7911 bearing: complete specifications & equivalents
The 7911 is a ISO 15 radial bearing sized 55 x 80 x 13 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 55 mm |
| Outer diameter D | 80 mm |
| Width B | 13 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 19.2 kN |
| Basic static load rating C0 | 16.1 kN |
| Fatigue load limit Pu | 1.07 kN |
| Limiting speed (mechanical) | 8400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 214 g |
| Manufacturer designation | NTN 7911 |
| 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 | 2.165 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 0.512 in |
| ISO bore code | 11 |
| Radial section height (D−d)/2 | 12.5 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) | 7 of 32 |
| Bore above smallest 7900-series size | 30 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7911 | 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 7911 model number is decoded
The extra-light, high-speed 7900 single-row family entry 7911 carries a 55 mm bore in a 80 mm outside diameter, 13 mm wide envelope. NTN builds the number from 79 is the single-row dimension series (extra-light, high-speed 7900 single-row family), then 11 encodes the 55 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. Catalogue mass is about 214 g, which at this 12.5 mm radial section keeps the bearing comfortably inside high-speed spindle weight budgets. If the duty is mainly high speed with modest thrust, the 7900-series cross-section is the lighter alternative; if thrust dominates, the 7300-series section carries more. A 55 mm shaft typically takes a k5/m5 fit for rotating inner-ring load; keep the housing bore to G6/H6 class so the contact geometry is not distorted.
Typical equipment & failure modes
Common applications
- gearbox input shafts under helical-gear thrust
- electric motor shafts with axial locating duty
- conveyor drive and tension-drum shafts
- agricultural gearbox and PTO shaft supports
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
- machined-cage land scoring when a high-speed spindle runs past its grease rating and the cage runs dry on its guidance surface
- contamination-induced denting — hard particles rolled into the contact ellipse become the initiation points for surface fatigue
- 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
- In this size class the common miss is lubrication interval, not fit — a 55 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 16.1 kN really covers the worst static case before substituting it for a 7000.
- On a 55 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.
- If the application vibrates at standstill (transport, idle machine next to a running line), specify protection: the contact ellipse of a preloaded bearing false-brinells faster than a loose one.
- If the application vibrates at standstill (transport, idle machine next to a running line), specify protection: the contact ellipse of a preloaded bearing false-brinells faster than a loose one.
- The 19.2/16.1 kN ratings and 1.07 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7911; 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 7911?
7911 is a single-row angular contact ball bearing to ISO 15: 55 mm bore, 80 mm outside diameter, 13 mm width (2.165 x 3.15 x 0.512 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 19.2 kN, C0 16.1 kN and a 1.07 kN fatigue load limit Pu; the grease limiting speed is 8,400 r/min and the oil rating 11,000 r/min; mass about 214 g.
How is the 7911 designation structured?
79 is the single-row dimension series (extra-light, high-speed 7900 single-row family); 11 encodes the 55 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 80 mm OD and 13 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7911 support?
One 7911 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 7911?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 8,400 r/min and the oil rating 11,000 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 7911?
The 55/80/13 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 19.2 kN / C0 16.1 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.