QJ312 bearing: complete specifications & equivalents
The QJ312 is a ISO 15 radial bearing sized 60 x 130 x 31 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 60 mm |
| Outer diameter D | 130 mm |
| Width B | 31 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 135 kN |
| Basic static load rating C0 | 198 kN |
| Fatigue load limit Pu | 8.5 kN |
| Limiting speed (mechanical) | 4200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2180 g |
| Manufacturer designation | NTN QJ312 |
| 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 | 2.362 in |
|---|---|
| Outer diameter D | 5.118 in |
| Width B | 1.22 in |
| ISO bore code | 12 |
| Radial section height (D−d)/2 | 35 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) | 10 of 28 |
| Bore above smallest QJ300-series size | 43 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| QJ312 | 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 QJ312 model number is decoded
The heavy-duty QJ300 four-point family entry QJ312 carries a 60 mm bore in a 130 mm outside diameter, 31 mm wide envelope. NTN builds the number from QJ3 is the four-point dimension series (heavy-duty QJ300 four-point family), then the last two digits 12 give the bore by the standard code table (60 mm); there is no suffix — the split inner ring and 35 deg contact angle are inherent to the QJ design. At roughly 35.0 mm of radial section, the catalogue still quotes 135 kN dynamic capacity for the 60 mm bore. Selection starts from the thrust share: as axial load grows past roughly half the radial load, an angular-contact position of this section usually outlives a deep-groove one. Mount with the thrust against the marked face: the contact angle runs from the low shoulder of the inner ring to the high shoulder of the outer ring, and reversing it throws the capacity away.
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
- 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
- current-erosion pitting on VFD-driven motor shafts, first visible as a grey frosted band across both raceways
- flaking that starts at the raceway shoulder on the thrust-loaded side when axial load repeatedly exceeds the design share
Selection pitfalls — read before you substitute
- Bearings of 60 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.
- Catalogue mass and ratings belong to the open execution; shields, seals and resin cages change both the speed ceiling and the thermal behaviour of the same basic size.
- Grease rated for deep-groove motor duty is not automatically right at 4,200 r/min with preload; check the grease speed factor against the catalogue figure.
- Catalogue mass and ratings belong to the open execution; shields, seals and resin cages change both the speed ceiling and the thermal behaviour of the same basic size.
- The 135/198 kN ratings and 8.5 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for QJ312; 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 QJ312?
QJ312 is a four-point contact ball bearing to ISO 15: 60 mm bore, 130 mm outside diameter, 31 mm width (2.362 x 5.118 x 1.22 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 135 kN, C0 198 kN and a 8.5 kN fatigue load limit Pu; the grease limiting speed is 4,200 r/min and the oil rating 5,700 r/min; mass about 2180 g.
How is the QJ312 designation structured?
QJ3 is the four-point dimension series (heavy-duty QJ300 four-point family); the last two digits 12 give the bore by the standard code table (60 mm); there is no suffix — the split inner ring and 35 deg contact angle are inherent to the QJ design. The 130 mm OD and 31 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does QJ312 support?
QJ312 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 QJ312?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 4,200 r/min and the oil rating 5,700 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 QJ312?
The 60/130/31 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 135 kN / C0 198 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.