623 bearing dimensions
A 623 bearing is 3 mm bore × 10 mm outside diameter × 4 mm wide (0.118 × 0.394 × 0.157 in). The sealed version is 623-2RS; the shielded version is 623-ZZ.
623 at a glance
Boundary dimensions in millimetres and inches, and the common closure designations.
- Bore, d
- 3 mm 0.1181"
- Outside diameter, D
- 10 mm 0.3937"
- Width, B
- 4 mm 0.1575"
- Section height, (D − d)/2
- 3.5 mm 0.1378"
- Series
- 62 series light
- Bore code
- 3 Under 10 mm bore the last digit is the bore itself: 3 = 3 mm
- Sealed, both sides
- 623-2RS
- Shielded, both sides
- 623-ZZ
- Open
- 623 no closures; any version may add C3 for extra internal clearance
Reading the number 623
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 | 623 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. | 623 |
| Z | One metal shield, on one side only. | 623-Z |
| ZZ, 2Z | Metal shields on both sides. Non-contact, so low friction; keeps out larger dirt. Usually greased for life. | 623-ZZ |
| RS | One rubber contact seal, on one side only. | 623-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. | 623-2RS |
| 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. | 623-2RS C3 |
623 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 | 623-2RSH | 623-2Z |
| FAG (Schaeffler) | 623-2RSR | 623-2ZR |
| NSK | 623DDU | 623ZZ |
| NTN | 623LLU | 623ZZ |
| Koyo (JTEKT) | 623-2RS | 623ZZ |
| Timken | 623-2RS | 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 623 bearing?
3 mm bore, 10 mm outside diameter and 4 mm wide, which is 0.118 × 0.394 × 0.157 in.
What does 2RS mean on a 623 bearing?
623-2RS has rubber contact seals on both sides. 623-ZZ (also written 623-2Z) has metal shields on both sides. Both have the same 3 × 10 × 4 mm dimensions.
Is 623-2RS the same as 623-ZZ?
They are the same size and interchangeable in a housing. The sealed 623-2RS keeps out fine dirt and water better; the shielded 623-ZZ runs with less friction.
What is the SKF equivalent of 623-2RS?
SKF writes it 623-2RSH; FAG 623-2RSR, NSK 623DDU, NTN 623LLU and Koyo 623-2RS. Check the maker's catalogue for the exact seal type.
What does the number 623 mean?
6 is the deep groove ball bearing type, 2 is the light dimension series, and under 10 mm bore the last digit is the bore itself: 3 = 3 mm.