81220-TN bearing: complete specifications & equivalents
The 81220-TN is a ISO 104 radial bearing sized 100 x 150 x 38 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 100 mm |
| Outer diameter D | 150 mm |
| Width B | 38 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 270 kN |
| Basic static load rating C0 | 1060 kN |
| Fatigue load limit Pu | 104 kN |
| Reference speed (thermal) | 900 rpm |
| Limiting speed (mechanical) | 1800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2200 g |
| Manufacturer designation | 81220 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 | 3.937 in |
|---|---|
| Outer diameter D | 5.906 in |
| Width B | 1.496 in |
| ISO bore code | 20 |
| Radial section height (D−d)/2 | 25 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) | 14 of 28 |
| Bore above smallest 81200-series size | 70 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 81220-TN model number is decoded
The heavy 812 series bearing 81220 TN carries pure axial load at low to moderate speed: 270 kN dynamic and 1060 kN static across a 100×150 mm washer pair, 38 mm overall height. 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 — 81220 TN sits in the heavy 812 series. Small sizes ship with machined brass M cages to guide heavy rollers at the lubricant limit; the 270 kN rating assumes oil or grease reaching the full washer face. Minimum axial load is explicit at factor A 0.09: 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 100 mm bore the minimum load (A 0.09) 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.
- 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 81220 TN size.
- the 900 r/min reference speed is the thermal criterion under load, the 1,800 r/min limiting speed is mechanical and oil lubrication typically raises the usable figure.
- Factor A 0.09 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 270/1060 kN ratings and 2200 g mass are SKF catalogue values transcribed from ch. 11.1 of PUB BU/P1 17000 (PDF table page 892); 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
What ruins a 81220 TN in service?
Unloaded running below factor A 0.09 causes skidding; non-square or narrow shoulders fret the washer backs; dry starts and contamination do the rest. Speed ceiling: 1,800 r/min limiting.
Which dimensions does the 81220 TN have?
A 81220 TN measures 100 mm bore × 150 mm outside diameter × 38 mm width (3.937 × 5.906 × 1.496 in). From SKF catalogue PUB BU/P1 17000: dynamic C 270 kN, static C0 1060 kN, fatigue limit Pu 104 kN, reference speed 900 r/min, limiting speed 1,800 r/min, mass about 2200 g. Raceway diameters Ea 107 mm / Eb 142 mm and minimum load factor A 0.09 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. 81220 TN belongs to the heavy 812 series, 100×150×38 mm.
Are the washers of 81220 TN separable?
Yes — shaft washer WS, roller-and-cage set and housing washer GS are separate and interchangeable within the size, but never across series: an 811 and an 812 washer for the same bore differ in OD and height.
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.