61988-MA bearing: complete specifications & equivalents
The 61988-MA is a ISO 15 radial bearing sized 440 x 600 x 74 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 440 mm |
| Outer diameter D | 600 mm |
| Width B | 74 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 410 kN |
| Basic static load rating C0 | 720 kN |
| Fatigue load limit Pu | 13.2 kN |
| Reference speed (thermal) | 2000 rpm |
| Limiting speed (mechanical) | 1600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 60500 g |
| Manufacturer designation | 61988 MA |
| 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 | 17.323 in |
|---|---|
| Outer diameter D | 23.622 in |
| Width B | 2.913 in |
| ISO bore code | 88 |
| Radial section height (D−d)/2 | 80 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) | 51 of 63 |
| Bore above smallest 61900-series size | 437 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 61988 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | NTN bearing NTN 6988 on the same 440×600×74 mm envelope, but catalogue C/C0 differ (410/720 kN vs 405/615 kN) — envelope interchange only after a load check. |
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 61988-MA model number is decoded
In the 61900-series, the last two digits encode the bore: 61988 carries code 88 = 440 mm (code × 5). The envelope is 440×600×74 mm (17.323×23.622×2.913 in) with a 80.0 mm radial section height, C 410 kN, C0 720 kN and Pu 13.2 kN. The open 61988 MA carries no shields or seals and relies on application lubrication and external sealing. The MA suffix identifies the machined brass cage execution, a separate order number from the pressed-steel version. Limiting speed 1600 r/min, catalogue mass 60500 g. A thin section saves space but leaves little margin for misalignment or shaft deflection.
Typical equipment & failure modes
Common applications
- lay shafts and idler shafts
- textile and packaging machinery
- slew and indexing drives
- large industrial gearboxes
Known failure patterns
- contamination wear when the open arrangement is used without external seals
- lubricant starvation where no regreasing interval is maintained
- false brinelling from vibration while the shaft stands idle
- fretting corrosion on a creeping shaft or housing seat
Selection pitfalls — read before you substitute
- Deep-groove geometry tolerates only minutes of misalignment; if the 600 mm housing bore cannot be aligned, move to a self-aligning bearing rather than shimming 61988-MA.
- Mount by heating the inner ring (max 120 °C) — driving 61988-MA home through the outer ring or balls brinells the raceways.
- The MA suffix on 61988-MA denotes a machined brass cage: it is the choice for high speeds, marginal lubrication and shock/vibration duty, and it is temperature-tolerant where polymer cages are not — the 60500 g quoted mass includes the heavier cage.
- Open 61988-MA needs external sealing at the arrangement level; in dusty housings its life depends entirely on those external seals and the regreasing schedule.
- Plan a relubrication interval for 61988-MA; run-to-failure on open deep-groove bearings is the dominant early-failure cause.
- At 440 mm bore, C3 clearance is the safe choice when interference fits plus temperature rise consume the CN clearance; a hot tight bearing with no residual clearance fails fast.
Frequently asked questions
What are the dimensions of 61988-MA?
The SKF 61988 MA measures 440 mm bore × 600 mm OD × 74 mm width (17.323 × 23.622 × 2.913 in), mass about 60500 g. It is open, with no shields or seals.
How does the bore code in 61988 work?
The final two digits of 61988 are bore code 88, multiplied by 5 to give 440 mm.
How heavy is 61988-MA?
Catalogue mass is 60500 g for 61988 MA; seal and cage executions of the same envelope differ by a few grams.
What load can 61988-MA take?
Catalogue values for 61988 MA: dynamic C 410 kN, static C0 720 kN, fatigue limit Pu 13.2 kN. Use C in life calculation and C0 for static checks at 440 mm bore.
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.