30248UTG bearing: complete specifications & equivalents
The 30248UTG is a ISO 355 radial bearing sized 240 x 440 x 79 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 240 mm |
| Outer diameter D | 440 mm |
| Width B | 79 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 1250 kN |
| Basic static load rating C0 | 1480 kN |
| Fatigue load limit Pu | 125 kN |
| Limiting speed (mechanical) | 760 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 47700 g |
| Manufacturer designation | NTN 30248UTG |
| 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 | 9.449 in |
|---|---|
| Outer diameter D | 17.323 in |
| Width B | 3.11 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 100 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) | 33 of 37 |
| Bore above smallest 30200-series size | 225 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30248UTG | 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 30248UTG model number is decoded
30248UTG is the NTN 4T catalogue entry for a 240×440×79 mm metric tapered roller bearing — separable cone and cup, designed for combined radial and axial load as an individually adjusted bearing. On the NTN nameplate the parts carry 4T plus the bare code, while 2203E orders 30248UTG by the metric ISO 355 number: 240 mm bore, 440 mm OD. At 1250 kN C the bearing offers about 5.2 kN of dynamic capacity per millimetre of the 240 mm bore — compare any substitution on this ratio and the 79 mm assembled T, not on bore alone. Imperial cross-check for the drawing: 240×440×79 mm is 9.449 × 17.323 × 3.11 in; ISO 355 makes the envelope interchangeable but C/C0, 1250/1480 kN, is NTN-specific. When pairing 30248UTG with a second tapered bearing, keep the matched arrangement clean: a single stray grit particle between cup and housing changes preload faster than the adjustment range can correct.
Typical equipment & failure modes
Common applications
- wind-turbine gearbox and main-shaft arrangements
- offshore crane and drawworks drums
- heavy haul railway traction gearboxes
- large marine propulsion reduction gears
Known failure patterns
- cup creep and housing fretting when the specified outer-ring press fit is not achieved
- 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
- cage fatigue when the pair is run continuously near the grease limiting speed without oil cooling
- fretting corrosion on a loose cone seat that creeps under rotating load
Selection pitfalls — read before you substitute
- At 240 mm bore the 30248UTG 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 1250 kN C level.
- The standard-section 30200 family at 240 mm bore (440×79 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 1,100 r/min oil ceiling.
- Do not confuse T (79 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.
- Open 30248UTG units have no seals: a wheel-hub or gearbox application needs external sealing or the 760 r/min grease figure is meaningless once water reaches the cone rib.
- Open 30248UTG units have no seals: a wheel-hub or gearbox application needs external sealing or the 760 r/min grease figure is meaningless once water reaches the cone rib.
- The 1250/1480 kN ratings and 125 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30248UTG; 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 30248UTG?
30248UTG is a metric 4T tapered roller bearing to ISO 355: 240 mm bore, 440 mm outside diameter and 79 mm assembled width T (9.449 × 17.323 × 3.11 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 1250 kN, C0 1480 kN, Pu 125 kN, grease limiting speed 760 r/min, oil speed 1,100 r/min, mass about 47700 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 30248UTG?
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 (30248UTG); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 30248UTG designation encode the 240 mm bore?
last two digits 48 are the ISO bore code, ×5 = 240 mm (codes 00–03 use the 10/12/15/17 exception table). The 440 mm OD and 79 mm assembled T follow the ISO 355 dimension-series plan.
Why does 30248UTG list two speeds, 760 and 1,100 r/min?
The lower figure, 760 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 30248UTG at 1,100 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 30248UTG mean?
Suffix reading on 30248UTG: 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.