61904-RSR bearing: complete specifications & equivalents
The 61904-RSR is a ISO 15 radial bearing sized 20 x 37 x 9 mm (bore x OD x width) with RSR sealing. Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 20 mm |
| Outer diameter D | 37 mm |
| Width B | 9 mm |
| Material | GCr15 |
| Seal / shield | RSR |
| Internal clearance | CN / C3 available |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 6.37 kN |
| Basic static load rating C0 | 3.65 kN |
| Fatigue load limit Pu | 0.156 kN |
| Reference speed (thermal) | 43000 rpm |
| Limiting speed (mechanical) | 20000 rpm |
| Operating temperature | -30 to +120 °C |
| Mass | 38 g |
| Manufacturer designation | SKF 61904-2RZ |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-25 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-24
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018)); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.
Dimensions in inches & 61900-series range
| Bore d | 0.787 in |
|---|---|
| Outer diameter D | 1.457 in |
| Width B | 0.354 in |
| ISO bore code | 04 |
| Radial section height (D−d)/2 | 8.5 mm |
| Smallest bore in 61900-series | 3 mm |
| Largest outer diameter in 61900-series | 1120 mm |
| Width range across 61900-series | 3–118 mm |
| Bore position in 61900-series (smallest first) | 12 of 63 |
| Bore above smallest 61900-series size | 17 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 61904-2RS-FAG | FAG | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×37×9 mm envelope per ISO 15; seal variant differs (RSR vs 2RS) — confirm sealing suits the duty. |
| 61904-FAG | FAG | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×37×9 mm envelope per ISO 15; seal variant differs (RSR vs OPEN) — confirm sealing suits the duty. |
| 61904-ZZ-FAG | FAG | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×37×9 mm envelope per ISO 15; seal variant differs (RSR vs ZZ) — confirm sealing suits the duty. |
| 61904-2RS-NSK | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×37×9 mm envelope per ISO 15; seal variant differs (RSR vs 2RS) — confirm sealing suits the duty. |
| 61904-NSK | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×37×9 mm envelope per ISO 15; seal variant differs (RSR vs OPEN) — confirm sealing suits the duty. |
| 61904-RSR-NSK | NSK | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
| 61904-ZZ | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×37×9 mm envelope per ISO 15; seal variant differs (RSR vs ZZ) — confirm sealing suits the duty. |
| 61904-2RS-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×37×9 mm envelope per ISO 15; seal variant differs (RSR vs 2RS) — confirm sealing suits the duty. |
| 61904-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×37×9 mm envelope per ISO 15; seal variant differs (RSR vs OPEN) — confirm sealing suits the duty. |
| 61904-RSR-NTN | NTN | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
| 61904-ZZ-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×37×9 mm envelope per ISO 15; seal variant differs (RSR vs ZZ) — confirm sealing suits the duty. |
| W61904-2RS | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF stainless execution W 61904-2RS1 shares the 20×37×9 mm envelope but rates differently (6.37/3.65 kN vs 5.53/3.65 kN) — not a load-rating equivalent. |
| W61904 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF stainless execution W 61904 shares the 20×37×9 mm envelope but rates differently (6.37/3.65 kN vs 5.53/3.65 kN) — not a load-rating equivalent. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the 61904-RSR model number is decoded
In the 61900-series (diameter series 9 of ISO 15) the last two digits encode the bore: 61904 carries bore code 04 = 20 mm. Outside diameter 37 mm and width 9 mm come from the ISO 15 boundary-dimensions general plan. Suffix -RSR denotes two low-friction non-contact elastomer seals; they keep coarse debris out with minimal drag but are not liquid-tight. For normal-load mounting with a rotating inner ring on a 20 mm shaft, typical catalogue practice is a k5 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. SKF's low-friction seal suffix is 2RSL/2RZ (this page's industry-neutral spelling is -RSR); catalogue number 61904-2RZ.
Typical equipment & failure modes
Common applications
- robotics and automation joints
- lay shafts and idler shafts
- textile machinery
- packaging machinery
Known failure patterns
- ingress of fine dust or moisture past the non-contact lip in dirty or wet duty (RSR is not liquid-tight)
- lip-lubricant starvation if the bearing runs dry for extended periods
- cage damage from operation beyond the limiting speed
- electrical pitting in VFD-driven motors without grounding protection
Selection pitfalls — read before you substitute
- Sizes around 20 mm bore are normally pressed on cold with a sleeve against the inner-ring face; the press force must never route through the outer ring or the balls of 61904-RSR.
- The 619xx thin section (8.5 mm section height at 20 mm bore) trades load capacity for compactness; stiff, accurately aligned seats are essential or edge loading will spall the raceway early.
- RSR low-friction seals on 61904-RSR run faster than contact-seal 61904-2RS but let fine dust and moisture past the non-contact lip; in dirty or wet duty specify 61904-2RS instead.
- The non-contact lip of 61904-RSR does not retain a lifetime grease fill the way a contact seal does; confirm the regreasing interval for the 20 mm bore position before relying on it as sealed-for-life.
- Never mix components between two 61904-RSR units: rings, cage and balls are factory-matched and are not field-interchangeable, even between identical designations.
- Shaft and housing fillets must clear the bearing chamfer so the 9 mm-wide ring seats square; provide an undercut or withdrawal groove instead of relying on an oversized radius.
- SKF catalogues the low-friction seal as 61904-2RZ (suffix -2RSL or -2RZ): a non-contact elastomer lip that runs near the open 20000 r/min limiting speed, closer to the open bearing's 43000 r/min reference than the contact-seal version. It keeps coarse debris out without the drag of a contact seal, but is not liquid-tight — use 2RSH for wet or fine-dust positions.
- The 6.37/3.65 kN ratings here are SKF Explorer-class figures from catalogue PUB BU/P1 17000/1 EN (Oct 2018); SKF can revise internal geometry and ratings without changing the designation, so treat the catalogue version and date as part of the specification and re-verify for critical drives.
Frequently asked questions
What are the dimensions of a 61904-RSR bearing?
A 61904-RSR deep-groove ball bearing has a 20 mm bore, 37 mm outer diameter and 9 mm width (0.787 × 1.457 × 0.354 in), per ISO 15 boundary dimensions. It is fitted with two low-friction non-contact rubber seals.
What does the RSR suffix on 61904-RSR mean?
RSR means two low-friction non-contact rubber seals. They keep coarse debris out with minimal drag (speed close to the open bearing) but are not liquid-tight; use -2RS contact seals for wet or fine-dust environments.
How does the 61900 compare with other series at the same 20 mm bore?
619 is a thin section one step above 618: 37×9 mm with an 8.5 mm radial section at 20 mm bore; a 6204 on the same bore is substantially larger and more heavily rated.
Are 61904 bearings from different brands interchangeable?
For boundary dimensions, yes: every brand's 61904 uses the same ISO 15 envelope (20×37×9 mm). Load ratings, limiting speeds, clearance, precision class and sealing design can differ, so verify those in the supplier catalogue when substituting. Seal suffixes also differ by brand (2RS, DDU, LLU, 2RSL and similar).
What is the SKF designation and catalogue data for 61904-RSR?
In the SKF Rolling Bearings catalogue this size is listed as 61904-2RZ — two low-friction non-contact elastomer seals, 20×37×9 mm per ISO 15. Quoted values: C 6.37 kN, C0 3.65 kN, Pu 0.156 kN, limiting speed 20000 r/min, mass 38 g. Brand suffixes (2Z, 2RSH, 2RSL) differ from the industry-neutral spelling 61904-RSR.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-25. Read our editorial & correction policy.