71911 bearing: complete specifications & equivalents
The 71911 is a ISO 15 radial bearing sized 55 x 80 x 13 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 | 55 mm |
| Outer diameter D | 80 mm |
| Width B | 13 mm |
| Seal / shield | open |
| Internal clearance | CN / C3 available |
| Tolerance class | P0 |
| Cage | brass |
| Operating temperature | -40 to +150 °C |
| Mass (geometry estimate) | 176 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 71911 are being backfilled — use the inquiry form for certified values.
Dimensions in inches & 71900-series range
| Bore d | 2.165 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 0.512 in |
| ISO bore code | 11 |
| Radial section height (D−d)/2 | 12.5 mm |
| Smallest bore in 71900-series | 20 mm |
| Largest outer diameter in 71900-series | 140 mm |
| Width range across 71900-series | 9–20 mm |
| Bore position in 71900-series (smallest first) | 8 of 17 |
| Bore above smallest 71900-series size | 35 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 71911 model number is decoded
In the 71900-series (ISO 15 diameter series 9) the last two digits encode the bore: 71911 carries bore code 11 = 55 mm. Outside diameter 80 mm and width 13 mm come from the ISO 15 boundary-dimensions general plan, shared with the 61911 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 55 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
- clutch and idler shafts
- semiconductor handling axes
- packaging machinery
- robotics joint arms
Known failure patterns
- 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
- false brinelling from vibration while the shaft is stationary
Selection pitfalls — read before you substitute
- Thermal expansion on this 55 mm bore consumes preload in a DB pair; size the preload class and clearance for the operating temperature, not the cold state.
- The 719xx thin section (12.5 mm section height at 55 mm bore) trades capacity for compactness; stiff, accurately aligned seats are essential or edge loading will spall the raceway early.
- Pair thin-section 71911 units as a factory-matched set (universal SU/DU pairing): bench-pairing two singles with only 12.5 mm of section gives uncontrolled preload — order DB or DF pairs as one line item for the 55 mm spindle seat.
- A single 71911 angular-contact bearing takes axial load in ONE direction only — for bidirectional thrust, mount a matched pair (DB back-to-back or DF face-to-face), never rely on one row.
- 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°.
Frequently asked questions
What are the dimensions of a 71911 angular-contact bearing?
A 71911 single-row angular-contact ball bearing has a 55 mm bore, 80 mm outer diameter and 13 mm width (2.165 × 3.15 × 0.512 in), per ISO 15 boundary dimensions. It is an open bearing with a nominal 40° contact angle. Geometry-based estimated mass is about 176 g for a brass-cage unit; catalogue masses vary with cage and ball complement.
How does the 71911 bore code work?
The last two digits of 71911 are bore code 11, giving 11 × 5 = 55 mm bore. The 80 mm outside diameter and 13 mm width follow the ISO 15 diameter series, shared with the 61911 deep-groove envelope.
What is the contact angle of 71911?
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 71911 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 71911 run?
Thin-section angular-contact bearings reach high speeds because the 12.5 mm section keeps the ball set light, but the practical limit is set by the lubricant and the precision of the 55 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.