7228-BM bearing: complete specifications & equivalents
The 7228-BM is a ISO 15 radial bearing sized 140 x 250 x 42 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 140 mm |
| Outer diameter D | 250 mm |
| Width B | 42 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 199 kN |
| Basic static load rating C0 | 212 kN |
| Fatigue load limit Pu | 6.4 kN |
| Reference speed (thermal) | 3000 rpm |
| Limiting speed (mechanical) | 3600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 8850 g |
| Manufacturer designation | 7228 BM |
| 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 & 7200-series range
| Bore d | 5.512 in |
|---|---|
| Outer diameter D | 9.843 in |
| Width B | 1.654 in |
| ISO bore code | 28 |
| Radial section height (D−d)/2 | 55 mm |
| Smallest bore in 7200-series | 10 mm |
| Largest outer diameter in 7200-series | 540 mm |
| Width range across 7200-series | 9–85 mm |
| Bore position in 7200-series (smallest first) | 26 of 36 |
| Bore above smallest 7200-series size | 130 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7228-BCBM | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 140×250×42 mm envelope with catalogue ratings within 10 %; 7228 BCBM is the brass cage, open arrangement execution of this size — boundary dimensions interchangeable, execution differs. |
| QJ-228-N2MA | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 140×250×42 mm envelope, but catalogue C/C0 differ between executions (199/212 kN vs 345/475 kN) — boundary dimensions match, 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 7228-BM model number is decoded
7228 BM is SKF's 140 mm-bore single-row angular-contact ball bearing in the 7200 series, nominal 40° (B) contact angle, 140×250×42 mm to the ISO dimension plan. 40° contact angle (suffix B): the steep standard single-row angle, giving the highest axial capacity at the cost of speed, with a recommended load ratio Fa/Fr ≥ 1. machined brass cage, ball-centred (suffix M), the choice for high speed, marginal lubrication and shock duty. The BM is the non-optimized basic 40° execution with a machined brass cage; it predates the E geometry and is stocked for positions built around its specific figures.. Envelope 140×250×42 mm (5.512×9.843×1.654 in), 55.0 mm radial section height, C 199 kN, C0 212 kN, Pu 6.4 kN.reference speed 3,000 r/min (thermal) and limiting speed 3,600 r/min (mechanical), catalogue mass 8850 g. Speed planning distinguishes the two published ceilings mechanically: the cage and balls tolerate 3,600 r/min while thermal balance under catalogue load sets the 3,000 r/min reference; at dm ≈ 195.0 mm the corresponding dn is approximately 702k mm·r/min. At the printed limiting speed of 3,600 r/min the mean pitch diameter dm ≈ 195.0 mm implies a dn value around 702k mm·r/min; the 3,000 r/min reference speed is the thermal-planning figure under catalogue load. Speed-ratio note for this exact unit: the reference speed is 3,000 r/min against a 3,600 r/min limiting speed, i.e. a reference-to-limit ratio of 0.83. Non-optimized basic execution: BM is the earlier 40-degree design without the E internal upgrade, fitted with a machined brass ball-centred cage as a single (non-universal) bearing; quote it for housings and spacers designed around the legacy geometry.
Typical equipment & failure modes
Common applications
- heavy dredge and excavator swing drives
- vertical mill separator drives
- heavy industrial gearboxes
Known failure patterns
- raceway spalling from axial overload beyond the single-direction thrust rating
- ball skidding when the induced axial load unloads the inactive bearing of a pair
- ball skidding when Fa/Fr stays below the 1,0 (40°) or 0,55 (25°) ratio and the contact ellipse is unloaded
- legacy-geometry cage smearing when the non-E basic bearing is run at speeds developed for the optimized E design
- mounting score marks when the bearing is cocked over a burr or keyway
- mounting score marks when the bearing is cocked over a burr or keyway
Selection pitfalls — read before you substitute
- Fillet radii must clear the chamfer so the 42 mm-wide ring seats square; an oversized shaft radius creates point contact on the ring face.
- One 7228-BM locates the shaft in one axial direction only; reversing-thrust positions need a DB or DF pair — or a double-row bearing — with preload set from the load diagram, never from assembly feel.
- Keep the load ratio in the SKF design range: Fa/Fr ≥ 1 for this angle; below it the balls unload the contact ellipse and skid, which is why the catalogue insists on a minimum axial load (Fam ≈ A·(n·dm/1000)²) at high speed.
- Reference and limiting speeds are different ceilings: design to both, and remember preload and oil/air cooling move the real thermal limit far from the catalogue reference value.
- The steep 40° angle of 7228-BM favours thrust-heavy combined loads; for a predominantly radial high-speed position the 25° ACCBM execution of the same size is the alternative order number.
- Catalogue ratings are SKF PUB BU/P1 17000 figures for 7228 BM as the single non e brass execution; the other order numbers of the 7228 size are different products and may carry different ratings — always quote the full designation when purchasing.
Frequently asked questions
What are the dimensions and catalogue data of 7228-BM?
7228 BM measures 140 mm bore × 250 mm OD × 42 mm width (5.512 × 9.843 × 1.654 in), mass about 8850 g. SKF 17000 ratings: C 199 kN, C0 212 kN, Pu 6.4 kN, reference speed 3,000 r/min (thermal) and limiting speed 3,600 r/min (mechanical).
What does the BM suffix mean?
40° contact angle (suffix B): the steep standard single-row angle, giving the highest axial capacity at the cost of speed, with a recommended load ratio Fa/Fr ≥ 1. machined brass cage, ball-centred (suffix M), the choice for high speed, marginal lubrication and shock duty. The BM is the non-optimized basic 40° execution with a machined brass cage; it predates the E geometry and is stocked for positions built around its specific figures..
Which fits should I use for 7228-BM?
With a rotating inner ring use roughly m6 on the 140 mm shaft and H7 in the housing; give the stationary ring a slide fit for axial setting, and reverse the logic when the outer ring rotates.
Which grease and fill for 7228-BM?
A premium mineral-oil grease with polyurea or lithium complex thickener and NLGI 2 consistency suits normal operating temperature; fill roughly 25–35 % of the free volume. Oil-air or oil-jet lubrication is the choice near the 3,600 r/min ceiling.
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.