61808 bearing: complete specifications & equivalents
The 61808 is a ISO 15 radial bearing sized 40 x 52 x 7 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Bore diameter d | 40 mm |
| Outer diameter D | 52 mm |
| Width B | 7 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN / C3 available |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 4.49 kN |
| Basic static load rating C0 | 3.75 kN |
| Fatigue load limit Pu | 0.16 kN |
| Reference speed (thermal) | 26000 rpm |
| Limiting speed (mechanical) | 16000 rpm |
| Operating temperature | -40 to +150 °C |
| Mass | 32 g |
| Manufacturer designation | SKF 61808 |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-24 |
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 & 61800-series range
| Bore d | 1.575 in |
|---|---|
| Outer diameter D | 2.047 in |
| Width B | 0.276 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 6 mm |
| Smallest bore in 61800-series | 10 mm |
| Largest outer diameter in 61800-series | 420 mm |
| Width range across 61800-series | 5–38 mm |
| Bore position in 61800-series (smallest first) | 9 of 39 |
| Bore above smallest 61800-series size | 30 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 61808-ZZ | GENERIC-ISO | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 40×52×7 mm envelope per ISO 15; seal variant differs (OPEN vs ZZ) — 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 61808 model number is decoded
In the 61800-series (ISO 15 diameter series 8) the last two digits encode the bore: 61808 carries bore code 08 = 40 mm. Outside diameter 52 mm and width 7 mm come from the ISO 15 boundary-dimensions general plan. With no seal suffix the bearing is open: no shields or seals are fitted and lubrication is supplied by the application. 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
- textile machinery
- packaging machinery
- space-constrained gearboxes
- clutch and transmission assemblies
Known failure patterns
- contamination wear from dust and dirt ingress through the open arrangement
- lubricant starvation when no regreasing interval is maintained
- cage damage from operation beyond the limiting speed
- electrical pitting in VFD-driven motors without grounding protection
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 61808; check shaft finish and runout (target Ra ≤ 1.6 µm) before pressing it home.
- The 618xx thin section at 40 mm bore has only a 6.0 mm radial section height: it saves space but is highly sensitive to misalignment, shaft deflection and shock loads — verify shaft stiffness before choosing it over a 6208.
- The open 61808 has no lubricant retention: grease escapes and contaminants migrate straight into the 40×52×7 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
- Open bearings tolerate the highest speeds in the 61800-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 61808 units.
- Shaft and housing fillets must clear the bearing chamfer so the 7 mm-wide ring seats square; provide an undercut or withdrawal groove instead of relying on an oversized radius.
- The open 61808 needs external sealing and application-supplied lubrication; in the SKF catalogue the protected variants are separate order numbers 61808-2Z (shields) and 61808-2RSH (contact seals), not suffix-free 61808.
- The 4.49/3.75 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 61808 bearing?
A 61808 deep-groove ball bearing has a 40 mm bore, 52 mm outer diameter and 7 mm width (1.575 × 2.047 × 0.276 in), per ISO 15 boundary dimensions. It is an open bearing with no seals or shields.
How does the 61808 bore code work?
The last two digits of 61808 are bore code 08, giving 08 × 5 = 40 mm bore. The 52 mm outside diameter and 7 mm width follow the ISO 15 diameter series, not the bore code alone.
What does no suffix on 61808 mean?
A bare 61808 designation means open: no shields or seals, normal CN radial clearance and P0 normal tolerance unless further suffixes are ordered. The application must supply and retain the lubrication.
How does the 61800 compare with other series at the same 40 mm bore?
618 is an extra-thin section: 52×7 mm, only 6.0 mm radial section at 40 mm bore, far smaller than a 6208, for space-limited layouts at the cost of load rating and misalignment tolerance.
What is the SKF designation and catalogue data for 61808?
In the SKF Rolling Bearings catalogue this size is listed as 61808 — the open (unsealed) execution, 40×52×7 mm per ISO 15. Quoted values: C 4.49 kN, C0 3.75 kN, Pu 0.16 kN, limiting speed 16000 r/min, mass 32 g. Brand suffixes (2Z, 2RSH, 2RSL) differ from the industry-neutral spelling 61808.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-24. Read our editorial & correction policy.