Rolling bearings—Rolling element residual magnetism evaluation
Chinese: 滚动轴承 滚动体残磁及其评定方法
ISO alignment: Similar to JB/T 6641 for residual magnetism.
JB/T 8571-1997: Sealed deep-groove ball bearing—Dust protection, grease leakage, temperature rise performance test methods
Chinese: 滚动轴承 密封深沟球轴承 防尘、漏脂、温升性能试验规程
ISO alignment: ISO 15243 / ISO 281 for temperature rise; sealing performance tests reference ISO 281 or manufacturer catalogs.
JB/T 8921-1999: Rolling bearings and parts—Inspection rules
Chinese: 滚动轴承 及其零件检验规则
ISO alignment: ISO 199 for bearing quality grading; ISO 492 for dimensional tolerances.
JB/T 10336-2002: Rolling bearings and parts—Supplemental technical conditions
Chinese: 滚动轴承及其零件补充技术条件
ISO alignment: Supplements GB/T/ISO requirements for special situations.
JB/T 50013-2000: Rolling bearings—Life and reliability test rules
Chinese: 滚动轴承 寿命及可靠性试验规程
ISO alignment: ISO 281 life calculations; reliability tests follow ISO accelerated life test methods.
JB/T 50093-1997: Rolling bearings—Life and reliability evaluation method
Chinese: 滚动轴承 寿命及可靠性试验评定方法
ISO alignment: ISO 281 and related standards for evaluating bearing life/reliability.
Note: For JB/T standards without explicit public ISO equivalent numbers, one infers that test or measurement methods align with the general ISO series on bearings (ISO 492, ISO 281, ISO 5753, ISO 6194, ISO 4287, etc.). When designing or testing, refer to the latest ISO documents for dimension, tolerance, surface finish, hardness, magnetism, and lubrication/sealing tests; these match JB/T requirements in practice.
6. International Manufacturer Catalog Equivalents (SKF/NSK/INA, etc.)
Because Chinese GB/T dimensions equal ISO dimensions, catalogs from SKF, NSK, INA can be used directly. Common suffix conventions in these catalogs match the translated suffixes above:
Deep-groove ball bearings: e.g., SKF 6206-2Z/C3 corresponds to GB/T 6206-2Z/C3.
Cylindrical rollers: e.g., NSK NU204E corresponds to GB/T NU204E (inner ring flange arrangement).
Needle bearings: e.g., INA NK/NA types match GB/T NA/NK designations; outer rings or pressed shells align dimensionally via ISO 3096.
Tapered rollers: e.g., SKF 30206 with 1:12 bore taper corresponds to GB/T 30206K.
Spherical roller bearings: NSK 223 series corresponds to GB/T 223 series for spherical roller dimensions.
Thrust bearings: e.g., SKF 51105 corresponds to GB/T 5105 thrust ball bearing.
Usage: When ordering or referencing bearings, engineers can cross-check GB/T codes with SKF/NSK catalog numbers, since bore, OD, width, clearance classes, and suffix meanings coincide under ISO conventions. For any special suffix not in GB/T (e.g., specific manufacturer internal codes), consult the manufacturer’s catalog for the meaning.
