32321 bearing: complete specifications & equivalents
The 32321 is a ISO 355 radial bearing sized 105 x 225 x 81.5 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 105 mm |
| Outer diameter D | 225 mm |
| Width B | 81.5 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 645 kN |
| Basic static load rating C0 | 815 kN |
| Fatigue load limit Pu | 85 kN |
| Reference speed (thermal) | 2000 rpm |
| Limiting speed (mechanical) | 3000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 14000 g |
| Manufacturer designation | SKF 32321 |
| Standard | ISO 355 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.
Dimensions in inches & 32300-series range
| Bore d | 4.134 in |
|---|---|
| Outer diameter D | 8.858 in |
| Width B | 3.209 in |
| ISO bore code | 21 |
| Radial section height (D−d)/2 | 60 mm |
| Smallest bore in 32300-series | 20 mm |
| Largest outer diameter in 32300-series | 460 mm |
| Width range across 32300-series | 22.25–154 mm |
| Bore position in 32300-series (smallest first) | 19 of 30 |
| Bore above smallest 32300-series size | 85 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32321 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the supplier. |
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 32321 model number is decoded
SKF 32321 (SKF 32321) is the extra-heavy section tapered roller choice for a 105 mm shaft — one row of tapered rollers on an asymmetric raceway inside the 225×81.5 mm ISO 355 envelope.The code breaks down as type prefix 3 (tapered roller), series 2 (the extra-heavy section), and bore code 21 = 105 mm; dimensions 105×225×81.5 mm therefore match the ISO 355 envelope. SKF lists the plain number as the basic execution; letter suffixes such as B denote a steeper contact angle and are different order numbers. At 2,000 r/min reference speed the 60.0 mm-section 32321 is governed thermally by preload and lubricant flow; grease or oil selection should be made against that value, with 3,000 r/min as the mechanical ceiling. Note the minimum-axial-load requirement: at light radial load and high speed the rollers of 32321 must still be held into the rib contact, which is another reason the catalogue recommends paired mounting with controlled setting.
Typical equipment & failure modes
Common applications
- marine deck machinery shafts
- heavy industrial gearboxes and speed reducers
- large process pump and compressor shafts
- rolling-mill auxiliary drives
Known failure patterns
- cup or cone misalignment when the separable rings are not seated square during mounting
- loose cup rotation in the housing when the specified press fit is not achieved
- thermal preload runaway in an O-arrangement pair when inner-ring heat expands the setting
- uneven load sharing in a pair when spacer faces are not parallel to the bore
- cage pocket scoring when the bearing starts cold with grease of too-high base-oil viscosity
- grease degradation after long shelf storage without rotation or re-greasing
Selection pitfalls — read before you substitute
- Mount the 105 mm bore 32321 by induction heating of the cone (max 120 °C — the pressed-steel cage sets the ceiling, not the steel); driving it home through the cup or rollers brinells the tapered raceway.
- The 323 series at 105 mm bore (225×81.5 mm) is the heavy-duty section of the tapered family; it runs hotter at the same speed than a 30221, so recalculate dn and lubricant film before substitution.
- Do not mix brands or executions inside one 32321 pair — matched sets are ground for a specific setting, and pairing a SKF basic unit with a different suffix variant will not share the setting evenly.
- When the outer ring rotates, reverse the fit logic and provide cup location; the tapered contact of 32321 pushes the rings apart under load, so a non-located cup walks its seat even when the shaft is fixed.
- Shaft and housing fillets must clear the bearing chamfer so the 81.5 mm-wide cup seats square; use an undercut or withdrawal groove rather than an oversized radius that locks on the ring face.
- The 645/815 kN ratings are SKF catalogue 17000 values for the basic execution; SKF can revise internal geometry without changing the order number, so keep the catalogue version (PUB BU/P1 17000/1 EN, 2018) with the specification and re-verify for critical drives.
- SKF lists several executions of 32321 (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF 32321 designation when purchasing and match the execution to the mounting arrangement.
Frequently asked questions
What are the dimensions and catalogue data of 32321?
The SKF 32321 is a single-row tapered roller bearing with 105 mm bore, 225 mm outer diameter and 81.5 mm width (4.134 × 8.858 × 3.209 in) per ISO 355. From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 645 kN, C0 815 kN, fatigue load limit Pu 85 kN, reference speed 2,000 r/min, limiting speed 3,000 r/min, mass about 14000 g. It is an open, separable bearing with a pressed-steel cage.
How does the 32321 bore code work?
The last two digits of 32321 are bore code 21, so 21 × 5 = 105 mm bore. The 225 mm OD and 81.5 mm width come from the ISO 355 dimension-series plan, shared with other tapered bearings of the same code.
What do the 32321 series and basic execution designations mean?
The leading 3 marks a single-row tapered roller bearing; the second digit 2 is the ISO 355 series (extra-heavy section). The SKF catalogue lists the ISO 355 dimension-series code after the bare number. A steeper-contact-angle variant (B suffix) is a different order number and is not interchangeable with the basic execution.
Can a single 32321 take axial load in both directions?
No — one single-row tapered roller bearing reacts thrust in one direction only, and under radial load its contact angle induces an axial force. Use two bearings as a matched pair: O (back-to-back) for a rigid, moment-resisting arrangement, X (face-to-face) where thermal expansion must be tolerated, or tandem where one-direction thrust is shared.
How does 32321 compare with a ball bearing of the same bore?
A tapered roller bearing has line contact and a steep contact angle: much higher combined axial-plus-radial capacity and shock resistance than a ball bearing of the same bore, at the cost of speed, one-direction thrust, mandatory pairing for reversing loads and a minimum axial load requirement. A ball bearing cannot be dropped into a combined-load 32321 position and vice versa — verify load direction, Fa/Fr ratio and speed before substituting.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB on 2026-09-26. Read our editorial & correction policy.