344A-332 bearing: complete specifications & equivalents
The 344A-332 is a ISO 355 radial bearing sized 40 x 80 x 21 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 40 mm |
| Outer diameter D | 80 mm |
| Width B | 21 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 87.6 kN |
| Basic static load rating C0 | 80 kN |
| Fatigue load limit Pu | 9.15 kN |
| Reference speed (thermal) | 7000 rpm |
| Limiting speed (mechanical) | 8500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 480 g |
| Manufacturer designation | SKF 344 A/332 |
| Standard | ISO 355 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.2 inch single-row TRB |
| Last verified | 2026-09-28 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.2 inch single-row TRB) · extracted 2026-09-28
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.2 inch 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 & 335-series range
| Bore d | 1.575 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 0.827 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 20 mm |
| Smallest bore in 335-series | 40 mm |
| Largest outer diameter in 335-series | 80 mm |
| Width range across 335-series | 21–21 mm |
| Bore position in 335-series (smallest first) | 1 of 1 |
| Bore above smallest 335-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 344A-332 | Timken | full Dimensions and internal design equivalent — standard interchange. | Same inch-series cone/cup boundary envelope (d/D/T); load ratings and speed limits are brand-specific and may differ. |
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 344A-332 model number is decoded
The SKF catalogue adds the ISO 355 dimension-series code after the bare number (e.g. ); it is the dimensional series, not a separate part number. Catalogue mass 480 g for the 40×80×21 mm open execution covers the pressed-steel cage and standard roller complement; sealed or special-clearance variants differ slightly in mass and carry their own order numbers. Specify pairs rather than single units wherever thrust reverses: the tapered contact of 344A generates an induced axial load under radial force, and an unpaired bearing on a reversing shaft will run slack and fret its seat. Load system: the 87.6 kN basic dynamic rating C and 80 kN static rating C0 give a C0/C balance of 0.91, and dividing C by the 40 mm bore yields 2.19 kN per millimetre of journal — a density metric that compares across families; the 9.15 kN fatigue limit Pu is the floor beneath which the adjusted-life calculation drops below acceptable L10 hours for a 40 mm shaft carrying variable duty. Cup-side note for 332: the outer ring's rib profile and the 80 mm outside diameter are cup-specific within the 335-series tables, so substituting a different cup against the same 344 A cone changes both the assembled 21 mm width and the axial free-play setting of the mounted pair.SKF 344A (SKF 344 A/332) is the 335-series tapered roller choice for a 40 mm shaft — one row of tapered rollers on an asymmetric raceway inside the 80×21 mm envelope.On the SKF nameplate, 344A denotes a matched cone-and-cup pair: the designation is not a single number but a cone reference and cup reference joined by a slash, with the 335-series marking the dimensional series.
Typical equipment & failure modes
Common applications
- differential and pinion drives
- pump and compressor shafts
- machine-tool spindles
- axle-boxes in material-handling equipment
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
- uneven load sharing in a pair when spacer faces are not parallel to the bore
- preload loss as the mounted pair relaxes, letting rollers skid and smear the raceways
- pressed-steel cage wear or fracture after prolonged running above the limiting speed
- mounting score marks when the cone is cocked over the shaft keyway or a burr
Selection pitfalls — read before you substitute
- On this 40 mm bore, interference and temperature rise consume clearance inside a preloaded pair; calculate the residual clearance after mounting and at operating temperature — an over-tight 344A pair heats, loses setting control and smears the roller-rib contact.
- The 320 series at 40 mm bore (80×21 mm) is the low-friction, higher-speed section; it carries less thrust than a 302 of the same bore, so verify the axial load share before swapping.
- Do not mix brands or executions inside one 344A 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.
- Setting is a design value, not an assembly feel: excessive preload in the 344A pair raises operating temperature and can trigger thermal runaway, while too little lets the rollers skid and smear the raceway under light load.
- Shaft and housing fillets must clear the bearing chamfer so the 21 mm-wide cup seats square; use an undercut or withdrawal groove rather than an oversized radius that locks on the ring face.
- The 87.6/80 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 344A (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF 344 A/332 designation when purchasing and match the execution to the mounting arrangement.
Frequently asked questions
What do the cone and cup numbers in 344A mean?
The cone number (before the slash) identifies the inner ring, rollers and cage; the cup number (after the slash) identifies the outer ring. Both are quoted together because a single-row tapered roller bearing is a matched separable pair — the cone and cup are ground to work together and are not interchangeable with arbitrary other parts. The series prefix (335-series) groups sizes that share the same boundary-dimension plan.
Can a single 344A 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 344A 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 344A position and vice versa — verify load direction, Fa/Fr ratio and speed before substituting.
What shaft and housing fits suit 344A?
For a rotating shaft under normal load, seat the cone on a k5 shaft fit; the cup is usually a loose-to-transition fit in the housing so it can creep slightly and distribute wear. Chamfer and shoulder diameters must clear the bearing rings so the 21 mm-wide cup seats square; the mounting setting (end play or preload) is set by the axial position of the cup relative to the cone.
Is 344A interchangeable with other brands?
Inch-series tapered roller bearings follow a long-standing industry boundary plan, so cones and cups of the same basic number are generally dimensionally interchangeable across manufacturers. However, internal geometry, cage design and load ratings differ by brand, so for paired or precision applications keep both halves of the set from one manufacturer — or re-verify ratings and setting when mixing.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.2 inch single-row TRB on 2026-09-28. Read our editorial & correction policy.