81111-TN bearing: complete specifications & equivalents
The 81111-TN is a ISO 104 radial bearing sized 55 x 78 x 16 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 | 78 mm |
| Width B | 16 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 69.5 kN |
| Basic static load rating C0 | 285 kN |
| Fatigue load limit Pu | 29 kN |
| Reference speed (thermal) | 1900 rpm |
| Limiting speed (mechanical) | 3800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 230 g |
| Manufacturer designation | 81111 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 & 81100-series range
| Bore d | 2.165 in |
|---|---|
| Outer diameter D | 3.071 in |
| Width B | 0.63 in |
| ISO bore code | 11 |
| Radial section height (D−d)/2 | 11.5 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) | 10 of 34 |
| Bore above smallest 81100-series size | 40 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 81111-TN model number is decoded
81111 TN is a single-direction cylindrical roller thrust bearing to ISO 104 in the light 811 series: a flat shaft washer, a roller-and-cage set and a housing washer stacked to 55×78×16 mm, listed in SKF catalogue PUB BU/P1 17000 ch. 11.1. Reading the code: the first three digits 811 give the dimension series (light 811 series), the last two 11 encode the 55 mm shaft washer bore (code 11 × 5), and TN names the cage execution. Rigid washers mean no self-alignment: the shaft and housing shoulders must be square and parallel to within the catalogue seat tolerances, or the rollers edge-load across the 16 mm height. Selection arithmetic: C 69.5 kN against C0 285 kN gives a C0/C ratio of 4.10 — thrust bearings are chosen on static rating and F_a/C0 more often than on L10 life. 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
- 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
- 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
- abrasive paste forming as dust bypasses the housing seals into the open washer set
- 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 55 mm bore the minimum load (A 0.0065) 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 81111 TN size.
- the 1,900 r/min reference speed is the thermal criterion under load, the 3,800 r/min limiting speed is mechanical and oil lubrication typically raises the usable figure.
- The 69.5/285 kN ratings assume flat, full-support washer seats; a housing face narrower than the 78 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 81111 TN need different minimum load and lubrication despite the shared 55×78 mm outline.
- The 69.5/285 kN ratings and 230 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
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. 81111 TN belongs to the light 811 series, 55×78×16 mm.
Are the washers of 81111 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.
Can a thrust ball bearing replace the 81111 TN?
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 81111 TN in service?
Unloaded running below factor A 0.0065 causes skidding; non-square or narrow shoulders fret the washer backs; dry starts and contamination do the rest. Speed ceiling: 3,800 r/min limiting.
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.