7. Comparative Tables
7.1 Bearing Category Codes
| Chinese Code | English Category | ISO/Catalog Series Example |
|---|---|---|
| 6 | Single-row deep-groove ball bearing | 6000, 6200, 6300 series |
| 4 | Double-row deep-groove ball bearing | 4200, 4300 series |
| 1 / 2 | Self-aligning ball bearing | 1200, 2200 series |
| 21–24 | Spherical/self-aligning roller bearing | 223xx series |
| N | Cylindrical roller bearing | NU, NJ, NF, NNU, etc. |
| Needle (NA/NK/K) | Needle roller bearing | NA / NK / K series |
| 7 | Single-row angular-contact ball bearing | 7000, 7200 series |
| 3 | Tapered roller bearing | 30000, 32000 series |
| 51–53 | Thrust radial ball bearing | 51100, 51200 series |
| 81 | Thrust short cylindrical roller bearing | 81100 series |
| 29 | Thrust spherical roller bearing | 292xx series |
7.2 Prefix/Suffix Equivalents (GB/T ↔ SKF/NSK/INA)
| Suffix | GB/T Meaning | SKF/NSK/INA Equivalent | Example |
|---|---|---|---|
| N | Outer ring groove (no ring) | “N” | 6006N |
| NR | Groove + snap ring | “NR” | 6006NR |
| Z / 1Z | One side metal shield | “Z” | 6206-Z |
| 2Z/ZZ | Two metal shields | “ZZ” or “2Z” | 6206-2Z |
| RS | One side rubber seal | “RS” | 6206RS |
| 2RS | Two side rubber seals | “2RS” | 6206-2RS |
| E | Low-noise / precision design | “E” | 6206 C3 E |
| C2–C4 | Internal clearance grades | “C2/C3/C4” | 6206 C3 |
| P6/P5/P4/P2 | Tolerance classes | “P6/P5/P4/P2” | 6206 P5 |
| CV | Full-complement cylindrical roller | “CV” | NJ220CV |
| V | Full-complement bearing | “V” | NU207V |
| VT | Full-complement with separators | “VT” | 51120VT |
| HG | High spindle precision | “HG” | 7004C-TPA-HG-K5-UL |
| UA/UO/UL | Paired bearing configurations | “TA”, “TB” or pairing codes | As per catalog pairing codes |
| S0–S4 | High-temperature tempering suffix | Often custom; see catalog | e.g., S2 for 250 °C |
Table usage: Use the table above to interpret a GB/T bearing code and find the equivalent catalog code in SKF/NSK/INA documents, since the suffix meanings align.
8. Standards Mapping Summary
Below summarizes each Chinese standard listed originally, with English title and known ISO equivalent:
| Chinese Standard | English Title | ISO Equivalent / Notes | Citation |
|---|---|---|---|
| GB/T 305-1998 | Rolling bearings—Snap ring groove and snap ring on outer ring—Dimensions and tolerances | Adopted ISO (e.g., ISO for snap ring groove in rolling bearings) | openstd.samr.gov.cn |
| GB/T 308-2002 | Rolling bearings—Steel balls | ISO 3290:1998 | doc88.com |
| GB/T 309-2000 | Rolling bearings—Needle rollers | ISO 3096:2018 | doc88.com |
| GB/T 4661-2002 | Rolling bearings—Cylindrical rollers | ISO cylindrical roller dimensions (e.g., ISO 303) | antpedia.com |
| GB/T 4662-2003 | Rolling bearings—Static load ratings | ISO 76:2006 | std.samr.gov.cn |
| GB/T 6391-2003 | Rolling bearings—Dynamic load ratings and rated life | ISO 281:2007 | std.samr.gov.cn |
| JB/T 3034-1993 | Rolling bearings—Sealing, rust-proof packaging | Aligns with ISO cleanliness/packaging principles | bzxz.net |
| JB/T 3573-2004 | Rolling bearings—Methods for measurement of radial internal clearance | Aligns with ISO 11341/ISO clearance definitions | doc88.com |
| JB/T 6639-2004 | Bearing parts—Nitrile rubber seal ring technical conditions | Approx. ISO 6194 series | – |
| JB/T 6641-2007 | Rolling bearings—Residual magnetism evaluation | Aligns with ISO magnetic testing methods | – |
| JB/T 6642-2004 | Bearing parts—Roundness & waviness measurement and evaluation | Aligns with ISO 4287/25178 | – |
| JB/T 7048-2002 | Bearing parts—Engineering plastic cages | Aligns with ISO cage dimension rules | – |
| JB/T 7050-2005 | Rolling bearings—Cleanliness evaluation | Aligns with ISO cleanliness principles | – |
| JB/T 7051-2006 | Bearing parts—Surface roughness measurement | ISO 4287/4288 | – |
| JB/T 7361-2007 | Bearing parts—Hardness test methods | ISO 6507/6508 | – |
| JB/T 7752-2005 | Sealed deep-groove ball bearing technical conditions | Aligns with ISO sealing & temperature rise tests | – |
| JB/T 8196-1996 | Rolling bearings—Rolling element residual magnetism evaluation | Similar to JB/T 6641 | – |
| JB/T 8571-1997 | Sealed deep-groove ball bearing—Dust, grease leakage, temperature rise tests | Aligns with ISO temperature rise & sealing tests | – |
| JB/T 8921-1999 | Rolling bearings & parts—Inspection rules | Aligns with ISO 492 dimensional tolerances | – |
| JB/T 10336-2002 | Rolling bearings & parts—Supplemental technical conditions | Supplement to GB/T/ISO standards | – |
| JB/T 50013-2000 | Rolling bearings—Life & reliability test rules | Aligns with ISO 281 life calculation methods | – |
| JB/T 50093-1997 | Rolling bearings—Life & reliability evaluation | Aligns with ISO life evaluation methods | – |
For JB/T entries without explicit ISO numbers publicly listed, one assumes alignment with relevant ISO test or measurement standards (e.g. ISO 492 for geometry, ISO 281 for life, ISO 5753 for clearance, ISO 4287 for surface finish, ISO 6507/6508 for hardness, ISO 6194 for seals).
