21075-21212 bearing: complete specifications & equivalents
The 21075-21212 is a ANSI ABMA 19.2 radial bearing sized 19.05 x 53.975 x 22.225 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 19.05 mm |
| Outer diameter D | 53.975 mm |
| Width B | 22.225 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 44.5 kN |
| Basic static load rating C0 | 39 kN |
| Limiting speed (mechanical) | 8000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 248 g |
| Manufacturer designation | NTN 4T-21075/21212 |
| 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 | 0.75 in |
|---|---|
| Outer diameter D | 2.125 in |
| Width B | 0.875 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 17.5 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) | 6 of 148 |
| Bore above smallest 4t-inch-series size | 6.350000000000001 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 21075 | 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 21075-21212 model number is decoded
For an inch shaft of 19.05 mm carrying combined radial and thrust load, NTN lists 4T-21075/21212, a single-row 4T tapered roller set of 44.5 kN C and 39 kN C0 inside the 53.975 mm OD cup. Cone and cup of 4T-21075/21212 are separately stocked parts: a worn 21212 cup can be replaced against the existing 21075 cone, provided the new cup carries the identical reference — pairing across references changes the 22.225 mm assembled width and the rating. Grease relubrication at the 8,000 r/min limiting speed targets the cone-rib contact; sustaining 11,000 r/min needs an oil supply directed at the large roller ends. The printed 44.5/39 kN ratings belong to the assembled 21075+21212 pair; a sibling row using the same cone with a different cup carries its own rating row because the raceway track shifts with the cup. Running clearance of 4T-21075/21212 is set at mounting by axial displacement of cone or cup — the catalogue does not ship a preloaded set, so the drawing must state end play or preload.
Typical equipment & failure modes
Common applications
- small agricultural implement wheels and auger drives
- lawn, garden and powersport axle positions
- small inch-shaft gearbox and reducer shafts
- conveyor roller and pulley shafts in inch-frame machinery
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
- indentation of the raceways by hard particles in an open, unsealed arrangement
Selection pitfalls — read before you substitute
- At 19.05 mm (0.75 in) bore the thin cone and cup distort under an over-tight shaft nut; set the 4T-21075/21212 pair with a dial indicator on end play rather than by locknut feel.
- The pure-numeric inch family at 19.05 mm bore (53.975×22.225 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 21075/21212 reference at purchase.
- Do not confuse T (22.225 mm, the assembled cone-plus-cup width) with the cone width when drawing spacers; an abutment sized to T leaves the cup unseated.
- Inch and metric bores collide on paper — 19.05 mm is 0.75 in, not a round metric size; a metric bearing that seems 0.1 mm off will not seat on the inch shaft.
- Fit selection follows the rotating ring: a rotating cone on a 19.05 mm shaft takes a k5/m5 seat, and a rotating cup reverses the logic — decide from the load diagram, not from habit.
- The 44.5/39 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-21075/21212; 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-21075/21212?
4T-21075/21212 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 19.05 mm bore (0.75 in), 53.975 mm outside diameter and 22.225 mm assembled width T (2.125 × 0.875 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 44.5 kN, C0 39 kN, grease limiting speed 8,000 r/min, oil speed 11,000 r/min, mass about 248 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-21075/21212 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 21075 cone or the 21212 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 44.5/39 kN ratings change with the cup.
What is the difference between 4T-21075/21212 and a metric ISO 355 tapered bearing?
4T-21075/21212 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 19.05×53.975×22.225 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-21075/21212 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 21075/21212 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-21075/21212 list two speeds, 8,000 and 11,000 r/min?
The lower figure, 8,000 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-21075/21212 at 11,000 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.