71820 bearing: complete specifications & equivalents
The 71820 is a ISO 15 radial bearing sized 100 x 125 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 | 100 mm |
| Outer diameter D | 125 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) | 293 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 71820 are being backfilled — use the inquiry form for certified values.
Dimensions in inches & 71800-series range
| Bore d | 3.937 in |
|---|---|
| Outer diameter D | 4.921 in |
| Width B | 0.512 in |
| ISO bore code | 20 |
| Radial section height (D−d)/2 | 12.5 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) | 17 of 17 |
| Bore above smallest 71800-series size | 80 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 71820 model number is decoded
In the 71800-series (ISO 15 diameter series 8) the last two digits encode the bore: 71820 carries bore code 20 = 100 mm. Outside diameter 125 mm and width 13 mm come from the ISO 15 boundary-dimensions general plan, shared with the 61820 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 100 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
- raceway spalling from axial overload exceeding the single-direction thrust rating
- 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
Selection pitfalls — read before you substitute
- Mount this 100 mm bore angular-contact pair by heating the inner rings (induction heater, max 120 °C) and clocking both faces; never drive a pair home through the outer rings.
- The 718xx thin section at 100 mm bore has only a 12.5 mm radial section height: it saves space but is highly sensitive to misalignment and deflection — verify spindle stiffness before choosing it over a 7220.
- With a 12.5 mm radial section on a 100 mm bore, the 71820 ring has little stiffness of its own: it copies the seat geometry, so grind the 100 mm shaft in one setup and check roundness — an out-of-round journal distorts the thin inner ring and reappears as vibration at the 125 mm housing.
- A single 71820 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 71820 angular-contact bearing?
A 71820 single-row angular-contact ball bearing has a 100 mm bore, 125 mm outer diameter and 13 mm width (3.937 × 4.921 × 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 293 g for a brass-cage unit; catalogue masses vary with cage and ball complement.
How does the 71820 bore code work?
The last two digits of 71820 are bore code 20, giving 20 × 5 = 100 mm bore. The 125 mm outside diameter and 13 mm width follow the ISO 15 diameter series, shared with the 61820 deep-groove envelope.
What is the contact angle of 71820?
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 71820 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 71820 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 100 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.