HM911242-HM911210 bearing: complete specifications & equivalents
The HM911242-HM911210 is a ANSI ABMA 19.2 radial bearing sized 53.975 x 130.175 x 36.512 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 53.975 mm |
| Outer diameter D | 130.175 mm |
| Width B | 36.512 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 173 kN |
| Basic static load rating C0 | 186 kN |
| Limiting speed (mechanical) | 2700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2280 g |
| Manufacturer designation | NTN 4T-HM911242/HM911210 |
| 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 | 2.125 in |
|---|---|
| Outer diameter D | 5.125 in |
| Width B | 1.437 in |
| ISO bore code | 42 |
| Radial section height (D−d)/2 | 38.1 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) | 67 of 148 |
| Bore above smallest 4t-inch-series size | 41.275000000000006 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| HM911242 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
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 HM911242-HM911210 model number is decoded
4T-HM911242/HM911210 belongs to the NTN inch 4T tapered roller range (heavy-medium HM family); cone and cup are ordered by their own references and are individually interchangeable with like-numbered parts. Unlike ISO 355 metric numbers, this ABMA code does not encode the bore arithmetically: HM911242 identifies the cone of 53.975 mm (2.125 in) bore by catalogue lookup, and HM911210 fixes the 130.175 mm OD. Grease relubrication at the 2,700 r/min limiting speed targets the cone-rib contact; sustaining 3,600 r/min needs an oil supply directed at the large roller ends. The printed 173/186 kN ratings belong to the assembled HM911242+HM911210 pair; a sibling row using the same cone with a different cup carries its own rating row because the raceway track shifts with the cup. Contact-pattern check with marking blue: a pattern biased to one roller end means the 53.975 mm pair is misadjusted and the set will edge-load in service.
Typical equipment & failure modes
Common applications
- mining and quarry conveyor drive pulleys
- machine-tool headstocks on inch spindles
- pump and blower drive shafts with combined load
- truck and trailer axle hubs on inch-dimensioned axles
Known failure patterns
- cone-rib and roller large-end smearing when the adjusted pair runs with preload but starved lubricant film
- preload loss and noise after one bearing of the adjusted pair is replaced without resetting end play
- false brinelling on a stationary pair exposed to vibration during transport or standby
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- indentation of the raceways by hard particles in an open, unsealed arrangement
Selection pitfalls — read before you substitute
- Hub and pinion positions of this 53.975 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-HM911242/HM911210.
- The heavy-medium HM family is proportioned for a high thrust share; swapping to a lighter LM or pure-numeric series at the same 53.975 mm bore cuts axial capacity even when the envelope fits — re-verify the load split before downgrading.
- Do not confuse T (36.512 mm, the assembled cone-plus-cup width) with the cone width when drawing spacers; an abutment sized to T leaves the cup unseated.
- Do not confuse T (36.512 mm, the assembled cone-plus-cup width) with the cone width when drawing spacers; an abutment sized to T leaves the cup unseated.
- ABMA makes the 53.975×130.175 mm envelope interchangeable, not the ratings: NTN prints 173/186 kN for this execution and another make of the same number can differ in roller complement.
- The 173/186 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-HM911242/HM911210; 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-HM911242/HM911210?
4T-HM911242/HM911210 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 53.975 mm bore (2.125 in), 130.175 mm outside diameter and 36.512 mm assembled width T (5.125 × 1.437 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 173 kN, C0 186 kN, grease limiting speed 2,700 r/min, oil speed 3,600 r/min, mass about 2280 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-HM911242/HM911210 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the HM911242 cone or the HM911210 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 173/186 kN ratings change with the cup.
What is the difference between 4T-HM911242/HM911210 and a metric ISO 355 tapered bearing?
4T-HM911242/HM911210 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 53.975×130.175×36.512 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-HM911242/HM911210 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 HM911242/HM911210 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-HM911242/HM911210 list two speeds, 2,700 and 3,600 r/min?
The lower figure, 2,700 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-HM911242/HM911210 at 3,600 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.