W61903-ZZ bearing: complete specifications & equivalents
The W61903-ZZ is a ISO 15 radial bearing sized 17 x 30 x 7 mm (bore x OD x width) with ZZ sealing. 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 | SS440C |
| Seal / shield | ZZ |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 3.97 kN |
| Basic static load rating C0 | 2.55 kN |
| Fatigue load limit Pu | 0.108 kN |
| Reference speed (thermal) | 50000 rpm |
| Limiting speed (mechanical) | 24000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 17 g |
| Manufacturer designation | W 61903-2Z |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-27 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-27
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 |
|---|---|---|---|
| W61903-2RS | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 17×30×7 mm envelope and equivalent catalogue ratings; W 61903-2RS1 is the two contact elastomer seals execution of this size — boundary dimensions interchangeable, only the seal/shield/cage execution differs. |
| W61903 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 17×30×7 mm envelope and equivalent catalogue ratings; W 61903 is the open arrangement execution of this size — boundary dimensions interchangeable, only the seal/shield/cage execution differs. |
| 61903 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF SKF 61903 shares the 17×30×7 mm envelope but carries different catalogue ratings (3.97/2.55 kN vs 4.62/2.55 kN) — the stainless execution is not a load-rating equivalent. |
| 61903-2RS | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF SKF 61903-2RS1 shares the 17×30×7 mm envelope but carries different catalogue ratings (3.97/2.55 kN vs 4.62/2.55 kN) — the stainless execution is not a load-rating equivalent. |
| 61903-RSR | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF SKF 61903-2RZ shares the 17×30×7 mm envelope but carries different catalogue ratings (3.97/2.55 kN vs 4.62/2.55 kN) — the stainless execution is not a load-rating equivalent. |
| 61903-ZZ | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF SKF 61903-2Z shares the 17×30×7 mm envelope but carries different catalogue ratings (3.97/2.55 kN vs 4.62/2.55 kN) — the stainless execution is 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 W61903-ZZ model number is decoded
The W prefix denotes SKF stainless steel deep-groove bearings (X108CrMo17 / AISI 440C class rings). In the 61900-series, bore code 03 follows the 10/12/15/17 mm exception table, so 61903 fits a 17 mm shaft. Envelope 17×30×7 mm (0.669×1.181×0.276 in), C 3.97 kN, C0 2.55 kN, Pu 0.108 kN; limiting speed 24000 r/min and mass 17 g. SKF spells the double shield W 61903-2Z (suffix 2Z); the shields are non-contact, retain grease and block coarse debris but are not liquid-tight. Stainless is chosen for corrosion and washdown duty, not for extra load — the same-envelope chrome-steel bearing rates higher.
Typical equipment & failure modes
Common applications
- appliances exposed to moisture
- food and beverage conveyors
- pharmaceutical and packaging machines
- washdown-duty equipment
Known failure patterns
- surface staining and pitting when even the stainless steel is left unlubricated in salty or acidic duty
- seal and grease failure before the rings corrode in sustained washdown service
- fine-particle abrasion when non-contact shields let dust through in a dirty environment
- grease aging inside the shielded cavity with no relubrication path
Selection pitfalls — read before you substitute
- Corrosion resistance depends on clean, undamaged surfaces: never weld near W61903-ZZ or scratch the raceways during mounting, since the damaged spot starts corrosion.
- Temperatures above roughly 300 °C temper the stainless races; even standard greases fail far earlier — keep W61903-ZZ inside the quoted grease temperature range.
- W-prefix stainless rings (X108CrMo17 / AISI 440C class) resist moisture and weak chemicals but will still rust in chloride-rich or salt-spray duty without protection — W61903-ZZ is not marine-grade stainless.
- The stainless steel is martensitic and MAGNETIC; do not reject W61903-ZZ over magnetism — only austenitic grades are non-magnetic, and those are too soft for bearing raceways.
- Catalogue ratings for W61903-ZZ (C 3.97 kN, C0 2.55 kN) are SKF figures from PUB BU/P1 17000; geometry revisions can change ratings without changing the designation, so keep the catalogue edition with the specification.
- Catalogue ratings for W61903-ZZ (C 3.97 kN, C0 2.55 kN) are SKF figures from PUB BU/P1 17000; geometry revisions can change ratings without changing the designation, so keep the catalogue edition with the specification.
Frequently asked questions
What are the dimensions of the stainless W61903-ZZ?
SKF W 61903-2Z measures 17×30×7 mm (0.669×1.181×0.276 in), about 17 g, C 3.97 kN.
What does the W in W 61903-2Z mean?
W is the SKF prefix for stainless steel deep-groove bearings (rings in X108CrMo17 / AISI 440C class); the rest of the designation follows the normal series and bore rules.
Is the stainless bearing magnetic?
Yes. Bearing stainless steels are martensitic (hardened) and magnetic; non-magnetic austenitic grades cannot be hardened enough for raceways and balls.
Where is W61903-ZZ typically used?
Food and packaging machines, pharmaceutical equipment, washdown conveyors, chemical and marine-atmosphere drives and appliances exposed to moisture.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-27. Read our editorial & correction policy.