QJ318 bearing: complete specifications & equivalents
The QJ318 is a ISO 15 radial bearing sized 90 x 190 x 43 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 90 mm |
| Outer diameter D | 190 mm |
| Width B | 43 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 235 kN |
| Basic static load rating C0 | 410 kN |
| Fatigue load limit Pu | 14.8 kN |
| Limiting speed (mechanical) | 2800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 6310 g |
| Manufacturer designation | NTN QJ318 |
| 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 & QJ300-series range
| Bore d | 3.543 in |
|---|---|
| Outer diameter D | 7.48 in |
| Width B | 1.693 in |
| ISO bore code | 18 |
| Radial section height (D−d)/2 | 50 mm |
| Smallest bore in QJ300-series | 17 mm |
| Largest outer diameter in QJ300-series | 400 mm |
| Width range across QJ300-series | 14–78 mm |
| Bore position in QJ300-series (smallest first) | 16 of 28 |
| Bore above smallest QJ300-series size | 73 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| QJ318 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the supplier. |
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 QJ318 model number is decoded
NTN QJ318 belongs to the heavy-duty QJ300 four-point family: the catalogue boundary dimensions read 90 / 190 / 43 mm (bore / OD / width). The designation breaks down as QJ3 is the four-point dimension series (heavy-duty QJ300 four-point family); the last two digits 18 give the bore by the standard code table (90 mm); there is no suffix — the split inner ring and 35 deg contact angle are inherent to the QJ design. On speed, the grease limiting speed is 2,800 r/min and the oil rating 3,800 r/min. When axial load reverses, specify the bearing as a matched pair (DB, DF or DT) instead of two random singles — the catalogue right-hand columns give the paired ratings for exactly this reason. Heat-mounting to 80-90 deg C is the clean route onto a 90 mm shaft; drive-fits through the balls transmit force through the contact ellipse and can brinell it.
Typical equipment & failure modes
Common applications
- extruder and mixer gearbox output shafts
- mining conveyor head-shaft positions
- marine auxiliary and winch gearbox shafts
- rolling-mill and metalworking drive 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
- thermal runaway from excessive preload: the pair runs hot, grease darkens and the contact ellipse spreads until the raceways smear
- machined-cage land scoring when a high-speed spindle runs past its grease rating and the cage runs dry on its guidance surface
- edge loading and early spalling from housing bores that are out of round or shoulders that are too small for the ring face
- lubricant starvation scoring at the ball/raceway contact when grease volume or relubrication interval is guessed instead of calculated
Selection pitfalls — read before you substitute
- Bearings of 90 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.
- Do not pair two random QJ318 bearings from stock and expect catalogue paired ratings — matched-set grinding is what makes DB/DF/DT preload behave, and NTN sells those as separate order numbers.
- The 2,800 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.
- The C0 of 410 kN is a static rating, not a permissible running thrust — sizing continuous axial load from C0 alone is a recurring drawing-office error.
- The 235/410 kN ratings and 14.8 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for QJ318; 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 QJ318?
QJ318 is a four-point contact ball bearing to ISO 15: 90 mm bore, 190 mm outside diameter, 43 mm width (3.543 x 7.48 x 1.693 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 235 kN, C0 410 kN and a 14.8 kN fatigue load limit Pu; the grease limiting speed is 2,800 r/min and the oil rating 3,800 r/min; mass about 6310 g.
How is the QJ318 designation structured?
QJ3 is the four-point dimension series (heavy-duty QJ300 four-point family); the last two digits 18 give the bore by the standard code table (90 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 43 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does QJ318 support?
QJ318 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 QJ318?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 2,800 r/min and the oil rating 3,800 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 QJ318?
The 90/190/43 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 235 kN / C0 410 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.