61856 bearing: complete specifications & equivalents
The 61856 is a ISO 15 radial bearing sized 280 x 350 x 33 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 280 mm |
| Outer diameter D | 350 mm |
| Width B | 33 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 | 138 kN |
| Basic static load rating C0 | 200 kN |
| Fatigue load limit Pu | 4.75 kN |
| Reference speed (thermal) | 3400 rpm |
| Limiting speed (mechanical) | 2200 rpm |
| Operating temperature | -40 to +150 °C |
| Mass | 6250 g |
| Manufacturer designation | SKF 61856 |
| 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 | 11.024 in |
|---|---|
| Outer diameter D | 13.78 in |
| Width B | 1.299 in |
| ISO bore code | 56 |
| Radial section height (D−d)/2 | 35 mm |
| Smallest bore in 61800-series | 1 mm |
| Largest outer diameter in 61800-series | 1820 mm |
| Width range across 61800-series | 1–140 mm |
| Bore position in 61800-series (smallest first) | 46 of 74 |
| Bore above smallest 61800-series size | 279 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 61856 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the supplier. |
| 61856-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 280×350×33 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 61856-MA | SKF | full Dimensions and internal design equivalent — standard interchange. | SKF 61856 MA (machined brass cage, open arrangement) is the same-size execution on the 280×350×33 mm envelope with ratings within 10 % — boundary dimensions interchangeable. |
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 61856 model number is decoded
61856 is supplied open, without shields or seals, so the arrangement around it must supply and retain the lubricant. Within the extra-thin 618xx section (diameter series 8 of ISO 15), multiplying bore code 56 by five gives the 280 mm bore; the 350 mm outside diameter and 33 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 280 mm shaft under normal load, catalogue practice seats it on a m6 shaft fit with an H7 housing bore — confirm against the actual load direction and magnitude before committing. In the SKF catalogue this open execution carries the bare designation; protected variants are ordered separately as -2Z and -2RSH.
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
- contamination wear from dust and dirt ingress through the open arrangement
- lubricant starvation when no regreasing interval is maintained
- raceway smearing under marginal lubrication at start-up
- edge loading from shaft deflection or housing misalignment
Selection pitfalls — read before you substitute
- Mount this 280 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.
- Only 35.0 mm of radial section separates bore and OD on the 618xx series at 280 mm: ring flex from clamping or an oval housing bore transfers straight into raceway stress, so seat roundness matters more here than on a 6256.
- Storage matters for open bearings: 61856 leaves the factory with rust preventive only, so clean it and apply the service grease at assembly even if the rings look oily from the wrapper.
- 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 61856 units.
- Grease compatibility is not guaranteed between fills: mixing lithium and polyurea thickeners in a 61800-series position can soften the mixture and leak — clean out the old fill before switching grease types.
- Axial location must clamp the ring face, not the seal area: a shoulder or circlip bearing on the seal side of the 33 mm-wide ring of 61856 drags the lip and overheats it.
- The open 61856 needs external sealing and application-supplied lubrication; in the SKF catalogue the protected variants are separate order numbers 61856-2Z (shields) and 61856-2RSH (contact seals), not suffix-free 61856.
- The 138/200 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 61856 bearing?
A 61856 deep-groove ball bearing has a 280 mm bore, 350 mm outer diameter and 33 mm width (11.024 × 13.78 × 1.299 in), per ISO 15 boundary dimensions. It is an open bearing with no seals or shields.
How does the 61800 compare with other series at the same 280 mm bore?
618 is an extra-thin section: 350×33 mm, only 35.0 mm radial section at 280 mm bore, far smaller than a 6256, for space-limited layouts at the cost of load rating and misalignment tolerance.
Are 61856 bearings from different brands interchangeable?
For boundary dimensions, yes: every brand's 61856 uses the same ISO 15 envelope (280×350×33 mm). Load ratings, limiting speeds, clearance, precision class and sealing design can differ, so verify those in the supplier catalogue when substituting.
What internal clearance does 61856 have?
Unless a clearance suffix says otherwise, 61856 is manufactured to normal (CN) radial internal clearance. Tight fits and hot shafts consume clearance in service — for those conditions order the C3 execution of 61856 and verify the residual clearance after mounting.
What is the SKF designation and catalogue data for 61856?
In the SKF Rolling Bearings catalogue this size is listed as 61856 — the open (unsealed) execution, 280×350×33 mm per ISO 15. Quoted values: C 138 kN, C0 200 kN, Pu 4.75 kN, limiting speed 2200 r/min, mass 6250 g. Brand suffixes (2Z, 2RSH, 2RSL) differ from the industry-neutral spelling 61856.
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.