780-772 bearing: complete specifications & equivalents
The 780-772 is a ANSI ABMA 19.2 radial bearing sized 101.6 x 180.975 x 47.625 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 101.6 mm |
| Outer diameter D | 180.975 mm |
| Width B | 47.625 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 315 kN |
| Basic static load rating C0 | 430 kN |
| Limiting speed (mechanical) | 2000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 5120 g |
| Manufacturer designation | NTN 4T-780/772 |
| 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 | 4 in |
|---|---|
| Outer diameter D | 7.125 in |
| Width B | 1.875 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 39.7 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) | 119 of 148 |
| Bore above smallest 4t-inch-series size | 88.89999999999999 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 780 | 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 780-772 model number is decoded
For an inch shaft of 101.6 mm carrying combined radial and thrust load, NTN lists 4T-780/772, a single-row 4T tapered roller set of 315 kN C and 430 kN C0 inside the 180.975 mm OD cup. Unlike ISO 355 metric numbers, this ABMA code does not encode the bore arithmetically: 780 identifies the cone of 101.6 mm (4 in) bore by catalogue lookup, and 772 fixes the 180.975 mm OD. The 39.7 mm radial section over the 101.6 mm bore positions the contact line of the pair; abutment shoulders and spacers are dimensioned from that geometry, not from the bore alone. Cup-side note for 772: within the pure-numeric inch family tables the 780 cone is listed against several cup options, and it is the cup that fixes the 180.975 mm OD and the 47.625 mm assembled width — quote the full 780/772 pair, never the cone alone. Back-to-back (O) and face-to-face (X) arrangements of two 4T-780/772 sets react differently to shaft bending; choose the orientation for the moment load before locking shoulder geometry.
Typical equipment & failure modes
Common applications
- crusher and screening-plant eccentric shafts
- heavy truck and bus drive-axle differentials
- plant gearboxes on inch-dimensioned shaft lines
- large conveyor head pulleys in bulk-handling plant
Known failure patterns
- cone-rib and roller large-end smearing when the adjusted pair runs with preload but starved lubricant film
- 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 fatigue when the pair runs continuously near the grease limiting speed without oil cooling
- brinell marks on cone and cup raceways from impact during handling or hammer fitting
Selection pitfalls — read before you substitute
- Mount the 101.6 mm cone by induction heating (max 120 °C) and the 180.975 mm cup with a press sleeve; at 5120 g a cocked ring brinells the raceway directly.
- The pure-numeric inch family at 101.6 mm bore (180.975×47.625 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 780/772 reference at purchase.
- Grease packs must leave free volume inside the 47.625 mm-wide set; over-greasing a pair churning near the oil-band speed of 2,700 r/min raises temperature and destroys the setting.
- An unloaded 4T-780/772 near 2,000 r/min lets rollers skid and smear the cone rib; spring-preload lightly loaded high-speed pairs.
- Shaft and housing fillets must clear the ring chamfers of 780 and 772; use undercut shoulders so the rings seat on the face, not on a radius.
- The 315/430 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-780/772; 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-780/772?
4T-780/772 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 101.6 mm bore (4 in), 180.975 mm outside diameter and 47.625 mm assembled width T (7.125 × 1.875 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 315 kN, C0 430 kN, grease limiting speed 2,000 r/min, oil speed 2,700 r/min, mass about 5120 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-780/772 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 780 cone or the 772 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 315/430 kN ratings change with the cup.
What is the difference between 4T-780/772 and a metric ISO 355 tapered bearing?
4T-780/772 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 101.6×180.975×47.625 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-780/772 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 780/772 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-780/772 list two speeds, 2,000 and 2,700 r/min?
The lower figure, 2,000 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-780/772 at 2,700 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.