81240-M bearing: complete specifications & equivalents
The 81240-M is a ISO 104 radial bearing sized 200 x 280 x 62 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 200 mm |
| Outer diameter D | 280 mm |
| Width B | 62 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 720 kN |
| Basic static load rating C0 | 3100 kN |
| Fatigue load limit Pu | 255 kN |
| Reference speed (thermal) | 500 rpm |
| Limiting speed (mechanical) | 1000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 13500 g |
| Manufacturer designation | 81240 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 | 7.874 in |
|---|---|
| Outer diameter D | 11.024 in |
| Width B | 2.441 in |
| ISO bore code | 40 |
| 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) | 24 of 28 |
| Bore above smallest 81200-series size | 170 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 81240-M model number is decoded
SKF supplies 81240 M as a separable thrust bearing: the 200 mm shaft washer (WS), the machined brass M cage holding short cylindrical rollers, and the 280 mm housing washer (GS) can be ordered and mounted individually. The designation 81240 M states 812 series, 200 mm bore, machined brass M cage; shaft and housing washers are also orderable separately as WS and GS parts of the same size. 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. The 13500 g mass and 62 mm axial height sit between 200 and 280 mm washer diameters; check the seat shoulder spans the full ring face — a narrow shoulder causes washer fretting long before fatigue does. 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 0.77) is present without clamping the rollers.
Typical equipment & failure modes
Common applications
- 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
- crane hook crossheads carrying pure hook thrust while the hook swivels
Known failure patterns
- smearing at roller-raceway contacts during unloaded startup before the oil film or preload is established
- 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
- cage wear from rollers being dragged through unloaded zones under fluctuating thrust
Selection pitfalls — read before you substitute
- At 200 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 62 mm.
- Factor A 0.77 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 500 r/min reference speed is the thermal criterion under load, the 1,000 r/min limiting speed is mechanical and oil lubrication typically raises the usable figure.
- The 720/3100 kN ratings assume flat, full-support washer seats; a housing face narrower than the 280 mm washer OD invalidates the rating through edge stress.
- The 720/3100 kN ratings and 13500 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 the 81240 M take reversing thrust?
No. It carries axial load in one direction only; reversing force unloads and impacts the roller set. Use a mirrored pair of bearings for reversing shafts, with a separate arrangement for radial load.
How should a 81240 M be mounted?
Interference fit for the shaft washer, sliding fit for the housing washer, full-area square shoulders both sides, press on washer backs only, and shim the cover so the rollers turn freely while the factor-A 0.77 minimum load is present.
What are the dimensions and ratings of the 81240 M?
A 81240 M measures 200 mm bore × 280 mm outside diameter × 62 mm width (7.874 × 11.024 × 2.441 in). From SKF catalogue PUB BU/P1 17000: dynamic C 720 kN, static C0 3100 kN, fatigue limit Pu 255 kN, reference speed 500 r/min, limiting speed 1,000 r/min, mass about 13500 g. Raceway diameters Ea 215 mm / Eb 273 mm and minimum load factor A 0.77 guide the seat design.
How is the 81240 M designation read?
The first three digits 812 give the dimension series (heavy 812 series); 40 encodes the 200 mm bore (code 40 × 5); the suffix denotes the machined brass M cage. WS and GS washers of the same size can be ordered separately.
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.