6903 bearing dimensions
A 6903 bearing is 17 mm bore × 30 mm outside diameter × 7 mm wide (0.669 × 1.181 × 0.276 in). The sealed version is 6903-2RS; the shielded version is 6903-ZZ.
6903 at a glance
Boundary dimensions in millimetres and inches, and the common closure designations.
- Bore, d
- 17 mm 0.6693"
- Outside diameter, D
- 30 mm 1.1811"
- Width, B
- 7 mm 0.2756"
- Section height, (D − d)/2
- 6.5 mm 0.2559"
- Series
- 69 series thin-section
- Bore code
- 03 03 = 17 mm
- Sealed, both sides
- 6903-2RS
- Shielded, both sides
- 6903-ZZ
- Open
- 6903 no closures; any version may add C3 for extra internal clearance
Reading the number 6903
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 | 6903 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. | 6903 |
| Z | One metal shield, on one side only. | 6903-Z |
| ZZ, 2Z | Metal shields on both sides. Non-contact, so low friction; keeps out larger dirt. Usually greased for life. | 6903-ZZ |
| RS | One rubber contact seal, on one side only. | 6903-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. | 6903-2RS |
| 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. | 6903-2RS C3 |
6903 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 | 6903-2RSH | 6903-2Z |
| FAG (Schaeffler) | 6903-2RSR | 6903-2ZR |
| NSK | 6903DDU | 6903ZZ |
| NTN | 6903LLU | 6903ZZ |
| Koyo (JTEKT) | 6903-2RS | 6903ZZ |
| Timken | 6903-2RS | 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 17 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.
69 series
Common questions
What size is a 6903 bearing?
17 mm bore, 30 mm outside diameter and 7 mm wide, which is 0.669 × 1.181 × 0.276 in.
What does 2RS mean on a 6903 bearing?
6903-2RS has rubber contact seals on both sides. 6903-ZZ (also written 6903-2Z) has metal shields on both sides. Both have the same 17 × 30 × 7 mm dimensions.
Is 6903-2RS the same as 6903-ZZ?
They are the same size and interchangeable in a housing. The sealed 6903-2RS keeps out fine dirt and water better; the shielded 6903-ZZ runs with less friction.
What is the SKF equivalent of 6903-2RS?
SKF writes it 6903-2RSH; FAG 6903-2RSR, NSK 6903DDU, NTN 6903LLU and Koyo 6903-2RS. Check the maker's catalogue for the exact seal type.
What does the number 6903 mean?
6 is the deep groove ball bearing type, 9 is the thin-section dimension series, and 03 = 17 mm (codes 00 to 03 are fixed: 10, 12, 15 and 17 mm).
Which bearings have the same bore as 6903?
6803, 6003, 6203, 6303 also have a 17 mm bore, with different outside diameters and widths.