NJ408-M bearing: complete specifications & equivalents
The NJ408-M is a ISO 15 radial bearing sized 40 x 110 x 27 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 40 mm |
| Outer diameter D | 110 mm |
| Width B | 27 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 96.8 kN |
| Basic static load rating C0 | 90 kN |
| Fatigue load limit Pu | 11.6 kN |
| Reference speed (thermal) | 7000 rpm |
| Limiting speed (mechanical) | 8500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1300 g |
| Manufacturer designation | SKF NJ 408 M |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.1 single-row cylindrical roller bearings |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.1 single-row cylindrical roller bearings) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.1 single-row cylindrical roller bearings); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.
Dimensions in inches & NJ400-series range
| Bore d | 1.575 in |
|---|---|
| Outer diameter D | 4.331 in |
| Width B | 1.063 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 35 mm |
| Smallest bore in NJ400-series | 25 mm |
| Largest outer diameter in NJ400-series | 280 mm |
| Width range across NJ400-series | 21–65 mm |
| Bore position in NJ400-series (smallest first) | 4 of 13 |
| Bore above smallest NJ400-series size | 15 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NJ408 | NTN | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
| NU408-M | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 40×110×27 mm and equivalent catalogue ratings; the NU execution differs in flange/retaining-ring configuration — boundary-dimension interchangeable, but axial-locating behaviour is not identical. |
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 NJ408-M model number is decoded
NJ408-M is the 40 mm bore entry in the NJ400 range: a 40×110×27 mm single-row caged cylindrical roller bearing with a one-piece machined brass cage, rated C 96.8 kN / C0 90 kN. Structurally, the NJ design has two integral flanges on the inner ring and no flanges on the outer ring; the inner ring retains the roller set. In arrangement terms it is able to locate the shaft axially in one direction; an HJ angle ring on the opposite side converts it into two-direction location. Reading the order-string suffix M: the basic (non-E) M execution with a machined brass cage, standard for the larger and earlier-design sizes. Selection arithmetic: C0/C ≈ 0.93 (90 against 96.8 kN), and the Pu figure 11.6 kN is the fatigue load-limit floor for the SKF life equation; the catalogue lists 7,000 r/min thermal reference speed and 8,500 r/min mechanical limiting speed. Mounting: orient the inner-ring flange side toward the axial load direction; if an HJ angle ring is used, verify its fit and clearance before locking the arrangement. A 40 mm seat normally takes a k5 interference with an H7 housing bore when the inner ring rotates.
Typical equipment & failure modes
Common applications
- medium industrial gearbox shafts
- electric-motor shafts in pumps and fans
- compressor crank and rotor shafts
- machine-tool radial spindle supports
Known failure patterns
- inner-ring raceway spalling from overload or contamination in the line-contact hertz zone
- outer-ring raceway fatigue after extended service at loads above the catalogue L10 rating
- cage pocket wear from roller skew at light load
- cage pocket wear from roller skidding at insufficient radial load or during start-up before oil film build-up
- surface distress (micro-pitting) when the EHL film falls below the composite roughness at high specific load
- edge-loading fatigue after shaft deflection beyond the 3–4 minute alignment limit
- brinelling from static overload or impact during handling and mounting
Selection pitfalls — read before you substitute
- Do not use a NJ bearing where two-direction axial location is required without an HJ angle ring
- The dimension series 4 (heavy-section ISO 15 envelope) envelope is shared with the N/NU/NJ/NUP executions of 408, but flange configuration and axial-locating behaviour differ — quote the full SKF NJ 408 M and do not substitute rib styles without checking the shaft locating scheme.
- Catalogue reference and limiting speeds are different criteria: observe the mechanical ceiling even when thermal calculations allow more.
- Catalogue reference and limiting speeds are different criteria: observe the mechanical ceiling even when thermal calculations allow more.
- The 96.8/90 kN ratings are SKF catalogue 17000 (2018) values for the M execution; re-verify against the current catalogue for critical drives and keep the catalogue version with the specification.
Frequently asked questions
What are the dimensions and catalogue data of NJ408-M?
SKF NJ 408 M is a single-row caged cylindrical roller bearing with 40 mm bore, 110 mm OD and 27 mm width per ISO 15. SKF lists C 96.8 kN, C0 90 kN, Pu 11.6 kN, reference speed 7,000 r/min and limiting speed 8,500 r/min, mass about 1300 g.
What does the NJ designation and M suffix mean?
The M suffix marks the basic (non-E) execution with a machined brass cage, the standard choice for the larger and earlier-design sizes. Structurally this execution has two integral flanges on the inner ring and no flanges on the outer ring; the inner ring retains the roller set.
Can NJ408-M take axial load and locate the shaft?
In one direction only, via the two inner-ring flanges. Add an HJ angle ring on the opposite side for two-direction location.
How does NJ408-M compare with the other executions in the same envelope?
The N/NU/NJ/NUP executions share the ISO 15 envelope and load ratings but differ in flange arrangement and axial-locating behaviour; quote the exact order number.
What limits the service life of this bearing most often?
Line-contact fatigue above the L10 rating, cage wear at light loads and high temperatures, and edge loading from misalignment beyond about 3–4 minutes of arc are the typical failure drivers.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.1 single-row cylindrical roller bearings on 2026-09-26. Read our editorial & correction policy.