Designation Systems / Self-Aligning Ball Bearings
Self-Aligning Ball Bearing Designation System
A self-aligning ball bearing designation is a basic designation (dimension series + bore code) plus optional suffixes that describe the bore type, seals, cage and clearance. Two rows of balls running on a common spherical raceway let the bearing tolerate shaft misalignment. Each manufacturer publishes its own designation system — the tables below put the four brands that catalogue this type side by side.
Anatomy of a Designation
2205 E-2RS1KTN9
Example shown in SKF style
2205Basic designation — 22 (wide light) series, bore code 05 = 25 mm
EInternal design & boreOptimized internal design (reinforced ball set)
KInternal design & boreTapered bore, taper 1:12
2RS1SealsContact seal (NBR) on both sides
TN9CageGlass fibre reinforced PA66 cage
Bore code (last two digits of the basic designation)
00 = 10 mm bore01 = 12 mm bore02 = 15 mm bore03 = 17 mm bore04 and up = bore (mm) = code × 53-digit sizes = legacy 108/126/127/129/135 — bore = last digit
SKF
Internal design & bore
| E | Optimized internal design (reinforced ball set) |
| K | Tapered bore, taper 1:12 |
Seals
| -2RS1 | Contact seal (NBR) on both sides |
Cage
| TN9 | Glass fibre reinforced PA66 cage |
Clearance & accuracy
| C2 | Clearance smaller than Normal |
| CN | Normal clearance (usually omitted) |
| C3 | Clearance greater than Normal |
Series names
| 12xx | Light series, narrow |
| 13xx | Medium series, narrow |
| 22xx | Light series, wide |
| 23xx | Medium series, wide |
| 112xx | Extended inner ring |
NSK
Internal design & bore
| K | Tapered bore, taper 1:12 |
Clearance & accuracy
| C2 | Clearance less than normal |
| CN | Normal clearance (omitted) |
| C3 | Clearance greater than normal |
Series names
| 1xx | Small bores (108, 126, 127, 129, 135) |
| 12xx / 13xx | Narrow light / medium series |
| 22xx / 23xx | Wide light / medium series |
Schaeffler (FAG)
Internal design & bore
| K | Tapered bore, taper 1:12 |
Seals
| -2RS | Contact seal (lip seal) on both sides |
Cage
| TVH | Glass fibre reinforced PA66 cage |
| M | Solid brass cage, ball-guided |
Clearance & accuracy
| C3 | Radial internal clearance larger than normal |
Series names
| 12xx | Light series, narrow |
| 13xx | Medium series, narrow |
| 22xx | Light series, wide |
| 23xx | Medium series, wide |
| 112xx | Extended inner ring |
NTN
Internal design & bore
| S | Cylindrical bore — NTN appends S to the basic number (1205S) |
| K | Tapered bore, taper 1:12 (1205SK) |
Cage
| (none) | Pressed steel cage (machined brass for 2321S/2322S) |
Clearance & accuracy
| CN | Normal clearance (not indicated) |
| C3 | Internal clearance greater than normal |
Series names
| 12xxS / 13xxS | Narrow light / medium series, cylindrical bore |
| 22xxS / 23xxS | Wide light / medium series, cylindrical bore |
Good to Know
- Two bore types share one row: a cylindrical-bore bearing (e.g. 2205) and its tapered-bore version (2205 K, taper 1:12) have identical boundary dimensions and load ratings.
- The same bearing is written differently by each brand: SKF 2205 ETN9 (E design + TN9 cage), FAG 2205-TVH (dash suffix), NSK 2205 (plain), NTN 2205S (trailing S).
- The first digit is the width series (1 = narrow, 2 = wide) and the second the diameter series (2 = light, 3 = medium); the type is not encoded in the number, unlike the 6 of a deep groove ball bearing.
- Sizes 108, 126, 127, 129 and 135 are legacy three-digit designations whose bore is the last digit (108 = 8 mm, 135 = 5 mm), not an ISO bore code.
- Not every size offers the tapered bore: NSK/NTN omit K for bores up to 03 and for a few large sizes (1214, 1221, 2214, 2314, ...).
- Availability of a suffix varies by size — always confirm the exact designation in the manufacturer catalog you are ordering from.
Disclaimer: Data on this page is compiled from publicly available online sources for reference only, and not every model appears in a manufacturer's published catalog. Values may differ between sources and editions — always verify against the manufacturer's current documentation before design or purchase.Full disclaimer →
