NN4934 bearing: complete specifications & equivalents
The NN4934 is a ISO 15 radial bearing sized 170 x 230 x 60 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 | 60 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 400 kN |
| Basic static load rating C0 | 765 kN |
| Fatigue load limit Pu | 75.5 kN |
| Limiting speed (mechanical) | 2500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 6560 g |
| Manufacturer designation | NTN NN4934 |
| 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 & NN4900-series range
| Bore d | 6.693 in |
|---|---|
| Outer diameter D | 9.055 in |
| Width B | 2.362 in |
| ISO bore code | 34 |
| Radial section height (D−d)/2 | 30 mm |
| Smallest bore in NN4900-series | 100 mm |
| Largest outer diameter in NN4900-series | 440 mm |
| Width range across NN4900-series | 40–118 mm |
| Bore position in NN4900-series (smallest first) | 9 of 18 |
| Bore above smallest NN4900-series size | 70 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NN4934 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
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 NN4934 model number is decoded
NN4934 is the extra-light (10/49) section of the NTN NN4900 dimension series for a 170 mm shaft — 400 kN of basic dynamic capacity in a 6560 g, open bearing. The leading NN defines the rib arrangement (double row, ribbed inner ring, separable outer); the dimension-series digits and the two-digit bore code resolve to 170 mm, with 230 mm OD and 60 mm width from the ISO 15 general plan. NTN ships these bearings open with normal (CN) radial clearance and P0 tolerance as standard; precision classes and C3/C4 clearance are separate order suffixes, not part of NN4934. The 170 mm (6.693 in) bore and 230 mm (9.055 in) OD are ISO 15 boundary values; fillet and shoulder dimensions must still come from the NTN mounting table for the 60 mm-wide ring. Provide axial location with an adjacent locating bearing rather than expecting the float cylindrical set to hold thrust on the 170 mm shaft.
Typical equipment & failure modes
Common applications
- precision rotary-table and dividing-head bearings
- high-speed turbine and turbo-blower rotor supports
- coordinate-measuring and semiconductor-equipment drives
- machine-tool main spindles requiring high radial stiffness
Known failure patterns
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- cage wear accelerated when the EA high-capacity roller complement runs continuously above its thermal balance
- roller-end and raceway scoring from inadequate oil flow under heavy radial load
- electrical pitting on VFD-driven motor shafts without grounding protection
- false brinelling on standby machines exposed to external vibration
Selection pitfalls — read before you substitute
- At 170 mm bore, oil-lubricated arrangements toward 2,900 r/min need positive flow and drain design; the 6560 g NN4934 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Open NN4934 units need application-supplied sealing and a defined lubricant schedule; film thickness is the first failure mode for line contact when viscosity drops at the 170 mm contact.
- Grease limiting speed 2,500 r/min and oil 2,900 r/min are different limits for NN4934: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- Open NN4934 units need application-supplied sealing and a defined lubricant schedule; film thickness is the first failure mode for line contact when viscosity drops at the 170 mm contact.
- Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 230 mm race brinells and releases as vibration within hours.
- The 400/765 kN ratings, 75.5 kN Pu and 6560 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NN4934 (standard execution); other makes sharing the ISO 15 envelope revise internal geometry without changing the order number, so keep the 2203E reference with the specification for critical drives.
Frequently asked questions
What are the dimensions and catalogue data of NN4934?
NN4934 is an NTN NN double-row precision cylindrical roller bearing to ISO 15: 170 mm bore, 230 mm OD and 60 mm width (6.693 × 9.055 × 2.362 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 400 kN, C0 765 kN, Pu 75.5 kN, grease limiting speed 2,500 r/min, oil 2,900 r/min, mass about 6560 g. It is open, with a machined or stamped steel cage per the precision execution.
What is the difference between NU, NJ, NUP, N and NF cylindrical roller bearings?
NN and NNU are double-row precision designs rather than single-row rib variants: NN has a ribbed inner ring and separable outer ring, NNU the reverse; both give high radial stiffness for spindles and are commonly ordered with P5/P4 precision and a K 1:12 tapered bore for preload setting. NN4934 is the NN execution.
What do the EA, E and ＊ suffixes mean on NTN cylindrical roller bearings?
EA is NTN's high-capacity design with a pressed sheet-steel cage and optimised roller complement in the same ISO 15 envelope; E marks the high-capacity design at the larger bores; the ＊ symbol printed before the code in the NTN catalogue marks the ULTAGE new-generation specification and is not typed as part of the order number. NN4934 is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NN bearing like NN4934?
NN4934 has a cylindrical bore and mounts on a plain machined shaft seat; a K execution (1:12 taper) exists in the NN4900 series when preload must be set by drive-up on a tapered seat.
What do Fw and Ew mean for NN4934?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 188.5 mm, Ew 216.5179 mm. The nominal bore/OD remain 170/230 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 2,500 r/min grease / 2,900 r/min oil.
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.