Deep Groove Ball Bearing Numbers Explained: 6204-2RS, 6305ZZ C3 and More
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A deep-groove bearing number usually encodes type, size series and bore. Suffixes then add seals, shields, snap rings, clearance or precision. Reading the full code avoids the most common replacement error.
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Deep groove ball bearings are among the most widely used rolling bearings. Their designation is generally built from a basic code - bearing type, size series and bore code - followed by suffixes for seals, shields, clearance or other special features.
Basic designation structure
| Part | Meaning | Example |
|---|---|---|
| First digit | 6 = single-row deep groove ball bearing | 6 |
| Width series | 0, 1, 2 or 3; larger values generally indicate a wider bearing | 2 |
| Diameter series | 0, 1, 2 or 3; larger values generally indicate a larger outside diameter | 2 |
| Bore code | Special codes 00 to 03; from 04 upward, code × 5 mm | 04 = 20 mm |
Bore code quick reference
Code 00 means 10 mm, 01 means 12 mm, 02 means 15 mm and 03 means 17 mm. From 04 upward, multiply the code by 5 to obtain the bore in millimeters. For example, 05 = 25 mm and 08 = 40 mm.
Common suffixes
- ZZ: shields on both sides.
- 2RS / DDU: contact rubber seals on both sides.
- VV: non-contact rubber seals on both sides.
- N: snap-ring groove in the outer ring.
- C3: radial internal clearance larger than normal clearance.
- C4: radial internal clearance larger than C3.
- P5 / P6: precision classes.
Examples
6204-2RS: 6 = deep groove ball bearing; 2 = series; 04 = 20 mm bore; 2RS = two contact rubber seals.
6305ZZ C3: 6 = deep groove ball bearing; 3 = series; 05 = 25 mm bore; ZZ = two shields; C3 = larger-than-normal radial internal clearance.
FAQ
Are 2RS and ZZ interchangeable?
No. Seals and shields have different contact, contamination and speed characteristics. Select according to the environment and lubrication strategy.
What does C3 mean?
C3 indicates greater-than-normal radial internal clearance. It should be chosen only where fit, temperature and running conditions require it.
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Technical FAQ
What does 6204-2RS mean?
6204 identifies the basic size family and 2RS indicates two rubber seals. Confirm clearance and grease requirements separately.
What does 6305ZZ C3 mean?
ZZ indicates shields and C3 indicates greater internal clearance than normal. Verify the application temperature and fit.