7909 bearing: complete specifications & equivalents
The 7909 is a ISO 15 radial bearing sized 45 x 68 x 12 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 | 68 mm |
| Width B | 12 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 17.4 kN |
| Basic static load rating C0 | 12.9 kN |
| Fatigue load limit Pu | 0.9 kN |
| Limiting speed (mechanical) | 10000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 150 g |
| Manufacturer designation | NTN 7909 |
| 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 & 7900-series range
| Bore d | 1.772 in |
|---|---|
| Outer diameter D | 2.677 in |
| Width B | 0.472 in |
| ISO bore code | 09 |
| Radial section height (D−d)/2 | 11.5 mm |
| Smallest bore in 7900-series | 25 mm |
| Largest outer diameter in 7900-series | 420 mm |
| Width range across 7900-series | 9–56 mm |
| Bore position in 7900-series (smallest first) | 5 of 32 |
| Bore above smallest 7900-series size | 20 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7909 | 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 7909 model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, 7909 appears as a extra-light, high-speed 7900 single-row family bearing of 45 mm bore, 68 mm outside diameter and 12 mm width. The designation breaks down as 79 is the single-row dimension series (extra-light, high-speed 7900 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 oil rating of 14,000 r/min sits 4,000 r/min above the 10,000 r/min grease figure — a 1.40x step that says how much headroom oil cooling buys. The 45/68/12 envelope is an ISO 15 boundary plan, so dimensional interchange with other makers holds — ratings and internal geometry do not automatically follow. Shaft and housing shoulders must clear the ring corners yet support enough face — the catalogue abutment diameters for the 45 mm bore give the working limits.
Typical equipment & failure modes
Common applications
- electric motor shafts with axial locating duty
- conveyor drive and tension-drum shafts
- agricultural gearbox and PTO shaft supports
- printing-press cylinder and folder 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
- 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
- flaking that starts at the raceway shoulder on the thrust-loaded side when axial load repeatedly exceeds the design share
- 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
- 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 7900 extra-light section is chosen for speed and stiffness, not for load margin — check that C0 12.9 kN really covers the worst static case before substituting it for a 7000.
- A 7909 mounted the wrong way round still turns smoothly by hand; the failure shows up weeks later as raceway flaking on the unloaded-looking side.
- Grease rated for deep-groove motor duty is not automatically right at 10,000 r/min with preload; check the grease speed factor against the catalogue figure.
- Grease rated for deep-groove motor duty is not automatically right at 10,000 r/min with preload; check the grease speed factor against the catalogue figure.
- The 17.4/12.9 kN ratings and 0.9 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7909; 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 7909?
7909 is a single-row angular contact ball bearing to ISO 15: 45 mm bore, 68 mm outside diameter, 12 mm width (1.772 x 2.677 x 0.472 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 17.4 kN, C0 12.9 kN and a 0.9 kN fatigue load limit Pu; the grease limiting speed is 10,000 r/min and the oil rating 14,000 r/min; mass about 150 g.
How is the 7909 designation structured?
79 is the single-row dimension series (extra-light, high-speed 7900 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 68 mm OD and 12 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7909 support?
One 7909 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 7909?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 10,000 r/min and the oil rating 14,000 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 7909?
The 45/68/12 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 17.4 kN / C0 12.9 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.