81211-TN bearing: complete specifications & equivalents
The 81211-TN is a ISO 104 radial bearing sized 55 x 90 x 25 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 55 mm |
| Outer diameter D | 90 mm |
| Width B | 25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 122 kN |
| Basic static load rating C0 | 390 kN |
| Fatigue load limit Pu | 40 kN |
| Reference speed (thermal) | 1400 rpm |
| Limiting speed (mechanical) | 2800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 570 g |
| Manufacturer designation | 81211 TN |
| 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 | 2.165 in |
|---|---|
| Outer diameter D | 3.543 in |
| Width B | 0.984 in |
| ISO bore code | 11 |
| Radial section height (D−d)/2 | 17.5 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) | 6 of 28 |
| Bore above smallest 81200-series size | 25 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 81211-TN model number is decoded
In SKF catalogue PUB BU/P1 17000, 81211 TN denotes a cylindrical roller thrust bearing whose rollers run flat on hardened, ground washers — no radial capacity, one axial direction only, and a minimum axial load of factor A 0.012. The designation 81211 TN states 812 series, 55 mm bore, glass fibre reinforced PA66 TN cage; shaft and housing washers are also orderable separately as WS and GS parts of the same size. Small sizes ship with machined brass M cages to guide heavy rollers at the lubricant limit; the 122 kN rating assumes oil or grease reaching the full washer face. Static safety matters for shock duty: compare peak axial force against C0 390 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 55 mm seat (it rotates and takes an interference fit), leave the housing washer a sliding fit in the 90 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
- smearing at roller-raceway contacts during unloaded startup before the oil film or preload is established
- 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
- cage wear from rollers being dragged through unloaded zones under fluctuating thrust
Selection pitfalls — read before you substitute
- At 55 mm bore the minimum load (A 0.012) is still small, but a vertical shaft at rest loses it entirely — specify springs or check the rotor weight exceeds F_am at zero speed.
- Factor A 0.012 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 glass fibre reinforced PA66 TN 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 122/390 kN ratings assume flat, full-support washer seats; a housing face narrower than the 90 mm washer OD invalidates the rating through edge stress.
- Do not substitute a thrust ball bearing of the same ISO envelope by rating alone: the cylindrical rollers of 81211 TN need different minimum load and lubrication despite the shared 55×90 mm outline.
- The 122/390 kN ratings and 570 g mass are SKF catalogue values transcribed from ch. 11.1 of PUB BU/P1 17000 (PDF table page 890); 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 81211 TN 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 81211 TN 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 0.012 minimum load is present.
What are the dimensions and ratings of the 81211 TN?
A 81211 TN measures 55 mm bore × 90 mm outside diameter × 25 mm width (2.165 × 3.543 × 0.984 in). From SKF catalogue PUB BU/P1 17000: dynamic C 122 kN, static C0 390 kN, fatigue limit Pu 40 kN, reference speed 1,400 r/min, limiting speed 2,800 r/min, mass about 570 g. Raceway diameters Ea 59 mm / Eb 85 mm and minimum load factor A 0.012 guide the seat design.
How is the 81211 TN designation read?
The first three digits 812 give the dimension series (heavy 812 series); 11 encodes the 55 mm bore (code 11 × 5); the suffix denotes the glass fibre reinforced PA66 TN 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.