81104-TN bearing: complete specifications & equivalents
The 81104-TN is a ISO 104 radial bearing sized 20 x 35 x 10 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 20 mm |
| Outer diameter D | 35 mm |
| Width B | 10 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 18.6 kN |
| Basic static load rating C0 | 48 kN |
| Fatigue load limit Pu | 4.65 kN |
| Reference speed (thermal) | 3800 rpm |
| Limiting speed (mechanical) | 7500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 37 g |
| Manufacturer designation | 81104 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 | 0.787 in |
|---|---|
| Outer diameter D | 1.378 in |
| Width B | 0.394 in |
| ISO bore code | 04 |
| Radial section height (D−d)/2 | 7.5 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) | 3 of 34 |
| Bore above smallest 81100-series size | 5 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 81104-TN model number is decoded
81104 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 20×35×10 mm, listed in SKF catalogue PUB BU/P1 17000 ch. 11.1. 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 — 81104 TN sits in the light 811 series. Small sizes ship with glass-fibre PA66 TN cages for quiet, low-friction running; the 18.6 kN rating assumes oil or grease reaching the full washer face. Selection arithmetic: C 18.6 kN against C0 48 kN gives a C0/C ratio of 2.58 — 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 a 20 mm seat the 10 mm stack is easy to over-clamp — a cover torqued solid removes all roller clearance; shim to the catalogue endplay and keep factor A 1.80e-4 as the floor.
- 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 81104 TN size.
- the 3,800 r/min reference speed is the thermal criterion under load, the 7,500 r/min limiting speed is mechanical and oil lubrication typically raises the usable figure.
- The 18.6/48 kN ratings assume flat, full-support washer seats; a housing face narrower than the 35 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 81104 TN need different minimum load and lubrication despite the shared 20×35 mm outline.
- The 18.6/48 kN ratings and 37 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 ruins a 81104 TN in service?
Unloaded running below factor A 1.80e-4 causes skidding; non-square or narrow shoulders fret the washer backs; dry starts and contamination do the rest. Speed ceiling: 7,500 r/min limiting.
Which dimensions does the 81104 TN have?
A 81104 TN measures 20 mm bore × 35 mm outside diameter × 10 mm width (0.787 × 1.378 × 0.394 in). From SKF catalogue PUB BU/P1 17000: dynamic C 18.6 kN, static C0 48 kN, fatigue limit Pu 4.65 kN, reference speed 3,800 r/min, limiting speed 7,500 r/min, mass about 37 g. Raceway diameters Ea 21 mm / Eb 34 mm and minimum load factor A 1.80e-4 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. 81104 TN belongs to the light 811 series, 20×35×10 mm.
Are the washers of 81104 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.