7917 bearing: complete specifications & equivalents
The 7917 is a ISO 15 radial bearing sized 85 x 120 x 18 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 85 mm |
| Outer diameter D | 120 mm |
| Width B | 18 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 40 kN |
| Basic static load rating C0 | 38 kN |
| Fatigue load limit Pu | 2.49 kN |
| Limiting speed (mechanical) | 5500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 628 g |
| Manufacturer designation | NTN 7917 |
| 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 | 3.346 in |
|---|---|
| Outer diameter D | 4.724 in |
| Width B | 0.709 in |
| ISO bore code | 17 |
| Radial section height (D−d)/2 | 17.5 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) | 13 of 32 |
| Bore above smallest 7900-series size | 60 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7917 | 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 7917 model number is decoded
NTN 7917 belongs to the extra-light, high-speed 7900 single-row family: the catalogue boundary dimensions read 85 / 120 / 18 mm (bore / OD / width). The designation breaks down as 79 is the single-row dimension series (extra-light, high-speed 7900 single-row family); 17 encodes the 85 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 7,400 r/min sits 1,900 r/min above the 5,500 r/min grease figure — a 1.35x step that says how much headroom oil cooling buys. Selection starts from the thrust share: as axial load grows past roughly half the radial load, an angular-contact position of this section usually outlives a deep-groove one. 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
- rolling-mill and metalworking drive shafts
- large pump, fan and compressor rotor shafts
- crane and hoist gearbox shafts
- paper-machine roll and calendar drives
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
- lubricant starvation scoring at the ball/raceway contact when grease volume or relubrication interval is guessed instead of calculated
- 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
- Bearings of 85 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 7900 extra-light section is chosen for speed and stiffness, not for load margin — check that C0 38 kN really covers the worst static case before substituting it for a 7000.
- A single-row angular contact left loose on the shaft to "help assembly" will fret the seat: the contact angle keeps driving the ring axially under load.
- On a 85 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.
- Grease rated for deep-groove motor duty is not automatically right at 5,500 r/min with preload; check the grease speed factor against the catalogue figure.
- The 40/38 kN ratings and 2.49 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7917; 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 7917?
7917 is a single-row angular contact ball bearing to ISO 15: 85 mm bore, 120 mm outside diameter, 18 mm width (3.346 x 4.724 x 0.709 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 40 kN, C0 38 kN and a 2.49 kN fatigue load limit Pu; the grease limiting speed is 5,500 r/min and the oil rating 7,400 r/min; mass about 628 g.
How is the 7917 designation structured?
79 is the single-row dimension series (extra-light, high-speed 7900 single-row family); 17 encodes the 85 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 120 mm OD and 18 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7917 support?
One 7917 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 7917?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 5,500 r/min and the oil rating 7,400 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 7917?
The 85/120/18 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 40 kN / C0 38 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.