6904 Bearing
Bore (d) 20 mm
Outside diameter (D) 37 mm
Width (B) 9 mm
Inches (bore × OD × width) 0.7874 × 1.4567 × 0.3543″
Deep-groove ball bearing, thin section (6900) series. Seal/shield suffixes (ZZ, 2RS, …) change the closures, never these dimensions — a 6904-ZZ and 6904-2RS are the same size.
What the number means
- 6 — deep-groove ball bearing
- 9 — dimension series (thin section (6900))
- 04 — bore code × 5 = 20 mm
Neighboring sizes (thin section (6900) series)
| Designation | Bore | OD | Width |
|---|---|---|---|
| 6902 | 15 mm | 28 mm | 7 mm |
| 6903 | 17 mm | 30 mm | 7 mm |
| 6904 | 20 mm | 37 mm | 9 mm |
| 6905 | 25 mm | 42 mm | 9 mm |
| 6906 | 30 mm | 47 mm | 9 mm |
Same bore, other series
Fits the same 20 mm shaft with a different OD/width envelope and load capacity.
- 6804 — 20 × 32 × 7 mm (thin section (6800))
- 6004 — 20 × 42 × 12 mm (extra light (6000))
- 6204 — 20 × 47 × 14 mm (light (6200))
- 6304 — 20 × 52 × 15 mm (medium (6300))
Common suffixes on a 6904
| Suffix | Meaning |
|---|---|
| ZZ / 2Z | steel shields both sides (metal, non-contact) |
| Z | steel shield, one side |
| 2RS | contact rubber seals both sides (SKF 2RS1, NSK DDU, NTN LLU) |
| RS | contact rubber seal, one side |
| 2RZ | low-friction non-contact seals both sides (NSK VV, NTN LLB) |
| C3 | radial internal clearance greater than Normal (common in motors) |
| C2 | radial internal clearance smaller than Normal |
| NR | snap ring groove in the outer ring, with snap ring |
| P6 / P5 / P4 | ISO precision classes (≈ ABEC 3 / 5 / 7) |