81228-M bearing: complete specifications & equivalents
The 81228-M is a ISO 104 radial bearing sized 140 x 200 x 46 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 | 200 mm |
| Width B | 46 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 360 kN |
| Basic static load rating C0 | 1400 kN |
| Fatigue load limit Pu | 129 kN |
| Reference speed (thermal) | 700 rpm |
| Limiting speed (mechanical) | 1400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 5050 g |
| Manufacturer designation | 81228 M |
| Standard | ISO 104 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 11.1 cylindrical roller thrust bearings |
| Last verified | 2026-09-27 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 11.1 cylindrical roller thrust bearings) · extracted 2026-09-27
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 11.1 cylindrical roller thrust bearings); 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 & 81200-series range
| Bore d | 5.512 in |
|---|---|
| Outer diameter D | 7.874 in |
| Width B | 1.811 in |
| ISO bore code | 28 |
| Radial section height (D−d)/2 | 30 mm |
| Smallest bore in 81200-series | 30 mm |
| Largest outer diameter in 81200-series | 420 mm |
| Width range across 81200-series | 16–95 mm |
| Bore position in 81200-series (smallest first) | 18 of 28 |
| Bore above smallest 81200-series size | 110 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 81228-M model number is decoded
SKF supplies 81228 M as a separable thrust bearing: the 140 mm shaft washer (WS), the machined brass M cage holding short cylindrical rollers, and the 200 mm housing washer (GS) can be ordered and mounted individually. Reading the code: the first three digits 812 give the dimension series (heavy 812 series), the last two 28 encode the 140 mm shaft washer bore (code 28 × 5), and M names the cage execution. The bearing takes thrust in one direction only — reverse loads lift the roller set off its track; arrange a mirrored second bearing for reversing duty, and keep the applied load above factor A 0.16. Minimum axial load is explicit at factor A 0.16: below F_am = A·n² (or the catalogue's slow-speed floor) the cylindrical rollers skid; springs or the rotor's own weight are part of the selection, not an accessory. Press only on washer backs, never through the roller set; seat both washers against full-area square shoulders, and shim the housing cover so the minimum load (A 0.16) is present without clamping the rollers.
Typical equipment & failure modes
Common applications
- vertical electric motor and pump shafts whose rotor weight loads one bearing
- extruder and injection press screw thrust blocks at low speed
- rolling-mill screwdown mechanisms and press adjusters
- slewing and turntable pivots with predominantly axial force
Known failure patterns
- roller skidding and raceway glazing once the thrust falls below the catalogue minimum axial load (factor A)
- washer back-face fretting where the seat is too narrow to support the full ring face
- oil starvation at the sliding contact zones of large spherical roller thrust bearings on forced-feed trips
- brinelling of washer raceways from impact or mounting force applied through the rolling elements
- smearing at roller-raceway contacts during unloaded startup before the oil film or preload is established
Selection pitfalls — read before you substitute
- At 140 mm bore the washers are too stiff to conform to a non-square seat: machine the shoulders parallel or the roller ends concentrate load into a narrow stripe across 46 mm.
- The 360/1400 kN ratings assume flat, full-support washer seats; a housing face narrower than the 200 mm washer OD invalidates the rating through edge stress.
- Factor A 0.16 is a mounting requirement, not advice: below the minimum axial load the rollers skid at speed — most "mysterious" early thrust failures are unloaded running.
- the 700 r/min reference speed is the thermal criterion under load, the 1,400 r/min limiting speed is mechanical and oil lubrication typically raises the usable figure.
- Do not substitute a thrust ball bearing of the same ISO envelope by rating alone: the cylindrical rollers of 81228 M need different minimum load and lubrication despite the shared 140×200 mm outline.
- The 360/1400 kN ratings and 5050 g mass are SKF catalogue values transcribed from ch. 11.1 of PUB BU/P1 17000 (PDF table page 892); mounting data — Ea/Eb raceway diameters and the minimum load factor A — appears in the running text because the structured record carries the boundary envelope only.
Frequently asked questions
Which dimensions does the 81228 M have?
A 81228 M measures 140 mm bore × 200 mm outside diameter × 46 mm width (5.512 × 7.874 × 1.811 in). From SKF catalogue PUB BU/P1 17000: dynamic C 360 kN, static C0 1400 kN, fatigue limit Pu 129 kN, reference speed 700 r/min, limiting speed 1,400 r/min, mass about 5050 g. Raceway diameters Ea 150 mm / Eb 191 mm and minimum load factor A 0.16 guide the seat design.
What is the difference between 811 and 812 series?
811 is the light section and 812 the higher, heavier section for the same bore; 893/894 are the extra-heavy series. 81228 M belongs to the heavy 812 series, 140×200×46 mm.
Are the washers of 81228 M separable?
Yes — shaft washer WS, roller-and-cage set and housing washer GS are separate and interchangeable within the size, but never across series: an 811 and an 812 washer for the same bore differ in OD and height.
Can a thrust ball bearing replace the 81228 M?
They share ISO boundary outlines (e.g. 511 vs 811), but the roller bearing needs a higher minimum axial load and different lubrication, and its C/C0 figures are not interchangeable — re-run the selection before substituting.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 11.1 cylindrical roller thrust bearings on 2026-09-27. Read our editorial & correction policy.