HM903249-HM903210 bearing: complete specifications & equivalents
The HM903249-HM903210 is a ANSI ABMA 19.2 radial bearing sized 44.45 x 95.25 x 30.958 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 44.45 mm |
| Outer diameter D | 95.25 mm |
| Width B | 30.958 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 107 kN |
| Basic static load rating C0 | 116 kN |
| Limiting speed (mechanical) | 3700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 999 g |
| Manufacturer designation | NTN 4T-HM903249/HM903210 |
| Standard | ANSI ABMA 19.2 |
| Catalog version | NTN 2203E 2026-09-25 |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN 2203E 2026-09-25) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN 2203E 2026-09-25); 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 & 4t-inch-series range
| Bore d | 1.75 in |
|---|---|
| Outer diameter D | 3.75 in |
| Width B | 1.219 in |
| ISO bore code | 49 |
| Radial section height (D−d)/2 | 25.4 mm |
| Smallest bore in 4t-inch-series | 12.7 mm |
| Largest outer diameter in 4t-inch-series | 260 mm |
| Width range across 4t-inch-series | 10.998–77.788 mm |
| Bore position in 4t-inch-series (smallest first) | 51 of 148 |
| Bore above smallest 4t-inch-series size | 31.750000000000004 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| HM903249-210 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 44.45×95.25×30.958 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
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 HM903249-HM903210 model number is decoded
NTN supplies this 1.75 in (44.45 mm) shaft position as 4T-HM903249/HM903210: cone HM903249, cup HM903210, profiled rollers and a pressed-steel cage, rated 107 kN basic dynamic and 116 kN static. Letter prefixes inherited from the inch convention mark the load family: LM reads as light-medium, HM as heavy-medium, LL as extra-light, J-prefixed codes as metric-envelope families — HM903249 sits in the heavy-medium HM family. The 2.4 kN of dynamic capacity per millimetre of bore summarises the 107 kN rating over the 44.45 mm bore — sanity-check any interchange candidate against this ratio and the 30.958 mm T. Cup-side note for HM903210: within the heavy-medium HM family tables the HM903249 cone is listed against several cup options, and it is the cup that fixes the 95.25 mm OD and the 30.958 mm assembled width — quote the full HM903249/HM903210 pair, never the cone alone. Back-to-back (O) and face-to-face (X) arrangements of two 4T-HM903249/HM903210 sets react differently to shaft bending; choose the orientation for the moment load before locking shoulder geometry.
Typical equipment & failure modes
Common applications
- pump and blower drive shafts with combined load
- truck and trailer axle hubs on inch-dimensioned axles
- agricultural tractor transmission and PTO shafts
- industrial gearboxes built to inch shafting
Known failure patterns
- rib-face scoring when the thrust share of the combined load exceeds what the cone rib of this size carries
- false brinelling on a stationary pair exposed to vibration during transport or standby
- preload loss and noise after one bearing of the adjusted pair is replaced without resetting end play
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- rolling-contact fatigue spalling after the catalogue L10 life at the actual combined load
Selection pitfalls — read before you substitute
- Hub and pinion positions of this 44.45 mm class are adjusted in pairs; verify end play against the axle or gearbox drawing and re-torque after bedding-in instead of trusting the first setting on 4T-HM903249/HM903210.
- The heavy-medium HM family is proportioned for a high thrust share; swapping to a lighter LM or pure-numeric series at the same 44.45 mm bore cuts axial capacity even when the envelope fits — re-verify the load split before downgrading.
- Never drive the 95.25 mm cup home through the rollers: fitting force goes through the ring faces only, or brinell marks release as noise within the first running hours.
- Inch and metric bores collide on paper — 44.45 mm is 1.75 in, not a round metric size; a metric bearing that seems 0.1 mm off will not seat on the inch shaft.
- Never drive the 95.25 mm cup home through the rollers: fitting force goes through the ring faces only, or brinell marks release as noise within the first running hours.
- The 107/116 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-HM903249/HM903210; internal geometry legitimately differs between inch-series makers, so re-verify ratings, adjustment and the exact cone/cup references before substituting another brand on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 4T-HM903249/HM903210?
4T-HM903249/HM903210 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 44.45 mm bore (1.75 in), 95.25 mm outside diameter and 30.958 mm assembled width T (3.75 × 1.219 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 107 kN, C0 116 kN, grease limiting speed 3,700 r/min, oil speed 4,900 r/min, mass about 999 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-HM903249/HM903210 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the HM903249 cone or the HM903210 cup can be replaced by an identical reference from NTN or another ABMA-dimensioned maker. Pairing the cone with a different cup reference is a different catalogue row: OD, assembled T and the 107/116 kN ratings change with the cup.
What is the difference between 4T-HM903249/HM903210 and a metric ISO 355 tapered bearing?
4T-HM903249/HM903210 follows the ABMA inch boundary plan with cone/cup references; ISO 355 bearings use metric dimension-series numbers (302, 322, …). Even where a metric size looks close to 44.45×95.25×30.958 mm, the envelopes and contact angles differ — the two systems are not drop-in interchangeable; check every boundary value before substituting.
What does the 4T prefix on 4T-HM903249/HM903210 mean?
4T is NTN's tapered roller bearing quality mark, stamped on cone and cup in the factory. It identifies NTN's 4T programme and is not a dimension or variant code, so interchange lists quote the bare HM903249/HM903210 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-HM903249/HM903210 list two speeds, 3,700 and 4,900 r/min?
The lower figure, 3,700 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 4T-HM903249/HM903210 at 4,900 r/min because oil removes rib-contact heat better. Real limits still depend on pair adjustment, oil flow and cooling.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN 2203E 2026-09-25 on 2026-10-01. Read our editorial & correction policy.