61921-2RS bearing: complete specifications & equivalents
The 61921-2RS is a ISO 15 radial bearing sized 105 x 145 x 20 mm (bore x OD x width) with 2RS sealing. Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Bore diameter d | 105 mm |
| Outer diameter D | 145 mm |
| Width B | 20 mm |
| Seal / shield | 2RS |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Mass (geometry estimate) | 801 g |
| Standard | ISO 15 |
| Catalog version | iso15-ed4-geometry |
| Last verified | 2026-09-24 |
Source: ISO 15 boundary-dimensions standard · extracted 2026-09-24
Standard-interchange bearing: dimensions per ISO 15; CN clearance, P0 tolerance and a stamped-steel cage are catalogue defaults unless the supplier states otherwise, and mass is a geometry-derived estimate. Brand catalogue load ratings and limiting speeds for 61921 are being backfilled — use the inquiry form for certified values.
Dimensions in inches & 61900-series range
| Bore d | 4.134 in |
|---|---|
| Outer diameter D | 5.709 in |
| Width B | 0.787 in |
| ISO bore code | 21 |
| Radial section height (D−d)/2 | 20 mm |
| Smallest bore in 61900-series | 10 mm |
| Largest outer diameter in 61900-series | 420 mm |
| Width range across 61900-series | 6–56 mm |
| Bore position in 61900-series (smallest first) | 22 of 35 |
| Bore above smallest 61900-series size | 95 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 61921 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 105×145×20 mm envelope per ISO 15; seal variant differs (2RS vs OPEN) — confirm sealing suits the duty. |
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 61921-2RS model number is decoded
In the 61900-series (ISO 15 diameter series 9) the last two digits encode the bore: 61921 carries bore code 21 = 105 mm. Outside diameter 145 mm and width 20 mm come from the ISO 15 boundary-dimensions general plan. Suffix -2RS denotes two contact-type elastomer seals over a lifetime grease fill; the sealing lips add drag compared with open or shielded versions. For normal-load mounting with a rotating inner ring on a 105 mm shaft, typical catalogue practice is a m6 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude.
Typical equipment & failure modes
Common applications
- clutch and transmission assemblies
- robotics and automation joints
- lay shafts and idler shafts
- textile machinery
Known failure patterns
- seal-lip hardening and loss of pre-grease in sustained high-temperature service
- grease-life expiry in the sealed-for-life cavity (no relubrication path)
- rolling-contact fatigue spalling after the rated L10 life is exceeded
- brinelling from static overload or hammering during mounting
Selection pitfalls — read before you substitute
- Mount this 105 mm bore bearing by heating the inner ring (induction heater, max 120 °C) — never drive it home through the outer ring or balls, that brinells the raceways.
- The 619xx thin section (20.0 mm section height at 105 mm bore) trades load capacity for compactness; stiff, accurately aligned seats are essential or edge loading will spall the raceway early.
- Contact seals add drag and heat: 61921-2RS runs slower and cooler-limited than the open 61921; rubber lips are generally limited to roughly 80–110 °C continuous depending on grease, and C3 clearance is the common hot-duty choice.
- Never wash a sealed 61921-2RS in solvent or press it home via the outer ring; solvent destroys the grease thickener and mounting force through the seal deforms the lip.
- Shaft and housing fillets must clear the bearing chamfer so the 20 mm-wide ring seats square; provide an undercut or withdrawal groove instead of relying on an oversized radius.
Frequently asked questions
What are the dimensions of a 61921-2RS bearing?
A 61921-2RS deep-groove ball bearing has a 105 mm bore, 145 mm outer diameter and 20 mm width (4.134 × 5.709 × 0.787 in), per ISO 15 boundary dimensions. It is fitted with two contact rubber seals and is normally pre-greased. Geometry-based estimated mass is about 801 g for a steel-cage unit; catalogue masses vary slightly with seal and cage design.
How does the 61921 bore code work?
The last two digits of 61921 are bore code 21, giving 21 × 5 = 105 mm bore. The 145 mm outside diameter and 20 mm width follow the ISO 15 diameter series, not the bore code alone.
What does the 2RS suffix on 61921-2RS mean?
2RS means two contact elastomer seals, one each side, usually over a lifetime grease fill. Sealing against dust and moisture is better than ZZ shields, but the lip drag lowers the speed and temperature ceiling.
How does the 61900 compare with other series at the same 105 mm bore?
619 is a thin section one step above 618: 145×20 mm with a 20.0 mm radial section at 105 mm bore; a 6221 on the same bore is substantially larger and more heavily rated.
Are 61921 bearings from different brands interchangeable?
For boundary dimensions, yes: every brand's 61921 uses the same ISO 15 envelope (105×145×20 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 and similar).
Reviewed & verified by the MPN Base engineering desk against source catalog iso15-ed4-geometry on 2026-09-24. Read our editorial & correction policy.