7309-NTN bearing: complete specifications & equivalents
The 7309-NTN is a ISO 15 radial bearing sized 45 x 100 x 25 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 45 mm |
| Outer diameter D | 100 mm |
| Width B | 25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 70.5 kN |
| Basic static load rating C0 | 44 kN |
| Fatigue load limit Pu | 3.45 kN |
| Limiting speed (mechanical) | 7800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 837 g |
| Manufacturer designation | NTN 7309 |
| 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 | 1.772 in |
|---|---|
| Outer diameter D | 3.937 in |
| Width B | 0.984 in |
| ISO bore code | 09 |
| Radial section height (D−d)/2 | 27.5 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) | 10 of 32 |
| Bore above smallest 7300-series size | 35 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7309 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×25 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7309-ACCBM | SKF | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
| 7309-BE-2RZP | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×25 mm envelope per ISO 15; seal variant (OPEN vs RSR) and load ratings differ — confirm sealing and rating before substituting. |
| 7309-BECBM | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×25 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7309-BECBP | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×25 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7309-BECBY | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×25 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7309-BEGAPH | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×25 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7309-BEP | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×25 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 7309-NTN model number is decoded
7309 is an NTN single-row angular contact ball bearing: heavy-duty 7300 single-row family, listed in NTN Ball and Roller Bearings CAT.No.2203E at 45 x 100 x 25 mm. Decoding 7309: 73 is the single-row dimension series (heavy-duty 7300 single-row family), with 09 encodes the 45 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 static margin, C0 44 kN versus C 70.5 kN, is what supports slow oscillating duty and shock without immediate brinelling. The 45/100/25 envelope is an ISO 15 boundary plan, so dimensional interchange with other makers holds — ratings and internal geometry do not automatically follow. Set preload or end-play with the pair as a unit and lock the adjustment; a single angular-contact bearing cannot run free like a deep-groove one.
Typical equipment & failure modes
Common applications
- conveyor drive and tension-drum shafts
- agricultural gearbox and PTO shaft supports
- printing-press cylinder and folder shafts
- machine-tool spindle cartridges and driven tooling
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
- pressed-steel cage pocket wear and rivet loosening after repeated ball skid at light load and high speed
- current-erosion pitting on VFD-driven motor shafts, first visible as a grey frosted band across both raceways
- current-erosion pitting on VFD-driven motor shafts, first visible as a grey frosted band across both raceways
Selection pitfalls — read before you substitute
- In this size class the common miss is lubrication interval, not fit — a 45 mm spindle at the catalogue speeds needs a calculated relubrication plan, not a calendar one.
- 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 7,800 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.
- 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.
- Do not pair two random 7309 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 70.5/44 kN ratings and 3.45 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7309; 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 7309?
7309 is a single-row angular contact ball bearing to ISO 15: 45 mm bore, 100 mm outside diameter, 25 mm width (1.772 x 3.937 x 0.984 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 70.5 kN, C0 44 kN and a 3.45 kN fatigue load limit Pu; the grease limiting speed is 7,800 r/min and the oil rating 10,000 r/min; mass about 837 g.
How is the 7309 designation structured?
73 is the single-row dimension series (heavy-duty 7300 single-row family); 09 encodes the 45 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 100 mm OD and 25 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7309 support?
One 7309 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 7309?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 7,800 r/min and the oil rating 10,000 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 7309?
The 45/100/25 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 70.5 kN / C0 44 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.