71909 bearing: complete specifications & equivalents
The 71909 is a ISO 15 radial bearing sized 45 x 68 x 12 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 | 45 mm |
| Outer diameter D | 68 mm |
| Width B | 12 mm |
| Seal / shield | open |
| Internal clearance | CN / C3 available |
| Tolerance class | P0 |
| Cage | brass |
| Operating temperature | -40 to +150 °C |
| Mass (geometry estimate) | 125 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 71909 are being backfilled — use the inquiry form for certified values.
Dimensions in inches & 71900-series range
| Bore d | 1.772 in |
|---|---|
| Outer diameter D | 2.677 in |
| Width B | 0.472 in |
| ISO bore code | 09 |
| Radial section height (D−d)/2 | 11.5 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) | 6 of 17 |
| Bore above smallest 71900-series size | 25 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 71909 model number is decoded
In the 71900-series (ISO 15 diameter series 9) the last two digits encode the bore: 71909 carries bore code 09 = 45 mm. Outside diameter 68 mm and width 12 mm come from the ISO 15 boundary-dimensions general plan, shared with the 61909 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 45 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
- 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
- At a 45 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 719xx thin section (11.5 mm section height at 45 mm bore) trades capacity for compactness; stiff, accurately aligned seats are essential or edge loading will spall the raceway early.
- Draw-up on a thin-section 71909 is lighter than on a 72/73 bearing of the same bore: a 12 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.
- Shaft and housing fillets must clear the bearing chamfer so the 12 mm-wide ring seats square; provide an undercut or withdrawal groove instead of relying on an oversized radius.
- Assign fits by which ring rotates: an interference shaft fit for a rotating inner ring; if the outer ring rotates instead, reverse the logic — a loose rotating ring creeps and frets its seat.
Frequently asked questions
What are the dimensions of a 71909 angular-contact bearing?
A 71909 single-row angular-contact ball bearing has a 45 mm bore, 68 mm outer diameter and 12 mm width (1.772 × 2.677 × 0.472 in), per ISO 15 boundary dimensions. It is an open bearing with a nominal 40° contact angle. Geometry-based estimated mass is about 125 g for a brass-cage unit; catalogue masses vary with cage and ball complement.
How does the 71909 bore code work?
The last two digits of 71909 are bore code 09, giving 09 × 5 = 45 mm bore. The 68 mm outside diameter and 12 mm width follow the ISO 15 diameter series, shared with the 61909 deep-groove envelope.
What is the contact angle of 71909?
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 71909 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.
Why is the 71909 ring section so thin?
The 718/719 dimension series save radial space: at a 45 mm bore the 71909 envelope is 45×68×12 mm with a 11.5 mm radial section. That trades absolute load capacity for compactness and weight in robotics, medical and rotary-table axes — capacity per mm of section is high, but the ratings sit below a 72-series bearing of the same bore.
Reviewed & verified by the MPN Base engineering desk against source catalog iso15-ed4-geometry on 2026-09-24. Read our editorial & correction policy.