A4059-A4138-NTN bearing: complete specifications & equivalents
The A4059-A4138-NTN is a ANSI ABMA 19.2 radial bearing sized 14.989 x 34.988 x 10.998 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 14.989 mm |
| Outer diameter D | 34.988 mm |
| Width B | 10.998 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 13.7 kN |
| Basic static load rating C0 | 11.6 kN |
| Limiting speed (mechanical) | 12000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 49 g |
| Manufacturer designation | NTN 4T-A4059/A4138 |
| 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 | 0.59 in |
|---|---|
| Outer diameter D | 1.377 in |
| Width B | 0.433 in |
| ISO bore code | 59 |
| Radial section height (D−d)/2 | 10 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) | 2 of 148 |
| Bore above smallest 4t-inch-series size | 2.2890000000000015 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| A4059-A4138 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 14.989×34.988×10.998 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 A4059-A4138-NTN model number is decoded
The NTN 2203E inch table prints 4T-A4059/A4138 at 14.989 mm bore (0.59 in), 34.988 mm cup OD and 10.998 mm assembled T, with a grease limiting speed of 12,000 r/min and an oil ceiling of 16,000 r/min. Unlike ISO 355 metric numbers, this ABMA code does not encode the bore arithmetically: A4059 identifies the cone of 14.989 mm (0.59 in) bore by catalogue lookup, and A4138 fixes the 34.988 mm OD. Speed planning uses both catalogue columns: grease 12,000 r/min is the mechanical ceiling for 4T-A4059/A4138, oil 16,000 r/min with circulating oil — a 4,000 r/min margin at this size. Housing fitment sequence for 4T-A4059/A4138: press the A4138 cup square into the 34.988 mm seat first, then bring the A4059 cone (on its 14.989 mm shaft) into adjustment — the two references are separate engineering parts that happen to ship as one set. A single-row tapered bearing reacts thrust in one direction only; 4T-A4059/A4138 is adjusted against a second bearing so the shaft is located in both directions.
Typical equipment & failure modes
Common applications
- light trailer and boat-trailer wheel hubs
- small agricultural implement wheels and auger drives
- lawn, garden and powersport axle positions
- small inch-shaft gearbox and reducer shafts
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
- fretting corrosion on a loose cone seat that creeps under rotating load
Selection pitfalls — read before you substitute
- At 14.989 mm (0.59 in) bore the thin cone and cup distort under an over-tight shaft nut; set the 4T-A4059/A4138 pair with a dial indicator on end play rather than by locknut feel.
- The A small-size family at 14.989 mm bore (34.988×10.998 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full A4059/A4138 reference at purchase.
- Shaft and housing fillets must clear the ring chamfers of A4059 and A4138; use undercut shoulders so the rings seat on the face, not on a radius.
- Fit selection follows the rotating ring: a rotating cone on a 14.989 mm shaft takes a j5/k5 seat, and a rotating cup reverses the logic — decide from the load diagram, not from habit.
- Grease packs must leave free volume inside the 10.998 mm-wide set; over-greasing a pair churning near the oil-band speed of 16,000 r/min raises temperature and destroys the setting.
- The 13.7/11.6 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-A4059/A4138; 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-A4059/A4138?
4T-A4059/A4138 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 14.989 mm bore (0.59 in), 34.988 mm outside diameter and 10.998 mm assembled width T (1.377 × 0.433 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 13.7 kN, C0 11.6 kN, grease limiting speed 12,000 r/min, oil speed 16,000 r/min, mass about 49 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-A4059/A4138 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the A4059 cone or the A4138 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 13.7/11.6 kN ratings change with the cup.
What is the difference between 4T-A4059/A4138 and a metric ISO 355 tapered bearing?
4T-A4059/A4138 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 14.989×34.988×10.998 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-A4059/A4138 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 A4059/A4138 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-A4059/A4138 list two speeds, 12,000 and 16,000 r/min?
The lower figure, 12,000 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-A4059/A4138 at 16,000 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.