61938 bearing: complete specifications & equivalents
The 61938 is a ISO 15 radial bearing sized 190 x 260 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 | 190 mm |
| Outer diameter D | 260 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 | 117 kN |
| Basic static load rating C0 | 134 kN |
| Fatigue load limit Pu | 3.8 kN |
| Reference speed (thermal) | 5000 rpm |
| Limiting speed (mechanical) | 3200 rpm |
| Operating temperature | -40 to +150 °C |
| Mass | 4500 g |
| Manufacturer designation | SKF 61938 |
| 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 | 7.48 in |
|---|---|
| Outer diameter D | 10.236 in |
| Width B | 1.299 in |
| ISO bore code | 38 |
| Radial section height (D−d)/2 | 35 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) | 38 of 63 |
| Bore above smallest 61900-series size | 187 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 61938-FAG | FAG | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 190×260×33 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 61938 | 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. |
| 61938-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. |
| 61938-NTN | NTN | 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. |
| 61938-MA | SKF | full Dimensions and internal design equivalent — standard interchange. | SKF 61938 MA (machined brass cage, open arrangement) is the same-size execution on the 190×260×33 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 61938 model number is decoded
In the 61900-series (diameter series 9 of ISO 15) the last two digits encode the bore: 61938 carries bore code 38 = 190 mm. Outside diameter 260 mm and width 33 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 190 mm shaft, typical catalogue practice is a m6 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
- robotics and automation joints
- lay shafts and idler shafts
- textile machinery
- packaging machinery
Known failure patterns
- contamination wear from dust and dirt ingress through the open arrangement
- lubricant starvation when no regreasing interval is maintained
- electrical pitting in VFD-driven motors without grounding protection
- raceway smearing under marginal lubrication at start-up
Selection pitfalls — read before you substitute
- Large bores like the 190 mm of 61938 demand clean, burr-free seats; one raised burr under a ring this size cocks the bearing and concentrates load at the raceway edge, cutting life drastically.
- The 619xx thin section at 190 mm bore (35.0 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: 61938 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 61938 units.
- Never mix components between two 61938 units: rings, cage and balls are factory-matched and are not field-interchangeable, even between identical designations.
- Shaft and housing fillets must clear the bearing chamfer so the 33 mm-wide ring seats square; provide an undercut or withdrawal groove instead of relying on an oversized radius.
- The open 61938 needs external sealing and application-supplied lubrication; in the SKF catalogue the protected variants are separate order numbers 61938-2Z (shields) and 61938-2RSH (contact seals), not suffix-free 61938.
- The 117/134 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 61938 bearing?
A 61938 deep-groove ball bearing has a 190 mm bore, 260 mm outer diameter and 33 mm width (7.48 × 10.236 × 1.299 in), per ISO 15 boundary dimensions. It is an open bearing with no seals or shields.
What lubrication does 61938 need?
The open 61938 is lubricated by the application; a NLGI 2 lithium-soap grease filled to roughly 25–35% of the free volume is the common choice, with a defined relubrication interval.
How does the 61938 bore code work?
The last two digits of 61938 are bore code 38, giving 38 × 5 = 190 mm bore. The 260 mm outside diameter and 33 mm width follow the ISO 15 diameter series, not the bore code alone.
What does no suffix on 61938 mean?
A bare 61938 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.
What is the SKF designation and catalogue data for 61938?
In the SKF Rolling Bearings catalogue this size is listed as 61938 — the open (unsealed) execution, 190×260×33 mm per ISO 15. Quoted values: C 117 kN, C0 134 kN, Pu 3.8 kN, limiting speed 3200 r/min, mass 4500 g. Brand suffixes (2Z, 2RSH, 2RSL) differ from the industry-neutral spelling 61938.
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.