749-742 bearing: complete specifications & equivalents
The 749-742 is a ANSI ABMA 19.2 radial bearing sized 85.026 x 150.089 x 44.45 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 85.026 mm |
| Outer diameter D | 150.089 mm |
| Width B | 44.45 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 289 kN |
| Basic static load rating C0 | 360 kN |
| Limiting speed (mechanical) | 2400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3240 g |
| Manufacturer designation | NTN 4T-749/742 |
| 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 | 3.347 in |
|---|---|
| Outer diameter D | 5.909 in |
| Width B | 1.75 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 32.5 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) | 103 of 148 |
| Bore above smallest 4t-inch-series size | 72.326 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 749 | 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 749-742 model number is decoded
4T-749/742 belongs to the NTN inch 4T tapered roller range (pure-numeric inch family); cone and cup are ordered by their own references and are individually interchangeable with like-numbered parts. Cone and cup of 4T-749/742 are separately stocked parts: a worn 742 cup can be replaced against the existing 749 cone, provided the new cup carries the identical reference — pairing across references changes the 44.45 mm assembled width and the rating. Grease relubrication at the 2,400 r/min limiting speed targets the cone-rib contact; sustaining 3,200 r/min needs an oil supply directed at the large roller ends. Cup-side note for 742: within the pure-numeric inch family tables the 749 cone is listed against several cup options, and it is the cup that fixes the 150.089 mm OD and the 44.45 mm assembled width — quote the full 749/742 pair, never the cone alone. Mount the 85.026 mm cone with an induction heater (max 120 °C) and press the 150.089 mm cup with a sleeve; driving either ring through the rollers brinells the raceways.
Typical equipment & failure modes
Common applications
- off-highway and forestry machine axles
- marine winch and deck-machinery shafts
- crusher and screening-plant eccentric shafts
- heavy truck and bus drive-axle differentials
Known failure patterns
- rib-face scoring when the thrust share of the combined load exceeds what the cone rib of this size carries
- flaking on one cone only when a bent shaft loads the O/X pair unevenly
- cup creep and housing fretting when the cup seat is cut too loose for the rotating load
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- brinell marks on cone and cup raceways from impact during handling or hammer fitting
Selection pitfalls — read before you substitute
- Mount the 85.026 mm cone by induction heating (max 120 °C) and the 150.089 mm cup with a press sleeve; at 3240 g a cocked ring brinells the raceway directly.
- The pure-numeric inch family at 85.026 mm bore (150.089×44.45 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 749/742 reference at purchase.
- Shaft and housing fillets must clear the ring chamfers of 749 and 742; use undercut shoulders so the rings seat on the face, not on a radius.
- Grease packs must leave free volume inside the 44.45 mm-wide set; over-greasing a pair churning near the oil-band speed of 3,200 r/min raises temperature and destroys the setting.
- Fit selection follows the rotating ring: a rotating cone on a 85.026 mm shaft takes a k5/m5 seat, and a rotating cup reverses the logic — decide from the load diagram, not from habit.
- The 289/360 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-749/742; 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-749/742?
4T-749/742 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 85.026 mm bore (3.347 in), 150.089 mm outside diameter and 44.45 mm assembled width T (5.909 × 1.75 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 289 kN, C0 360 kN, grease limiting speed 2,400 r/min, oil speed 3,200 r/min, mass about 3240 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-749/742 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 749 cone or the 742 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 289/360 kN ratings change with the cup.
What is the difference between 4T-749/742 and a metric ISO 355 tapered bearing?
4T-749/742 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 85.026×150.089×44.45 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-749/742 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 749/742 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-749/742 list two speeds, 2,400 and 3,200 r/min?
The lower figure, 2,400 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-749/742 at 3,200 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.