32306 bearing: complete specifications & equivalents
The 32306 is a ISO 355 radial bearing sized 30 x 72 x 28.75 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Bore diameter d | 30 mm |
| Outer diameter D | 72 mm |
| Width B | 28.75 mm |
| Seal / shield | open |
| Internal clearance | CN available |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Operating temperature | -30 to +120 °C |
| Mass (geometry estimate) | 494 g |
| Standard | ISO 355 |
| Catalog version | iso355-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 32306 are being backfilled — use the inquiry form for certified values.
Dimensions in inches & 32300-series range
| Bore d | 1.181 in |
|---|---|
| Outer diameter D | 2.835 in |
| Width B | 1.132 in |
| ISO bore code | 06 |
| Radial section height (D−d)/2 | 21 mm |
| Smallest bore in 32300-series | 20 mm |
| Largest outer diameter in 32300-series | 240 mm |
| Width range across 32300-series | 22.25–84.5 mm |
| Bore position in 32300-series (smallest first) | 3 of 19 |
| Bore above smallest 32300-series size | 10 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32306 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the 32306 model number is decoded
In the 32300-series the last two digits of 32306 encode the bore: code 06 = 30 mm (code × 5 from 04 upward). The ISO 355 envelope is 72 mm outside diameter and 28.75 mm total assembly width T over the separable cone and cup — 1.181 × 2.835 × 1.132 in, with a 21.0 mm radial section height. Tapered rollers carry combined radial and single-direction axial load; bidirectional thrust needs an opposed pair (X face-to-face or O back-to-back) adjusted at fit-up. With a rotating cone on a 30 mm shaft, typical catalogue practice is a k5 shaft seat with an H7 housing bore, EP lubrication and a defined end-play setting — verify against the load direction and magnitude.
Typical equipment & failure modes
Common applications
- passenger-car wheel hubs
- small trailer axles
- light differential pinions
- steering knuckles
- small gearbox shafts
Known failure patterns
- cup creep and housing bore fretting when the outer ring is left without its specified press fit
- roller large-end smearing and scoring against the inner-ring guide rib from loss of the EP lubricant film
- raceway spalling at the roller-rib junction after the L10 life or sustained axial overload
- over-preload heat: a shim stack cut too thin drives contact stress up and seizes the cone on the seat
- under-preload end play that lets the rollers skid, producing noise and false brinelling
Selection pitfalls — read before you substitute
- At 30 mm bore the small 32306 is commonly factory-adjusted in a hub unit; an after-market fit-up must reproduce the specified end play (a typical starting range of 0.02–0.10 mm at the 30 mm shaft) or the wheel runs hot within the first hundred kilometres.
- The 323 heavy wide series at 30 mm bore (72×28.75 mm) is a steep-angle, high-thrust row for heavy final drives; its 21.0 mm section and 28.75 mm width dwarf the 30206, and its speed ceiling is the lowest of the four series.
- The 28.75 mm-wide 32306 ring seats against a shaft and housing shoulder whose fillet must clear the bearing chamfer: keep the corner radius small enough that the 30 mm bore and 72 mm cup seat square — an undercut beats an oversized radius, which lifts the ring and edge-loads the 21.0 mm section.
- When mounting 32306 to a 30 mm shaft, warm the cone to 80–100 °C and slide it dry to the shoulder; cooling shrinks it into its interference, whereas hammering a cold cone through a 72 mm assembly dents the tapered raceway before first run.
- Relubrication for 32306 must reach the rib-roller end contact, not just the 30 mm bore; in a hub repack, work EP grease through the roller set until it exudes at both faces of the 28.75 mm-wide assembly or the sliding rib contact starves first.
- The cone and the cup of 32306 are separable: order and fit them as a matched set; never mix a cone from one manufacturer with another brand's cup — roller geometry and contact angle are not identical across brands.
- Set running clearance (or preload) with the shim pack or adjusting nut at fit-up; a 30 mm-bore 32306 that is too tight overheats and scores the rib, one too loose develops end play and noise — follow the torque-and-untighten procedure.
Frequently asked questions
What are the dimensions of a 32306 tapered roller bearing?
A 32306 single-row metric tapered roller bearing per ISO 355 has a 30 mm bore, 72 mm outer diameter and 28.75 mm total assembly width (1.181 × 2.835 × 1.132 in), a 21.0 mm radial section and roughly 494 g geometry-based estimated mass; catalogue masses vary with roller and cage design.
How does the 32306 bore code work?
The last two digits of 32306 are bore code 06, giving 06 × 5 = 30 mm bore — the same convention as 6xx ball bearings, starting at code 04 (20 mm). The 72 mm OD and 28.75 mm width come from the ISO 355 diameter and width series, not the bore code alone.
What is the cone and cup of 32306?
Tapered roller bearings are separable: the cone is the inner ring with the tapered rollers and cage, the cup is the outer ring. 32306 denotes a matched cone-and-cup set. They are fitted separately — cone pressed on the shaft, cup in the housing — and adjusted against each other.
How is the preload or clearance of 32306 set?
At fit-up the 30 mm-bore cone is tightened against the cup while the hub is rotated, seated, then backed off to the specified end play — a typical starting range of 0.02–0.10 mm for a 30 mm bore — and locked with shims, a locknut or a spacer. Too tight overheats and seizes the rib; too loose causes skid, noise and early wear. Confirm the exact figure in the hub or axle-maker procedure.
Can 32306 take axial load in both directions?
A single 32306 takes thrust in one direction only — the roller large ends bear against the inner-ring rib under load. Bidirectional axial load requires an opposed pair: X (face-to-face) tolerates misalignment slightly better, O (back-to-back) gives a wider load centre and more moment stiffness.
Reviewed & verified by the MPN Base engineering desk against source catalog iso355-geometry on 2026-09-24. Read our editorial & correction policy.