30256UTG bearing: complete specifications & equivalents
The 30256UTG is a ISO 355 radial bearing sized 280 x 500 x 89 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 280 mm |
| Outer diameter D | 500 mm |
| Width B | 89 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 1590 kN |
| Basic static load rating C0 | 1910 kN |
| Fatigue load limit Pu | 155 kN |
| Limiting speed (mechanical) | 630 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 66500 g |
| Manufacturer designation | NTN 30256UTG |
| 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 & 30200-series range
| Bore d | 11.024 in |
|---|---|
| Outer diameter D | 19.685 in |
| Width B | 3.504 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 110 mm |
| Smallest bore in 30200-series | 15 mm |
| Largest outer diameter in 30200-series | 580 mm |
| Width range across 30200-series | 11.75–104 mm |
| Bore position in 30200-series (smallest first) | 35 of 37 |
| Bore above smallest 30200-series size | 265 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30256UTG | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the 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 30256UTG model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, the NTN order number 30256UTG denotes the standard-section 30200 family of metric tapered roller bearings, 280 mm bore, 500 mm outside diameter and 89 mm assembled width T (11.024 × 19.685 × 3.504 in) to the ISO 355 boundary plan. The last two digits 56 are the ISO bore code, ×5 = 280 mm (codes 00–03 use the 10/12/15/17 exception table) under the ISO 355 numbering; the 89 mm value printed here is T, the width of the fully assembled cone-plus-cup set, not the inner-ring width alone. The 110.0 mm radial section carries the roller complement across the 280–500 mm envelope; section and contact angle differ between NTN metric families even at the same bore, so 302/322/323 are not drop-in swaps. Speed planning uses both catalogue columns: grease 630 r/min is the cage/rib mechanical ceiling for 30256UTG, oil 900 r/min is available with circulating oil — a 270 r/min margin at this size. After mounting check the contact pattern with marking blue: a pattern biased to the large or small roller end means the 280 mm pair is misadjusted and the 89 mm T set will edge-load in service.
Typical equipment & failure modes
Common applications
- large marine propulsion reduction gears
- cement-plant kiln and mill drive trains
- rolling-mill roll-neck and gearbox positions
- large crusher and SAG/AG-mill drive shafts
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- rib scoring when axial load is carried beyond the cone rib capacity of the adjusted pair
- preload loss from racewear when one bearing of the paired set is replaced without re-adjusting end play
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- indentation of the raceways by hard particles in unsealed open arrangements
Selection pitfalls — read before you substitute
- At 280 mm bore the 30256UTG set is adjusted with hydraulic nuts on large mill and wind positions; follow the drive-up angle/end-play procedure, because manual torque methods cannot control preload at the 1590 kN C level.
- The standard-section 30200 family at 280 mm bore (500×89 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 900 r/min oil ceiling.
- Minimum load matters at high speed: an unloaded 30256UTG at a large fraction of 630 r/min lets rollers skid and smear the cone rib; spring-preload lightly loaded pair arrangements.
- Do not confuse T (89 mm assembled width of cone + cup) with the cone width when drawing spacers; an abutment sized to T instead of the ring width leaves the cup unseated.
- The U/UTG/X/C/CA/D suffix variants of a base number share the bore but not the article: ordering 30256UTG by size alone can deliver the wrong contact-angle execution for a pinion position.
- The 1590/1910 kN ratings and 155 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30256UTG; 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 30256UTG?
30256UTG is a metric 4T tapered roller bearing to ISO 355: 280 mm bore, 500 mm outside diameter and 89 mm assembled width T (11.024 × 19.685 × 3.504 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 1590 kN, C0 1910 kN, Pu 155 kN, grease limiting speed 630 r/min, oil speed 900 r/min, mass about 66500 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 30256UTG?
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 (30256UTG); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 30256UTG designation encode the 280 mm bore?
last two digits 56 are the ISO bore code, ×5 = 280 mm (codes 00–03 use the 10/12/15/17 exception table). The 500 mm OD and 89 mm assembled T follow the ISO 355 dimension-series plan.
Why does 30256UTG list two speeds, 630 and 900 r/min?
The lower figure, 630 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 30256UTG at 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 30256UTG mean?
Suffix reading on 30256UTG: the UTG suffix marks the ULTAGE specification for large NTN tapered rollers — upgraded material and internal design for longer life inside the unchanged ISO 355 envelope; the suffix is part of the order number and the variants are not interchangeable articles.
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.