9. English Translation of Original Chinese Explanations
Below is a direct translation into English of the original sections for clarity:
Preface:
“This is a mini bearing handbook summarizing bearing code classifications. When you read this, some codes may be unfamiliar, but as long as you are in the bearing field, you will need them someday!”
Bearing Classification:
Read first digit (or first two digits) from left:
“6” = deep-groove ball bearing (0-class)
“4” = double-row deep-groove ball bearing (0-class)
“2” or “1” = self-aligning ball bearing (basic model has four digits) (1-class)
“21”, “22”, “23”, “24” = spherical/self-aligning roller bearing (3-class)
“N” = cylindrical roller bearing (includes short cylindrical rollers and some long needle portions) (2-class)
“NU”: inner ring without flange.
“NJ”: inner ring with single flange.
“NF”: outer ring with single flange.
“N”: outer ring without flange.
“NN”: double-row cylindrical roller, outer ring without flange.
“NNU”: double-row cylindrical roller, inner ring without flange.
Roller length ≥ 5× diameter = needle roller bearing (4-class)
“NA”: turned outer ring needle bearing.
“NK”: pressed outer shell needle bearing.
“K”: needle & cage assembly without rings.
“7” = angular-contact ball bearing (6-class)
“3” = tapered roller bearing (metric) (7-class)
“51”, “52”, “53” = thrust radial ball bearing (basic model five digits) (8-class)
“81” = thrust short cylindrical roller bearing (9-class)
“29” = thrust self-aligning roller bearing (9-class)
National Standards (list with English titles & ISO mapping):
GB-T 305-1998 Rolling bearings—Snap ring groove and snap ring on outer ring—Dimensions and tolerances
GB-T 308-2002 Rolling bearings—Steel balls (ISO 3290:1998)
GB-T 309-2000 Rolling bearings—Needle rollers (now GB/T 309-2021; ISO 3096:2018)
GB-T 4661-2002 Rolling bearings—Cylindrical rollers (ISO cylindrical roller dims)
GB-T 4662-2003 Rolling bearings—Static load ratings (ISO 76:2006)
GB-T 6391-2003 Rolling bearings—Dynamic load ratings and life (ISO 281 series)
JB-T 3034-1993 Rolling bearings—Sealing, rust-proof packaging (aligns ISO)
JB-T 3573-2004 Rolling bearings—Radial clearance measurement methods (aligns ISO clearance definitions)
JB-T 6639-2004 Bearing parts—Nitrile rubber seal ring technical conditions
JB-T 6641-2007 Rolling bearings—Residual magnetism evaluation
JB-T 6642-2004 Bearing parts—Roundness & waviness measurement & evaluation
JB-T 7048-2002 Bearing parts—Engineering plastic cages
JB-T 7050-2005 Rolling bearings—Cleanliness evaluation methods
JB-T 7051-2006 Bearing parts—Surface roughness measurement & evaluation
JB-T 7361-2007 Bearing parts—Hardness test methods
JB-T 7752-2005 Sealed deep-groove ball bearing technical conditions
JB-T 8196-1996 Rolling bearings—Rolling element residual magnetism evaluation
JB-T 8571-1997 Sealed deep-groove ball bearing—Dust, grease leakage, temperature rise tests
JB-T 8921-1999 Rolling bearings & parts—Inspection rules
JB-T 10336-2002 Rolling bearings & parts—Supplemental technical conditions
JB-T 50013-2000 Rolling bearings—Life & reliability test rules
JB-T 50093-1997 Rolling bearings—Life & reliability evaluation methods
Prefix Codes:
“R” before basic code: no separable inner or outer ring (e.g.
RNU207).“GS.”: thrust cylindrical roller bearing seat ring (e.g.
