81244-M bearing: complete specifications & equivalents
The 81244-M is a ISO 104 radial bearing sized 220 x 300 x 63 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 | 63 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 750 kN |
| Basic static load rating C0 | 3350 kN |
| Fatigue load limit Pu | 275 kN |
| Reference speed (thermal) | 480 rpm |
| Limiting speed (mechanical) | 950 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 15000 g |
| Manufacturer designation | 81244 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 | 8.661 in |
|---|---|
| Outer diameter D | 11.811 in |
| Width B | 2.48 in |
| ISO bore code | 44 |
| Radial section height (D−d)/2 | 40 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) | 25 of 28 |
| Bore above smallest 81200-series size | 190 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 81244-M model number is decoded
81244 M is a single-direction cylindrical roller thrust bearing to ISO 104 in the heavy 812 series: a flat shaft washer, a roller-and-cage set and a housing washer stacked to 220×300×63 mm, listed in SKF catalogue PUB BU/P1 17000 ch. 11.1. Reading the code: the first three digits 812 give the dimension series (heavy 812 series), the last two 44 encode the 220 mm shaft washer bore (code 44 × 5), and M names the cage execution. The three components are separable and interchangeable within the size: WS shaft washer, K-cage roller set, GS housing washer, all running on flat, square seats; the machined brass M cage is standard for this size. One direction only: 81244 M cannot be reversed to take opposite thrust — mirror a second bearing for reversing shafts, and keep housing and shaft seats square within the ISO 104 tolerances. Mounting: locate the shaft washer on the 220 mm seat (it rotates and takes an interference fit), leave the housing washer a sliding fit in the 300 mm bore, and check the stack can tilt freely before clamping.
Typical equipment & failure modes
Common applications
- slewing and turntable pivots with predominantly axial force
- crane hook crossheads carrying pure hook thrust while the hook swivels
- screw jack and lifting screw thrust positions under slow, steady load
- vertical electric motor and pump shafts whose rotor weight loads one bearing
Known failure patterns
- cage wear from rollers being dragged through unloaded zones under fluctuating thrust
- shaft-washer creep and fretting corrosion on a soft or undersized shaft shoulder
- oil starvation at the sliding contact zones of large spherical roller thrust bearings on forced-feed trips
- rolling-contact fatigue spalling after the catalogue L10 life is exhausted
- roller skidding and raceway glazing once the thrust falls below the catalogue minimum axial load (factor A)
Selection pitfalls — read before you substitute
- At 220 mm bore the 15 kg washer set needs forced lubrication and controlled start-up sequencing; dry first rotation under load is the classic destruction mode for very large thrust bearings.
- Keep the machined brass M cage out of chemical contact with aggressive EP additives beyond its compatibility list; cage damage here redistributes rollers and destroys the washer in hours.
- Do not substitute a thrust ball bearing of the same ISO envelope by rating alone: the cylindrical rollers of 81244 M need different minimum load and lubrication despite the shared 220×300 mm outline.
- The 750/3350 kN ratings assume flat, full-support washer seats; a housing face narrower than the 300 mm washer OD invalidates the rating through edge stress.
- Factor A 0.9 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 750/3350 kN ratings and 15000 g mass are SKF catalogue values transcribed from ch. 11.1 of PUB BU/P1 17000 (PDF table page 894); 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
What ruins a 81244 M in service?
Unloaded running below factor A 0.9 causes skidding; non-square or narrow shoulders fret the washer backs; dry starts and contamination do the rest. Speed ceiling: 950 r/min limiting.
Which dimensions does the 81244 M have?
A 81244 M measures 220 mm bore × 300 mm outside diameter × 63 mm width (8.661 × 11.811 × 2.48 in). From SKF catalogue PUB BU/P1 17000: dynamic C 750 kN, static C0 3350 kN, fatigue limit Pu 275 kN, reference speed 480 r/min, limiting speed 950 r/min, mass about 15000 g. Raceway diameters Ea 236 mm / Eb 294 mm and minimum load factor A 0.9 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. 81244 M belongs to the heavy 812 series, 220×300×63 mm.
Are the washers of 81244 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.
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.