61944 bearing: complete specifications & equivalents
The 61944 is a ISO 15 radial bearing sized 220 x 300 x 38 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 220 mm |
| Outer diameter D | 300 mm |
| Width B | 38 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 | 151 kN |
| Basic static load rating C0 | 180 kN |
| Fatigue load limit Pu | 4.75 kN |
| Reference speed (thermal) | 4300 rpm |
| Limiting speed (mechanical) | 2600 rpm |
| Operating temperature | -40 to +150 °C |
| Mass | 6800 g |
| Manufacturer designation | SKF 61944 |
| 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 & 61900-series range
| Bore d | 8.661 in |
|---|---|
| Outer diameter D | 11.811 in |
| Width B | 1.496 in |
| ISO bore code | 44 |
| Radial section height (D−d)/2 | 40 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) | 40 of 63 |
| Bore above smallest 61900-series size | 217 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 61944-FAG | FAG | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 220×300×38 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 61944 | 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. |
| 61944-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. |
| 61944-ZZ | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 220×300×38 mm envelope per ISO 15; seal variant differs (OPEN vs ZZ) — confirm sealing suits the duty. |
| 61944-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 220×300×38 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 61944-MA | SKF | full Dimensions and internal design equivalent — standard interchange. | SKF 61944 MA (machined brass cage, open arrangement) is the same-size execution on the 220×300×38 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 61944 model number is decoded
In the 61900-series (diameter series 9 of ISO 15) the last two digits encode the bore: 61944 carries bore code 44 = 220 mm. Outside diameter 300 mm and width 38 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 220 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
- 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
- cage damage from operation beyond the limiting speed
- electrical pitting in VFD-driven motors without grounding protection
Selection pitfalls — read before you substitute
- At 220 mm bore the ring mass is significant: heat 61944 on an induction heater (max 120 °C), never over an open flame, and plan puller access or a withdrawal sleeve now for the day it has to come off again.
- The 619xx thin section at 220 mm bore (40.0 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.
- The open 61944 has no lubricant retention: grease escapes and contaminants migrate straight into the 220×300×38 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
- 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 61944 units.
- Axial location must clamp the ring face, not the seal area: a shoulder or circlip bearing on the seal side of the 38 mm-wide ring of 61944 drags the lip and overheats it.
- Never mix components between two 61944 units: rings, cage and balls are factory-matched and are not field-interchangeable, even between identical designations.
- The open 61944 needs external sealing and application-supplied lubrication; in the SKF catalogue the protected variants are separate order numbers 61944-2Z (shields) and 61944-2RSH (contact seals), not suffix-free 61944.
- The 151/180 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 61944 bearing?
A 61944 deep-groove ball bearing has a 220 mm bore, 300 mm outer diameter and 38 mm width (8.661 × 11.811 × 1.496 in), per ISO 15 boundary dimensions. It is an open bearing with no seals or shields.
What lubrication does 61944 need?
The open 61944 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 61944 bore code work?
The last two digits of 61944 are bore code 44, giving 44 × 5 = 220 mm bore. The 300 mm outside diameter and 38 mm width follow the ISO 15 diameter series, not the bore code alone.
What does no suffix on 61944 mean?
A bare 61944 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 61944?
In the SKF Rolling Bearings catalogue this size is listed as 61944 — the open (unsealed) execution, 220×300×38 mm per ISO 15. Quoted values: C 151 kN, C0 180 kN, Pu 4.75 kN, limiting speed 2600 r/min, mass 6800 g. Brand suffixes (2Z, 2RSH, 2RSL) differ from the industry-neutral spelling 61944.
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.