624 bearing dimensions
A 624 bearing is 4 mm bore × 13 mm outside diameter × 5 mm wide (0.157 × 0.512 × 0.197 in). The sealed version is 624-2RS; the shielded version is 624-ZZ.
624 at a glance
Boundary dimensions in millimetres and inches, and the common closure designations.
- Bore, d
- 4 mm 0.1575"
- Outside diameter, D
- 13 mm 0.5118"
- Width, B
- 5 mm 0.1969"
- Section height, (D − d)/2
- 4.5 mm 0.1772"
- Series
- 62 series light
- Bore code
- 4 Under 10 mm bore the last digit is the bore itself: 4 = 4 mm
- Sealed, both sides
- 624-2RS
- Shielded, both sides
- 624-ZZ
- Open
- 624 no closures; any version may add C3 for extra internal clearance
Reading the number 624
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 | 624 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. | 624 |
| Z | One metal shield, on one side only. | 624-Z |
| ZZ, 2Z | Metal shields on both sides. Non-contact, so low friction; keeps out larger dirt. Usually greased for life. | 624-ZZ |
| RS | One rubber contact seal, on one side only. | 624-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. | 624-2RS |
| 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. | 624-2RS C3 |
624 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 | 624-2RSH | 624-2Z |
| FAG (Schaeffler) | 624-2RSR | 624-2ZR |
| NSK | 624DDU | 624ZZ |
| NTN | 624LLU | 624ZZ |
| Koyo (JTEKT) | 624-2RS | 624ZZ |
| Timken | 624-2RS | 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 624 bearing?
4 mm bore, 13 mm outside diameter and 5 mm wide, which is 0.157 × 0.512 × 0.197 in.
What does 2RS mean on a 624 bearing?
624-2RS has rubber contact seals on both sides. 624-ZZ (also written 624-2Z) has metal shields on both sides. Both have the same 4 × 13 × 5 mm dimensions.
Is 624-2RS the same as 624-ZZ?
They are the same size and interchangeable in a housing. The sealed 624-2RS keeps out fine dirt and water better; the shielded 624-ZZ runs with less friction.
What is the SKF equivalent of 624-2RS?
SKF writes it 624-2RSH; FAG 624-2RSR, NSK 624DDU, NTN 624LLU and Koyo 624-2RS. Check the maker's catalogue for the exact seal type.
What does the number 624 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: 4 = 4 mm.