33109-NTN bearing: complete specifications & equivalents
The 33109-NTN is a ISO 355 radial bearing sized 45 x 80 x 26 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 45 mm |
| Outer diameter D | 80 mm |
| Width B | 26 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 94 kN |
| Basic static load rating C0 | 115 kN |
| Limiting speed (mechanical) | 4700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 544 g |
| Manufacturer designation | NTN 33109 |
| Standard | ISO 355 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
Dimensions in inches & 33100-series range
| Bore d | 1.772 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 1.024 in |
| ISO bore code | 09 |
| Radial section height (D−d)/2 | 17.5 mm |
| Smallest bore in 33100-series | 40 mm |
| Largest outer diameter in 33100-series | 200 mm |
| Width range across 33100-series | 26–62 mm |
| Bore position in 33100-series (smallest first) | 2 of 13 |
| Bore above smallest 33100-series size | 5 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 33109 | SKF | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the 33109-NTN model number is decoded
33109 is the NTN 4T catalogue entry for a 45×80×26 mm metric tapered roller bearing — separable cone and cup, designed for combined radial and axial load as an individually adjusted bearing. Digit by digit, the bare number identifies the light-wide 33100 family and a bore code resolving to 45 mm; 80 mm OD and 26 mm assembled T are the matching ISO 355 boundary dimensions shared with other makers of the same dimension series. The pressed-steel cage and surface-finished roller ends are standard 4T execution; ULTAGE-marked variants use upgraded material and internal geometry aimed at longer rating life with the same ISO 355 envelope. The 17.5 mm section height over the 45 mm bore positions the load centre; axial location of the pair depends on that contact line, so spacer faces must be square within the P0 tolerance of the bearing. After mounting check the contact pattern with marking blue: a pattern biased to the large or small roller end means the 45 mm pair is misadjusted and the 26 mm T set will edge-load in service.
Typical equipment & failure modes
Common applications
- pump and compressor drive shafts carrying combined load
- machine-tool gearbox and headstock shafts
- axle final-drive and differential positions
- construction-equipment wheel and pivot hubs
Known failure patterns
- cup creep and housing fretting when the specified outer-ring press fit is not achieved
- smearing on the roller large ends and cone rib after a dry start with preload but no oil film
- flaking on one cone only when a back-to-back / face-to-face pair is loaded unevenly by a bent shaft
- cage fatigue when the pair is run continuously near the grease limiting speed without oil cooling
- brinell marks on cone and cup raceways from impact during handling or hammering during fitting
Selection pitfalls — read before you substitute
- Hub and pinion bearings of this 45 mm bore class are commonly adjusted in pairs; verify end play against the axle drawing and re-torque after bedding-in rather than trusting the initial preload on 33109.
- The light-wide 33100 family at 45 mm bore (80×26 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 6,200 r/min oil ceiling.
- Never fit the 45 mm cone by hammering the 80 mm cup: force for both press fits goes through the ring faces only, or brinell marks release as noise within the first running hours.
- The 17.5 mm section leaves little room for an oversized shaft fillet; check the mounting-chamfer table for 33109 or the ring will bottom out on the radius instead of the shoulder face.
- Replacing one half of an adjusted pair without resetting end play negates the 26 mm T dimension logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- The 94/115 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 33109 (ISO 355 3CE); internal geometry legitimately differs between manufacturers, so re-verify ratings, adjustment and suffix before substituting another make on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 33109?
33109 is a metric 4T tapered roller bearing to ISO 355: 45 mm bore, 80 mm outside diameter and 26 mm assembled width T (1.772 × 3.15 × 1.024 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 94 kN, C0 115 kN (2203E prints no Pu for this size), grease limiting speed 4,700 r/min, oil speed 6,200 r/min, mass about 544 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 33109?
4T is NTN's tapered roller bearing brand mark, stamped on the cone and cup in the factory. It identifies the NTN 4T programme and is not a dimension, so the catalogue and this page list the bare ISO 355 number (33109); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 33109 designation encode the 45 mm bore and what is 3CE?
last two digits 09 are the ISO bore code, ×5 = 45 mm (codes 00–03 use the 10/12/15/17 exception table). The 80 mm OD and 26 mm assembled T follow the ISO 355 dimension-series plan. 3CE is the maker-neutral ISO 355 abbreviation for this dimension series (the same code other manufacturers print); 4T is NTN's own brand mark.
Why does 33109 list two speeds, 4,700 and 6,200 r/min?
The lower figure, 4,700 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 33109 at 6,200 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 33109 mean?
It is the basic open 4T execution — steel cage, adjusted mounting, no seal or feature suffix. NTN uses U for the uprated design, UTG for ULTAGE large-bearing specs, X for the ISO boundary section, and C/CA/D/A for contact-angle or internal-design variants; all are separate order numbers.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.