71808 bearing: complete specifications & equivalents
The 71808 is a ISO 15 radial bearing sized 40 x 52 x 7 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | Generic ISO interchange (unbranded) |
| Bore diameter d | 40 mm |
| Outer diameter D | 52 mm |
| Width B | 7 mm |
| Seal / shield | open |
| Internal clearance | CN / C3 available |
| Tolerance class | P0 |
| Cage | brass |
| Operating temperature | -40 to +150 °C |
| Mass (geometry estimate) | 31 g |
| Standard | ISO 15 |
| Catalog version | iso15-ed4-geometry |
| Last verified | 2026-09-24 |
Source: ISO 15 boundary-dimensions standard · extracted 2026-09-24
Standard-interchange bearing: dimensions per ISO 15; CN clearance, P0 tolerance and a stamped-steel cage are catalogue defaults unless the supplier states otherwise, and mass is a geometry-derived estimate. Brand catalogue load ratings and limiting speeds for 71808 are being backfilled — use the inquiry form for certified values.
Dimensions in inches & 71800-series range
| Bore d | 1.575 in |
|---|---|
| Outer diameter D | 2.047 in |
| Width B | 0.276 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 6 mm |
| Smallest bore in 71800-series | 20 mm |
| Largest outer diameter in 71800-series | 125 mm |
| Width range across 71800-series | 7–13 mm |
| Bore position in 71800-series (smallest first) | 5 of 17 |
| Bore above smallest 71800-series size | 20 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 71808 model number is decoded
In the 71800-series (ISO 15 diameter series 8) the last two digits encode the bore: 71808 carries bore code 08 = 40 mm. Outside diameter 52 mm and width 7 mm come from the ISO 15 boundary-dimensions general plan, shared with the 61808 deep-groove envelope. The '7' prefix marks a single-row angular-contact design with an asymmetric raceway and a nominal 40° contact angle (suffix C); a higher-angle variant carries more axial load, a 25° (E / A5) variant runs faster. For combined radial and axial load with a rotating inner ring on a 40 mm shaft, specify a k5 shaft seat with an H7 housing bore — verify against the load direction and magnitude, and pair two units (DB or DF) for bidirectional thrust.
Typical equipment & failure modes
Common applications
- semiconductor handling axes
- packaging machinery
- robotics joint arms
- precision rotary tables
Known failure patterns
- fretting corrosion on a loose shaft seat that lets the inner ring creep
- false brinelling from vibration while the shaft is stationary
- edge loading and early spalling from shaft deflection or housing misalignment
- electric pitting in VFD-driven spindles without shaft grounding protection
Selection pitfalls — read before you substitute
- At a 40 mm bore, shaft-seat finish and runout (target Ra ≤ 0.8 µm) govern angular-contact noise; a rough or out-of-round seat shows up as spindle runout before it shows as failure.
- The 718xx thin section at 40 mm bore has only a 6.0 mm radial section height: it saves space but is highly sensitive to misalignment and deflection — verify spindle stiffness before choosing it over a 7208.
- With a 6.0 mm radial section on a 40 mm bore, the 71808 ring has little stiffness of its own: it copies the seat geometry, so grind the 40 mm shaft in one setup and check roundness — an out-of-round journal distorts the thin inner ring and reappears as vibration at the 52 mm housing.
- Mounting direction is fixed by the asymmetric raceway — the marked side faces the axial load; installing 71808 backwards loads the low shoulder and displaces the balls out of the raceway.
- Do not run a single 71808 where a deep-groove 61808 would do: same 40×52×7 mm envelope, but the angular contact trades speed and noise for axial capacity and needs pairing.
Frequently asked questions
What are the dimensions of a 71808 angular-contact bearing?
A 71808 single-row angular-contact ball bearing has a 40 mm bore, 52 mm outer diameter and 7 mm width (1.575 × 2.047 × 0.276 in), per ISO 15 boundary dimensions. It is an open bearing with a nominal 40° contact angle. Geometry-based estimated mass is about 31 g for a brass-cage unit; catalogue masses vary with cage and ball complement.
How does the 71808 bore code work?
The last two digits of 71808 are bore code 08, giving 08 × 5 = 40 mm bore. The 52 mm outside diameter and 7 mm width follow the ISO 15 diameter series, shared with the 61808 deep-groove envelope.
What is the contact angle of 71808?
The nominal contact angle is 40° (suffix C): a higher angle carries more axial load but limits speed. A 25° (suffix E or A5) variant runs faster and is preferred for high-speed spindles; a 15° (suffix C7) version exists for very-high-speed duty. Confirm the angle and ball complement in the supplier catalogue.
Can a single 71808 take axial load in both directions?
No. A single-row angular-contact bearing carries axial load in one direction only. For bidirectional thrust, mount a matched pair — DB (back-to-back) for a rigid, moment-resisting arrangement with preload class light (L) for speed or heavy (H) for stiffness, DF (face-to-face) for thermal expansion tolerance, or DT (tandem) to share one-direction load.
How fast can a 71808 run?
Thin-section angular-contact bearings reach high speeds because the 6.0 mm section keeps the ball set light, but the practical limit is set by the lubricant and the precision of the 40 mm seat rather than the geometry alone; a 25° (E/A5) contact-angle variant and a light (L) preload class run faster than a 40° heavy-preloaded pair. Confirm the limiting speed in the supplier catalogue.
Reviewed & verified by the MPN Base engineering desk against source catalog iso15-ed4-geometry on 2026-09-24. Read our editorial & correction policy.