608 bearing dimensions
A 608 bearing is 8 mm bore × 22 mm outside diameter × 7 mm wide (0.315 × 0.866 × 0.276 in). The sealed version is 608-2RS; the shielded version is 608-ZZ.
608 at a glance
Boundary dimensions in millimetres and inches, and the common closure designations.
- Bore, d
- 8 mm 0.3150"
- Outside diameter, D
- 22 mm 0.8661"
- Width, B
- 7 mm 0.2756"
- Section height, (D − d)/2
- 7 mm 0.2756"
- Series
- 60 series extra-light
- Bore code
- 8 Under 10 mm bore the last digit is the bore itself: 8 = 8 mm
- Sealed, both sides
- 608-2RS
- Shielded, both sides
- 608-ZZ
- Open
- 608 no closures; any version may add C3 for extra internal clearance
Reading the number 608
Every deep groove ball bearing number follows the same pattern: type, dimension series and bore code, then suffixes.
Seals, shields and suffixes
Suffixes add closures and internal clearance. They do not change the boundary dimensions: a sealed and an open bearing of the same number are interchangeable in size.
| Suffix | Meaning | 608 example |
|---|---|---|
| Open (no suffix) | No seals or shields. Can be relubricated, or run in an oil bath; the housing needs its own seal against dirt. | 608 |
| Z | One metal shield, on one side only. | 608-Z |
| ZZ, 2Z | Metal shields on both sides. Non-contact, so low friction; keeps out larger dirt. Usually greased for life. | 608-ZZ |
| RS | One rubber contact seal, on one side only. | 608-RS |
| 2RS, 2RS1, 2RSH, 2RSR, DDU, LLU | Rubber contact seals on both sides. Better than shields against fine dirt and splashing water, with a little more friction. Usually greased for life. | 608-2RS |
| C3 | Radial internal clearance greater than normal (CN). Used with tight shaft or housing fits, or where the inner ring runs hotter than the outer ring. | 608-2RS C3 |
608 in other brands
The sealed and shielded versions as each maker writes them. All share the same boundary dimensions.
| Maker | Sealed both sides | Shielded both sides |
|---|---|---|
| SKF | 608-2RSH | 608-2Z |
| FAG (Schaeffler) | 608-2RSR | 608-2ZR |
| NSK | 608DDU | 608ZZ |
| NTN | 608LLU | 608ZZ |
| Koyo (JTEKT) | 608-2RS | 608ZZ |
| Timken | 608-2RS | see catalogue |
Seal designs and suffixes vary by maker, size range and product generation, for example contact versus low-friction seals. Confirm the exact designation in the maker's catalogue before ordering.
Miniature bearings
Common questions
What size is a 608 bearing?
8 mm bore, 22 mm outside diameter and 7 mm wide, which is 0.315 × 0.866 × 0.276 in.
What does 2RS mean on a 608 bearing?
608-2RS has rubber contact seals on both sides. 608-ZZ (also written 608-2Z) has metal shields on both sides. Both have the same 8 × 22 × 7 mm dimensions.
Is 608-2RS the same as 608-ZZ?
They are the same size and interchangeable in a housing. The sealed 608-2RS keeps out fine dirt and water better; the shielded 608-ZZ runs with less friction.
What is the SKF equivalent of 608-2RS?
SKF writes it 608-2RSH; FAG 608-2RSR, NSK 608DDU, NTN 608LLU and Koyo 608-2RS. Check the maker's catalogue for the exact seal type.
What does the number 608 mean?
6 is the deep groove ball bearing type, 0 is the extra-light dimension series, and under 10 mm bore the last digit is the bore itself: 8 = 8 mm.