6309 bearing dimensions
A 6309 bearing is 45 mm bore × 100 mm outside diameter × 25 mm wide (1.772 × 3.937 × 0.984 in). The sealed version is 6309-2RS; the shielded version is 6309-ZZ.
6309 at a glance
Boundary dimensions in millimetres and inches, and the common closure designations.
- Bore, d
- 45 mm 1.7717"
- Outside diameter, D
- 100 mm 3.9370"
- Width, B
- 25 mm 0.9843"
- Section height, (D − d)/2
- 27.5 mm 1.0827"
- Series
- 63 series medium
- Bore code
- 09 09 × 5 = 45 mm
- Sealed, both sides
- 6309-2RS
- Shielded, both sides
- 6309-ZZ
- Open
- 6309 no closures; any version may add C3 for extra internal clearance
Reading the number 6309
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 | 6309 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. | 6309 |
| Z | One metal shield, on one side only. | 6309-Z |
| ZZ, 2Z | Metal shields on both sides. Non-contact, so low friction; keeps out larger dirt. Usually greased for life. | 6309-ZZ |
| RS | One rubber contact seal, on one side only. | 6309-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. | 6309-2RS |
| 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. | 6309-2RS C3 |
6309 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 | 6309-2RSH | 6309-2Z |
| FAG (Schaeffler) | 6309-2RSR | 6309-2ZR |
| NSK | 6309DDU | 6309ZZ |
| NTN | 6309LLU | 6309ZZ |
| Koyo (JTEKT) | 6309-2RS | 6309ZZ |
| Timken | 6309-2RS | 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.
Same 45 mm bore, other series
Bearings that fit the same shaft. A heavier series carries more load in a bigger housing bore; a thin-section series saves space and weight.
| Bearing | Series | OD | Width | Section | vs 6309 |
|---|---|---|---|---|---|
| 6809 | thin-section | 58 mm | 7 mm | 6.5 mm | −42 mm OD, −18 mm wide |
| 6909 | thin-section | 68 mm | 12 mm | 11.5 mm | −32 mm OD, −13 mm wide |
| 6009 | extra-light | 75 mm | 16 mm | 15 mm | −25 mm OD, −9 mm wide |
| 6209 | light | 85 mm | 19 mm | 20 mm | −15 mm OD, −6 mm wide |
| 6309 | medium | 100 mm | 25 mm | 27.5 mm | this bearing |
63 series
Common questions
What size is a 6309 bearing?
45 mm bore, 100 mm outside diameter and 25 mm wide, which is 1.772 × 3.937 × 0.984 in.
What does 2RS mean on a 6309 bearing?
6309-2RS has rubber contact seals on both sides. 6309-ZZ (also written 6309-2Z) has metal shields on both sides. Both have the same 45 × 100 × 25 mm dimensions.
Is 6309-2RS the same as 6309-ZZ?
They are the same size and interchangeable in a housing. The sealed 6309-2RS keeps out fine dirt and water better; the shielded 6309-ZZ runs with less friction.
What is the SKF equivalent of 6309-2RS?
SKF writes it 6309-2RSH; FAG 6309-2RSR, NSK 6309DDU, NTN 6309LLU and Koyo 6309-2RS. Check the maker's catalogue for the exact seal type.
What does the number 6309 mean?
6 is the deep groove ball bearing type, 3 is the medium dimension series, and 09 × 5 = 45 mm (from 04 up, multiply by 5).
Which bearings have the same bore as 6309?
6809, 6909, 6009, 6209 also have a 45 mm bore, with different outside diameters and widths.