GS.81112).“K.”: roller & cage assembly (e.g.
K.81108).“WS”: thrust cylindrical roller bearing shaft ring (e.g.
WS.81112).
Suffix Codes:
Placed after basic code; if multiple, left-to-right as per table; sometimes separated by dot.
Internal structure: A/B/C/D/E for internal changes (e.g. contact angle changes in angular-contact:
7205C= 15°;7205E= 25°;7205B= 40°).Strengthened design: e.g.
N309E,21309E,29412E.VH: self-locking full-complement cylindrical roller bearing (e.g.
NJ2312VH).
External structure:
DA: separable double-row angular-contact with double half inner rings (e.g.
3306DA).DZ: cylindrical OD roller bearing (e.g.
ST017DZ).K / K30: tapered bore (1:12 / 1:30) (e.g.
2308K,24040K30).2LS: two inner rings + two dust covers, full-complement rollers (e.g.
NNF5026VC.2LS.V).N / NR / N2-: outer ring groove(s) for snap ring (e.g.
6207N,6207NR,QJ315N2).S: lubrication groove & holes on outer ring (e.g.
23040S).X: dimension per international standard (e.g.
32036X).Z… / ZZ: special structures (e.g. stainless steel
Z15, roller guiding flangesZZ).
Sealing/dust:
RSR / .2RSR: one/two side seal rings (e.g.
6207RSR,6207.2RSR).ZR / .2ZR: dust covers (e.g.
6207ZR,6207.2ZR).ZRN / .2ZRN: dust cover + groove combination (e.g.
6207ZRN,6207.2ZRN).
Cage & material: variety of codes for steel, brass, light-metal, phenolic, plastic, nylon cages with guidance type.
No-cage: V (full-complement), VT (with separators).
Tolerance: P0 (omitted), P6, P6X, P5, P4, P2, SP, UP, HG.
Clearance: C1–C5, combined with tolerance (e.g. P63 = P6 + C3). Non-standard via R/A μm values.
Noise: F3 (low noise, cylindrical & large deep-groove), G (low noise deep-groove ≤60 mm).
Heat treatment: S0–S4 (150–350 °C).
Special tech: F…, K…, .ZB, .ZB2, ZW, .700…, Z52JN.790144, KDA, K/K30 (tapered bore), N (snap groove), S (lubrication groove), W03B (stainless), N2 (two snap grooves).
Paired/spindle: K1–K11 (paired arrangements), UA/UO/UL (general paired), TPA.HG.K5.UL etc., contact angle C (15°), D (25°), P4S tolerance for spindles.
10. How to Use This Handbook
Identify the basic code: Read the first digit(s) to determine bearing type (deep-groove “6”, cylindrical “N…”, angular “7…”, etc.).
Translate suffixes: Use the Suffix Codes section (4) and Comparative Tables (7.2) to interpret modifications (seals, shields, flanges, clearance/tolerance).
Map to catalogs: Because GB/T dimensions equal ISO dimensions, find the equivalent in SKF/NSK/INA catalogs by matching basic code and suffix meanings.
Check standards: For design, testing, or manufacturing details (dimensions, tolerances, load ratings, life calculation, clearance measurement, surface finish, sealing performance, etc.), refer to the mapped ISO standards: ISO 3290 (balls), ISO 3096 (needle rollers), ISO 76 (static load), ISO 281 (dynamic load/life), ISO 492 (dimensional tolerances), ISO 5753 (clearance), ISO 4287/4288 (surface finish), ISO 6507/6508 (hardness), ISO 6194 (seals), ISO 11341 (clearance measurement), etc.
Consult JB/T: For packaging, cleanliness, magnetism, noise testing, life/reliability tests in Chinese manufacturing context, use JB/T methods aligned with ISO principles as noted.
11. Example Interpretations
Example 1:
6206-2Z/C3EType “6” → single-row deep-groove ball bearing.
Bore code “06” → 30 mm bore.
Suffix “2Z” → metal shields both sides.
Clearance “C3” → greater-than-normal radial clearance.
“E” → low-noise/precision design.
Equivalent in SKF: 6206-2Z/C3E; in NSK: 6206ZZC3E; in INA: 6206-2Z-C3.
ISO dimensions per ISO 15 series; clearance per ISO 5753; noise per ISO 15243 tests.
Example 2:
NU204EType “N” → cylindrical roller bearing.
