61908-ZZ bearing: complete specifications & equivalents
The 61908-ZZ is a ISO 15 radial bearing sized 40 x 62 x 12 mm (bore x OD x width) with ZZ sealing. Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Bore diameter d | 40 mm |
| Outer diameter D | 62 mm |
| Width B | 12 mm |
| Seal / shield | ZZ |
| Internal clearance | CN / C3 available |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Operating temperature | -30 to +120 °C |
| Mass (geometry estimate) | 108 g |
| Standard | ISO 15 |
| Catalog version | iso15-ed4-geometry |
| Last verified | 2026-09-23 |
Source: ISO 15 boundary-dimensions standard · extracted 2026-09-23
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 61908 are being backfilled — use the inquiry form for certified values.
Dimensions in inches & 61900-series range
| Bore d | 1.575 in |
|---|---|
| Outer diameter D | 2.441 in |
| Width B | 0.472 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 11 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) | 9 of 35 |
| Bore above smallest 61900-series size | 30 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 61908 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 40×62×12 mm envelope per ISO 15; seal variant differs (ZZ vs OPEN) — confirm sealing suits the duty. |
| 61908-2RS | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 40×62×12 mm envelope per ISO 15; seal variant differs (ZZ vs 2RS) — confirm sealing suits the duty. |
| 61908-RSR | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 40×62×12 mm envelope per ISO 15; seal variant differs (ZZ vs RSR) — 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 61908-ZZ model number is decoded
In the 61900-series (ISO 15 diameter series 9) the last two digits encode the bore: 61908 carries bore code 08 = 40 mm. Outside diameter 62 mm and width 12 mm come from the ISO 15 boundary-dimensions general plan. Suffix -ZZ denotes two non-contact metallic shields; they retain grease and block coarse debris but are not liquid-tight. For normal-load mounting with a rotating inner ring on a 40 mm shaft, typical catalogue practice is a k5 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude.
Typical equipment & failure modes
Common applications
- space-constrained gearboxes
- clutch and transmission assemblies
- robotics and automation joints
- lay shafts and idler shafts
Known failure patterns
- fine-particle abrasion when non-contact shields let dust past in dirty duty
- grease aging in the shield-for-life cavity with 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
- At a 40 mm bore, a shaft-seat burr or an overtight setscrew can score the thin inner ring of 61908-ZZ; check shaft finish and runout (target Ra ≤ 1.6 µm) before pressing it home.
- The 619xx thin section (11.0 mm section height at 40 mm bore) trades load capacity for compactness; stiff, accurately aligned seats are essential or edge loading will spall the raceway early.
- ZZ shields are non-contact: 61908-ZZ blocks chips and coarse dust but is not waterproof — do not install it expecting a pressure-wash seal, step up to 61908-2RS for that.
- Shielded 61908-ZZ units are typically greased for life; prying the shields out for regreasing usually bends them and leaves a gap that throws grease in service.
- Do not quieten a noisy bearing by preloading it: the 61900-series is a deep-groove design, not angular-contact; axial preload raises temperature and shortens grease life.
Frequently asked questions
What are the dimensions of a 61908-ZZ bearing?
A 61908-ZZ deep-groove ball bearing has a 40 mm bore, 62 mm outer diameter and 12 mm width (1.575 × 2.441 × 0.472 in), per ISO 15 boundary dimensions. It is fitted with two non-contact metallic shields. Geometry-based estimated mass is about 108 g for a steel-cage unit; catalogue masses vary slightly with seal and cage design.
How does the 61908 bore code work?
The last two digits of 61908 are bore code 08, giving 08 × 5 = 40 mm bore. The 62 mm outside diameter and 12 mm width follow the ISO 15 diameter series, not the bore code alone.
What does the ZZ suffix on 61908-ZZ mean?
ZZ means two non-contact sheet-metal shields, one each side. They retain factory grease and block coarse particles with little friction, but do not seal against liquids, fine dust or pressure washing.
How does the 61900 compare with other series at the same 40 mm bore?
619 is a thin section one step above 618: 62×12 mm with a 11.0 mm radial section at 40 mm bore; a 6208 on the same bore is substantially larger and more heavily rated.
Are 61908 bearings from different brands interchangeable?
For boundary dimensions, yes: every brand's 61908 uses the same ISO 15 envelope (40×62×12 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 2026-09-23. Read our editorial & correction policy.