33108-NTN bearing: complete specifications & equivalents
The 33108-NTN is a ISO 355 radial bearing sized 40 x 75 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 | 40 mm |
| Outer diameter D | 75 mm |
| Width B | 26 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 88 kN |
| Basic static load rating C0 | 103 kN |
| Limiting speed (mechanical) | 5200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 498 g |
| Manufacturer designation | NTN 33108 |
| 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 | 1.575 in |
|---|---|
| Outer diameter D | 2.953 in |
| Width B | 1.024 in |
| ISO bore code | 08 |
| 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) | 1 of 13 |
| Bore above smallest 33100-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 33108 | 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. |
| 33108-DF | SKF | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | Model-number interchange per ISO 15; confirm dimensions, sealing and ratings in the supplier catalogue. |
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 33108-NTN model number is decoded
NTN supplies this 40 mm bore tapered roller position as 33108: one cone assembly, one cup, line-contact rollers and a steel cage, rated 88 kN basic dynamic and 103 kN static on the light-wide 33100 family. The last two digits 08 are the ISO bore code, ×5 = 40 mm (codes 00–03 use the 10/12/15/17 exception table) under the ISO 355 numbering; the 26 mm value printed here is T, the width of the fully assembled cone-plus-cup set, not the inner-ring width alone. The rollers run with their large ends against the cone's integral guide rib; the rib/end-flange contact carries the thrust component and is the reason lubricant must reach the rib face of 33108, not only the raceway. Grease relubrication at 5,200 r/min limiting speed targets the rib contact; if the drive needs 6,900 r/min it must be arranged for oil lubrication with a defined flow to the large roller ends. After mounting check the contact pattern with marking blue: a pattern biased to the large or small roller end means the 40 mm pair is misadjusted and the 26 mm T set will edge-load in service.
Typical equipment & failure modes
Common applications
- industrial gearbox and speed-reducer shafts
- bevel and helical pinion drives with high thrust component
- pump and compressor drive shafts carrying combined load
- machine-tool gearbox and headstock shafts
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- 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
- false brinelling on a stationary paired set exposed to external vibration
Selection pitfalls — read before you substitute
- Hub and pinion bearings of this 40 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 33108.
- The light-wide 33100 family at 40 mm bore (75×26 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 6,900 r/min oil ceiling.
- The 17.5 mm section leaves little room for an oversized shaft fillet; check the mounting-chamfer table for 33108 or the ring will bottom out on the radius instead of the shoulder face.
- The U/UTG/X/C/CA/D suffix variants of a base number share the bore but not the article: ordering 33108 by size alone can deliver the wrong contact-angle execution for a pinion position.
- Back-to-back and face-to-face arrangements react differently to shaft bending: pick the pair orientation for the moment load before locking the 40 mm shoulder geometry, because retrofitting flips the cups.
- The 88/103 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 33108 (ISO 355 2CE); 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 33108?
33108 is a metric 4T tapered roller bearing to ISO 355: 40 mm bore, 75 mm outside diameter and 26 mm assembled width T (1.575 × 2.953 × 1.024 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 88 kN, C0 103 kN (2203E prints no Pu for this size), grease limiting speed 5,200 r/min, oil speed 6,900 r/min, mass about 498 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 33108?
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 (33108); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 33108 designation encode the 40 mm bore and what is 2CE?
last two digits 08 are the ISO bore code, ×5 = 40 mm (codes 00–03 use the 10/12/15/17 exception table). The 75 mm OD and 26 mm assembled T follow the ISO 355 dimension-series plan. 2CE 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 33108 list two speeds, 5,200 and 6,900 r/min?
The lower figure, 5,200 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 33108 at 6,900 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 33108 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.