T4CB120 bearing: complete specifications & equivalents
The T4CB120 is a ISO 355 radial bearing sized 120 x 170 x 27 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 120 mm |
| Outer diameter D | 170 mm |
| Width B | 27 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 171 kN |
| Basic static load rating C0 | 235 kN |
| Limiting speed (mechanical) | 1900 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1690 g |
| Manufacturer designation | NTN T4CB120 |
| Standard | ISO 355 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); 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 & T4CB-series range
| Bore d | 4.724 in |
|---|---|
| Outer diameter D | 6.693 in |
| Width B | 1.063 in |
| ISO bore code | 20 |
| Radial section height (D−d)/2 | 25 mm |
| Smallest bore in T4CB-series | 100 mm |
| Largest outer diameter in T4CB-series | 195 mm |
| Width range across T4CB-series | 24–29 mm |
| Bore position in T4CB-series (smallest first) | 2 of 3 |
| Bore above smallest T4CB-series size | 20 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| T4CB120 | 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 T4CB120 model number is decoded
NTN supplies this 120 mm bore tapered roller position as T4CB120: one cone assembly, one cup, line-contact rollers and a steel cage, rated 171 kN basic dynamic and 235 kN static on the large-size ISO 355 tapered-roller family. Digit by digit, the bare number identifies the large-size ISO 355 tapered-roller family and a bore code resolving to 120 mm; 170 mm OD and 27 mm assembled T are the matching ISO 355 boundary dimensions shared with other makers of the same dimension series. The T2/T4/T7-style code is NTN's large-size tapered roller designation within ISO 355; it identifies the dimension series and 120 mm bore directly, and remains an open 4T execution ordered under its own code. Speed planning uses both catalogue columns: grease 1,900 r/min is the cage/rib mechanical ceiling for T4CB120, oil 2,600 r/min is available with circulating oil — a 700 r/min margin at this size. Mount the 120 mm-bore cone on the shaft first (induction heat, max 120 °C), fit the cup square in its housing, then set preload or end play; never drive the cup home through the rollers of T4CB120.
Typical equipment & failure modes
Common applications
- wind-turbine gearbox and main-shaft arrangements
- offshore crane and drawworks drums
- heavy haul railway traction gearboxes
- large marine propulsion reduction gears
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- smearing on the roller large ends and cone rib after a dry start with preload but no oil film
- flaking on one cone only when a back-to-back / face-to-face pair is loaded unevenly by a bent shaft
- cage damage from a mounting blow delivered through the roller complement instead of the ring face
- water-induced pitting when the open bearing is exposed to washdown without external seals
Selection pitfalls — read before you substitute
- At 120 mm bore the T4CB120 set is adjusted with hydraulic nuts on large mill and wind positions; follow the drive-up angle/end-play procedure, because manual torque methods cannot control preload at the 171 kN C level.
- The large-size ISO 355 tapered-roller family at 120 mm bore (170×27 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 2,600 r/min oil ceiling.
- Minimum load matters at high speed: an unloaded T4CB120 at a large fraction of 1,900 r/min lets rollers skid and smear the cone rib; spring-preload lightly loaded pair arrangements.
- Replacing one half of an adjusted pair without resetting end play negates the 27 mm T dimension logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- ISO 355 makes the 120×170 mm envelope interchangeable but not the ratings: NTN prints 171/235 kN for this execution, and a cheaper same-number part can differ in roller complement and steel.
- The 171/235 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for T4CB120 (ISO 355 4CB); internal geometry legitimately differs between manufacturers, so re-verify ratings, adjustment and suffix before substituting another make on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN T4CB120?
T4CB120 is a metric 4T tapered roller bearing to ISO 355: 120 mm bore, 170 mm outside diameter and 27 mm assembled width T (4.724 × 6.693 × 1.063 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 171 kN, C0 235 kN (2203E prints no Pu for this size), grease limiting speed 1,900 r/min, oil speed 2,600 r/min, mass about 1690 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on T4CB120?
4T is NTN's tapered roller bearing brand mark, stamped on the cone and cup in the factory. It identifies the NTN 4T programme and is not a dimension, so the catalogue and this page list the bare ISO 355 number (T4CB120); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the T4CB120 designation encode the 120 mm bore and what is 4CB?
trailing dimension block 120 prints the 120 mm bore directly for this large-size T-code. The 170 mm OD and 27 mm assembled T follow the ISO 355 dimension-series plan. 4CB is the maker-neutral ISO 355 abbreviation for this dimension series (the same code other manufacturers print); 4T is NTN's own brand mark.
Why does T4CB120 list two speeds, 1,900 and 2,600 r/min?
The lower figure, 1,900 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates T4CB120 at 2,600 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on T4CB120 mean?
The T2/T4/T7-style code is NTN's large-size tapered roller designation within ISO 355; it identifies the dimension series and 120 mm bore directly, and remains an open 4T execution ordered under its own code.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.