QJ221 bearing: complete specifications & equivalents
The QJ221 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 | brass |
| Basic dynamic load rating C | 218 kN |
| Basic static load rating C0 | 400 kN |
| Fatigue load limit Pu | 14.2 kN |
| Limiting speed (mechanical) | 2700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 4750 g |
| Manufacturer designation | NTN QJ221 |
| 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 & QJ200-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 QJ200-series | 15 mm |
| Largest outer diameter in QJ200-series | 360 mm |
| Width range across QJ200-series | 11–58 mm |
| Bore position in QJ200-series (smallest first) | 19 of 29 |
| Bore above smallest QJ200-series size | 90 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the QJ221 model number is decoded
The medium-duty QJ200 four-point family entry QJ221 carries a 105 mm bore in a 190 mm outside diameter, 36 mm wide envelope. Reading the code: QJ2 is the four-point dimension series (medium-duty QJ200 four-point family), the last two digits 21 give the bore by the standard code table (105 mm); there is no suffix — the split inner ring and 35 deg contact angle are inherent to the QJ design. The oil rating of 3,600 r/min sits 900 r/min above the 2,700 r/min grease figure — a 1.33x step that says how much headroom oil cooling buys. 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. Shaft and housing shoulders must clear the ring corners yet support enough face — the catalogue abutment diameters for the 105 mm bore give the working limits.
Typical equipment & failure modes
Common applications
- marine auxiliary and winch gearbox shafts
- rolling-mill and metalworking drive shafts
- large pump, fan and compressor rotor shafts
- crane and hoist gearbox shafts
Known failure patterns
- false brinelling on the raceway contact ellipses when a preloaded spindle sits vibrating at standstill — visible as evenly spaced flute-like wear at ball pitch
- 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
- current-erosion pitting on VFD-driven motor shafts, first visible as a grey frosted band across both raceways
- 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 QJ split inner ring must be clamped by the shaft nut/shoulder on both halves — assembling it against a single small shoulder leaves one half-ring free to walk.
- Never use a four-point or double-row bearing as a like-for-like swap for a single QJ221 without re-checking axial float, heat and housing width — the kinematics differ.
- On a 105 mm shaft, an interference fit eats internal clearance; skipping the clearance/preload recalculation is the classic cause of a new bearing running 20 deg C hotter than the drawing suggests.
- Grease rated for deep-groove motor duty is not automatically right at 2,700 r/min with preload; check the grease speed factor against the catalogue figure.
- The 218/400 kN ratings and 14.2 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for QJ221; 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 QJ221?
QJ221 is a four-point 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 218 kN, C0 400 kN and a 14.2 kN fatigue load limit Pu; the grease limiting speed is 2,700 r/min and the oil rating 3,600 r/min; mass about 4750 g.
How is the QJ221 designation structured?
QJ2 is the four-point dimension series (medium-duty QJ200 four-point family); the last two digits 21 give the bore by the standard code table (105 mm); there is no suffix — the split inner ring and 35 deg contact angle are inherent to the QJ design. The 190 mm OD and 36 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does QJ221 support?
QJ221 is a four-point contact bearing: the split inner ring lets each ball touch the raceways at two points, so one bearing locates the shaft in both axial directions at its 35 deg contact angle. It is normally mounted with slight radial clearance against the housing as the axial-locating member.
What lubrication speeds does NTN print for QJ221?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 2,700 r/min and the oil rating 3,600 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 QJ221?
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 218 kN / C0 400 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.