81252-M bearing: complete specifications & equivalents
The 81252-M is a ISO 104 radial bearing sized 260 x 360 x 79 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 260 mm |
| Outer diameter D | 360 mm |
| Width B | 79 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 1140 kN |
| Basic static load rating C0 | 5300 kN |
| Fatigue load limit Pu | 415 kN |
| Reference speed (thermal) | 380 rpm |
| Limiting speed (mechanical) | 750 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 27000 g |
| Manufacturer designation | 81252 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 | 10.236 in |
|---|---|
| Outer diameter D | 14.173 in |
| Width B | 3.11 in |
| ISO bore code | 52 |
| Radial section height (D−d)/2 | 50 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) | 27 of 28 |
| Bore above smallest 81200-series size | 230 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 81252-M model number is decoded
81252 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 260×360×79 mm, listed in SKF catalogue PUB BU/P1 17000 ch. 11.1. SKF thrust-roller numbering mirrors the ball 511/512 plan with 811/812: 812 is the higher (heavier) section per bore, and 893/894 are the very heavy series — 81252 M sits in the heavy 812 series. Small sizes ship with machined brass M cages to guide heavy rollers at the lubricant limit; the 1140 kN rating assumes oil or grease reaching the full washer face. Selection arithmetic: C 1140 kN against C0 5300 kN gives a C0/C ratio of 4.65 — thrust bearings are chosen on static rating and F_a/C0 more often than on L10 life. Mounting: locate the shaft washer on the 260 mm seat (it rotates and takes an interference fit), leave the housing washer a sliding fit in the 360 mm bore, and check the stack can tilt freely before clamping.
Typical equipment & failure modes
Common applications
- 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
- extruder and injection press screw thrust blocks at low speed
Known failure patterns
- roller skidding and raceway glazing once the thrust falls below the catalogue minimum axial load (factor A)
- 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
- hard-particle indentation where oil or grease filtration is inadequate
- smearing at roller-raceway contacts during unloaded startup before the oil film or preload is established
Selection pitfalls — read before you substitute
- At 260 mm bore the 27 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 1140/5300 kN ratings assume flat, full-support washer seats; a housing face narrower than the 360 mm washer OD invalidates the rating through edge stress.
- Factor A 2.25 is a mounting requirement, not advice: below the minimum axial load the rollers skid at speed — most "mysterious" early thrust failures are unloaded running.
- Do not substitute a thrust ball bearing of the same ISO envelope by rating alone: the cylindrical rollers of 81252 M need different minimum load and lubrication despite the shared 260×360 mm outline.
- 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 81252 M size.
- The 1140/5300 kN ratings and 27000 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 81252 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 81252 M in service?
Unloaded running below factor A 2.25 causes skidding; non-square or narrow shoulders fret the washer backs; dry starts and contamination do the rest. Speed ceiling: 750 r/min limiting.
Which dimensions does the 81252 M have?
A 81252 M measures 260 mm bore × 360 mm outside diameter × 79 mm width (10.236 × 14.173 × 3.11 in). From SKF catalogue PUB BU/P1 17000: dynamic C 1140 kN, static C0 5300 kN, fatigue limit Pu 415 kN, reference speed 380 r/min, limiting speed 750 r/min, mass about 27000 g. Raceway diameters Ea 281 mm / Eb 351 mm and minimum load factor A 2.25 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. 81252 M belongs to the heavy 812 series, 260×360×79 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.