71805 bearing: complete specifications & equivalents
The 71805 is a ISO 15 radial bearing sized 25 x 37 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 | 25 mm |
| Outer diameter D | 37 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) | 21 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 71805 are being backfilled — use the inquiry form for certified values.
Dimensions in inches & 71800-series range
| Bore d | 0.984 in |
|---|---|
| Outer diameter D | 1.457 in |
| Width B | 0.276 in |
| ISO bore code | 05 |
| 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) | 2 of 17 |
| Bore above smallest 71800-series size | 5 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 71805 model number is decoded
In the 71800-series (ISO 15 diameter series 8) the last two digits encode the bore: 71805 carries bore code 05 = 25 mm. Outside diameter 37 mm and width 7 mm come from the ISO 15 boundary-dimensions general plan, shared with the 61805 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 25 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
- precision rotary tables
- medical and lab spindles
- clutch and idler shafts
- semiconductor handling axes
Known failure patterns
- preload loss after a paired set runs loose, letting the balls skid and smear the raceway
- raceway smearing under marginal lubrication at start-up before oil climb reaches the contact
- cage fracture from operation beyond the limiting speed with inadequate lubricant
- fretting corrosion on a loose shaft seat that lets the inner ring creep
Selection pitfalls — read before you substitute
- At a 25 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 25 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 7205.
- Draw-up on a thin-section 71805 is lighter than on a 72/73 bearing of the same bore: a 7 mm-wide ring clamps with a controlled light interference, and over-driving it bows the raceway — measure the mounted preload or runout rather than copying heavy-section fit tables.
- The 40° contact angle (suffix C) raises axial capacity but lowers speed versus a 25° (E / A5) variant; for high-speed spindles specify the 25° version, for heavy thrust specify 40°.
- Angular-contact 71805 tolerates only minutes of misalignment; a deflected shaft or a tilted housing face edge-loads the asymmetric raceway and spalls it early — align the seats to better than 0.001 radian.
Frequently asked questions
What are the dimensions of a 71805 angular-contact bearing?
A 71805 single-row angular-contact ball bearing has a 25 mm bore, 37 mm outer diameter and 7 mm width (0.984 × 1.457 × 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 21 g for a brass-cage unit; catalogue masses vary with cage and ball complement.
How does the 71805 bore code work?
The last two digits of 71805 are bore code 05, giving 05 × 5 = 25 mm bore. The 37 mm outside diameter and 7 mm width follow the ISO 15 diameter series, shared with the 61805 deep-groove envelope.
What is the contact angle of 71805?
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 71805 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 71805 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 25 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.