81148-M bearing: complete specifications & equivalents
The 81148-M is a ISO 104 radial bearing sized 240 x 300 x 45 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 240 mm |
| Outer diameter D | 300 mm |
| Width B | 45 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 475 kN |
| Basic static load rating C0 | 2450 kN |
| Fatigue load limit Pu | 196 kN |
| Reference speed (thermal) | 560 rpm |
| Limiting speed (mechanical) | 1100 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 8450 g |
| Manufacturer designation | 81148 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 | 9.449 in |
|---|---|
| Outer diameter D | 11.811 in |
| Width B | 1.772 in |
| ISO bore code | 48 |
| Radial section height (D−d)/2 | 30 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) | 30 of 34 |
| Bore above smallest 81100-series size | 225 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 81148-M model number is decoded
The light 811 series bearing 81148 M carries pure axial load at low to moderate speed: 475 kN dynamic and 2450 kN static across a 240×300 mm washer pair, 45 mm overall height. In 81148 M, 811 fixes the 300 mm OD and 45 mm height; 48 selects the 240 mm seat, and the machined brass M cage is the only execution suffix on these rigid-washer bearings. 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. Static safety matters for shock duty: compare peak axial force against C0 2450 kN with the application's static factor, since crane hooks and screw positions see their worst load at zero or low speed. Mounting: locate the shaft washer on the 240 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
- 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
- screw jack and lifting screw thrust positions under slow, steady load
Known failure patterns
- cage wear from rollers being dragged through unloaded zones under fluctuating thrust
- washer back-face fretting where the seat is too narrow to support the full ring face
- grease churning and overheating when a high-speed thrust position is over-packed
- 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 240 mm bore the 8.4 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 560 r/min reference speed is the thermal criterion under load, the 1,100 r/min limiting speed is mechanical and oil lubrication typically raises the usable figure.
- The 475/2450 kN ratings assume flat, full-support washer seats; a housing face narrower than the 300 mm washer OD invalidates the rating through edge stress.
- 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 81148 M need different minimum load and lubrication despite the shared 240×300 mm outline.
- The 475/2450 kN ratings and 8450 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
How should a 81148 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 0.48 minimum load is present.
What are the dimensions and ratings of the 81148 M?
A 81148 M measures 240 mm bore × 300 mm outside diameter × 45 mm width (9.449 × 11.811 × 1.772 in). From SKF catalogue PUB BU/P1 17000: dynamic C 475 kN, static C0 2450 kN, fatigue limit Pu 196 kN, reference speed 560 r/min, limiting speed 1,100 r/min, mass about 8450 g. Raceway diameters Ea 248 mm / Eb 296 mm and minimum load factor A 0.48 guide the seat design.
How is the 81148 M designation read?
The first three digits 811 give the dimension series (light 811 series); 48 encodes the 240 mm bore (code 48 × 5); the suffix denotes the machined brass M cage. WS and GS washers of the same size can be ordered separately.
Why does 81148 M need a minimum axial load?
Below factor A 0.48 the cylindrical rollers skid instead of rolling, glazing and smearing the washer tracks. Springs, preload shims or rotor weight must keep the thrust above the catalogue minimum, especially during unloaded starts.
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.