L44643-L44610 bearing: complete specifications & equivalents
The L44643-L44610 is a ANSI ABMA 19.2 radial bearing sized 25.4 x 50.292 x 14.224 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 25.4 mm |
| Outer diameter D | 50.292 mm |
| Width B | 14.224 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 32 kN |
| Basic static load rating C0 | 34 kN |
| Limiting speed (mechanical) | 7400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 130 g |
| Manufacturer designation | NTN 4T-L44643/L44610 |
| 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 in |
|---|---|
| Outer diameter D | 1.98 in |
| Width B | 0.56 in |
| ISO bore code | 43 |
| Radial section height (D−d)/2 | 12.4 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) | 19 of 148 |
| Bore above smallest 4t-inch-series size | 12.7 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| L44643-610 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 25.4×50.292×14.224 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 L44643-L44610 model number is decoded
4T-L44643/L44610 is the NTN 4T catalogue entry for a 25.4×50.292×14.224 mm inch tapered roller bearing — an ABMA-dimensioned cone/cup set, not an ISO 355 metric bearing, even though the table quotes metric equivalents. 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 — L44643 sits in the light L family. Imperial cross-check for the drawing: 25.4×50.292×14.224 mm converts to 1 × 1.98 × 0.56 in; the ABMA envelope swaps with like-numbered inch parts but the 32/34 kN ratings are NTN-specific. The printed 32/34 kN ratings belong to the assembled L44643+L44610 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. NTN grades inch 4T bearings as open bearings without integral seals; at 25.4 mm bore the application supplies sealing and the grease fill or oil feed.
Typical equipment & failure modes
Common applications
- machine-tool headstocks on inch spindles
- pump and blower drive shafts with combined load
- truck and trailer axle hubs on inch-dimensioned axles
- agricultural tractor transmission and PTO shafts
Known failure patterns
- rib-face scoring when the thrust share of the combined load exceeds what the cone rib of this size carries
- cup creep and housing fretting when the cup seat is cut too loose for the rotating load
- flaking on one cone only when a bent shaft loads the O/X pair unevenly
- cage damage from a mounting blow transmitted through the roller complement
- water-induced pitting when the open bearing sees washdown without external seals
Selection pitfalls — read before you substitute
- Hub and pinion positions of this 25.4 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-L44643/L44610.
- The light L family at 25.4 mm bore (50.292×14.224 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full L44643/L44610 reference at purchase.
- Never drive the 50.292 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.
- Replacing one half of an adjusted pair without resetting end play negates the 14.224 mm T logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- Grease packs must leave free volume inside the 14.224 mm-wide set; over-greasing a pair churning near the oil-band speed of 9,900 r/min raises temperature and destroys the setting.
- The 32/34 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-L44643/L44610; 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-L44643/L44610?
4T-L44643/L44610 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 25.4 mm bore (1 in), 50.292 mm outside diameter and 14.224 mm assembled width T (1.98 × 0.56 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 32 kN, C0 34 kN, grease limiting speed 7,400 r/min, oil speed 9,900 r/min, mass about 130 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-L44643/L44610 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the L44643 cone or the L44610 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 32/34 kN ratings change with the cup.
What is the difference between 4T-L44643/L44610 and a metric ISO 355 tapered bearing?
4T-L44643/L44610 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 25.4×50.292×14.224 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-L44643/L44610 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 L44643/L44610 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-L44643/L44610 list two speeds, 7,400 and 9,900 r/min?
The lower figure, 7,400 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-L44643/L44610 at 9,900 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.