81144-M bearing: complete specifications & equivalents
The 81144-M is a ISO 104 radial bearing sized 220 x 270 x 37 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 | 270 mm |
| Width B | 37 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 335 kN |
| Basic static load rating C0 | 1700 kN |
| Fatigue load limit Pu | 137 kN |
| Reference speed (thermal) | 670 rpm |
| Limiting speed (mechanical) | 1300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 5200 g |
| Manufacturer designation | 81144 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 & 81100-series range
| Bore d | 8.661 in |
|---|---|
| Outer diameter D | 10.63 in |
| Width B | 1.457 in |
| ISO bore code | 44 |
| Radial section height (D−d)/2 | 25 mm |
| Smallest bore in 81100-series | 15 mm |
| Largest outer diameter in 81100-series | 400 mm |
| Width range across 81100-series | 9–63 mm |
| Bore position in 81100-series (smallest first) | 29 of 34 |
| Bore above smallest 81100-series size | 205 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 81144-M model number is decoded
The light 811 series bearing 81144 M carries pure axial load at low to moderate speed: 335 kN dynamic and 1700 kN static across a 220×270 mm washer pair, 37 mm overall height. Reading the code: the first three digits 811 give the dimension series (light 811 series), the last two 44 encode the 220 mm shaft washer bore (code 44 × 5), and M names the cage execution. Small sizes ship with machined brass M cages to guide heavy rollers at the lubricant limit; the 335 kN rating assumes oil or grease reaching the full washer face. Minimum axial load is explicit at factor A 0.23: 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. In vertical shafts let the rotor weight provide the minimum load where possible; otherwise fit a spring pack above the housing washer, and verify the washer face is flooded with oil at first start.
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
- smearing at roller-raceway contacts during unloaded startup before the oil film or preload is established
- housing-washer rotation scored into an unmachined or loose seating face
- oil starvation at the sliding contact zones of large spherical roller thrust bearings on forced-feed trips
- condensation pitting in machines that run intermittently in humid environments
- cage wear from rollers being dragged through unloaded zones under fluctuating thrust
Selection pitfalls — read before you substitute
- At 220 mm bore the 5.2 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.
- The separable washers are not interchangeable across series: an 811 and an 812 washer for the same bore differ in OD and height — order WS/GS parts by the full 81144 M size.
- the 670 r/min reference speed is the thermal criterion under load, the 1,300 r/min limiting speed is mechanical and oil lubrication typically raises the usable figure.
- Factor A 0.23 is a mounting requirement, not advice: below the minimum axial load the rollers skid at speed — most "mysterious" early thrust failures are unloaded running.
- 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.
- The 335/1700 kN ratings and 5200 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
Can a thrust ball bearing replace the 81144 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.
What ruins a 81144 M in service?
Unloaded running below factor A 0.23 causes skidding; non-square or narrow shoulders fret the washer backs; dry starts and contamination do the rest. Speed ceiling: 1,300 r/min limiting.
Which dimensions does the 81144 M have?
A 81144 M measures 220 mm bore × 270 mm outside diameter × 37 mm width (8.661 × 10.63 × 1.457 in). From SKF catalogue PUB BU/P1 17000: dynamic C 335 kN, static C0 1700 kN, fatigue limit Pu 137 kN, reference speed 670 r/min, limiting speed 1,300 r/min, mass about 5200 g. Raceway diameters Ea 226 mm / Eb 263 mm and minimum load factor A 0.23 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. 81144 M belongs to the light 811 series, 220×270×37 mm.
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.