“U” → inner ring without flange; outer ring without flange by default.
Bore code “04” → 20 mm bore (04 × 5 mm).
Suffix “E” → strengthened design (higher load capacity).
Equivalent: SKF NU204-E; dimensions per ISO cylindrical series; load ratings per ISO 76/281.
Example 3:
RNU207Prefix “R” → no inner ring.
Type “NU207” → cylindrical roller bearing; inner ring flange absent, outer ring without flange.
Use with appropriate matched inner ring from manufacturer; code indicates just the outer ring and rollers.
Map to catalog: SKF NU207 housing mount with separate inner ring.
Example 4:
B7004C.TPA.P4.K5.ULType “7004C” → angular-contact ball bearing 15° contact angle (“C”).
Prefix “B” might indicate specific design variant (manufacturer-specific).
Suffix “TPA” → phenolic laminated fabric cage, outer-ring guided.
“P4” → ISO tolerance class 4 (high precision).
“K5” → compressed dimensional tolerances per manufacturer specification.
“UL” → paired for slight interference (universal).
This is a spindle bearing paired arrangement; dimensions per ISO 15; precision per ISO P4; pairing per catalog instructions.
12. Tables for Quick Reference
12.1 Basic Type Code → Bearing Category
| Code Prefix | Category (English) | Typical Series / Notes |
|---|---|---|
| 6 | Single-row deep-groove ball | 6000, 6200, 6300 series |
| 4 | Double-row deep-groove ball | 4200, 4300 series |
| 1 / 2 | Self-aligning ball | 1200, 2200 series |
| 21–24 | Spherical/self-aligning roller | 223xx series |
| N + letters | Cylindrical roller (NU/NJ/NF/NN…) | NU204, NJ306, NNU… etc. |
| Needle (NA/NK/K) | Needle roller bearing | NA495, NK… or cage-only “K…” |
| 7 | Angular-contact ball | 7000, 7200 series |
| 3 | Tapered roller | 30000, 32000 series |
| 51–53 | Thrust radial ball | 51100, 51200 series |
| 81 | Thrust short cylindrical roller | 81100 series |
| 29 | Thrust spherical roller | 292xx series |
12.2 Common Suffixes
| Suffix | Meaning (English) | ISO/Catalog Equivalent |
|---|---|---|
| N | Outer ring snap-ring groove | “N” |
| NR | Groove + snap ring | “NR” |
| Z / 1Z | One side metal shield | “Z” |
| 2Z / ZZ | Two metal shields | “ZZ” or “2Z” |
| RS / 2RS | One/two side rubber seal | “RS” / “2RS” |
| C1–C5 | Internal clearance grades | “C1”–“C5” (ISO 5753) |
| P6/P5/P4/P2 | Tolerance classes | ISO P6/P5/P4/P2 |
| E | Low noise / precision | “E” |
| V | Full-complement bearing | “V” |
| VT | Full-complement with separators | “VT” |
| HG | High spindle precision | “HG” |
| UA/UO/UL | Paired bearing configurations | See catalog pairing rules |
| S0–S4 | Ring heat treatment for high temperature | Catalog-specific suffix |
| F3 / G | Low-noise grading | “F3” / “G” |
| DA, DZ, S, X, etc. | External structure modifications | As per section 4.2 |
12.3 Standard Mappings (Selected)
| Chinese Standard | English Title | ISO Equivalent |
|---|---|---|
| GB/T 305-1998 | Rolling bearings—Snap ring groove & snap ring dims & tolerances | Adopted ISO (snap groove) |
| GB/T 308-2002 | Rolling bearings—Steel balls | ISO 3290:1998 |
| GB/T 309-2021 | Rolling bearings—Needle rollers | ISO 3096:2018 |
| GB/T 4661-2002 | Rolling bearings—Cylindrical rollers | ISO cylindrical dims |
| GB/T 4662-2012 | Rolling bearings—Static load ratings | ISO 76:2006 |
| GB/T 6391-2010 | Rolling bearings—Dynamic load ratings & life | ISO 281:2007 |
| JB/T 3573-2004 | Rolling bearings—Radial clearance measurement methods | Aligns ISO clearance tests |
| JB/T 8571-1997 | Sealed deep-groove bearing performance tests | Aligns ISO temp/seal tests |
13. How to Cross-Reference in Practice
Dimension and Load Ratings:
Use GB/T codes for Chinese-supplied bearings; verify dimensions against ISO catalogs.
