NN3008 bearing: complete specifications & equivalents
The NN3008 is a ISO 15 radial bearing sized 40 x 68 x 21 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 40 mm |
| Outer diameter D | 68 mm |
| Width B | 21 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 48 kN |
| Basic static load rating C0 | 55.5 kN |
| Fatigue load limit Pu | 6.75 kN |
| Limiting speed (mechanical) | 9700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 312 g |
| Manufacturer designation | NTN NN3008 |
| 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 & NN3000-series range
| Bore d | 1.575 in |
|---|---|
| Outer diameter D | 2.677 in |
| Width B | 0.827 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 14 mm |
| Smallest bore in NN3000-series | 25 mm |
| Largest outer diameter in NN3000-series | 680 mm |
| Width range across NN3000-series | 16–163 mm |
| Bore position in NN3000-series (smallest first) | 4 of 40 |
| Bore above smallest NN3000-series size | 15 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NN3008 | 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 NN3008 model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, NN3008 appears as a 40 mm bore single-row cylindrical roller bearing (48 kN C / 55.5 kN C0) with a machined or stamped steel cage per the precision execution, listed to the ISO 15 boundary plan. 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 40 mm, with 68 mm OD and 21 mm width from the ISO 15 general plan. The roller-set pitch sits inside the 14.0 mm radial section between the 40 mm bore and 68 mm OD; NTN prints Fw/Ew raceway diameters only for selected executions. With the inner ring rotating, catalogue practice is a k5/m5 shaft seat and an H7/H6 housing; the outer ring must remain free to creep slightly axially in non-locating NN arrangements. Housing and shaft fillets must clear the ring chamfers of NN3008; an oversized radius locks the ring on its face and tilts the 21 mm-wide seat.
Typical equipment & failure modes
Common applications
- high-speed turbine and turbo-blower rotor supports
- coordinate-measuring and semiconductor-equipment drives
- machine-tool main spindles requiring high radial stiffness
- precision gearbox and indexing-drive shafts
Known failure patterns
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- pressed-steel cage pocket wear when rollers skid at light load or too-thin lubricant
- grease starvation and cage drag when relubrication intervals are extended past the grease life
- fretting corrosion on a loose rotating shaft seat
- brinelling from static overload or impact during handling
Selection pitfalls — read before you substitute
- On this 40 mm bore, shaft thermal growth can preload the inner ring if the fit is too tight; verify residual interference at temperature and confirm the float ring still slides after mounting NN3008.
- The NN rib arrangement is not interchangeable with another prefix on the same 40 mm seat: double row, ribbed inner ring, separable outer. Swapping NU for NJ changes axial location behaviour even though the 68×21 mm envelope matches.
- Open NN3008 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 40 mm contact.
- The NN rib arrangement is not interchangeable with another prefix on the same 40 mm seat: double row, ribbed inner ring, separable outer. Swapping NU for NJ changes axial location behaviour even though the 68×21 mm envelope matches.
- The NN rib arrangement is not interchangeable with another prefix on the same 40 mm seat: double row, ribbed inner ring, separable outer. Swapping NU for NJ changes axial location behaviour even though the 68×21 mm envelope matches.
- The 48/55.5 kN ratings, 6.75 kN Pu and 312 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NN3008 (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 NN3008?
NN3008 is an NTN NN double-row precision cylindrical roller bearing to ISO 15: 40 mm bore, 68 mm OD and 21 mm width (1.575 × 2.677 × 0.827 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 48 kN, C0 55.5 kN, Pu 6.75 kN, grease limiting speed 9,700 r/min, oil 11,000 r/min, mass about 312 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. NN3008 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. NN3008 is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NN bearing like NN3008?
NN3008 has a cylindrical bore and mounts on a plain machined shaft seat; a K execution (1:12 taper) exists in the NN3000 series when preload must be set by drive-up on a tapered seat.
What speeds and lubrication apply to NN3008?
NTN rates NN3008 at 9,700 r/min with grease and 11,000 r/min with oil. The grease figure is the cage/film mechanical ceiling; the oil figure assumes circulating or carefully supplied oil that removes heat from the line-contact zone.
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.