7221-NTN bearing: complete specifications & equivalents
The 7221-NTN is a ISO 15 radial bearing sized 105 x 190 x 36 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 105 mm |
| Outer diameter D | 190 mm |
| Width B | 36 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 173 kN |
| Basic static load rating C0 | 142 kN |
| Fatigue load limit Pu | 9.1 kN |
| Limiting speed (mechanical) | 3700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3790 g |
| Manufacturer designation | NTN 7221 |
| Standard | ISO 15 |
| 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 & 7200-series range
| Bore d | 4.134 in |
|---|---|
| Outer diameter D | 7.48 in |
| Width B | 1.417 in |
| ISO bore code | 21 |
| Radial section height (D−d)/2 | 42.5 mm |
| Smallest bore in 7200-series | 10 mm |
| Largest outer diameter in 7200-series | 540 mm |
| Width range across 7200-series | 9–85 mm |
| Bore position in 7200-series (smallest first) | 22 of 36 |
| Bore above smallest 7200-series size | 95 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7221 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 105×190×36 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7221-BECBM | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 105×190×36 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7221-BECBP | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 105×190×36 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
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 7221-NTN model number is decoded
At 105 x 190 x 36 mm, NTN 7221 sits in the medium-duty 7200 single-row family of the angular-contact programme. Reading the code: 72 is the single-row dimension series (medium-duty 7200 single-row family), 21 encodes the 105 mm bore (bore code x 5); with no letter after the digits it is the standard 30 deg contact-angle execution — the 40 deg version carries a B. Catalogue mass is about 3790 g, which at this 42.5 mm radial section keeps the bearing comfortably inside high-speed spindle weight budgets. Against a deep-groove bearing of the same 105 mm bore, this bearing trades some pure-radial comfort for real one-direction thrust capacity and higher running accuracy. Heat-mounting to 80-90 deg C is the clean route onto a 105 mm shaft; drive-fits through the balls transmit force through the contact ellipse and can brinell it.
Typical equipment & failure modes
Common applications
- large pump, fan and compressor rotor shafts
- crane and hoist gearbox shafts
- paper-machine roll and calendar drives
- extruder and mixer gearbox output shafts
Known failure patterns
- impact brinelling dents on the 30 deg contact path after a shaft-side hammer blow during mounting, because axial shock travels straight through the contact angle
- loss of preload after housing-fret or shaft creep, leaving the pair loose — ball skidding, cage rattle and a falling natural frequency follow
- resin-cage cracking on the 7900-series sizes after hot, dry running or solvent attack on the polymer
- flaking that starts at the raceway shoulder on the thrust-loaded side when axial load repeatedly exceeds the design share
- edge loading and early spalling from housing bores that are out of round or shoulders that are too small for the ring face
Selection pitfalls — read before you substitute
- Bearings of 105 mm bore arrive heavy enough that handling damage (dents from slings, tilting on the shaft) is a real failure precursor — use proper lifting and heating kit.
- The standard 30 deg bearing and its B (40 deg) sibling share the envelope; picking between them is a load-direction decision, not a quality upgrade.
- The 3,700 r/min speed figure assumes the catalogue lubrication state and a correctly set pair; real limits drop fast with excess grease fill or heavy preload.
- A 7221 mounted the wrong way round still turns smoothly by hand; the failure shows up weeks later as raceway flaking on the unloaded-looking side.
- If the application vibrates at standstill (transport, idle machine next to a running line), specify protection: the contact ellipse of a preloaded bearing false-brinells faster than a loose one.
- The 173/142 kN ratings and 9.1 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7221; internal geometry legitimately differs between manufacturers, so re-verify ratings, contact angle and suffix before substituting another make on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 7221?
7221 is a single-row angular contact ball bearing to ISO 15: 105 mm bore, 190 mm outside diameter, 36 mm width (4.134 x 7.48 x 1.417 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 173 kN, C0 142 kN and a 9.1 kN fatigue load limit Pu; the grease limiting speed is 3,700 r/min and the oil rating 5,000 r/min; mass about 3790 g.
How is the 7221 designation structured?
72 is the single-row dimension series (medium-duty 7200 single-row family); 21 encodes the 105 mm bore (bore code x 5); with no letter after the digits it is the standard 30 deg contact-angle execution — the 40 deg version carries a B. The 190 mm OD and 36 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7221 support?
One 7221 alone takes thrust in one direction only, along its 30 deg contact angle; reversing thrust calls for a second bearing or a factory-matched DB/DF/DT pair (the catalogue right-hand columns list the paired ratings). Radial load is always carried as a combined load through the angled contact.
What lubrication speeds does NTN print for 7221?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 3,700 r/min and the oil rating 5,000 r/min. These are catalogue ceilings for a correctly mounted bearing with the stated lubricant; preload, fill quantity, ambient heat and paired arrangements all move the real limit.
What should be checked before substituting another make for 7221?
The 105/190/36 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 173 kN / C0 142 kN, the speed figures, contact angle and suffix meaning against the donor catalogue before swapping on a rated drive.
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.