23956-CCK-W33 bearing: complete specifications & equivalents
The 23956-CCK-W33 is a ISO 15 radial bearing sized 280 x 380 x 75 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 280 mm |
| Outer diameter D | 380 mm |
| Width B | 75 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 1016 kN |
| Basic static load rating C0 | 1760 kN |
| Fatigue load limit Pu | 143 kN |
| Reference speed (thermal) | 1600 rpm |
| Limiting speed (mechanical) | 1700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 40000 g |
| Manufacturer designation | SKF 23956 CCK/W33 |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 9.2 adapter-sleeve executions |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 9.2 adapter-sleeve executions) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 9.2 adapter-sleeve executions); 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 & 23900-series range
| Bore d | 11.024 in |
|---|---|
| Outer diameter D | 14.961 in |
| Width B | 2.953 in |
| ISO bore code | 56 |
| Radial section height (D−d)/2 | 50 mm |
| Smallest bore in 23900-series | 180 mm |
| Largest outer diameter in 23900-series | 650 mm |
| Width range across 23900-series | 52–128 mm |
| Bore position in 23900-series (smallest first) | 7 of 17 |
| Bore above smallest 23900-series size | 100 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 23956 | SKF | full Dimensions and internal design equivalent — standard interchange. | Tapered-bore (1:12) sleeve-mounted execution of 23956; identical ISO 15 envelope, fits OH3956 adapter sleeve on a 260 mm shaft. |
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 23956-CCK-W33 model number is decoded
The SKF 23956 CCK/W33 is a 280×380×75 mm spherical roller bearing with a 1:12 tapered bore — SKF catalogue execution for sleeve mounting on a 280 mm plain shaft, retaining the double-row self-aligning barrel-roller design. The code breaks down as type digit 2 (double-row spherical roller), dimension series 39 (dimension series 39 (compact OD, narrow)), and bore code 56 = 280 mm; dimensions 280×380×75 mm therefore match the ISO 15 envelope. Note that K means 1:12 taper; the rarer K30 suffix means 1:30. Adapter sleeves (H) and withdrawal sleeves (AH) are ordered separately by shaft diameter, and the KM locknut plus MB lock washer used for drive-up are also separate components. The 143 kN Pu figure feeds the adjusted-life equation at contaminated or partial-film conditions, and the 1.73 C0/C balance shows this execution is tuned to heavy radial-plus-axial duty with misalignment tolerance. At 280 mm bore, dismount after service is by KM locknut reversal or a hydraulic nut on larger sizes; oil-injection grooves on the bigger sleeves let pressurised oil float the 23956-cck-w33 off the taper without scoring either surface.
Typical equipment & failure modes
Common applications
- steel-plant continuous-caster segments
- large induced-draft fan rotors
- shafting produced to commercial tolerances, where the adapter sleeve supplies the precision seat
- split-housing plummer block arrangements with bearings swapped in situ
Known failure patterns
- raceway fatigue spalling of the sphered outer raceway after extended service above the catalogue L10 rating
- inner-ring raceway spalling from edge loading when misalignment exceeds the self-aligning recovery range
- fretting corrosion and sleeve-seat scoring when drive-up is insufficient and the tapered inner ring creeps on the adapter sleeve
- surface distress and smearing when the relubrication interval is exceeded — the W33 groove is only effective if grease actually reaches the roller rows
- electrical pitting on VFD-driven shafts without grounding protection
Selection pitfalls — read before you substitute
- At 280 mm bore the ring mass makes cocking during mounting a real risk; guide the bearing square, confirm seat contact around the full circumference, and re-check the self-aligning swing after the housing cap is torqued down.
- The 23900-series series at 280 mm bore (380×75 mm) is the slim-OD envelope: it buys radial space but gives up capacity against a 222-series bearing of the same bore — confirm the L10 margin before downsizing into it.
- The adapter sleeve is selected by actual shaft diameter, not by the 280 mm nominal bearing bore: H-sleeve part numbers span a small diameter range, so two different shaft diameters can use the same 23956-cck-w33 with different sleeves.
- The adapter sleeve is selected by actual shaft diameter, not by the 280 mm nominal bearing bore: H-sleeve part numbers span a small diameter range, so two different shaft diameters can use the same 23956-cck-w33 with different sleeves.
- Shaft and housing fillets must clear the bearing chamfer so the 75 mm-wide rings seat square; use an undercut or withdrawal groove rather than an oversized radius that locks on the ring face.
- The 1016/1760 kN ratings are SKF catalogue values for this tapered-bore execution (SKF 23956 CCK/W33); sleeve, KM nut and MB washer are separate order numbers, and the catalogue version (SKF catalogue PUB BU/P1 17000) should travel with the mounting specification.
Frequently asked questions
What are the dimensions and catalogue data of 23956-cck-w33?
The SKF 23956 CCK/W33 is a double-row spherical roller bearing with a 1:12 tapered bore, 280 mm nominal bore, 380 mm outer diameter and 75 mm width (11.024 × 14.961 × 2.953 in) per ISO 15. From SKF catalogue PUB BU/P1 17000: C 1016 kN, C0 1760 kN, Pu 143 kN, reference speed 1,600 r/min, limiting speed 1,700 r/min, mass about 40000 g. It is mounted on an adapter (H) or withdrawal (AH) sleeve, not directly on the shaft.
What does the K suffix mean on 23956-cck-w33?
K marks a 1:12 tapered bore for sleeve mounting — SKF writes EK or CCK(/W33), FAG writes -K- inside the suffix chain for sleeve mounting. The bearing seats on an H-series adapter sleeve with a KM locknut and MB lock washer (plain shaft, h9 tolerance), or on an AH withdrawal sleeve against a shaft shoulder. The rarer K30 suffix would instead mean a 1:30 taper; dimension series 40/41 spherical rollers commonly use it.
Which adapter sleeve fits the 23956-cck-w33?
The sleeve is selected by the actual shaft diameter in millimetres, not only by the 280 mm nominal bore: SKF H-sleeve numbers each cover a small shaft-diameter range and are width-series specific (H39/H30/H31/H32 matching dimension series 39/40/31/32), and each kit bundles the sleeve, KM locknut and MB lock washer. For shoulder locations use an AH withdrawal sleeve instead. Confirm the sleeve number against the SKF catalogue PUB BU/P1 17000 mounting tables for your shaft size.
How is the 23956-cck-w33 driven up and checked?
Mounting is controlled by radial-clearance reduction or axial drive-up distance from the SKF catalogue tables for the 1:12 taper, never by locknut torque. Measure clearance with feeler gauges before and after tightening the KM nut, stop at the tabulated decrease, and lock the MB washer tab. Over-drive removes too much clearance (inner-ring cracking risk); under-drive lets the sleeve creep and fret.
What is the difference between 23956-cck-w33 and 23956-cc-w33?
They share the ISO 15 envelope and the same 1016/1760 kN ratings, but 23956-cck-w33 has the 1:12 tapered bore for sleeve mounting on a plain shaft, while 23956-cc-w33 has a cylindrical bore for direct mounting on a machined interference journal (typically m6 with H7 housing). They are separate order numbers, not interchangeable in the same shaft arrangement.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 9.2 adapter-sleeve executions on 2026-09-26. Read our editorial & correction policy.