32021 bearing: complete specifications & equivalents
The 32021 is a ISO 355 radial bearing sized 105 x 160 x 35 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Bore diameter d | 105 mm |
| Outer diameter D | 160 mm |
| Width B | 35 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) | 2044 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 32021 are being backfilled — use the inquiry form for certified values.
Dimensions in inches & 32000-series range
| Bore d | 4.134 in |
|---|---|
| Outer diameter D | 6.299 in |
| Width B | 1.378 in |
| ISO bore code | 21 |
| Radial section height (D−d)/2 | 27.5 mm |
| Smallest bore in 32000-series | 20 mm |
| Largest outer diameter in 32000-series | 225 mm |
| Width range across 32000-series | 15–48 mm |
| Bore position in 32000-series (smallest first) | 18 of 23 |
| Bore above smallest 32000-series size | 85 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32021 | 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 32021 model number is decoded
In the 32000-series the last two digits of 32021 encode the bore: code 21 = 105 mm (code × 5 from 04 upward). The ISO 355 envelope is 160 mm outside diameter and 35 mm total assembly width T over the separable cone and cup — 4.134 × 6.299 × 1.378 in, with a 27.5 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 105 mm shaft, typical catalogue practice is a m6 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
- agricultural tractor axles
- truck and trailer wheel hubs
- heavy final drives and differentials
- large conveyor drum pulleys
- crane travel wheels and winch drums
Known failure patterns
- 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
- water and grit pitting in unsealed hubs where the cup-cone joint acts as a debris entry path
Selection pitfalls — read before you substitute
- The large 105 mm-bore 32021 develops substantial mounting forces; heat the cone (induction heater, max 120 °C) and never tighten the adjusting nut to seat it — draw it up by torque, then back off to the mark, leaving roughly 0.05–0.20 mm end play on the 105 mm shaft.
- The 320 narrow series at 105 mm bore keeps the OD down to 160 mm for space-limited hubs; its 35 mm width carries less load than a 30221, so do not substitute it into a 302 application without re-rating.
- The 35 mm-wide 32021 ring seats against a shaft and housing shoulder whose fillet must clear the bearing chamfer: keep the corner radius small enough that the 105 mm bore and 160 mm cup seat square — an undercut beats an oversized radius, which lifts the ring and edge-loads the 27.5 mm section.
- When mounting 32021 to a 105 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 160 mm assembly dents the tapered raceway before first run.
- Inspect the removed 32021 cone and cup as a pair: pitting on the 160 mm cup with a clean cone usually means seal failure and water ingress, while rib scoring on the 105 mm cone points to wrong preload or lost EP film — the two faults need different corrections.
- Do not swap a 32000 row for a ball bearing of the same bore: tapered rollers are heavier, slower (sliding rib contact caps the speed) and must be adjusted, but they outperform ball bearings on combined load and shock in gear and hub duty.
- Assign fits by which ring rotates: an interference shaft fit for a rotating cone; if the cup rotates instead, reverse the logic — a loose rotating ring creeps and frets its seat.
Frequently asked questions
What are the dimensions of a 32021 tapered roller bearing?
A 32021 single-row metric tapered roller bearing per ISO 355 has a 105 mm bore, 160 mm outer diameter and 35 mm total assembly width (4.134 × 6.299 × 1.378 in), a 27.5 mm radial section and roughly 2044 g geometry-based estimated mass; catalogue masses vary with roller and cage design.
How does the 32021 bore code work?
The last two digits of 32021 are bore code 21, giving 21 × 5 = 105 mm bore — the same convention as 6xx ball bearings, starting at code 04 (20 mm). The 160 mm OD and 35 mm width come from the ISO 355 diameter and width series, not the bore code alone.
What is the cone and cup of 32021?
Tapered roller bearings are separable: the cone is the inner ring with the tapered rollers and cage, the cup is the outer ring. 32021 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 32021 set?
At fit-up the 105 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 0.05–0.20 mm for a 105 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 32021 take axial load in both directions?
A single 32021 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.