7934 bearing: complete specifications & equivalents
The 7934 is a ISO 15 radial bearing sized 170 x 230 x 28 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 170 mm |
| Outer diameter D | 230 mm |
| Width B | 28 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 115 kN |
| Basic static load rating C0 | 129 kN |
| Fatigue load limit Pu | 6.05 kN |
| Limiting speed (mechanical) | 2700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3290 g |
| Manufacturer designation | NTN 7934 |
| 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 | 6.693 in |
|---|---|
| Outer diameter D | 9.055 in |
| Width B | 1.102 in |
| ISO bore code | 34 |
| Radial section height (D−d)/2 | 30 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) | 24 of 32 |
| Bore above smallest 7900-series size | 145 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7934 | 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 7934 model number is decoded
7934 is the 170 mm bore member of NTN's extra-light, high-speed 7900 single-row family, with a 230 mm outside diameter and 28 mm section width. Reading the code: 79 is the single-row dimension series (extra-light, high-speed 7900 single-row family), 34 encodes the 170 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 dynamic rating C is 115 kN against C0 129 kN — a C0/C ratio of 1.12 that is typical of an angular-contact contact ellipse. Against a deep-groove bearing of the same 170 mm bore, this bearing trades some pure-radial comfort for real one-direction thrust capacity and higher running accuracy. After mounting, check axial float or preload with a dial gauge on the shaft end — the specification, not hand feel, decides whether the contact angle works as rated.
Typical equipment & failure modes
Common applications
- crusher and mill pinion shafts
- large pump and turbine auxiliary shafts
- steel-plant conveyor and table roll drives
- wind-turbine and heavy-machinery auxiliaries
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
- resin-cage cracking on the 7900-series sizes after hot, dry running or solvent attack on the polymer
- lubricant starvation scoring at the ball/raceway contact when grease volume or relubrication interval is guessed instead of calculated
- edge loading and early spalling from housing bores that are out of round or shoulders that are too small for the ring face
Selection pitfalls — read before you substitute
- At this size the shaft fit, shoulder geometry and preload procedure dominate the outcome; a 170 mm bore bearing forgives nothing in a poorly machined housing.
- The 7900 extra-light section is chosen for speed and stiffness, not for load margin — check that C0 129 kN really covers the worst static case before substituting it for a 7000.
- On a 170 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.
- Catalogue mass and ratings belong to the open execution; shields, seals and resin cages change both the speed ceiling and the thermal behaviour of the same basic size.
- 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.
- The 115/129 kN ratings and 6.05 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7934; 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 7934?
7934 is a single-row angular contact ball bearing to ISO 15: 170 mm bore, 230 mm outside diameter, 28 mm width (6.693 x 9.055 x 1.102 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 115 kN, C0 129 kN and a 6.05 kN fatigue load limit Pu; the grease limiting speed is 2,700 r/min and the oil rating 3,600 r/min; mass about 3290 g.
How is the 7934 designation structured?
79 is the single-row dimension series (extra-light, high-speed 7900 single-row family); 34 encodes the 170 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 230 mm OD and 28 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7934 support?
One 7934 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 7934?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 2,700 r/min and the oil rating 3,600 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 7934?
The 170/230/28 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 115 kN / C0 129 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.