For load ratings, use ISO 76 (static) and ISO 281 (dynamic life) as applied by SKF/NSK/INA. Chinese GB/T values match these formulas.
Selection and Clearance:
Choose clearance class (C2–C4) per application (e.g., C3 for moderate thermal expansion). Methods per JB/T 3573–2004 align with ISO methods for measurement.
For high-speed/spindle: use tolerance class HG/P4S and paired arrangements codes.
Seals/Shields:
“RS”, “2RS”, “Z”, “ZZ” meanings identical to ISO-based catalogs.
For special seals (e.g. nitrile skeleton seals per JB/T 6639), consult manufacturer specifications referencing ISO 6194.
Material & Heat Treatment:
For high-temperature use, suffix S1–S4 indicate ring tempering—confirm with manufacturer for steel grade and hardness per ISO 6507/6508.
Testing & Quality:
Cleanliness, surface finish, hardness, magnetism tests per JB/T align with ISO methods: refer to ISO 4287, ISO 5753, ISO 6507/6508, ISO 15243.
Noise rating suffix (F3/G): test per ISO noise measurement guidelines.
Packaging & Handling:
Follow JB/T 3034 for packaging/rust prevention; aligns with general ISO best practices (dry, grease preservation, protective covers).
Cleanliness per JB/T 7050/7051 aligns with ISO cleanliness codes in bearing manufacturing.
14. Appendix: Sample Cross-Reference Workflow
Given Chinese Code: e.g.,
NJ2312VH.2ZR.P5.C3Type “NJ” → cylindrical roller bearing, inner ring single flange.
Series “312” → bore 60 mm (312×5 mm? verify via GB/T table).
“VH” → full-complement self-locking roller design.
“2ZR” → two dust covers/dust lips.
“P5” → ISO tolerance class 5 precision.
“C3” → greater-than-normal clearance.
Translate: “Cylindrical roller bearing (inner ring single flange) 60 mm bore, full-complement self-locking roller design, double-sided dust covers, ISO tolerance class 5, C3 clearance.”
Catalog Equivalent: Find in SKF/NSK catalog: e.g., NSK NJ2312VH2ZRP5C3 or similar. Confirm dimensions match ISO 303 series.
Check Standards:
Dimensions: GB/T 4661 / ISO cylindrical dims.
Load ratings: ISO 76/281.
Clearance: ISO 5753; measurement per JB/T 3573/ISO methods.
Precision: ISO 492 class P5.
Seals: Dust cover design per JB/T seal guidelines and ISO sealing tests.
Noise: as per F3/G tests if low-noise required.
Ordering/Specification: Use the translated description and ISO-based catalog code for procurement. Ensure packaging per JB/T 3034.
15. References (Selected)
GB/T 305-1998 Rolling bearings—Snap ring groove and snap ring on outer ring—Dimensions and tolerances openstd.samr.gov.cn
GB/T 308-2002 Rolling bearings—Steel balls; ISO 3290:1998 doc88.com
GB/T 309-2021 Rolling bearings—Needle rollers; ISO 3096:2018 doc88.com
GB/T 4661-2002 Rolling bearings—Cylindrical rollers antpedia.com
GB/T 4662-2012 Rolling bearings—Static load ratings; ISO 76:2006 std.samr.gov.cn
GB/T 6391-2010 Rolling bearings—Dynamic load ratings & life; ISO 281 std.samr.gov.cn
JB/T 3034-1993 Rolling bearings—Sealing, rust-proof packaging bzxz.net
JB/T 3573-2004 Rolling bearings—Radial clearance measurement methods doc88.com
Engineers should refer to the latest editions of GB/T (e.g., GB/T 309-2021 replacing GB/T 309-2000) and ISO standards for up-to-date dimensions and methods.
16. Conclusion
This handbook provides:
English translations of Chinese bearing classification rules.
Prefix/suffix interpretation aligned with ISO conventions.
Mappings of GB/T and JB/T standards to ISO equivalents, enabling use of SKF/NSK/INA catalogs directly.
Structured tables for quick lookup of codes and their meanings.
Keep this as a reference for decoding Chinese bearing codes, ensuring correct matching to international catalogs and conformity to standardized dimensions, tolerances, and test methods.
