HM813844-HM813810 bearing: complete specifications & equivalents
The HM813844-HM813810 is a ANSI ABMA 19.2 radial bearing sized 66.675 x 127 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 | 66.675 mm |
| Outer diameter D | 127 mm |
| Width B | 36.512 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 181 kN |
| Basic static load rating C0 | 228 kN |
| Limiting speed (mechanical) | 2900 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2030 g |
| Manufacturer designation | NTN 4T-HM813844/HM813810 |
| 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 | 2.625 in |
|---|---|
| Outer diameter D | 5 in |
| Width B | 1.437 in |
| ISO bore code | 44 |
| Radial section height (D−d)/2 | 30.2 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) | 84 of 148 |
| Bore above smallest 4t-inch-series size | 53.974999999999994 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| HM813844 | 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 HM813844-HM813810 model number is decoded
For an inch shaft of 66.675 mm carrying combined radial and thrust load, NTN lists 4T-HM813844/HM813810, a single-row 4T tapered roller set of 181 kN C and 228 kN C0 inside the 127 mm OD cup. The 4T prefix is NTN's tapered roller quality mark stamped on both parts; it is a brand mark, not a size code, so cross-references quote HM813844/HM813810 without it. Catalogue mass of the 4T-HM813844/HM813810 cone-plus-cup set is 2030 g; shaft and housing shoulders must carry that mass square to the axis during fitting. Cup-side note for HM813810: within the heavy-medium HM family tables the HM813844 cone is listed against several cup options, and it is the cup that fixes the 127 mm OD and the 36.512 mm assembled width — quote the full HM813844/HM813810 pair, never the cone alone. Fillet radii must clear the chamfers of the HM813844 cone and HM813810 cup; undercut shoulders seat the rings fully instead of bridging on a radius.
Typical equipment & failure modes
Common applications
- large conveyor head pulleys in bulk-handling plant
- paper-machine and calender roll supports
- off-highway and forestry machine axles
- marine winch and deck-machinery shafts
Known failure patterns
- rib-face scoring when the thrust share of the combined load exceeds what the cone rib of this size carries
- 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
- cage damage from a mounting blow transmitted through the roller complement
- rolling-contact fatigue spalling after the catalogue L10 life at the actual combined load
Selection pitfalls — read before you substitute
- Mount the 66.675 mm cone by induction heating (max 120 °C) and the 127 mm cup with a press sleeve; at 2030 g a cocked ring brinells the raceway directly.
- The heavy-medium HM family is proportioned for a high thrust share; swapping to a lighter LM or pure-numeric series at the same 66.675 mm bore cuts axial capacity even when the envelope fits — re-verify the load split before downgrading.
- Shaft and housing fillets must clear the ring chamfers of HM813844 and HM813810; use undercut shoulders so the rings seat on the face, not on a radius.
- Never drive the 127 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.
- 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.
- The 181/228 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-HM813844/HM813810; 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-HM813844/HM813810?
4T-HM813844/HM813810 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 66.675 mm bore (2.625 in), 127 mm outside diameter and 36.512 mm assembled width T (5 × 1.437 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 181 kN, C0 228 kN, grease limiting speed 2,900 r/min, oil speed 3,800 r/min, mass about 2030 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-HM813844/HM813810 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the HM813844 cone or the HM813810 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 181/228 kN ratings change with the cup.
What is the difference between 4T-HM813844/HM813810 and a metric ISO 355 tapered bearing?
4T-HM813844/HM813810 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 66.675×127×36.512 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-HM813844/HM813810 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 HM813844/HM813810 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-HM813844/HM813810 list two speeds, 2,900 and 3,800 r/min?
The lower figure, 2,900 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-HM813844/HM813810 at 3,800 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.