7906 bearing: complete specifications & equivalents
The 7906 is a ISO 15 radial bearing sized 30 x 47 x 9 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 30 mm |
| Outer diameter D | 47 mm |
| Width B | 9 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 8.35 kN |
| Basic static load rating C0 | 5.75 kN |
| Fatigue load limit Pu | 0.4 kN |
| Limiting speed (mechanical) | 14000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 58 g |
| Manufacturer designation | NTN 7906 |
| 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 | 1.181 in |
|---|---|
| Outer diameter D | 1.85 in |
| Width B | 0.354 in |
| ISO bore code | 06 |
| Radial section height (D−d)/2 | 8.5 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) | 2 of 32 |
| Bore above smallest 7900-series size | 5 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7906 | 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 7906 model number is decoded
7906 is the 30 mm bore member of NTN's extra-light, high-speed 7900 single-row family, with a 47 mm outside diameter and 9 mm section width. Two fields make up the code — 79 is the single-row dimension series (extra-light, high-speed 7900 single-row family) and 06 encodes the 30 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. On speed, the grease limiting speed is 14,000 r/min and the oil rating 19,000 r/min. For a 30 mm shaft with combined load, the practical shortlist is this series, its 7000-series standard section, and — where thrust reverses — a back-to-back pair rather than a single row. 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
- loss of preload after housing-fret or shaft creep, leaving the pair loose — ball skidding, cage rattle and a falling natural frequency follow
- pressed-steel cage pocket wear and rivet loosening after repeated ball skid at light load and high speed
- lubricant starvation scoring at the ball/raceway contact when grease volume or relubrication interval is guessed instead of calculated
- contamination-induced denting — hard particles rolled into the contact ellipse become the initiation points for surface fatigue
Selection pitfalls — read before you substitute
- In this size class the common miss is lubrication interval, not fit — a 30 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 5.75 kN really covers the worst static case before substituting it for a 7000.
- Never use a four-point or double-row bearing as a like-for-like swap for a single 7906 without re-checking axial float, heat and housing width — the kinematics differ.
- On a 30 mm shaft, an interference fit eats internal clearance; skipping the clearance/preload recalculation is the classic cause of a new bearing running 20 deg C hotter than the drawing suggests.
- The C0 of 5.75 kN is a static rating, not a permissible running thrust — sizing continuous axial load from C0 alone is a recurring drawing-office error.
- The 8.35/5.75 kN ratings and 0.4 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7906; 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 7906?
7906 is a single-row angular contact ball bearing to ISO 15: 30 mm bore, 47 mm outside diameter, 9 mm width (1.181 x 1.85 x 0.354 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 8.35 kN, C0 5.75 kN and a 0.4 kN fatigue load limit Pu; the grease limiting speed is 14,000 r/min and the oil rating 19,000 r/min; mass about 58 g.
How is the 7906 designation structured?
79 is the single-row dimension series (extra-light, high-speed 7900 single-row family); 06 encodes the 30 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 47 mm OD and 9 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7906 support?
One 7906 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 7906?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 14,000 r/min and the oil rating 19,000 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 7906?
The 30/47/9 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 8.35 kN / C0 5.75 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.