61903 bearing: complete specifications & equivalents
The 61903 is a ISO 15 radial bearing sized 17 x 30 x 7 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 17 mm |
| Outer diameter D | 30 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 | 4.62 kN |
| Basic static load rating C0 | 2.55 kN |
| Fatigue load limit Pu | 0.108 kN |
| Reference speed (thermal) | 50000 rpm |
| Limiting speed (mechanical) | 32000 rpm |
| Operating temperature | -40 to +150 °C |
| Mass | 16 g |
| Manufacturer designation | SKF 61903 |
| 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 | 0.669 in |
|---|---|
| Outer diameter D | 1.181 in |
| Width B | 0.276 in |
| ISO bore code | 03 |
| Radial section height (D−d)/2 | 6.5 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) | 11 of 63 |
| Bore above smallest 61900-series size | 14 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 61903-2RS-FAG | FAG | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 17×30×7 mm envelope per ISO 15; seal variant differs (OPEN vs 2RS) — confirm sealing suits the duty. |
| 61903-FAG | FAG | 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. |
| 61903-ZZ-FAG | FAG | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 17×30×7 mm envelope per ISO 15; seal variant differs (OPEN vs ZZ) — confirm sealing suits the duty. |
| 61903 | 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. |
| 61903-2RS-NSK | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 17×30×7 mm envelope per ISO 15; seal variant differs (OPEN vs 2RS) — confirm sealing suits the duty. |
| 61903-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. |
| 61903-RSR-NSK | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 17×30×7 mm envelope per ISO 15; seal variant differs (OPEN vs RSR) — confirm sealing suits the duty. |
| 61903-ZZ-NSK | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 17×30×7 mm envelope per ISO 15; seal variant differs (OPEN vs ZZ) — confirm sealing suits the duty. |
| 61903-2RS-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 17×30×7 mm envelope per ISO 15; seal variant (OPEN vs 2RS) and load ratings differ — confirm sealing and rating before substituting. |
| 61903-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 17×30×7 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 61903-RSR-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 17×30×7 mm envelope per ISO 15; seal variant (OPEN vs RSR) and load ratings differ — confirm sealing and rating before substituting. |
| 61903-ZZ-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 17×30×7 mm envelope per ISO 15; seal variant (OPEN vs ZZ) and load ratings differ — confirm sealing and rating before substituting. |
| W61903-2RS | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF stainless execution W 61903-2RS1 shares the 17×30×7 mm envelope but rates differently (4.62/2.55 kN vs 3.97/2.55 kN) — not a load-rating equivalent. |
| W61903-ZZ | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF stainless execution W 61903-2Z shares the 17×30×7 mm envelope but rates differently (4.62/2.55 kN vs 3.97/2.55 kN) — not a load-rating equivalent. |
| W61903 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF stainless execution W 61903 shares the 17×30×7 mm envelope but rates differently (4.62/2.55 kN vs 3.97/2.55 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 61903 model number is decoded
In the 61900-series (diameter series 9 of ISO 15) the last two digits encode the bore: 61903 carries bore code 03 = 17 mm. Codes 00–03 follow the 10/12/15/17 mm exception table rather than code × 5. Outside diameter 30 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 17 mm shaft, typical catalogue practice is a j5 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. 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
- lay shafts and idler shafts
- textile machinery
- packaging machinery
- space-constrained gearboxes
Known failure patterns
- contamination wear from dust and dirt ingress through the open arrangement
- lubricant starvation when no regreasing interval is maintained
- fretting corrosion on a loose shaft seat
- cage damage from operation beyond the limiting speed
Selection pitfalls — read before you substitute
- Codes 00–03 are the exception series: 61903 takes its 17 mm bore from the 10/12/15/17 mm table, so two designations only a few millimetres apart can read alike on paper — order by measured shaft size, not by code arithmetic.
- The 619xx thin section at 17 mm bore (6.5 mm section height) cannot shrug off the misalignment a standard section tolerates; keep the housing bores round and aligned, or edge contact will spall the raceways early.
- Storage matters for open bearings: 61903 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 61900-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 61903 units.
- 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.
- Deep-groove ball bearings tolerate only minutes of misalignment; if the 30 mm housing cannot be aligned, switch to a self-aligning type rather than shimming 61903.
- The open 61903 needs external sealing and application-supplied lubrication; in the SKF catalogue the protected variants are separate order numbers 61903-2Z (shields) and 61903-2RSH (contact seals), not suffix-free 61903.
- The 4.62/2.55 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 61903 bearing?
A 61903 deep-groove ball bearing has a 17 mm bore, 30 mm outer diameter and 7 mm width (0.669 × 1.181 × 0.276 in), per ISO 15 boundary dimensions. It is an open bearing with no seals or shields.
Are 61903 bearings from different brands interchangeable?
For boundary dimensions, yes: every brand's 61903 uses the same ISO 15 envelope (17×30×7 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 61903 have?
Unless a clearance suffix says otherwise, 61903 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 61903 and verify the residual clearance after mounting.
How should 61903 be mounted?
Apply the mounting force to the ring being fitted: on a 17 mm shaft seat the press load must pass through the inner-ring face only. A fitting sleeve and an arbor press are normally sufficient at this size. Never strike the outer ring, the cage or the seals.
What is the SKF designation and catalogue data for 61903?
In the SKF Rolling Bearings catalogue this size is listed as 61903 — the open (unsealed) execution, 17×30×7 mm per ISO 15. Quoted values: C 4.62 kN, C0 2.55 kN, Pu 0.108 kN, limiting speed 32000 r/min, mass 16 g. Brand suffixes (2Z, 2RSH, 2RSL) differ from the industry-neutral spelling 61903.
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.