74550-74850 bearing: complete specifications & equivalents
The 74550-74850 is a ANSI ABMA 19.2 radial bearing sized 136.525 x 215.9 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 | 136.525 mm |
| Outer diameter D | 215.9 mm |
| Width B | 47.625 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 355 kN |
| Basic static load rating C0 | 540 kN |
| Limiting speed (mechanical) | 1600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 6050 g |
| Manufacturer designation | NTN 4T-74550/74850 |
| 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 | 5.375 in |
|---|---|
| Outer diameter D | 8.5 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) | 137 of 148 |
| Bore above smallest 4t-inch-series size | 123.825 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 74550 | 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 74550-74850 model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, the order number 4T-74550/74850 denotes the pure-numeric inch family of NTN inch tapered roller bearings — cone 74550 and cup 74850 delivered as a matched, separable pair of 136.525 mm bore and 215.9 mm outside diameter. 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 — 74550 sits in the pure-numeric inch family. Catalogue mass of the 4T-74550/74850 cone-plus-cup set is 6050 g; shaft and housing shoulders must carry that mass square to the axis during fitting. Housing fitment sequence for 4T-74550/74850: press the 74850 cup square into the 215.9 mm seat first, then bring the 74550 cone (on its 136.525 mm shaft) into adjustment — the two references are separate engineering parts that happen to ship as one set. Mount the 136.525 mm cone with an induction heater (max 120 °C) and press the 215.9 mm cup with a sleeve; driving either ring through the rollers brinells the raceways.
Typical equipment & failure modes
Common applications
- heavy press and forging-machine drive shafts
- port-crane travel and hoist gearboxes
- cement-plant mill and kiln drive trains
- large shredder and recycler main shafts
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
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- edge loading when shaft deflection exceeds the few arc-minutes an adjusted pair tolerates
Selection pitfalls — read before you substitute
- At 136.525 mm bore the 4T-74550/74850 set is adjusted with hydraulic nuts or measured shims on mill and crane positions; manual torque methods cannot control preload at the 355 kN C level.
- The pure-numeric inch family at 136.525 mm bore (215.9×47.625 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 74550/74850 reference at purchase.
- Replacing one half of an adjusted pair without resetting end play negates the 47.625 mm T logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- Fit selection follows the rotating ring: a rotating cone on a 136.525 mm shaft takes a m6/n6 seat, and a rotating cup reverses the logic — decide from the load diagram, not from habit.
- ABMA makes the 136.525×215.9 mm envelope interchangeable, not the ratings: NTN prints 355/540 kN for this execution and another make of the same number can differ in roller complement.
- The 355/540 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-74550/74850; 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-74550/74850?
4T-74550/74850 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 136.525 mm bore (5.375 in), 215.9 mm outside diameter and 47.625 mm assembled width T (8.5 × 1.875 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 355 kN, C0 540 kN, grease limiting speed 1,600 r/min, oil speed 2,100 r/min, mass about 6050 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-74550/74850 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 74550 cone or the 74850 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 355/540 kN ratings change with the cup.
What is the difference between 4T-74550/74850 and a metric ISO 355 tapered bearing?
4T-74550/74850 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 136.525×215.9×47.625 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-74550/74850 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 74550/74850 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-74550/74850 list two speeds, 1,600 and 2,100 r/min?
The lower figure, 1,600 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-74550/74850 at 2,100 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.