7318-NTN bearing: complete specifications & equivalents
The 7318-NTN 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 | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 189 kN |
| Basic static load rating C0 | 147 kN |
| Fatigue load limit Pu | 9.7 kN |
| Limiting speed (mechanical) | 4000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 5060 g |
| Manufacturer designation | NTN 7318 |
| 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 & 7300-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 7300-series | 10 mm |
| Largest outer diameter in 7300-series | 420 mm |
| Width range across 7300-series | 11–80 mm |
| Bore position in 7300-series (smallest first) | 19 of 32 |
| Bore above smallest 7300-series size | 80 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7318 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×190×43 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7318-BECBM | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×190×43 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7318-BECBP | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×190×43 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7318-BECBY | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×190×43 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7318-BEGAPH | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×190×43 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7318-BEM | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×190×43 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7318-BEP | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×190×43 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 7318-NTN model number is decoded
From the heavy-duty 7300 single-row family, 7318 measures 90 mm across the bore, 190 mm over the outer ring and 43 mm across the faces. Two fields make up the code — 73 is the single-row dimension series (heavy-duty 7300 single-row family) and 18 encodes the 90 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 oil rating of 5,300 r/min sits 1,300 r/min above the 4,000 r/min grease figure — a 1.32x step that says how much headroom oil cooling buys. 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. 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
- 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
- contamination-induced denting — hard particles rolled into the contact ellipse become the initiation points for surface fatigue
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 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.
- Substituting the B (40 deg) execution for the standard 30 deg bearing changes the axial/radial load split — the shaft position and the mating bearing see different forces even though the envelope is identical.
- 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 4,000 r/min with preload; check the grease speed factor against the catalogue figure.
- The 189/147 kN ratings and 9.7 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7318; 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 7318?
7318 is a single-row angular 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 189 kN, C0 147 kN and a 9.7 kN fatigue load limit Pu; the grease limiting speed is 4,000 r/min and the oil rating 5,300 r/min; mass about 5060 g.
How is the 7318 designation structured?
73 is the single-row dimension series (heavy-duty 7300 single-row family); 18 encodes the 90 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 43 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7318 support?
One 7318 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 7318?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 4,000 r/min and the oil rating 5,300 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 7318?
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 189 kN / C0 147 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.